Budget DSLR Astrophotography - Equipment First Steps

[Jethro777]

After playing with the idea of telescopes, the reality dawned that the budget simply didn't allow it.
Instead, I decided to stop admiring images taken with others equipment and find joy with what I do have, and getting the best out of that.
I do have some nice equipment thus far:

- Sony Alpha A77

Some nice Lenses:

- Samyang 35mm f/1.4
- Minolta AF 24mm 2.8
- Minolta AF 100 Macro 2.8
- Sony DT 35mm 1.8 (In poor condition)

I suspect I could do a but with that.

I just have a terrestrial tripod, nothing too fancy, I have no star tracker, and so am limited to that equipment.

I can learn how to stack images, and take some photos.

What do you guys think? If you were to invest in something (why not, I'll save for something!) what should it be? A star tracker like the iOptron or Vixen Polarie? A proper mount?

Love to hear your thoughts!

[bojan]

How about DIY barn-door mount?

It would be quite adequate for 100mm lens.

[Jethro777]

That sounds like a great project!
I like it.

I found this : https://barn-door-tracker.co.uk/
This looks pretty good.
I should add I'm not much of a machinist or engineer, but I'm always up to learning or trying something new. :)

I'm in Brisbane, if someone here has built one, and knows where to get the bits and pieces, that would help me a lot later.

[bojan]

Bunnings rules ;) ....

[Jasp05]

I started in exactly your position. Minimal funds to get into the hobby. I owned a DSLR and a few lenses. Started taking long exposure from a static tripod. (up to 20sec exposures).

I built a Barn door tracker and powered it with an arduino and stepper motor.
This produced some half decent results although my polar alignment was never great. (Pics of my first images with the barn door tracker attached.) I posted these pics on the forums and here is the link for details.

http://www.iceinspace.com.au/forum/showthread.php?t=157418


I've since upgraded to an HEQ5Pro mount and not looked back.

The hardest thing is to know how far you want to go with this hobby. If your only interested in widefield imaging then something like a Star adventurer mount for $400-$500 would be the way to go. (I'm still considering getting one for portability over the heq5).

If you are going to get more serious in the future then a HEQ5pro or better mount will probably be needed.


But I'd definately start at the barn door tracker. It's simple and costs about 20 bucks and a few hours to make.

This is a calculator to help you work out rotations per minute etc depending on threads per inch. https://blarg.co.uk/astronomy/barn-door-tracker-calculator.

[Hoges]

I can't remember if this worked - I don't think it was very good. But it was a lot of fun to build. Sorry I don't have any shots of the drive mechanism but it was a little 12v motor. Barn Doors are suppose to be agricultural aren't they?

[RyanJones]

Hi Jethro,

Yeah, you're right, there's no such thing in this game as budget. Having said that, your first paragraph made me smile, making the best of what you've got. I started in humble beginnings and quite honestly, I'm still there. I just purchased a faster scope and, in a couple of hours in a dark site, took photos that would take me 3 or 4 sessions to produce at home. Call me a masacistic but I actually felt a little disappointed that it was so easy. If you like a challenge and genuinely want to the make the best of what you've got then a cheap mount ( alt-az with a wedge ) and a cheap scope. If you want to do it like the other guys on here then save your pennies. Fair go which ever way you go but be prepared for a very expensive addiction. ( relatively speaking )

[ripsnorter63]

I've just built a barn door tracker and I used ebay to get the extra tripod head and remote shutter release. I found some old floor board and various nuts in my extensive collection of nuts and bolts that will come in useful one day. M6 threaded rod and hinge came from my local hardware shop. Mine is wound by hand at the moment and I really just threw it together to see if it would work. It seems to work so I'm going to start work on the next version with a better handle and some marking lines so I can more accurately turn the handle, right now I'm using the beeps from my remote shutter release and counting to 15 and moving the handle what I think is 90 degrees in that time.

[ChrisV]

Yes be careful what you wish for. Expanding the Definition of Addiction: DSM-5 vs. ICD-11
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5328289/

[Saturnine]

Barn Door trackers are a relatively cheap , simple solution to being able to do longer exposure images, 30 to 60 sec is enough when also stacking several ( or many ) together. Made myself one last year , though it is a bit more high tech, as it is powered by an 12VDC Geared Motor.
Guess I'm a bit fortunate in that I was a Fitter & Machinist by trade, now retired and still have access to a lathe and milling machine. Did some basic math for the curvature of the 6mm x 1mm pitch, threaded rod, motor speed and gear ratio vs the distance from the hinge to the threaded rod ( radius of curvature ) to achieve the desired tracking rate.
Speed is not perfect, is out by about 1 deg. an hour which equates to 1 arc/ min for an 60 sec exposure. for wide angle lens is hardly noticeable.
Intend to add an PWM unit to fine tune the speed for greater tracking accuracy soon but I'm happy with the results so far.
All up the bits and pieces cost about $30, motor , ball head , hinge, paint etc. and machined the pulleys to suit with an "o" ring as the drive belt. Had some aluminium plate already but wood can be used quite successfully .
Polar alignment is achieved by mounting an old finder scope butted against the hinge, held by an elastic band and pointing at Sigma Octans and offsetting the required distance to the SCP.

[Jethro777]

Really enjoying your thoughts and pics of your home projects. Nice!

So - this one looks pretty good, https://barn-door-tracker.co.uk/

(Reason I like this one, is because for a non-technical guy, I like fixed measurements and instructions. :D)

If I wanted to make an Aussie version, would that hinge be the right way? (No Polaris, Southern Hemisphere).

Might go to some fleamarkets and see what bits I can get. :D

[Merlin66]

I made a double arm Trott barn door tracker a few (?!) years ago....
standard aluminium sections and a quick release nut.

[silv]

I remember I spent NZD 200 on all new materials including all new tools (didn't have any, not even a screwdriver) I needed for a wooden BDT almost like your favorite in your link there. It worked, sort of. Wasn't precise enough to give me more than 12 secs with a 200mm lens. Was my first ever DIY product. So I was proud nevertheless.
Not being gifted with imagination in mechanics, I then proceeded to build another out of colourful ~8mm plastic cutting boards, thinking it'd be more lightweight than the rather heavy wooden version and fit better on my plastic $50 tripod. It did look real cool. But it was too floppy for the heavy camera :D

[Jethro777]

Awesome story.

Thanks for sharing your experience!

[silv]

:D
Story continues.
Not having succeeded (enough) with my BDT, I then went over to the dark side and spent $$$ on 2nd hand gear. I really really really wanted my backyard Hubble telescope photos. And I wanted them NOW.

The only affordable set on Trademe then was an EQ5 Goto with retrofitted GotoNova handcontroller (now iOptron) and an 8" newton. NZD 1000. The owner had used it for visual and that had worked for him. I took it home, got familiar with the scope tech and the weight... 8kg was the scope, I remember, all included (tube rings, finder, focuser).
On an EQ5... 'nough said.

Or not?

Well. My camera, mounted piggy back onto the scope, certainly gained exposure time before star trailing. 2 minutes at ~18-55mm was no problem. But the motor and the stability of the EQ5 didn't appreciate being ridden by an 8kg ~1m long tube with the majority of the weight being far away from the tripod, and reasonably heavier at the very top end of the tube.
So the 20 secs exposures I took in prime focus = camera mounted onto the focuser, all showed dips in very regular intervals. As if jumping from one little tooth to the next was heavy duty for the little wheels inside. Broke my heart.

The mount's load capacity for visual must have been something between 9 and maybe 12kg. Half that weight in a scope would have been proper astrophotography standards. I did know that from reading threads on iceinspace. But I felt that wouldn't apply to me. Like with cancer from smoking. It only ever happens to others. :D

[silv]

That was all in 2012. Sold on the mount and scope the same year. Stopped taking photos of the night sky, except some [beautiful] aurora photos when I lived on the S.I.

Yesterday, a new iOptron CubePro II magically arrived at my doorstep. :D Not intended for astrophotography, only for visual to carry a 2nd hand "fast" refractor 102/500mm, f/4.9 It's a good thing that I now live in a Bortle (http://www.bigskyastroclub.org/lp_bortle.html) 6-7 area and I know I can't and I won't afford gear capable of gathering meaningful photons from here. But I conjured up a cheap binoviewer as well. So am very much looking forward to "grazing" up and down the milky way here in my western sky . 'Cause that's what I enjoyed the most, really, back in 2012: spending time with my eyes and mind in the ocean of stars.

[Jethro777]

Well,

I took the camera for a spin to see what it could do to start with.

I shot Mars and surrounding stars

Tripod Only - No Tracker of any sort
2 second delay, remote shutter on concrete

First Set
High ISO Adjust
1600 ISO
15 second exposure
F/8

Second Set
Low ISO Adjust
1600 ISO
13 Second Exposure
F/8


Third Set
1000 ISO
10 Second Exposure
F/1.4

Camera is a Sony SLT-A77 with a Samyang 35mm f/1.4 lens.
I live in a fairly light polluted area, shooting from the backyard.
I used Long Exposure NR Reduction on the camera.
ISO adjustment LOW. (only has low, medium, high).

I took from between 6-9 images, and used DSS to stack them using just the default settings. No use of dark files, flat files, dark flat files or offset/bias files (no idea what they mean yet).

I have attached a small 100% size cut of the imaging.

Some questions:

When I used the RAW pictures I took, DSS barely recognised many stars. When I used the camera processed JPEGS, it recognised hundreds.
DSS Scored my final pic 4326.51, then threw it down to 827 when I changed the aperture to 1.4 lol.

What can help me improve?
How many pictures might it be good to have in a stack, realistically?

[bojan]

Do not use long exposure compensation - separate master dark is better from SNR point of view.
And do not use jpg for stacking - lot of information is lost with conversion, especially where you do not want - at the low intensity level..
The difference in number of stars comes from the fact RAW is 16-bit, and jpg is-8-bit deep.



I am usually taking 16 or 32 frames for stacking.

[JA]

Hi J,
That lens is best used around f/4- f/5.6, but probably OK down to f/2 to f/2.8. An aperture of f/1.4 is too wide open for that lens (and most others) without significant image penalties. If you have the non-autofocus version then look to these data as the justification for this:
https://www.lenstip.com/297.4-Lens_review-Samyang_35_mm_f_1.4_AS_UMC__Image_r esolution.html

Bear in mind however; the Samyang 35mm f/1.4 is a full-Frame lens and you are using it on the APS-c sensor of the Sony A77. It behaves like a 50mm f/2 in that respect. The APS-c sensor doesn't see all of the full frame image circle and as a result the image quality may not be as degraded at f/1.4 as it would be on a full frame camera. Of course the light collection would be doubled on fullframe and hence the noise less but, you're not concerned of that here.



Best
JA

[bojan]

Hmm.. not quite like that.
Full frame lens used with APS sensor will collect exactly the same amout of light, and it will still be 35mm FL..

Difference will be in FOV - with APS sensor, fileld will be smaller, but this will not be an issue because image quality in FF corners is probably not great, so you woul want to crop it anuway (and APS sensor does it for you :-) )

[Jethro777]

Right.

So, here's some adjustments I'll try. Let me know if there are more, if I have them right or if I have missed something else.

Forum suggested

- Switch off noise reduction. Since I am shooting in raw, it's pointless anyway.
- Aperture should be 2-2.8 from what that lens date looks like - not 1.4 or 8, lol.
- Increase number of frames taken from 9 to 16 or 32 for stacking.
- Make a 'dark' shot (I guess same length as the normal frames I am taking but with the lens on? Is that how I make one?)

My ideas

- Start building a barn door tracker, lol.
- Maybe drop down from 10 seconds to 8, as I can still see star trailing.
- Mozzie repellant. I paid for each final frame with three bites last night.

Questions

1. If the pictures I take look quite 'bright' (light), will DSS 'darken' them so I get a black sky? - Sorry for the stupid question.) If it is quite 'bright' - what should I be adjusting then? For example, I am going to do f/2.0 on a f/1.4 lens at 1600 ISO at 10 seconds. That's going to result in a bright image - right? In my head, I'm thinking "That isn't right!" - but it is, as DSS adjusts it?
2. Also, does the fact that I have a 'bright' object, like Mars mean that the camera is less able to pick up the stars around it? Would I have gotten better results if I hadn't chosen mars? :)
3. What ISO is best for my particular situation? From what I was reading, some are doing anything up to 12,000+ and claiming it doesn't matter, while others go for 400-800, or 1200. I'm thinking I should go 1600.
4. Is the best focus actually just short of infinity, or infinity?

Next up will be the Southern Cross with modifications applied.

Edit

Ok, several (e.g.16/32) 'dark shots'. Good for one night. :)

[bojan]

You should take the same number of darks and lights...
DSS will create "master dark", you can use that one for more photos on the same night.



"Black sky" is obtained by post processing of resulting tiff file, I am using DPP (Canon software) for that.

[sil]

I do most of my AP with DSLR from regular tripod, no trackers, no barndoor mounts etc. Its definitely doable and can take a bit of fiddling to fine tune. First I suggest ignoring your lenses unless you want to use for wide angle shots, instead find a good quality fast (f2.8) lens around 150-200mm. Prime not zoom. And work around this being your astro setup.

First do tests with manual settings (its all manual setting really) adjusting just f-stop to find your combos optimimal sharp sweet spot with stars (with a f2.8 lens f4 tends to be much sharper, but an f4 lens it'll be more f5.6/6.3. Once you find that you have one manual setting to stay put on. Next use the "500 rule" as a guidline. divide 500 by the focal length of the lens to get your starting test exposure time. eg 150mm lens is 500/150 = 3.333s call it 3 sec. now set exposure time to 3sec and point at night sky (pick random direction each time as linear rates change and take a test shot each time and zoom in on the pics to see the stars should be more round than little streaks, adjust shutter speed one increment on your camera and repeat until the stars are a good roundness and not streaking . It'll be close to the initial 500 rule value. Note the stars will distort anyway in a camera lens but the more they start to streak the harder it becomes to align and stack images. So you've now got the second manual setting value you need, th third and final is ISO, set your camera with the first two values and take shots at each iso setting until the images are obviously too noisy on the lcd. decide which are starting to get too noisy to work with. Too much noise and again aligning is problematic. as you work you improve your workflow in time so can revise iso to try to capture fainter nebulosity by capturing a lot more shots. but basically those three settings you can lock off on the camera and are about the limit of the gear combo for capture.

use a remote trigger or intervalometer to take say batches of 100 shots, after that you'll need to reframe your camera as the stars will have moved. I take about 500 shots in batches of 100 which pretty much fills one memory card and drains one battery. when you register/align the images the movement and rotation is taken care of and stacking a lot of shots takes care of the iso noise giving you a good snr integrated image to start stretching etc.

next purchase should be a tracking mount, like an EQ6. something good that will last and can take a scope when budget allows. you will need to find a suitable dovetail plate for the mount that lets you attach a camera to it. You then use live view etc to do star alignment of the mount so it can track and slew to nonvisible targets. This means you can retest your maximum shutter speed to maintain round stars and iso too for cleaner subs. this will open up a whole lot more shooting opportunities for you. every mount has limitations and if you aren't precise with alignment, especially cheap travel options like polarie you are often limitied to little better than a static tripod anyway. A quality mount will give you the chance to go for longer telephoto lenses as well as scope OTA and imaging cam options. If you skimp on the mount it will be less stable and less flexible for options in the long run, best to save and wait until you can get the right long term mount rather than a quick disappointing stopgap.

[Jasp05]

Hi Jethro,

As I was in your spot not long ago and from the responses here, I'm not sure if it was clear why you would want to do some of the things noted above and the trade offs etc.

Focus to Infinity. Use your camera's live view on a bright star and zoom in as far as possible to focus. This should result in the best focus. If the moon is up or a street light is visible at a distance (more than 50 mtrs type thing) you can use the Auto focus to focus on it.
Just remember to switch back to manual focus when you go to take your images. (Nothing worse than setting focus, switching to you target to have the camera sit there and try to refocus because you left it on AF).


With star trailing, I thought someone mentioned the "Rule of 500" previously. But given you use an APS-C size sensor you will need to multiply the lens FL by the crop factor (it's 1.6 with Canon sensors).

So your 35mm lens is now "effectively" a 56mm lens. Divide 500 by this 56mm and you get how many seconds you can expose for before getting trailing. (about 8-9 secs). Its not a hard and fast rule but will get you in the ball park for exposure times.

Next point is stopping down the aperture. This is generally done to get better star shapes at the edge of the frame. When the lens is "wide open" (Low F Number) you will get star trailing towards the corners of the frame. Stopping the aperture down can reduce or eliminate this. It comes with the trade off however, that you will not collect as much light and you will need to up your iso or expose longer to compensate.


ISO settings is a bit of a trial and error thing. You should be able to do some google searches around what ISO works best for your camera. I found a page just the other day that mentioned 800 iso on my Canon 1200D was best. I'll try and find the link again.
Generally 800 - 1600 ISO is the sweet spot I think. When I was doing static exposures I would go up to 6400 iso. It brings in alot of additional noise, but with stacking and dark frames you can negate this to some degree. Its a learning curve, so try different iso's and then process them and see what works for your camera and location.

I found that link to ISO for different Camera's - http://dslr-astrophotography.com/iso-values-sony-cameras/


As for your questions about your images looking very "Bright" or white. You want to expose the image for long enough that the histogram is right around 50%. (Google how to bring up the histogram on your camera if you don't know how. It's quite helpful).
If its too low, up the exposure time or ISO or open the aperture up. If its "over -exposed" (Your image looks very white or histogram above 70%) drop the exposure time, ISO or close the aperture a bit. Experiment here till your around the 40-60% mark on your histogram. (Your images could just look very bright due to light pollution or sky glow. In this case your best to head out to a dark site, unless your pretty handy with photoshop, this will make post processing much more difficult).


And the more frames you can stack the better. It will result in a cleaner final image. So try for at least 15-20 frames for both light and dark. (Others may be able to correct me here but 20-30 dark frames will generally be enough even if you do more then that of the light frames).

And always shoot in RAW and turn off Noise reduction in your camera.


Alot of these point's were probably already covered, but from the way your asked your questions I got the feeling you may not of understood some of it. (I felt the same way when doing my research starting out). Hopefully this clarified things a bit and gave you a few more pointers. :thumbsup:

[bojan]

Jasp, there is no such thing as "effective FL" - 35mm FL lens will always be 35mm FL, regardless of sensor size.
Only the FOV of the camera is smaller.
This misconception was started by "artist"-photographers who had no knowledge about optics, and we should try to root it out - it doesn't help understanding the technology at all, and after all, AP is in essence techical photography...

[Jasp05]

I understand it may not be "technically" correct Bojan. But for a beginner it is probably the simplest way to understand the concept of how crop sensors affect field of view through a given Focal length lens.

I don't claim to be an expert and was just passing on information that I'd picked up over my first 12 months in this hobby. Apologies if I have misled anyone..

[bojan]

I can't agree with this... we can't feed beginners with misconceptions from the very start.
Cropped sensor is smaller and that is why the FOV is smaller .. not because "efective" FL is longer.
We had a discussion here on IIS, there was one begginer who after some time calculateed his camera scale (pixel size in arcsec) wrongly and was confused with results when he went to plate solving website - results did no match his figures....

[Jethro777]

Well, after a few further adjustments, here is a new attempt.
Naturally, I just pointed it at the stars and shot. Next time, I am going to try and point it at something specific.

Settings are now 1200 ISO, 2.8 (Samyang 35mm f/1.4), 10 seconds.
Took 17 Darks, 31 Lights.
I also removed the UV filter I had on front for day photography. Colours seem more vivid than my last attempt. I'm more optimistic.
DSS appears to have a setting to correct for 'bright' pictures. Awesome. Now I will collect more light!!

I can locate the large Magellanic cloud with an app, I wonder if I could expect to see that if I point correctly? :shrug:

There doesn't seem to be much 'straight up', does there? :lol:

Much of what I am trying to see is so close to the horizon that it is obscured by trees and houses / palm trees.

I have the 100mm lens also, I wonder if that would make a difference - maybe for the Magellanic cloud...

Thank you for the many helpful posts. I do read them all carefully.

Next attempt:

1. More ISO!!
2. Point the camera at something specific.
3. Take the dark shots at the end of the session rather than at the start.

QUESTION - what I see via a single raw shot is far... more detailed than the DSS result. This makes me suspect I'm not using DSS correctly, and that is where my issues lie.

Would someone be so kind as to look at my RAW and see how I am REALLY doing with my image capture?

LINK : https://drive.google.com/open?id=1oiyTkD9fr3bNHwUQ8kc-djFGIvPKWRKo

PIC EXPLANATION

1. Processed finished pic from DSS after processing (Whole frame)
2. Section from single RAW file captured (f/2.8, ISO 1200, 10 seconds)
3. What DSS did with it - same section
4. Section of the sky shown from sky mapping program

I have put up a close up of a raw - the dss conversion at the end, and a pic of the section of the sky it's taken from so you can recognize it.

What do you think?

As far as the star tracker - steady progress there.
I have bought a nice Velbon SGB3 which is built like a tank.
I've secured two wood boards, not solid pine, sadly, but will probably do the trick.
Cheap laser pointer ordered as well as various bits and pieces.

[JA]

YES, the lens will collect exactly the same amout of light, BUT it is incapable of delivering all of that light to the smaller APSc sensor (without further optics & a necessarily different flange distance).

The APSc sensor can only "see" a rectangle of 23.5mm x 15.7mm within the circa 43.2mm Full-frame image circle being cast by the Full-frame lens at the focal plane (based on an APSc sensor size of 23.5mm x 15.7mm).
The APSc image sensor therefore sees 25.2% of the area of the circa 43.2mm image circle cast by the Full-frame lens.

The Full-frame sensor on the other hand "sees" a rectangle of 36mm x 24mm within the circa 43.2mm Full-frame image circle being cast by the Full-frame lens at the focal plane (based on a Full-frame sensor size of 36mm x 24mm).
The Full-frame image sensor therefore sees 58.9% of the area of the circa 43.2mm image circle cast by the Full-frame lens.

Given equal flange distances, on an APSc and Full-frame camera, as is typical for Sony, Nikon, etc.. and not considering the use of reducers, etc on say mirrorless cameras, then The ratio of those two percentages, 2.33:1 indicates that the Full-frame image sensor receives 2.33 times more total light than the APSc image sensor, or put another way the APSc sensor receives 42.9% of the light received by the full-frame sensor. It should be noted however: that the light per unit area (of sensor), and hence the exposure, on both sensors will/can be the same, BUT the Total light delivered to the sensor, if you could count the number of photons delivered to the sensor, will NOT be.


YES of course, in this example it is physically ALWAYS a 35mm focal length lens, it's just that it behaves differently on a APSc sized sensor compared to the Full-frame sensor for which it was designed.

Best
JA

[Merlin66]

Jethro,
Have you looked at CCDCalc?
http://www.newastro.com/book_new/camera_app.html
This allows you to enter the lens and camera parameters and shows the image size using various astronomical objects as a guide.....

[silv]

That's true. But that magically changes over the course of the seasons and a single night, too.
But those objects will be higher in the sky either later at night or in winter. Have a look at your astronomy app how that changes. Following the 600 rule, you are right to avoid those low targets.
a huge difference. Also in terms of shorter exposures before stars are trailing. LMC and SMC are totally cool objects in the Southern Hemisphere Sky. 2 galaxies, hanging there like cloud puffs, so big? You got to take photos and investigate them!

:thumbsup:
Except for the higher ISO. Taken from a city, high ISO digital photos do contain more light because the computer inside the camera thinks it's meaningful light and amplifies it.
But it isn't, really. It's just streetlights. Better not to be amplified. But when the camera computer did amplify it and saved it into the ARW-file, you have a hard time later to get rid of the unwanted light.
At 10 secs exposure you don't "waste" much time when playing around. So test your theory of higher ISO against the reality. Take a set of lights (and darks afterwards, yes!) of a piece of sky and let DSS to its thing with that set. Take another set of lights with ISO 1250 of the same piece of sky like in your test shots here (and a set of darks with the same ISO afterwards, yes!) and compare the result.



a) Your raw-file is almost perfect in terms of star trailing. 1 second less would have been great, I think. The stars are oval shaped, drooping down.
b) The stars aren't quite in focus. Is the lens capable of that at f/2? It might gain in sharpness at f/4, actually.
DSS discards blurry stars - and that's in your case most of the visible light dots. DSS also counts the stars and you get the option at the very end of the settings process to tell DSS to reduce the amount of stars to some value. Maybe you did that. I think it's a DSS default setting to reduce the amount of stars. But I'm not too sure. But in any case: blurry stars are being left out. You have a lot of them. Because the lens wasn't focussed precisely enough.



:thumbsup: great project !

[Jethro777]

Amazingly helpful post Annette.

Thank you so much for taking the trouble to make such detailed observations and pinpointing some of the issues so clearly for me.

Much appreciated! :thumbsup:

Let's see what I can do with it.

[silv]

:thanks:

[speach]

Hate to disillusion you but there is no such thing a budget astrophotography you may start out not spending much but there is always, always that bit more kit that you'll need. It will more than likely stay in a draw unused after purchase but at the time you really need it!:eyepop:

[Jethro777]

Well,

I applied a lot of advice here (Thank you very much!), and I had some issues with star trailing (I got a bit greedy and went for a higher exposure than I could afford, lol).
I also got some tips on post auto-tiff (DSS) photoshop adjustment - just curves and levels, and black/white point adjustment that was very helpful.

It's made such a difference! I know it sounds silly, but I had no idea there were so many stars behind the stars. So, so satisfying.

I'm told the lens I am using (Minolta 100mm f/2.8) is unusually suited for astrophotography as it is a particular high grade macro lens with a flatter field than usual and is sharp.

Now I REALLY want to get that barn door tracker working.

Camera Settings:

Sony SLT A77 Mirrorless
Minolta 100mm f/2.8
f.2.8 wide open
3.2 second exposure time
ISO 2000

Dark, Bias and Light frames used. Did not use any Flat as I can't make them properly. (What suggestions do you have for making them?)

1x Full 100mm Frame (non cropped)
1 x 100% Small Pic of Nebula to see Detail

[bojan]

JA, total number of photons delivered to the sensor (as a whole) is irrelevant for exposure time etc... what is relevant is photon flux per pixel (or flux per mm^2) and that will be the same for the same lens (including f/ number).


ONLY difference with different sensor size will be the field of view.

[Jethro777]

JA/Bojan - I'm getting rather confused. Will this affect how I process / take my images?

I can't change my sensor size, and I think I've worked out my max. exposure time given what I have, right?

Or is the technical discussion probably way beyond me right now? :D

If so, I would love some more tips from you both on on how to get the most out of what gear I have!

[bojan]

Jethro,

Do not worry about processing - this discussion has no relevance to what you are doing...

It is about some definitions that need to be clarified.

The point I am making is the amount of light, collected by lens aperture that reaches the individual pixel is the same regardless of sensor size (of course, assuming the pixel size is the same), and it depends only on lens diameter and FL (F-number).

My cameras (60D, 450D) also have APS sensor and I am using lenses designed for FF (24x36mm sensor size).

Lens performance will always be compromised at the corners of the sensor (film, CCD...), and it will always be better in the centre.

So, smaller sensorr actually means you will not see those imperfections that would appear in corners of the FF sensor (and FF means 24x36mm, and that size comes from Leica-format film, which is considered as some sort od standard (not really relevant today really))


You are already achieving almost maximum with what you have.

Perhaps what you need is to use smaller aperture (higher f-number) to limit CA and coma (that also means longer exposures).
I have very good results with Canon FD 100mm f/2.8 lens, but I had to stop it dowm to f/3.5 ~ f/4 to remove CA (blue/red collars around bright stars).
(see here (http://www.iceinspace.com.au/forum/showthread.php?t=58629&highlight=canon+100mm))




I had best results with 200mm -400mm prime lenses with external aperture mask (made of black paper or some sheet material) placed in front of the lens.

This has the same effect as increasing f-number (F/4 ~ f/5.6) but there are no diffraction steaks (because the aperture is round, not segmented as with internal iris).

[bojan]

For flats, I used tracing paper placed to cover the lens and clear blue sky...

Take couple of exposures (histogram should have maximum at ~1/3), DSS will make the master flat, which you can use from then on (just make sure that for actual imaging you use the same camera, same lens, same f-stop).

[Jethro777]

Thanks, I will need to give this some more thought. As I am using a 100mm Minolta f/2.8 and a Sony SLT-A77V only, I am not sure how to use it, and to understand exactly what it does for me yet.




That's helpful. So really, I can make a set of 'master flats' of likely apertures I will use for my lens and reuse them.

Can I do the same for Darks / Bias or do these need to be done on the night?

I was wondering what exactly can be blended together in DSS when it comes to 'Lights'. Not aperture? Not ISO?

[bojan]

For darks and bias I would do them for each photo session separately (for specific ISO of course)- they will be dependent on envirimment teperature - especially darks.

[Merlin66]

Jethro,
I've entered your data into CCDCalc.
(Based on the Sony SLT having 3.88micron pixel and an array of 6056 x 4020)
You can see the wide field coverage!

Hope this helps. (You can change the target object in CCDCalc to see the differences)
You can then use the FOV (789.5 x 524.5 arcmin) to produce an overlay for your planetarium program (I use CdC) to arrange your target.....

[JA]

Well I think I kind of got that :D, since I emphasised for the sake of completeness virtually exactly that earlier, when I said:




Best
JA

[bojan]

Well, then we should really, finally have that beer, without much delay ;)

[JA]

Good Idea Bojan!
Cheers ..... :cheers:

Best
JA

[silv]

Darks need the information of the camera as it was during the actual photo shoot. Info like heat and dead pixels.
So you take them at the end of each session with all the settings the same as the actual pictures, ISO, exposure time, Aperture.

Flat frames are used to eliminate vignetting and dust from the stacked light frames. So in your current setup, almost no moving parts, it's cool to take them any time you want and re-use the resulting masterflat from DSS for many months. (For each individual lens a separate masterflat.)
I don't know anything about bias. Never bothered. But that is not a qualified attitude! ;)

I am thoroughly impressed with your cropped Orion photo! Is that a stack of several 3.5 secs exposures or a single frame?

Get that barndoor mount going! :D
Imagine how much more detail you get to capture and investigate from Orion with several exposures of, say, 15 seconds or more!!

[Jethro777]

Thanks for the feedback,

The moon is kind of out now, so I'm waiting until the new moon for the next set. :)

Perhaps by then the rest of the parts will arrive for the barn-door tracker and I will see what I can gather then. I'm also going to test an excellent terrestrial lens, and see if it has any astro characteristics. ;)

Silv, I am attaching some 100% RAWs as shot so you can see processed vs. unprocessed and different times. As you can see, a 3.2 second shot is just too much. As Bojan and JA pointed out, the 500 / 100mm rule is wrong because of the ASPC sensor - I'm still getting drift even at 3.2.

The 2 second shots were okay, taken in good night conditions (dark site), but the Maia nebula wasn't visible.

The RAW 100.jpg is the 3.2 second (f/2.5, 3200ISO) exposure from which I got LDN 1641. You can see the 2 (f/2.8 1600ISO), and 2.5 second (f/4.5, 1600 ISO) exposures.

Mind you - most shots are a total exposure of just 1.5 minutes max.

[bojan]

Jethro,

Regardless of sensor size, you will be getting drift after couple of seconds of exposure with this particular focal length.
It is simply the consequence of Earth rotation, 15° per hour (or 15 arcsec per second), at celestial equator.
That means, with 100mm FL lens, (and M42 is close to equator) you will have drift ~4.85um per second (which is close to your pixel sze, 3.88um).
With longer lens, that drift will be proportionally longer, and it's value does not depend on the sensor size, it depends only on FL of the lens.


With 2.5 sec exposure, you have drift of 12 arcsec, or ~3.12 pixels on your photo (see below),

[Jethro777]

So, really from that, is there "optimal drift" until I get the tracker going?
I think I have been wrongly trying to "eliminate it" when really, I will always have it given the current Setup. I have been seeing drift and thinking "exposure time too long".

Switching to a 35mm lens again would allow longer exposure but less resolution, what would be better for dss stacking / final quality?

[bojan]

Switching back to 35mm and you can have the ~3x longer exposure for the same drift...

I think you just have to build that barn door tracker ;)

[bojan]

Also, bear in mind M42 belongs in "worst case" cathegory in terms of drift...

So objects away from celestial equator (closer to SCP) will have lower drift, and you can consequently use longer exposures.
Another thing, without equatorial tracking, you will also notice "field rotation (http://calgary.rasc.ca/field_rotation.htm)"

All that discussion won't be necessary once you have equatorial mount and tracking (including here barn door tracker).

[Jethro777]

Update on the tracking project:

Boards have been organised.
They are chip board however so I have tried to weatherproof them.
Normally, the thread on a tripod is 3"8, however the tripod I have secured doesn't have that width, it uses the M8 width, so I have secured that rod and various bolts I am anticipating I will need.

I am concerned about how to secure the bottom board onto the tripod securely. It will need to hold the board, the dslr and the lens of course.

I am using a template to build it, so it should work.

https://barn-door-tracker.co.uk

I can't quite see how it is secured. :confused2:

Perhaps this will be one clearer when I secure the final parts.

[bojan]

Have you considered driving this with motor?
I think this tripod is not sturdy enough, it will move as you are turning the knob.... resulting in images worse that you already have.
This thread will have to move with very little friction.

Some sort of 1 rpm motor (https://www.ebay.com.au/itm/AC-220-V-0-8-1-RPM-Non-Directional-Synchronous-Motor-Silver/232203368443?hash=item36106637fb:rk :1:pf:0) (powered from mains) may be a quantum leap from this design.
Or his one (https://www.ebay.com.au/itm/AC-220-V-0-8-1-RPM-Non-Directional-Synchronous-Motor-Silver/232203368443?hash=item36106637fb:rk :1:pf:0) (requires transformer 240V -> 12V AC)

(This particular motor from ebay may be designed for 60Hz mains.. so it may be running 20% slower in AU, requiring 20% shorter arm of the barn-door tracker).

[Jethro777]

Well, this is exciting. :lol:

Will it hold? It is an old school 80s tripod, quite heavy and solid. I think it will carry the weight if I can secure it properly.
I am not sure about mounting the camera at that length, I might shorten the length of rod connecting it to the tracker.

I intend to lubricate the rod well with easy glide (a dry lubricant, PTFE) not wd40 which will make it very smooth and resist debris/dust.

Now the motor is interesting. What resources should I read on how to add gears? I am not a math or engineer head sadly... :shrug:

Picture of planned tracker for those that missed the pic earlier in the thread.

[bojan]

Yes, by all means shorthen the rod - perhaps the camera should be mounted directly on the board (https://www.pinterest.com.au/markmoraes/barn-door-trackers-aka-scotch-mounts-for-simple-as/?lp=true).
I would also have the knob (motor) on the bottom side (https://www.instructables.com/id/Build-a-Motorized-Barn-Door-Tracker/)..


Those motors are supposed to be 1rpm (1 rotation per minute) so the shaft should be directly mounted (or via 1:1 gear reduction) to the threaded rod.
(https://www.google.com/search?q=barn+door+mount+gears&client=firefox-b&tbm=isch&source=iu&ictx=1&fir=GVMtLJjwN-iaZM%253A%252CPd7RDgkt1G0wkM%252C_&usg=AI4_-kSMkTQhXgjxOHOWbJDwfOLN4yOhXQ&sa=X&ved=2ahUKEwizvuuZ2s3eAhWHpY8KHRwgAn QQ9QEwAnoECAYQCA&biw=1793&bih=729#imgrc=_)Perhaps with something like this (https://www.ebay.com.au/itm/2pcs-CNC-Motor-Shaft-Coupler-5mm-to-8mm-Flexible-Coupling-5-x-8-x-25mm-TE490/332162895749?epid=15016024872&hash=item4d56738f85:rk:1:pf:0).


As mentioned earlier, you can use 60Hz motor for this, but the distance between hinge and thredaed rod should be 20% smaller (or thread pich should be finer)

[Jethro777]

Just thinking, (and I feel really silly), I need the whole tripod to align the hinge/side of the wood. That means I actually require a ball head or similar to mount the DSLR.
Another part to acquire... Any ideas where I can get one cheap?

This is needed regardless of whether the DSLR is mounted on the rod or the board itself.

[Jasp05]

I think I might have my old tracker around the house somewhere. I'll have a look for it and send some pics. I used a plastic gear from a hobby store with the nut that suits your threaded rod glued to it.

Then used a cheap stepper motor with a spur gear to drive the gear attached to the threaded rod. Used an arduino to control the stepper motor. The wiring and coding was quite simple. The stepper motor and arduino can be purchased for like $5 each on Ebay. while the plastic gears were maybe a few dollars each.

I think the extra effort to motorise it will be well worth it. As Bojan mentioned unless your tripod is particularly sturdy your movements to spin the threaded rod will be transmitted through to the camera. (It takes a very small amount of movement to cause trailing in an image.)

I'll get some pics of my old tracker up tonight so you can see the design.

[Jasp05]

You could make a wedge that is cut at the same angle as the latitude of your imaging location. (Ball head for polar aligning can be painful as you have to get both directions aligned simultaneously).

This will get you in the ball park of your altitude adjustment. Any finer adjustment can be done through changing the height of the front tripod leg.

[bojan]

Or, you could mount the base directly on tripod (https://www.instructables.com/id/Build-a-Motorized-Barn-Door-Tracker/) head, which should have elevation axis (I think this is how it was done on UK website)...


As Aaron mentioned, arduino is an excellent way to do those things, but you have to be a little bit techical...

It is also good because you will be independent from mains supply.
I was using those motors and drivers (https://www.ebay.com.au/itm/28BYJ-48-2003-Stepper-Motor-Driver-Module-For-Arduino-DC-5V-Stepper-Motor/152925378159?hash=item239b10166f:m: muVKgyR0SuLyUuuorIXkqTQ:rk:20:pf:0) for many things (focus, tracking etc.).

[Jethro777]

Right. So, you just move the tripod left or right to align from location and adjust the legs a touch for "up" and "down". Can confirm I am going to try a green laser to align it.

So, I can try and use the existing head I have to move the DSLR.

Should I go curved rod, or straight rod? Curved looks correct right now and let me stay aligned longer, right?
I think I will make the attempt to motorize it.
1rpm, 3rpm or something else? Why this speed?
I need to decide on the motor (9v/even 6v compatible sounds good for portability?)
Will a lm317 kit be needed to regulate the speed? Will that work with 6v?

Perhaps this motor would be suitable? https://www.ebay.com.au/itm/DC-6V-1rpm-Reversible-High-Torque-Turbo-Worm-Geared-Motor-DC-motor-GW370/132320901284?hash=item1ecef0b8a4:g: zsAAAOSwH05ZsLCx

Also, this will probably become helpful: https://blarg.co.uk/astronomy/barn-door-tracker-calculator (thanks Aaron)

[bojan]

The UK website suggests using the green laser pointer for aligning..

I think you can do the same in Queensland (we in VIC need to have license for succh lasers).

I would use red dot finder (https://www.ebay.com.au/itm/Holographic-Laser-Sight-33mm-Scope-Reflex-4-Red-Green-Dot-Reticle-Picatinny-Rail/171007011997?ssPageName=STRK%3AMEBI DX%3AIT&_trksid=p2060353.m1438.l2649), or one of those polar finders (https://www.ebay.com.au/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313.TR4.TRC 2.A0.H0.Xpolar+finder.TRS0&_nkw=polar+finder&_sacat=0&LH_TitleDesc=0&_osacat=0&_odkw=stepper+motor+driver)(they are too expensive IMO)


BTW, Red Dot Finder (RDF) is very useful for aiming at objects on the shy...

[Jasp05]

I found my old tracker. Picture attached.

I attached my ballhead to the bolt on the top plate closest to the hinge. (the closer the camera is to the hinge the sturdier it will be and it makes it easier for the stepper to drive the weight up as it follows the sky.)

This was a 3/8 inch bolt in my case as my ball head could take either a 1/4 inch or 3/8.

The threaded rod was bent by printing out the required radius on A4 paper and then bending the rod by hand. I believe a curved rod will stay tracking better for longer than a straight rod.
I used a 1 mtr length and grabbed it by both ends and bent them in to get the curve. If you grab a short length to bend you will just make a a very sharp odd shaped curve instead of a nice round even curve. the middle of the 1 mtr length will have a decent curve (You only need 200-300mm at most in the centre). Everything else either side will still be to straight to be of use.

The gear on the threaded rod was just a kit from Jaycar electronics. Was like 10 bucks for about 6 different gears which all fit on stepper motors. So I used a small spur gear on the stepper (which is missing in the photo).

The larger gear was drilled to slightly under the diameter of the nut to suit your threaded rod. Then I just hammered the nut into place in the gear. Its stuck in there quite nicely just like that. (I put a thrust bearing under this gear to reduce friction against the base board. Probably not required but for an extra dollar or 2 it seemed worthwhile).

The only important thing about the gears is the ratio between them as you need that to calculate the RPM required from the stepper motor. and the larger the ratio the more torque can be applied to the drive rod. (I tested my setup and it was pushing around 2-3kg easily when weight was placed directly over the drive rod. so 2-3kg at the camera mount point was even easier). even though my camera setup weighed somewhere around 1kg at the time.

Hopefully this was helpful. If you need a hand with coding an arduino to drive the stepper, I'm no expert but can bumble my way through it enough to help.

[Jethro777]

Thanks Aaron,
That picture does help. I have to say I am very nervous about ordering a motor. I'm worried it's going to be the wrong speed, or that I have trouble attaching it because it is the wrong shape. It's not much though, so I may order one today that I can run on a 6v. AC worries me (electrocution), so it definitely needs to be DC.
Also, I need to get some gears, the middle part of the gear, how do I know if it will fit into the motor?

Can anyone recommend/link a motor (DC) and the gears that should be workable? :help:

Thinking this one? : https://www.ebay.com.au/itm/DC-6V-1rpm-Reversible-High-Torque-Turbo-Worm-Geared-Motor-DC-motor-GW370/132320901284?hash=item1ecef0b8a4:g: zsAAAOSwH05ZsLCx

I don't think I want any electronics/programming on it.

I have found a supplier of gears, just not sure what to match up. (https://www.ebay.com.au/itm/Various-Plastic-Gears-Pulley-Single-Double-Layer-Worm-Crown-Robot-Motor-Toy-DIY/222572181001?hash=item33d255f609:m: mwLJ71izvZGYsh8UePDHstQ:rk:1:pf:0)

I took out the camera for a test run last night at 135mm with a Minolta 28-135, which is truly an exceptional terrestrial lens - but it's a disaster for Astro.

This has really made me appreciate the 100mmm f/2.8 prime I am using, which flattens so well and is free of chromatic aberrations..

First shot is with a UV filter on the front (forgot to remove it)
Then, without (not that it really helps given that lens).

[bojan]

Jethro, for DC motor you will need more complicated servo electronics, to stabilise rotating speed.

Arduino controlled stepper is a good and very versatile aproach - but a bit more complicated, and I have a feeling you are not comfortable with hands-on to those things... that is why I suggested AC motor with (or without) transformer.

If it is "wrong" speed (50-60Hz issue) this is easily mitigated with suitable dimensioning of the mechancal design (the whole thing on UK website you mentioned earlier is designed such that you have to turn the knob once per minute, listerning to 5-sec beeps (and moving handle by 30°) or watching the seconds hand of your wristwatch)


Good source of gears are old trashed printers, scanners etc.
Also you can try Small parts (http://www.smallparts.com.au/?gclid=CjwKCAiA5qTfBRAoEiwAwQy-6XeWhxxg46TE5LJW2Di7uHp3k29u584ESvv _FFvLuHeBxPB63prj6hoCj5EQAvD_BwE),t hey have a lots of other stuff.


On your latest pictures - I think they are out of focus. You may want to use Bahtinov mask to achieve better focus.

[Jasp05]

I wouldn't stress too much over the electronics. Its plug and play with the wires. (Don't have to solder anything). wires just push on/off. I use hot glue to stop them falling out. (see picture below).

It's 2 power wires and 4 signal wires for controlling the stepper motor. The stepper motor has a cable harness which will plug into the driver board. (the driver board comes with the stepper when you buy it and is the little green board).

Only thing you really need to do is plug a usb cable into the arduino and "upload" code to the board. All you do is install the Arduino program on your desktop. There is plenty of code online or I can help with writing something that you copy paste into the window. Then hit upload. And its done.

And the best part is the whole thing is just slightly bigger than a credit card when put together.

[Jethro777]

It looks like working with the arduino won't electrocute me. :lol:
If I went this way, I would need the arduino board (there are several, right?), and some bits (motor - a little blue one will do it eh?).

Perhaps I could find a motor in a printer or broken scanner. I'll see what I can come up with.

[bojan]

Printers andd scanners are full of motors and gears :-)

However, they may be bipolar, and that little motor with driver from ebay is only 2$ (plus waiting to arrive from China.. I bought 5 some time ago and used them all) and it is what Aaron proposed (to be used with Arduino Uno, as pictured).
Also, you can get 3 Arduino Nano boards for 10$... (Nano is smaller but uses the same processor)

[Jethro777]

Can you link these please Bojan?

[bojan]

Sorry, my mistake, it was 3 for 9$ each..
https://www.ebay.com.au/itm/3-5-10-PC-Arduino-Nano-v3-5V-16M-Micro-controller-Board-ATMEGA328-CH340-USB/283083008107?hash=item41e90fe86b:m: mXN9wYghI305m2-k1SQvETw:rk:7:pf:0


steppers:
https://www.ebay.com.au/itm/28BYJ-48-2003-Stepper-Motor-Driver-Module-for-Arduino-DC-5V-Stepper-Motor/232726454649?hash=item362f93e179:rk :5:pf:0&var


Stepper is powered from 12V, so you need 5V regulator for processor board as well:
https://www.ebay.com.au/itm/0DB1-5V-Out-6V-To-12V-In-Step-Down-Linear-Voltage-Regulator-Power-Module-Board/202437502805?epid=14023800795&hash=item2f22372755:rk:5:pf:0

https://www.ebay.com.au/itm/1-2-5pc-L7805CV-5V-1-5A-LM7805-ST-Fixed-Positive-5V-Voltage-Regulator-TO-220/263873352425?hash=item3d7013d2e9:rk :5:pf:0&var
https://www.ebay.com.au/itm/78L05-5V-100mA-Voltage-Regulator/253904978098?epid=902647692&hash=item3b1dea80b2:g:j0YAAOSwsDZb5 xnm:rk:95:pf:0

[Jethro777]

Thanks Bojan! Ordered. :)

1 x Nano V3.0 MINI USB ATmega328P CH340G 5V 16M Micro-controller Board Arduino
1 x 28BYJ-48 2003 Stepper Motor Driver Module For Arduino
1 x DC 5V Stepper Motor
1 x 0DB1 5V Out 6V To 12V In Step Down Linear Voltage Regulator Power Module Board

Now, let's see..

Solder iron? Check.
Wire stripper? Check.
Wires, nope.
Solder, nope.

Few other bits I'll get and I'll be right thanks to those arduous wait times... Hinges also arrived today.

[bojan]

Don't forget 12V -> 5V regulator
https://www.ebay.com.au/itm/0DB1-5V-Out-6V-To-12V-In-Step-Down-Linear-Voltage-Regulator-Power-Module-Board/202437502805?epid=14023800795&hash=item2f22372755:rk:5:pf:0

[Jethro777]

Added, anything else?

[bojan]

You need Arduino IDE:
https://www.arduino.cc/en/Main/Software
And some sketch to start with

[bojan]

You may need something to couple stepper motor to threaded rod (like this below, check the diameters - stepper shaft will be 5mm, your threaded rod will be something else)

https://www.ebay.com.au/itm/19-25-mm-CNC-Motor-3D-PrinterJaw-Shaft-Coupler-Flexible-Coupling-best-Gifts/192537121685?hash=item2cd41b5395:m: mf8yOur4ACRylHpq-euAWEg:rk:13:pf:0


Or, do it like Aaron did.


BTW, bent threaded rod is OK because tracking speed will not change as the barn door opens.. but straight rod can also be used, the necessary change in speed can be achieved in the program (called "sketch" for whatever reason..)

[Jethro777]

I will definitely need some gears.
And yes, something to attach to the rod. The rod is an M6.



Bojan, I take it that I only need ONE of these - they are both the "same" voltage regulator, right? What does this / do they do? What/where do they attach onto? Do I need a "bread board" I think they call it?

So that I've got things right;

1 x Nano V3.0 MINI USB ATmega328P CH340G 5V 16M Micro-controller Board Arduino

Base board.

1 x 28BYJ-48 2003 Stepper Motor Driver Module For Arduino

Needed to run the motor, obviously

1 x DC 5V Stepper Motor

Actually moves things.

1 x 0DB1 5V Out 6V To 12V In Step Down Linear Voltage Regulator Power Module Board

Allows me to run the thing using 6v instead of 12V?

Software "Sketch" - to transfer the program to the board + USB Cable (got that).

https://www.ebay.com.au/itm/19-25-mm...WEg:rk:13:pf:0
It allows me to couple the stepper motor to threaded rod - how exactly?

[bojan]

And USB cable...

[bojan]

Here you can find the code for tracker:
https://kukuruku.co/post/diy-an-astro-tracker-in-two-nights/
(some parts of it are not necessary as they are for LCD)


Another one:
https://www.jjrobots.com/projects-2/startracker/


Google search (https://www.google.com/search?q=astro+tracker+sketch&client=firefox-b&tbm=isch&tbo=u&source=univ&sa=X&ved=2ahUKEwiQ4amgk9LeAhVMO48KHVY9Bi MQsAR6BAgFEAE&biw=1782&bih=823#imgrc=xe7U2YBlLRe9RM:) results in many more projects like those...

[Jasp05]

Jethro that Arduino board will operate from 12v just fine. Its input voltage should be between 5-12v. (It's regulated on the arduino pcb).

It's logic level is 5v. Which means its output signal to the pins is 5v. Which is neither here nor there when operating that stepper.

So just connect to a 12v battery/ power source and you will be fine.

The stepper will also run off 12v but they run hot. So if you can best option is a pack of 4x aa batteries running the system. This gives you 6v which is enough for both stepper and arduino without having to worry about dropping the voltage. (one less thing you need to do).

[Jasp05]

and are you doing straight or curved rod design Jethro?

My advice is curved rod. Bit more work to bend it and get the curve right, but it was easier for me to do that than try and code for the speed increase that will be required over time on a straight rod design.

with the curved rod, we can program it to just do 1 rotation per minute. (provided your gears are 1:1 ratio. if its different we just speed up or slow the stepper down which is a simple case of changing one value in the code).

I'll go home and have a play as I have all the parts you have purchased. I'll write something to get the stepper going 1 rpm so all you have to do is upload it if you like. (If you want the learning experience then by all means go for it).

Also with those CH340G arduino boards (their chinese clones of the original arduino) you will need the CH340G USB driver for your version of windows. Otherwise windows will not detect it when you plug it in.

What version windows do you have? I can find the download site, as their normally in chinese. A quick google search for "Arduino ch340g driver" will probably get you in the right place also. :thumbsup:

[Jethro777]

I am thinking curved.
I have windows 10.
So basically, I probably don't need the voltage regulator.
Do I need to get some wires and solder? Bread board project box or similar?
Now for the long wait for parts. :)
I am currently imaging the LMC as well as orion and I have noticed I can do far longer exposures for the LMC because of the much closer proximity to the southern pole. Fascinating!
It's huge. I didn't position the LMC correctly as I didn't know it was so large and the orientation isn't perfect, but the 100mm lens seems just right.
This is going to be a new favourite of mine to image.
Wow.

[bojan]

Yep, no need for voltage regulator - I was not thinkig straight, my apologies...
I forgot about Vin pin.
https://www.rs-online.com/designspark/reference-design-of-arduino-nano-3-0

[Jasp05]

Only thing you need once you have the arduino, stepper motor and driver board, is a battery pack and some jumper wires.

You should need Female to female wires as the driver board and arduino both have male headers. Look up dupont cable on ebay. They come in different lengths. I'd get around 20cm as that gives you some flexibility with placement.

https://www.ebay.com.au/itm/40x-Dupont-Cable-M-F-M-M-F-F-Jumper-Breadboard-Wire-Cord-For-Arduino-Breadboard/132679504234?hash=item1ee450916a:m: m68D4n08tnVu5u44jA6ZpCw:rk:10:pf:0

If you have windows 10 follow this link - http://www.wch.cn/download/CH341SER_EXE.html and click the blue download box on the right. then just run the installer.

[Jasp05]

Do you think it would be a worthwhile resource to these forums to do up a guide on making a barn door tracker and using arduino to motorise it?

Do up a parts list, and how to calculate distance from hinge for the drive rod etc?

I even had printable templates for holes to be drilled etc for hinges and drive rod, stepper motor placement. Just print it out, glue it to a piece of wood and cut it out. then screw it all together.

That way it is all in one place.

[Merlin66]

Jethro,
You just need to use CCDCalc and a planetarium software - Cartes du Ciel.
You can then properly frame your target with any lens you use.

[Jethro777]

I think this is kind of a "make your own barndoor tracker" thread, haha! :rofl:
Thanks to you guys, a newcomer should be able to figure it out. :thumbsup:

What battery pack do you suggest? Should be rechargable / come with a charger perhaps.

Photos of the LMC from last night after processing. A neighbouring Galaxy? No way!

Amazing I can get this without a telescope. This is also a non-darksite version. I might be able to do even better with the current gear and even longer exposures, as this is closer to the pole.

Detailed (25% version of full size)
1000 x 1000 pixel cut of a highlight

[Jasp05]

Those photos are looking good Jethro. Your getting the hang of things now. Wait till you get that tracker going :thumbsup:

As for a battery pack. Just find a battery holder that will take 4x AA batteries. You can put rechargeable batteries in if you want or just use normal Alkaline ones. (Try and find a battery pack with female headers on the connector. otherwise you might have to attach some to make it easier to connect to the arduino later. )

[Jethro777]

Lol,
I took some moon-shots yesterday with the DSLR and used registax for the first time. It's very different!

My first moon picture. :)

51 DSLR Frames, f/8, 1/125, ISO 200 stacked in registax

It also occurred to me this morning that I still need to get:

EVERYTHING that connects the motor to the rod.

That means gears and a doobelacky to connect to the rod, right?

Bojan suggested this:

https://www.ebay.com.au/itm/19-25-mm-CNC-Motor-3D-PrinterJaw-Shaft-Coupler-Flexible-Coupling-best-Gifts/192537121685?hash=item2cd41b5395:m: mf8yOur4ACRylHpq-euAWEg:rk:13:pf:0

I just don't get what that is, and how a gear or something is supposed to turn the rod. Must be my non-engineering mind. He mentioned that you Aaaron, didn't do it this way. How did you do it exactly? That round gear seems to move by means of the motor.