First Ever Attempt at DSS Imaging - M42 Unprocessed Single Images
This is my first ever attempt at Deep Sky Imaging... These two shots are cropped but, otherwise unprocessed.
Camera is a EOS1100D unmodded.. camera was mounted to the diagonal (I know I should do this differently but, I was just sorta seeing what I could do...) Scope is a Meade LX90 8" in az/alt forks, no wedge...
Had to really muck around getting my finderscope perfectly aligned with the main scope in order to get M42 in the camera FOV because I'm then shooting blind... nothing shows up in Live View
First one is a 30 second exposure at ISO 800 (I could see some star trail in this shot which lead me down the path of higher ISO & shorter exposures)
Second is a 4 second exposure at ISO 3200 (Stars are bloated.. I have no idea why that is.. someone hopefully can explain why this is)
First time I have ever used a Bhatinov mask (using Sirius)
I have about 20 or so captures & my next task is to try & figure out one of the imaging programs I have (Deep Sky Stacker, Registax, etc...) to see if I can get the data together & improve the image.
My stars are bloated, I can see that but, I don't really know why...
Please feel free to comment, suggest what I can do to improve my captures & if you have any tips on how I can use the data I have to end up with a better image then please share with me...
I have no darks, flats or anything else.. guess I could take some darks at least..... no idea on the others though....
My first step down the path of astrophotography.... I am a little excited as I've never captured anything like this in my life....
I know there is a steep, steep learning curve ahead & that there is a lot of improvement to go but, hey... everyone started out somewhere eh??
Great first effort. I think you're about to find out how hard but how rewarding this amazing hobby is. It's so exciting when you start getting images ! Make sure you keep them and you'll be amazed in 6 months tine when you look back at where you started and how far you've come.
Re: bloated stars. I got the same thing when I stated imaging though an SCT. I think because of the focal length, the stars become bigger and really wash out into the surrounding pixels. Your high ISO doesn't help. You're right about flying blind but as I've found, it's the nature of the beast. I very rarely can " see " what I'm imaging. A tip for that is to find the object visually ( often this is just lining up using star patterns you can see ) and set the object as a user/custom object in your hand controller. The slew to a bright star, fit the camera and focus it then return to your user object to take photos.
At that focal length, you'll only be able to take short exposures without a wedge because of feild rotation. This will also contribute to star bloating. This us also going to keep you ISO high. Globular clusters are good targets for short exposures. Trust me when I say that short exposures and high ISOs are not the end of the world though. You can still image, it's just A LOT harder. You'll need to collect at least 4 times the data and about 4 times the data again to reduce noise BUT IT IS POSSIBLE.
My suggestion to you would be to build your self a wedge. At least then you can polar align and that will deal with feild rotation. I'm not familiar with your specific mount but on my Nexstar At-az on a wedge, I could get 22sec subs reliably once polar aligned.
Keep at it Carlton and feel free to ask as many questions as you like. It's what we're all here for, to learn and help each other.
Thankyou for your kind words & encouragement...just capturing data was an amazing thing for me... had tried once before... all i achieved was frustration so, this was a quantum leap forward.
Never thought of saving something as a user object.... seems obvious now that you mention it... I'll have a look at how to do that...
Making a wedge... okay (gulp)... I will look into that....
Would a focal reducer assist in reducing bloat? If so, can I get away with a cheap BINTEL 0.5 reducer or do I need to spend some dollars on a 0.63 focal reducer.
Gotta have a crack at combining the data I have now & learn how to gain some enhancement.
I thought so too Marc. I've had far far worse stars than Carlton's.
Yes a focal reducer will help with not only star size but also you can track longer with it and also capture more light in a given amount of time because of the reduced F ratio..... All sounds perfect yeah ? But spend the time to understand why this is the case. This is where AP get technical. A focal reducer reduces the f ratio which also widens the effective field of view so and given object becomes smaller on the sensor. A smaller object means it's harder to resolve minor detail. Understand that SCTs are the focal length they are for a reason. As soon as you put a focal reducer on, you then become comparative to short Newts. Also as focal length reduces, coma on the edge of the image increases unless it's corrected. This is the difference between cheap reducers and ones that are designed for your size OTA . I know it all sounds like a lot to absorb and you're right it is. But learn as you go. Don't feel the need to go out and get everything NOW ! Going slowly will help you understand much better what's going on rather than buying something because Timmy has one and you like his pics
stick with the kit I have & see what I can understand & achieve.
Mate, if you can reproduce consistently what you're doing in #2 you're laughing. I too am trying to do a bit of long FL imaging lately and it's not easy.
Hi Carlton, Its much easier to align the finder with the main scope during the
day; align your main scope with the top of a streetlight or similar several
hundred metres away, and then align the finder to the target and you are done, taking care not to knock the finder once it is aligned.
Making a wedge is easy if you have access to a woodsaw and a drill, and either a cheap plastic protractor or an inclinometer. Just make two identical
squares of 5 ply and two identical wedges cut from the same material, at the angle of your latitude.
Glue and/or screw it all together so you end up with one square at the correct angle to the other, and drill holes in the appropriate places to attach it to
your mount's base and the top of the tripod. You will also need a few nuts and bolts.
I started off long FL and yeah, I agree Marc, it's hard. Add to that my stupidity or sheer stubbornness, I was doing it on a cheap Alt-Az mount lol. I'd have to say though, what I learned making it work has been invaluable.
As far as the dedicated camera goes, you're out of my league now, I've always used a dslr so I can't offer advice there but plenty of others here can.
At your FL you should be real proud.
Building a wedge should be a piece of cake and will help.
There must be utube vids on making them..if not build yours and make a vid at the same time.
Alex
You can try use a clothing peg on your focuser knob. Since you're turning the focuser from a larger diameter you'll be able to focus much easier!
You also dont shake the scope so much when adjusting the focus.
One of the coolest tricks I've learnt so far.
A bahtinov mask can also be very handy to get the focus spot on. I dont know if it's a good idea to focus on a binary star though, but i might be wrong.
With an 8" SCT you'll be able to capture a fair bit of detail in m42.
You can try use a clothing peg on your focuser knob. Since you're turning the focuser from a larger diameter you'll be able to focus much easier!
You also dont shake the scope so much when adjusting the focus.
One of the coolest tricks I've learnt so far.
A bahtinov mask can also be very handy to get the focus spot on. I dont know if it's a good idea to focus on a binary star though, but i might be wrong.
With an 8" SCT you'll be able to capture a fair bit of detail in m42.
Thankyou, fortunately, I don't need the clothing peg on the focuser knob.. a mate of mine machined me up a larger diameter wheel earlier this year for this exact reason. Fits on the original focuser knob, has a nylon inner section to protect the focuser knob & then held on by compression from three allen headed grub screws. Beautifully machined & knurled outer surface... tis a thing of beauty & makes getting to focus so much easier.. and best of all, it cost me nothing...
Re: Bhatinov mask, first time I've used one.. didn't even think about the binary star issue... gave me the diffraction spikes I needed though & focus seems to be okay... I'll google this later & see if it is in fact an issue to be concerned about..
Quote:
Originally Posted by xelasnave
At your FL you should be real proud.
Building a wedge should be a piece of cake and will help.
There must be utube vids on making them..if not build yours and make a vid at the same time.
Alex
Thanks Alex, encouraging as always...
I am going to look into that wedge more closely. I've had a brief look & found a few articles... will look for videos & plans possibly... will need to decide if I want it to be adjustable or just adhere to the KISS principle...
Binary stars will give two sets of diffraction spikes, initially a little confusing
to the eye, but can still be used; obviously better with a single star though.
If your likely imaging sites are within 50 or 60 klms of home, a fixed one will suffice.
raymo
Last edited by raymo; 18-12-2018 at 08:13 PM.
Reason: more text
Regarding the wedge, my advice would be to at least have a few degrees of fine adjustment. Sounds like you might have a mate who can help you out with this.... You may have to throw him a couple of dollars or beers for his one though lol. I like the KISS principal though for everything though. Do simple things perfectly !
