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xelasnave
31-08-2017, 06:03 PM
I am not sure of why gets its benefits but it seems the optics are key.
However one aspect that appeals to me, where I can only image an object for one hour a night, is possibly being able to capture ten hours in one.

Andrews have triplet binoculars for 270.
So I buy five set them in a 3d printed bracket to hold ten, remove prisms add tube and camera which is dedicated to one channel. So ten filters ten hours however you use it.
Ten $500 cameras...electric focus for each, ...
How to manage the captures would be a problem.
Could it work.
Or you could get ten high grade triplet 80mm scopes and ten high grade cameras.
But could it work on a simple level of using Andrews $270 binos.
What would it take.
Alex

Slawomir
31-08-2017, 06:17 PM
To boldly go where no IIS-er has gone before.

But I would not venture there. Seems to be a potential source of endless frustration n headaches. I would rather enjoy slow and less troublesome acquisition of quality data :)

xelasnave
31-08-2017, 06:48 PM
Well I would like to back up North where I could see the sky , darker, but the trees here ...hard to be relaxed when you get an hour a night.
You can bet there probably folk who have built what I am thinking about...
Last night I got in about ten snaps of the Moon but had the image and control on screen...if I had electric focus I could stay inside...
I think as a mental exercise ..its more than just ten cameras , well for a start you are going to be downloading ten times...
Alex

Wavytone
31-08-2017, 06:50 PM
Hi Alex,

The fly in your ointment is that binocular objectives are designed to work with the prisms in the optical train. The lengthy glass path in the prisms adds spherical aberration. If you remove the prisms the objectives will be less than sharp.

Better to buy a bunch of small APO objectives and assemble the rest yourself, but they'll cost rather more by the time you're done.

leon
31-08-2017, 06:51 PM
Alex, Andrews you would have to be kidding :mad2: :mad2: :mad2:

Leon :thumbsup:

xelasnave
31-08-2017, 07:02 PM
Well a box of them may turn up...surplus shed...
But leave the prisms in ,happy to less work .

I would like a pair so should get a pair and see how to fit a camera..just take some shots and see how good or bad they may be...

Probably a good thing having only an hour will see me pretty focused.
Alex

xelasnave
31-08-2017, 07:08 PM
I was happy with my $200 set, But who knows.
So I bet you are going to suggest ten of the best...what unit I wonder going 100 mm even 150 mm best glass as you would say Leon.
And best cameras...what could you do ...I imagin imaging over five days and bring in 200 hours...hang the expence ..
Alex

Wavytone
31-08-2017, 07:29 PM
Well, 10 of these https://m.aliexpress.com/s/item/32707734393.html?trace=storeDetail2 msiteDetail&spm=2114.12010612.0.0.5bdadf47nXEIJ j

And a frame to hold them plus all the electrics... :rofl:

Alternatively construct a 500mm Baker-Nunn at f/1 and do it all in one frame, in about 1 minute - provided you can find a full frame 50MP sensor !

xelasnave
31-08-2017, 10:47 PM
Ten of those then.

Alex

xelasnave
31-08-2017, 10:59 PM
It depends how many I could carry on eq6 I haven't done figures but four maybe five scopes, but five is five hours for every one ...even two scopes three ...but start to approach the game by get max exposure time ...electric leads every where..
Alex

xelasnave
01-09-2017, 11:45 AM
Gave the 8 inch a run.
Captured about five of the Moon but did it from the lap top. Then clouded over.
Investigated the various controls. I could get focus better but had to go between scope and lap top an add on electric focus would be great I could sit in side and do everything in comfort.

I wonder what the cheapest way out would be? I would be happy if two wires coming back to a hand box would be ok but to have control on screen would be great.


I had scope on mount using the dovetail it came with and it was bouncy, the tube is folded to make the tube with a big join, its constructed like a can.
I like my old 6 inch cause it a nice solid tube.

Plans to fix it.
I have a longer dovetail but I am thinking get the longest dovetail and another two tube rings.
In addition baffle the inside such that the baffles will add structure strength.
Proceedure at this stage...insert cardboard cylinder inside bare tube stick to inside of tube, add baffles in card board. paint the lot with resin which makes the cardboard very strong. You could also insert structural features with x in between baffles...follow a line similar to the framed newt.
Take care to use four mount rings and maybe additional support between dovetail and scope..

The focuser it the best I have owned and with the new camera I am reaching better focus than ever in a tenth of the time. I would take a shot examine it on the camera adjust take another shot...took ages and ...well now it better.

Designed the pier for this mini observatory.
Its on a patio so less than ideal but the idea is to lay down some ply make a concrete disk three inches thick and say two and a half feet diameter say three I could got to four....but ti will never leave..mmm a big one and it can stay when I go..with pvc pipe coming up to required height, cement in four blots at the top of your pipe pier, same as up North and use the fitting that I have and goes onto those four bolts.
The disk will be bolted to the patio and the surrounding floor will be ply with heaps of insulation cause in summer the patio gets hot...I see a challenge controlling heat here but whatever it is there the cards I have been dealt.
I wonder how imaging thru a glass sheet would effect things.. but with a glass top my box observatory could be airconditioned so hold at bay the patio heat. I know a flexible covering on the top of the box which goes right up to the scope so it peeks out off a sheet approach...everything inside could be keep cool.
And I need an air conditioner as well the house gets so hot in summer.
Things to do must rush.
Alex

xelasnave
01-09-2017, 11:55 AM
And I have to build my 8 inch a stray light baffled extrusion tube ... still don't test the old one... but I am convinced it helps in my situation with street lights.
Alex

leon
01-09-2017, 11:55 AM
To this day I will never give them a good report not after what they did to me. :mad2:

Leon :thumbsup:

xelasnave
01-09-2017, 01:01 PM
I must have missed that Leon.

I am sorry you have had a sad experience.

So moving forward I suppose the approach should be buy the best as possible and that runs the price up ... I should do a costing mmm a spread sheet where you can put in different prices of units cameras etc...

A scope, filter, electric focuser, flattener camera...easy to spend five k a scope...that's fifty grand for the real deal....ten scopes...
Say five that's still $25k.

But exposure time is so important and there is so little of it that we get, so when seeing is good you need to jump on the opportunity... so when its there you need to be able to guzzle in as many photons as possible...he who gathers the most photons wins... and then you take this rig out to some place real dark and no rain and gather huge numbers of photons.

alex

SimmoW
01-09-2017, 05:38 PM
Most interesting topic Alex!

I myself have started wondering about the advantages vs. cost. Big cost is the cameras and focusers, but with today's cheaper CMOS cams, getting more plausible.

Watch this space....or that space?

Wavytone
01-09-2017, 08:21 PM
Terribly badly.

If you have a thermal problem I'll suggest this is much better...In this case it's damn cold outside, you have the reverse.

A company that makes cabinets for industrial control systems could knock one up for much less than what you'll spend doing what you describe - its basically a cabinet for 19" rackmount electronics with door, with a few windows added and the internal rack removed.

To that add some insulation inside, strap on an air conditioner and you'd be cool as a cucumber :) This particular little number happened to be portable as it also fitted neatly in a box trailer. Details http://www.volnaengineering.com/tardis2-1.php

What's more you COULD cannibalise a PortaLoo for the same purpose - has a door, fan-forced ventilation, readymade seat, and will save you a trip to the bathroom in the middle of a session. Wife will be wondering WTF you are doing in there !

xelasnave
01-09-2017, 09:30 PM
I was talking to a friend he said yes some web cams are 20 meg..must look into that.
Back to cheap.
Andrews binos say$2000 and web cams maybe $250 each...have to build electric focuser to keep it cheap.
Alex

xelasnave
01-09-2017, 09:47 PM
Maybe use eyepiece projection and use what on the binos...
Would quantity win over quality.
Thinking today getting fifty hours is major for anyone plus you need a run of good viewing.
But with a multi scope rig on a good run you may get 300 hours before that object is gone forcthecyear.
Which raises the question what would say 300 hours produce in a final image???
Alex

lazjen
01-09-2017, 09:59 PM
You're going to have a heap of "fun" on the software side of things with this setup too - trying to control it all. Going to dither at all? Then you need to coordinate exposures to ensure all are finished before dithering. If you're doing L,R,G,B,Ha - you might need different exposure times.

Then you need to consider flats - going to do those, or just process them out?

And I suspect you're going to have a lot of issues trying to control it from one machine (USB ports/connections). Probably would be much easier with INDI than ASCOM, but that's just guessing on my part with no real world testing.

If you just have 1 filter per scope, you should be able to use a good achromat - no need for an apo. That would save cost.

Atmos
01-09-2017, 10:11 PM
If you wanted another way to do this, a cheaper and lighter way.
Get 5 cameras that have the older shutter release (non digital, not sure if this one would work) and 5 Samyang 135mm F/2. The reason for the older style shutter release cable is that they can be operated without a powered shutter release, camera powered.

You have one camera that is tethered into the software using a DSUSB connected to the shutter release. You split that shutter release into 5 so that it can be plugged into all 5 cameras. As the shutter release activates the exposure in bulb mode you only need one camera to be activated for all 5 to be controlled and synchronised.

If you don't guide (just have good PE and PEC) you don't have to worry at all about precise alignment as it is the guider that causes differential guiding errors. They are best when they're not even correctly aligned as it is a natural kind of dithering between each camera, you do still need to dither.

I say 5 cameras as these can be mounted on the largest/longest Losmandy/ADM plates without too much of an issue. It'll be tight but should fit.

Slawomir
02-09-2017, 06:19 AM
I'm not quite sure whether it is worth the effort, for me anyway. Cheap lenses, cheap cameras, perhaps cheap focusers eventually adding up to a substantial amount of $$$, but quite likely allowing to quickly capture only substandard data anyway. What's the point of having a high SNR when quality of data suffers :shrug:

Why not spend the same $$$ on a quality less complex rig that one enjoys using? And who cares if images are a bit noisy, if stars are pinpoint to the corners? Just my five cents.

lazjen
02-09-2017, 07:11 AM
The "real"way to win is to do both - lots of expensive scopes, expensive cameras, filters, focusers, etc and make that into a Dragonfly setup. :p

xelasnave
04-09-2017, 08:15 AM
I see some images that have 50 hours or more.

Would there be any benefit in being able to capture ten times that?

Would say five hundred hours of data be exciting or over kill?
Alex

JA
04-09-2017, 10:24 AM
Hi Alex,

I think that all else being equal, provided that the sub-exposures that make up your 50 or 500 hours are adequately exposed (not too underexposed/read noise limited or too overexposed as to blow out highlight detail) , then yes there is a benefit in the signal to noise ratio of the image, which if the data is randomly distributed should be around (up to) the square root of 10 = 3.16 times less noisy in the 500 hour compared to 50 hour images, processing not withstanding. How obvious that difference is, is another story and will depend on the starting point. How good is original 50 hour image reference? Was it taken with top end gear and therefore more likely to be high contrast/fine detailed/less noisy or was it taken with lower end gear such as webcams with "lesser" lenses.

To take your example, one might find the signal to noise ratio with top end equipment at 50 hours of total exposure already "entirely acceptable" and although 10 times the exposure duration would provide an improvement the improvement might be judged as potentially not worth the time for the incremental improvement (may have to occur over a few years of data collection depending on weather/conditions), whereas on lower end gear such as webcams/etc the improvement in signal to noise ratio will be more evident because of a lower starting point of the attendant 50 hour image.

That is not to say that quality images can't be achieved with certain gear, just that the higher you start, the better you'll be in terms of overall image quality with or without the 10 times exposure increase you proposed.

I think the Dragonfly telescope is a wonderful concept, that within certain parameters and in certain applications can and has been shown to outperform many of of the big boys. It's also the sort of project that really interests me.

Best
JA

Atmos
04-09-2017, 10:34 AM
There is more that needs to be considered that absolute imaging time. When you start getting into incredibly deep stacks - say 100+ hours - your limit can come down to how good you are with your calibration frames. If you don't have absolutely perfect calibration frames, I mean exceptional, the difference between 100 hours and 500 hours may be how hard you can stretch Fixed Pattern Noise.

xelasnave
04-09-2017, 02:55 PM
I like it when we identify specific issues.
How do we overcome this problem.

Well if nothing else for my part having a one hour window has me grasping at straws.

But realistically $5000 a unit, say... gets expensive each addition hour...from a quality point of view I would be happy if such a unit did as good a job as a normal rig... as I said it has dawned on me just how little observing time you get...but set up in a van and going to somewhere to image half the night a month or two each object you take on...say 8 hours a night times ten...each week...month even given filter requirements mean some stuff could be done even full moon..I think not sure...but say 100 days imaging at 80 hours a night...thats 8000 hours... how would you manage that??? could , assuming good what could you do..Hubble Deep space shots eat your heart out???

I could go four maybe but thats still $20,000...no wont happen.
I would still like to have a go at building one out of binos...I found out today focusers are cheaper than I thought..

Alex

Slawomir
04-09-2017, 03:03 PM
Maybe it would be worthwhile starting with a dual set up and perhaps after making it work reliably one could add more lenses?

xelasnave
04-09-2017, 03:10 PM
Yes ..now thats the go.
You set up two. Get them working.
Add another two... managable instalements and each stage would hint at the problems of the next stage.

A coulpe of binos held on the mount with duct tape and old suingle shot 30 second exposure also held on with duct tape..

Must look on the net and see if anyone out there is building one..you would think soeone will be.

Alex

Atmos
04-09-2017, 03:31 PM
I currently have the components to attach 3 DSLR to a mount at once. Overall cost of that was about $500 (bought the stuff a while back) but it is purely for DSLRs.
If you want to do really deep stacks, you cannot do it with a standard DSLR. You need to be able to precisely match temperatures with your images and darks otherwise the mismatch in thermal noise because your limiting stack depth.

Your flats should have 100+ and be 50% of saturation. Each camera will need its own set of Darks, Flat Darks and Flats. The more of everything the better! Remember, image calibration actually ADDS noise to your images but stacking allows you to average the left over random noise out.

xelasnave
04-09-2017, 07:13 PM
well I was thinking of just an approach to taking darks and bias and lights one after the other to try and average temp variations...not with this in mind but a system of imaging ...sorting would be a pain..well if it worked I am not sur ehow stacking programs work ... I dont know but what a challenge.
Actually just buy very old cheap dslr with a kit lens but a few new nikons..I expect the lens is probably ordinary but something like that you get remote focus.....use as a proto type to sort out everything...Anyways one rig at a time. You could mount them on a bar without much trouble..a none zoom lens other wise maybe issues...Alex

xelasnave
04-09-2017, 07:23 PM
All of a sudden even with dslr group the vision of cables everywhere..does a usb to your camera power it or does it still use the internal battery..I have not noticed..
Its like the guy who built the 48 cylinder motor bike..imagine the problems to sort that thing out..
but you still cant ride it.
I wonder once everyone has their dragon fly system and its reached that level of intensity...could we say link 10 different folk each with an array of 10 and gulp in 100 hours every hour...if you process more data can you still get more because you have so much data.
I forgot there is someone trying to sell units..that was on this forum a while back..I wonder what they claim and offer and charge...and if anyone is using them and to what degree.
Alex

Atmos
05-09-2017, 02:57 PM
The DSLR still runs off of the internal battery. Depending on how you do it you could possibly get away without needing all of them USB connected; just use a shutter release.

xelasnave
08-09-2017, 08:26 AM
Internal batteries would be a blessing saving a lot of cables.
Cord less remotes also. Just buttons to press.

alex

JA
08-09-2017, 10:36 AM
Hi Alex,

They also may be a curse.... as Lithium Ion batteries will give of some heat, certainly during charge, but also during discharge (use) which in the extreme, say with long runs, lots of images, lots of screen or live view or video use might heat the image sensor slightly and thereby increase noise in the image.

It's something which would be good to quantify by experiment... Image noise, say taking a dark (image) using the internal camera battery versus using a plug in external power adapter to the camera. To really test it, the battery should remain in use for a while and to be fair the external power soucre as well.

BUT The above is only really relevant for a DSLR or a device with internal batteries, not with USB powered webcams or astrocams that were discussed earlier in the thread

Best
JA