Imaging Source Cameras for DSOs

[samtheeagle]

Ok, so I know that these cameras are really all about planetary work and are not ideally suited to DSOs... But... I can't help looking at the specs and seeing that they can do exposures up to 60 minutes, so I guess Imaging Source have kinda thrown in a bit of a thought towards deep sky applications.

I've seen a number of posts in my travels where people ask this very question, and and of course the chorus of "they're planetary" cameras come rolling in. And yes, this is what they're ideally suited too, but other than NOT being specifically designed for DSO imaging, is there actually anything wrong with using them for it? Are they seriously deficient in a particular area? And we can keep our feet on the ground in this discussion please. I know it's never going to be anything like as good as a £4000 Atik in terms of sensitivity and noise and cooling and every thing else, but these cameras are 10% of the price of those, so bang for buck how do people view them?

I've done a load of googling this morning and have found a series of images taken with DMK/DBK 31/41 cameras, and some of the results have been pretty good, consdiering this "isn't" a DSO camera. Here are few examples:

Image of M42

Trapezium in M42 - by Aaron Worley

Four Spectacular Nebula Images

IC 434 in the Orion Constellation

I began pondering this issue as I'm thinking of upgrading my 350D, as I'd really like some kind of liveview facility. So the obvious first port of call is say a modded 1000D. But I was curious about dedicated astro cams. What I've found is that there's a SERIOUS step up from the £300-400 price range to £1000+++ One of the budget options is the Atik Titan, but that's £500+ and has a resolution that hasn't been seen in computing for a decade. I know resolution isn't everything, but 659 x 494 is going to be lost on any modern high resolution screen, and forget about printing anything other than stamps! After the Titan there's nothing until the big boys at or well above the £1000 mark. Unless of course you consider the Imaging Source cameras...

I'm well aware of the many decisions that come in picking a camera, it's a minefield. For me the biggest issue is price, sadly I'm not made of money, so realistically the pro astro cams just aren't and option for me. Coupled with that is the fact that my opportunities to image are very limited, so a simple one shot colour is definitely best for me, unless I can live without colour pics, and I don't really think I can.

So why not a DFK31 or DFK41? They have better resolutions than the Titan, and I have a PST and very much enjoy solar imaging too, which these cameras really are suited to...

So if the choice is between an IS camera and a new DSLR what do people think? I'd be very interested in the thoughts of my learned friends

[Ags]

I have often wondered this myself...

[samtheeagle]

Well I'm hoping for some considered responses, as I've yet to find a clear answer on the interwebs... Perhaps FLO would like to loan me one so I can conduct an extensive testing programme?

[Ags]

As an alternative, I've seen ancient full-frame cameras on sale on sites like MPB Photographic for 100-odd pounds. They are only 4 megapixel, but that is still more than the alternatives and they are full frame! Imagine buying one of those and getting it modded for Ha :-)

[Space Bat]

Hi - having one of these camera's I can tell you the following which may help

They are really planetary / Lunar camera's

They have very small field of view so anything other than planets or very bright regions such as the trapezium they wont be much use for DSO's

Also trying to centre these camera's on a DSO would be a hair pulling exercise not worth the bald patches.

They are a great planet cam and that is what you should consider this camera to be - and at this job it really does excel

I just went through some of the images at IS and notice that they are used either using hyperstar or very short focal reducers - this would be to increase FOV...

However still wouldn't recommend this route when a DSLR would beat it performance and image wise by a country mile...

[Merlin66]

I disagree.

Consider where the Lx modded webcams have been used for DSO.. galaxies, clusters double stars etc. Small FOV but so what?

The DMK will give the same if not substantially better results.

I'm not saying its perfect, but if you had one, you could use it and get good results.

[Trull]

As an owner of a DFK21AS, I'd have to say that its fine for planetary, and guiding, but imaging is better using my modded 350d. Have you considered cooling your 350d?

But saying that, the IS cameras will handily beat any webcam for longer exposures as the noise level is so much lower, and as they have a nice metal body, can be mounted securely unlike the plastic bodied cams. One other thing - they have a standard c/cs lens mount so you can use cheap ex-cctv side angle lenses - some of which are actually very high quality.

[samtheeagle]

I've just thrown the DFK 41 parameters into CCDCalc, and yes it does have a smaller FOV, but that makes it better suited for a lot of targets that are just lost with the wide view given by a DSLR... So I'd lose the ability to image some things, and gain some others. Yet another factor to consider.

[pete_l]

I've just thrown the DFK 41 parameters into CCDCalc, and yes it does have a smaller FOV, but that makes it better suited for a lot of targets that are just lost with the wide view given by a DSLR... So I'd lose the ability to image some things, and gain some others. Yet another factor to consider.

But be aware that the pixel size of a DFK41 is roughly the same as the pixel size of (say) a Canon 550D at around 4.3u. So while the size of the DSLR image is much, much bigger the number of actual pixels that a small object, e.g. Mars, requires will be about the same in both cases.

I'd say it's not the FoV that makes one camera better/worse at imaging small targets, it's other features like the sensitivity, noise/cooling and for the brighter planets especially: the ability to take lots of images quickly.

[samtheeagle]

Cheers Pete, yes I see your point... Interesting way of looking at it that hadn't occurred to me. So perhaps the DSLR route is the way to go, as it gives a greater range of targets... Even if a target appears small in the DSLR frame, whn cropped to the same res as a DFK41 the scale would be about the same. That is what you were saying right?

I'd still really like to see one of these cameras given a DSO workout mind, it's really got my interest as to what they could manage

[Freddie]

Took these on the CPC unguided about 100sec exposures with my DBK21 (older one not with the new 618 chip). I used a 3.3 focal reducer to get a decent FOV. Amp glow at these exposure times in the top left corner was a bit of an issue, but shows you can get some pics. Not as easy or same quality as with the Atik though!!

[samtheeagle]

Thanks Freddie, great to see some more examples So they're single subs those pics? I ask because I'm wondering about the sensitivity / noise balance. If those are single shots then it's really quite impressive, and a stack of similar frames would really be something.

[Sp@ce_d]

This has been going around in my head for the last year too. With the economic climate AND the weather in the UK, my planned progress from DSLR to CCD is seriously behind schedule. Also, looking at posts from others who've taken the leap there seems to be yet another steep learning curve going to mono + filters.

I'm pleased with the way my modded 1000D performs apart from the noise. The FOV compared to getting a target on the webcam is a breeze. I'm seriously thinking about the QHY8L now. Seems to be a quieter APS-C OSC with from what I understand Set Point Cooling. Some of the results seen on here are impressive. For less than the price of a 314L + Filterwheel I could have the QHY8L + the new WO ZS70 & reducer and still have a larger sensor!

... is it me?

[Freddie]

The shots are all stacks of something like 30 images. These being only ~100 secs and on a colour cam, the individual subs do not show anywhere near that much detail.

[samtheeagle]

Ok so stacks of ~30 images, each ~100 seconds in length? So approx 50 minutes in total. That's good to know, thanks again for the examples, and the info to get a feel for what these cameras can do.

[riklaunim]

With planetary cameras like TIS cams you can't use very long exposures (dark current - no cooling + high gain). So you use short exposures starting from few sec to 1-2 min max (usually below 1 min). The longer - the lower gain you have to use not to overburn any area... and you need a lot of such short frames (+ a dark frame).

This is handy for very small planetary nebulas - you can shoot them at high resolution without getting seeing and guiding problems of long exposures.

[Gina]

I did a lot of thinking and research into the various options for DSO imaging. I had a Sony A200 DSLR and webcams which I had used. The DSLR was good in some ways but without live view was a right pain to set up so I wanted something better for DSO - webcams will do for now for planetary. The small sensor size astro cameras were obviously only really suitable for planetary or the moon. Larger sensors soon got astronomically expensive from my viewpoint as an OAP particular if cooled.

So I decided to buy the Canon EOS 1100D body for dedicated AP (no doubt remove the IR filter later). I compared this with earlier models available second hand but the 1100D wins on having the latest processor, live view and video mode. I looked at the various sources for this camera, checking carefully what was contained "in the box". Many made no mention of software which I though I would need. In the end I bought one from Amazon at a few more pounds than some sources but the description mentioned the software. I have not had the opportunity to test it properly yet due to the weather mostly. But I have tried it on terrestrial objects running off a PC and it's extremely impressive. Such a difference using live view over the tiny image in the viewfinder on the Sony and with two levels of zoom on top of the full frame view. Having this live view on a 17" monitor is a real luxury.

I have tried a few night-time shots not PC controlled but using the screen on the back with live view and even this is a lot better than using a viewfinder. The noise level seems pretty good at around 0C ambient. I reckon I can get a minute or two exposure times before the noise becomes too apparent. That's without darks and astro processing software. Think I'll take some darks at various exposures and report back on that. That doesn't need clear skies!

[Gina]

Certainly no clear sky tonight - it's raining with snow forecast for later tonight!

Anyway... I've taken some darks indoors so the noise will be worse than outdoors in the cold. I've attached two images both ISO 1600 and 4 minutes :-

1. Full frame scaled to fit here.

2. Full resolution cropped part of image with the most hot pixels.

[samtheeagle]

Thanks Gina I must admit the 1100D is looking very tempting indeed, the low noise characteristics of it look great. But I'll miss the Ha sensitivity my modded 350D gives me. Like you said, the 1100D mod is something to be done down the line I suppose. Never enough money

It's been interesting to see what people think on the IS cameras for DSO work, hopefully it'll help clear up the quandry for others who might be wondering the same as I was. Be nice to be able to afford both eh?

[Gina]

And here's the same with ISO 1600 and 10 minutes :-

1. Full frame scaled to fit here.

2. Full resolution cropped part of image from the middle.

[Gina]

And now I'm really testing it - 10 minutes at the full ISO 6400 highest sensitivity! Full frame scaled and full res cropped. These are untouched JPG images straight from the camera just scaled or cropped. No curves or such like applied.

[Gina]

As a reference point, here is a photo taken from our sunlounge looking out into a wet, misty night with an exposure of 30sec and ISO 800. The lens is a 55mm set to f2.8. When the stars are visible this would be a good viewpoint for widefield though without tracking there would be small star trails. Image just scaled, nothing else.

[Gina]

Thought I'd see how my Sony A200 fared in similar tests. It's not a patch on the Canon!! Here are full frame scaled and full res cropped images taken with 2m and ISO 3200 (the Sony one's max). No point in going further.

Have to say, the more I use the Canon 1100D the more I like it - an excellent buy

[Ags]

I'm very happy with my 1100D too. The only problem is now I want more lenses for it!

[samtheeagle]

Ahhhhhh, the never ending cycle of money separation that our hobby brings us!