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OSC, Best Options, Sensible Sized Budget --- Limited Imaging Time


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Ok let's start by saying I know mono and a filter wheel would be the preferred choice (by a long way).. And I can understand the many benefits to this set-up. But would really like to hear from users actual hand on experience with good quality OSC cameras.

My circumstances just don't allow and I just don't get the imaging or processing time required.. But this doesn't mean I don't enjoy the little time I do get. I also really enjoy following this forum and seeing the amazing results people achieve.. Across the spectrum.

I have a Canon astro modded 450, which has been good and easy to use.. I maybe get 7-10 nights a year that I have the time when the nights seem the right conditions, with this in mind and shooting from a medium light polluted back garden.. I'm thinking of a high quality OSC, maybe where some of my imaging time isn't taken up with flats, bias and darks.

I have a reasonable budget that I'm willing to invest of up to/around 2k

So I guess the question is, would I get reasonable results which are far better then my inexpensive 450 or am I barking up the wrong tree and wasting my money in the hope of getting resonable images with OSC??

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You'll still need calibration frames, the only good thing is getting set point cooling and pixel size to suit your scope, I have an Atik 4000 OSC which produces nice images of appropriate targets.

Dave

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A Canon 7D Mark II (modified) should go on your shortlist.  It would offer a noticeable jump in performance over the 450D.  But if you have a medium light polluted back garden then you might be better off narrowband imaging with a cooled mono CCD.

Mark

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Hi,

Firstly, I definitely do not believe you would be wasting your time with OSC. I have had two of them, a QHY8 and an ST8300C. Bothe of these were used to take really nice images. I moved to mono/filter wheel, and whilst I am extremely happy with what I purchased, I actually don't see much difference in the images that were OSC versus the mono. If I'm really honest, I think I made a mistake, as I have limited observing opportunities and should have stayed with OSC. The results are hugely better than a dslr. I've attached a OSC M42, from memory this was about 90 minutes worth of data with the ST8300C

hope this helps

cheers

Gary

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I'm relatively new to astrophotography (just over a year now) and I had to make the decision to go down either the mono or colour CCD route. I went down the colour route and I don't regret it, I decided to buy a good quality CCD with large chip (Starlight Xpress Trius 26C) that would be "matched" to my scope assuming deep sky imaging. I went down this route mainly because I was attempting to minimise the complexity of my initial set up and because of the low number of clear nights in the UK weather. I use the camera with my SW ED80 with a SW 0.85x Focal Reducer and Field Flattener.  

With OSC you'll get the most optimum results with broadband objects (eg galaxies) and less optimum results with narrow band objects eg emission nebula. My best image to date is with M31 which I've attached below.

Alan

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I have a reasonable budget that I'm willing to invest of up to/around 2k

So I guess the question is, would I get reasonable results which are far better then my inexpensive 450 or am I barking up the wrong tree and wasting my money in the hope of getting resonable images with OSC??

I doubt that you'd get results that are £2,000 better, but that's always a difficult thing to quantify.

The pixel size of the camera's sensor is similar to that in most popular CCDs, so your arc-sec per pixel resolution won't change much.

The QE (light collecting efficiency) of the 450 is about average for a Canon camera - although much lower than an astronomical CCD. And there are lots of excellent images from Canon cameras. The 450 might suffer in the noise department, needing more subframes to get a clean image - but in a light-polluted environment, would that be your limiting factor - not the optical / electronic properties of the camera?

You have 2 scopes listed: an ED80 and a 9¼ inch SCT. You also have an Astrotrac.

On that basis, might I suggest the following strategy:

Refresh the Canon with a later model. The boost will be better noise performance. Have a think about a planetary cam to use with the SCT (planets are bright enough to be much less affected by light pollution). Maybe purchase a prime lens (the 200mm Canon is well thought of) to use the camera with the Astrotrac.

Also, if you haven't already: try to find a way to speed-up your setup time. When i was in your position, I found that the time taken to drag all the kit outside, let it thermally stabilise, align it and then start imaging was a big disincentive. You don't need a full-blown observatory, but even a permanent pier that you can drop the HEQ5 onto would be a good start.

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2 part answer (2 posts):

In answer too:

Gazza -- Great photo there and thanks for your feedback. Interesting reading on your view for the OSC and Mono

And

Alan4908 --- Another great photo and taken with one of the camera's I had put on a short list, so was great to see this and taken will same scope as mine!

The 2 camera's I had short listed:

Starlight Xpress Trius 26C, slightly more then I budgeted, but not out of range.

and

Atik 4120EX OSC, which I believe has just been reviewed in this months Sky at Night magazine and hope to pick up a copy tomorrow.

Would you mind sharing a little bit more information on this photo? How many subs etc?

Thank you

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I doubt that you'd get results that are £2,000 better, but that's always a difficult thing to quantify.

The pixel size of the camera's sensor is similar to that in most popular CCDs, so your arc-sec per pixel resolution won't change much.

The QE (light collecting efficiency) of the 450 is about average for a Canon camera - although much lower than an astronomical CCD. And there are lots of excellent images from Canon cameras. The 450 might suffer in the noise department, needing more subframes to get a clean image - but in a light-polluted environment, would that be your limiting factor - not the optical / electronic properties of the camera?

You have 2 scopes listed: an ED80 and a 9¼ inch SCT. You also have an Astrotrac.

On that basis, might I suggest the following strategy:

Refresh the Canon with a later model. The boost will be better noise performance. Have a think about a planetary cam to use with the SCT (planets are bright enough to be much less affected by light pollution). Maybe purchase a prime lens (the 200mm Canon is well thought of) to use the camera with the Astrotrac.

Also, if you haven't already: try to find a way to speed-up your setup time. When i was in your position, I found that the time taken to drag all the kit outside, let it thermally stabilise, align it and then start imaging was a big disincentive. You don't need a full-blown observatory, but even a permanent pier that you can drop the HEQ5 onto would be a good start.

And part 2 Answer:

Thanks pete_I

Also very informative reply and coving many things I had been also considering.

"

I doubt that you'd get results that are £2,000 better, but that's always a difficult thing to quantify."

This completely makes sense

"The pixel size of the camera's sensor is similar to that in most popular CCDs, so your arc-sec per pixel resolution won't change much.

The QE (light collecting efficiency) of the 450 is about average for a Canon camera - although much lower than an astronomical CCD. And there are lots of excellent images from Canon cameras. The 450 might suffer in the noise department, needing more subframes to get a clean image - but in a light-polluted environment, would that be your limiting factor - not the optical / electronic properties of the camera?"

As does this answer, thanks for the information.

"You have 2 scopes listed: an ED80 and a 9¼ inch SCT. You also have an Astrotrac.

On that basis, might I suggest the following strategy:

Refresh the Canon with a later model. The boost will be better noise performance. Have a think about a planetary cam to use with the SCT (planets are bright enough to be much less affected by light pollution). Maybe purchase a prime lens (the 200mm Canon is well thought of) to use the camera with the Astrotrac."

I have been very happy with the ED80, less so for the SCT 9 2.5" For me and my ability I think this was the wrong scope for me to chose in hindsight, including taking in to account my mount, and for the targets I'm most interested in. (Galaxies and nebula) Although I wouldn't completely discount planets as a target. Although probably can see me putting this almost unused scope up for sale.

I have been considering sticking with a DSLR and improving on the 450, with something like the 7dmk11 as mentioned by Sharkmelley.. I did at the beginning of this week order the 70-200 2.8l is ii canon lens and the 2 x extender to give me another option to shot at 400mm at 5.6, not to shabby, (which should be with me tomorrow) precisely to use with my Astrotrac.. I looked in to this and the prime 200 2.8l and there didn't appear to be a great deal of difference in quality, but could make use of the zoom for other types of photography.

"Also, if you haven't already: try to find a way to speed-up your setup time. When i was in your position, I found that the time taken to drag all the kit outside, let it thermally stabilise, align it and then start imaging was a big disincentive. You don't need a full-blown observatory, but even a permanent pier that you can drop the HEQ5 onto would be a good start."

This is something for me to consider and not out the realms of possibility, I find myself at the moment, and if I have the time, If I think there's a chance of a good nights viewing setting my equipment up during the day ready for the evening.. And polar align as soon as I can see polaris through my view scope.  Although this has worked fine on some occasions, I have also had to make a quick exit, I guess we've all been here!

I really want to make a decision soonish ready for the winters night sky and not be faced with what I read from another forum user asking a similar question and he ended up doing nothing, this kind of happened to me last year..

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After much thought I settled on doing nothing with my imaging gear but build an obsy this Spring instead and have a ready to go, polar aligned rig.  I can safely say it has increased the time I can devote to imaging greatly.  Now, time devoted to processing, that's another matter....

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Hi -  To answer your question regarding the details of the M31 image (taken with a Trius SX26C).  LIGHTS: 42 x 300s, DARKS: 30; BIAS:100; FLATS:40 all at -20C.  Calibration and stacking was done in MAXIM DL, Photoshop CC was used for post processing. It was my second attempt at M31 but I'm happy with the result. The most difficult part of creating the image was the post processing in PS. If you want to see some more images taken with this Trius SX26C/SW 80 ED combination, have a look at my gallery.

Alan

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For a spell of a little over two years I ran both versions of the Atik 4000 here, colour and mono. They are both good. Whenever this comes up I tend to do a quick sum to show why mono is faster - it simply is faster - but I understand the frustrations of few nights and interrupted runs so I'll spare you all that - for a change!

Darks, flats and bias, with a set point cooled CCD, consume precisely none of your imaging time. You do them in non-imaging time and would be crazy to do them under a clear sky.

(By the way, I have found that a single good lum master flat will work perfectly well for all my filters on all three mono rigs working here but that's by the by.)

The business of matching pixel size to focal length is a big issue. DSLR pixels are too small for most astronomical scopes and far too small for longer focal lengths.

So the big CCD gains are set point cooling and flexibility of choice on pixel size. (When I see posters trying to image at 0.4 arcsecnds per pixel through SCTs with a DSLR I want to cry.)

Olly

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Thanks Alan for your information on processing your picture.

Appreciate your reply also Olly, this is far more complicated then I ever thought (I do enjoy the challenge to a degree).. I understand your comment on mono being faster, but I think this really applies to someone used to using this type of set-up and who has become familiar with set-up, capturer and processing, for a novice like me, this I feel would be a much steeper learning curve.. And I don't want to make it so complicated that I end up not enjoying It.

I have spent a considerable amount of time over a long period deliberating my next camera purchase.. I've gone from improved DSLR, osc and mono and just going back and forward between the 2 now. I probably know deep down the mono route is where I should be spending my money, but the appeal of OSC is there also.

The Atik 4120 seems to get a very good write up in this months Sky at Night and then I look and see cameras like the Atik one 6.0 with OAG for only a small amount more (plus filters) and this might be a good solution... Ooh dear what to do lol

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That is a reasonable budget you have set there. I also live in the UK and I agree that imaging time is a scarce resource. The question is - how best to use this. I am still a beginner. When I started out, instant feedback was important to me. My goal was to come in from an evening with a 'finshed' image - and by this I mean a colour image. That meant capturing as many frames as the night (and my incompetence) allowed on my DSLR. Often I would do a quick process straight away.

It slowly began to dawn on me that the way to start getting better images was to gather more data. The top guys and gals were amassing several hours, sometimes double-digit hours of data on their images. I don't know if I am especially unlucky weather-wise where I am, but I am happy if I get 3-4 hours of data per night. As such, I realised that I had a choice - take a load of 'short' exposure time images that turned out OK .... ish, or concentrate on fewer targets and gather much more data on them.

I have decided to take the second route. Once I made that decision, I could see no real disadvantage to the mono plus filters option. Indeed, there were significant advantages - I read about 'interpolation' and came to the view this was a high-fallootin' word for guessing. It also allowed for some flexibility - some nights I could get some Ha data when RGB data would be no good.

I am still very early into this, and I don't know how it is going to turn out. I am finding with more data some processing tasks become much easier - noise reduction springs to mind.

Good luck.

Steve

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I struggle to understand how DSLR pixels can be 'too small'?

While you may not gain anything by oversampling, you don't lose anything either, and you can always bin the pixels.

Alternatively, if your pixels are too big, you can only use drizzle to try and recover resolution and that's hit and miss (for me at least).

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I struggle to understand how DSLR pixels can be 'too small'?

I think "non-optimal" is a better description.

The pixel-size in DSLRs pretty much matches the pixel size of astronomical CCDs: 5µ give or take. However the benefits of having an exactly matched (according to the theory, which makes some basic assumptions about atmospheric seeing conditions) focal length and pixel size - as opposed to one or other, or both, being "off" by a factor of two - are very slight, possibly even imperceptible to the observer.

If you're using a camera with 3µ pixels and a focal length of 3m then your images will be of quite a small section of sky. But for mostl CCDs and most telescopes with a focal length of 500mm-1500mm there's not going to be a lot of visual difference in one properly processed end result or another. I would suggest that within this range, the quality of the optics, CCD cooling, the calibration of the image and monitor or the quality of the print has a bigger impact.

Edited by pete_l
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Stub, please feel free to think out loud.. I'm taking everything in before I make a final decision.. I also know there isn't a one size fits all solution.

Now there is a thought if any camera manufacturers are listening to this thread!! I need a OSC also with mono built-in, automated filter wheel with varying pixel size, OAG and no cables... Ooh and while I'm dreaming all for under a generous £2k.. Please

I did say please... Thank you!

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I struggle to understand how DSLR pixels can be 'too small'?

While you may not gain anything by oversampling, you don't lose anything either, and you can always bin the pixels.

Alternatively, if your pixels are too big, you can only use drizzle to try and recover resolution and that's hit and miss (for me at least).

They can be too small because they don't collect enough light - because they sample too few arcseconds of sky - so what they lose is light. And no, you cannot bin the pixels under a Bayer Matrix because the colour information becomes garbled. (You bin different colours together in a way that the software connot unravel.)

Pixels can be too small and often are. Your pixels should be just large enough to match the resolution of your guiding and your seeing in DS imaging.

Olly

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"Also, if you haven't already: try to find a way to speed-up your setup time. When i was in your position, I found that the time taken to drag all the kit outside, let it thermally stabilise, align it and then start imaging was a big disincentive. You don't need a full-blown observatory, but even a permanent pier that you can drop the HEQ5 onto would be a good start."

This is something for me to consider and not out the realms of possibility, I find myself at the moment, and if I have the time, If I think there's a chance of a good nights viewing setting my equipment up during the day ready for the evening.. And polar align as soon as I can see polaris through my view scope.  Although this has worked fine on some occasions, I have also had to make a quick exit, I guess we've all been here!

I really want to make a decision soonish ready for the winters night sky and not be faced with what I read from another forum user asking a similar question and he ended up doing nothing, this kind of happened to me last year..

I set up a permanent pier in my backyard and it has HUGELY increased the likelihood that I will get the scope out on weeknights (I do EAA, i.e. lots of short imaging runs mostly to look at things rather than create nice pictures, but the principle is the same - you need an equilibrated scope on an aligned mount to start).  My setup is carefully marked - I carefully drift-aligned the scope once and then scribed the setup exactly from pier to mount.  Now I carry the mount head out, drop it on the pier, and I am perfectly polar aligned.  This is probably the single best thing I ever did for making astronomy easier and faster to do.

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  • 2 weeks later...

After much deliberation and time researching, I am now very seriously considering doing a U-turn and going down the Mono route, with the view of spending more time on a limited number of targets.

The camera of choice I think would be the Atik 383L plus

EFW2 Filter wheel, 7x36mm

And these filters, Astrodon 3nm Ha, 5nm OIII, 5nm SII and Baader LRGB set.

Does this sound like a good choice and combination? Or am I'm missing something obvious?

I must admit I am going to find this very daunting and hope I'm not biting off more then I can chew.

The problem I seem to be finding as I'm looking up costs and suppliers is finding the Astrodons in 36mm, anyone got any suggested websites? Am I best to purchase the filters from the USA?

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After much deliberation and time researching, I am now very seriously considering doing a U-turn and going down the Mono route, with the view of spending more time on a limited number of targets.

The camera of choice I think would be the Atik 383L plus

EFW2 Filter wheel, 7x36mm

And these filters, Astrodon 3nm Ha, 5nm OIII, 5nm SII and Baader LRGB set.

Does this sound like a good choice and combination? Or am I'm missing something obvious?

I must admit I am going to find this very daunting and hope I'm not biting off more then I can chew.

The problem I seem to be finding as I'm looking up costs and suppliers is finding the Astrodons in 36mm, anyone got any suggested websites? Am I best to purchase the filters from the USA?

You're gonna be over budget once you start adding the filters!

This was pretty much my initial shopping list for my last addition to the collection. However, once I'd done the research & sums I came to the conclusion that I'd rather push the budget just a bit more & buy into the "self contained package" of the QSI that will take the cheaper 1.25 astrodons, has good electronics & cooling which I regard as essential with the Kodak chip, no worrying about spacing issues and a single power & USB connection.

Don't get me wrong, I have 3 Atiks & a EFW2 but the QSI is in a different league, so far I haven't bothered with darks either. Also, on the advice of Ian King I went for the 5nm Ha & SII with 3nm OIII.

I know this is all going over budget but if you are serious about AP (and anyone looking at spending over 2 grand on CCDs has to be) then worth considering. I've looked at it as a long term investment that I had to get right. After all, it's not just concentrating on more hours on limited targets. The way things seem to be going with the weather, you'll need to be prepared to spend weeks, months and with some of my targets I've been trying, years to collect enough data!! So you won't want to be chopping & changing the rig about too much. [emoji3]

Sent from my iPhone using Tapatalk

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