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Old 22-07-2014, 09:48 AM
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archioptic (Nathan)
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DSLR upgrade

I'm looking to upgrade my camera sometime soon. I currently use a Nikon D3100 which has been working great, but I feel my final image quality, particularly in regards to noise levels, is limiting. I image through both my scope (Skywatcher BD ED100) and camera lenses so I'd like to stick with a DSLR for now as opposed to moving to a CCD imaging system.

I've been considering purchasing the Nikon D600 for the full frame bonus of better ISO performance but I'm concerned that the vignetting on the scope would be excessive. I've also been looking at sticking with the crop sensor and going for the D7000 or D7100 but I'm not too sure if the raw image quality would be worth the upgrade from the D3100.

Because all my current lenses fit my Nikon I'd like to stick with the Nikon system, but I'd definitely consider moving to Canon if the pros out-weighed the cons.

I guess what I'm asking is:
Is it worth moving to full frame from crop sensor? Anyone familiar with a FF&ED100 set up who could comment?
Is it worth moving to Canon at this point? Besides the software support available is there any other benefit? I've been managing fine without it so far.
With a moderate budget in mind (<$1600) are there any other options I should consider?

Any help is greatly appreciated.
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  #2  
Old 23-07-2014, 09:26 PM
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Originally Posted by archioptic View Post
Anyone familiar with a FF&ED100 set up who could comment?
I'd like to know this also.

If FF does work on the ED100, consider the Sony A7s. Low noise high ISO and with an adapter will fit Nikon lenses. Otherwise upgrade to a model with 14 bit ADC.
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Old 24-07-2014, 08:07 AM
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rmuhlack (Richard)
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Apparently astro software support for Nikon is catching up - see here: http://forum.otelescope.com/post/bac...pid=1282424740
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Old 24-07-2014, 10:50 AM
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Amaranthus (Barry)
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Sony software support is not great, especially for remote camera control. Otherwise, the cameras are top notch - it's a shame!
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Old 24-07-2014, 11:03 AM
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killswitch (Edison)
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I had quite a bit of vignetting on my D800 from what i remember.
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Old 24-07-2014, 11:29 AM
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I had quite a bit of vignetting on my D800 from what i remember.
That's disappointing. Would you have an uncropped pic to show?
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Old 24-07-2014, 03:16 PM
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Saturn%5 (Graeme)
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Hi Nathan
Have you looked at the d5100 it gets some good reviews for astro work.

Also with Backyardnikon in beta mode this should make life better for Nikon users

cheers

Graeme
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Old 24-07-2014, 04:24 PM
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codemonkey (Lee)
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The D5100 is pretty damned good, but there's a number of issues with using it for astro work. First off, if you want to shoot nebulas, like any other dSLR it's got a pretty good near-IR cut filter that significantly increases exposure times.

Secondly, it has no support for bulb over USB, so you'll need a third party intervalometer if you want (automatically-triggered) exposures over 30 seconds. This could be a purpose built hardware device, or a DSUSB that enables you to hook up to things like Backyard Nikon.

Finally, if you decide you want to have your camera converted, it's harder to find places to do that, particularly if you want a mono conversion.

I've got a D5100, and it's great, but honestly with the sort of money you're talking about spending I'd recommend keeping that D3100 which is perfectly acceptable for general use, and go with a mono CCD. If you're insistent on OSC, I'd recommend a OSC CCD then instead.

Until recently I was planning on sticking with dSLR, thinking that bang for buck it was better than a CCD, but once I tabled all of the important things and gave them a weighting, I found that bang for buck you can't go wrong with a purpose built CCD.
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Old 24-07-2014, 06:27 PM
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killswitch (Edison)
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Quote:
Originally Posted by cometcatcher View Post
That's disappointing. Would you have an uncropped pic to show?
Sure. Prime focus using Bintel T-ring/adapter.
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Old 24-07-2014, 08:39 PM
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Thanks for that. There goes my grand desire for FF. Not to mention how much worse it would be with a reducer.
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Old 25-07-2014, 05:54 AM
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Sure. Prime focus using Bintel T-ring/adapter.
Maybe a 2" prime focus adapter from http://www.telescopeadapters.com/ would help. You get a greater clear aperture with these units as they are a combo unit with the T-Ring being part of the adapter. Must order specific for your camera.
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Old 25-07-2014, 11:41 AM
DJT (David)
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Sure. Prime focus using Bintel T-ring/adapter.
Was that with a 42mm or 48mm Tring? When using the SW Reducer flattener, I had to use the 48mm so might be a different outcome?
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Old 25-07-2014, 01:07 PM
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archioptic (Nathan)
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Thanks very much for the replies. I've definitely got a few more things to consider.

Quote:
Originally Posted by DJT View Post
Was that with a 42mm or 48mm Tring? When using the SW Reducer flattener, I had to use the 48mm so might be a different outcome?
David, what did you use to image with the ED100 & SW FF/FR setup? Was it full frame or cropped sensor?
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Old 25-07-2014, 01:12 PM
DJT (David)
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Quote:
Originally Posted by archioptic View Post
Thanks very much for the replies. I've definitely got a few more things to consider.



David, what did you use to image with the ED100 & SW FF/FR setup? Was it full frame or cropped sensor?
Cropped sensor which worked fine but doesnt answer your question. Cant recall what the vignetting was like but flats dealt with any issues.
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Old 25-07-2014, 01:22 PM
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killswitch (Edison)
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Quote:
Originally Posted by DJT View Post
Was that with a 42mm or 48mm Tring? When using the SW Reducer flattener, I had to use the 48mm so might be a different outcome?
Not sure.. but its these two

http://www.bintel.com.au/Astrophotog...oductview.aspx

http://www.bintel.com.au/Astrophotography/Camera-Adapters---T-Rings/Nikon-T-Ring/1227/productview.aspx

The inner diameter does look restrictive compared to the sensor size, so perhaps it is the 42mm.

Im not happy with the Bintel T-ring as theres abit of play when it attaches to the camera mount.
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Old 25-07-2014, 01:40 PM
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I have not used a full frame DSLR/Mirrorless for deep sky work only APS sized but in mono CCD I have used 35mm full frame sized sensors.

Basically you need a corrected circle of light about 44mm for full frame, 54mm for the 16803 chipped cameras which are bigger than full frame.

I had a Tak FS152 with a 2.7 inch focuser. With the full frame CCD I found I got bad coma in the outer corners. When I tried a small flattener I got bad vignetting.

I replaced the focuser with a 4 inch and the troubles disappeared.

My TEC180 scope has a 3.5 inch focuser and that has no problem.

My TEC110 scope has about a 2.7 inch focuser and field flattener (I'd have to measure it maybe its 3 inches) and no problem with a 16803 chip.

So depends on the scope but for sure you will need a field flattener. I think you can forget about a reducer that will work unless you go Tak and larger focuser. And even then it will be problematic and unlikely to work (maybe the APM Riccardi one will work?? For an ED100 probably a Tak 4 inch flattener would work. They seem to be fairly generic in that they work on lots of scopes (I use a 4 inch Tak flattener on an AP140, a TEC180 and it works beautifully).

The first thing you would do is open up the existing aperture and that is usually the DSLR adapter. Astrophysics make a cheap wider open DSLR adapter which would not cost a lot to try out.

Full frame is always better than APS simply by physics. A larger surface collection area of the sensor equals a number of stops better low light performance depending on the sensor.

On the subject of cameras - the Sony A7S is the low light king but the difference only kicks in above ISO6400, at or below that an A7r/A7 matches it so does a 5D3, 6D. Above that and it says good bye to everybody else!

But then what is the advantage of ISO12800 in a deep sky shot? Answer - nothing.

ISO is simply amplified gain of the existing signal. I think sometimes it is done before conversion to digital and sometimes after. So ISO is often optimised for a certain point. For example the Nikon D800 ISO is optimised for ISO1600.

DSO shots and a DSLR are best done around ISO800. If you look at mono CCDs you'll see the gain used on the signal is minimal - like just above 1.

But APS versus full frame - I say go for the real estate. You can always crop a vignetted image but you can't make your image bigger from an APS.

Look at the comparison tool at DPreview to see the noise differences between the various models. Then factor in amp glow which they don't talk about. Then factor in software support. A modified 6D would be my choice at present. Perhaps a modified Sony A7s would be nice as well. A modified Sony A7s could be sensational. It also has well depth of 157,000 electrons which is considerably more than even the best mono CCDs currently in use. QE of 58% is also very high, again on par with most of the best mono CCDs and better than many.12 megapixels also means smaller file sizes. It also has a very large dynamic range - greater than most DSLRs. An SBIG STL11 which has stood the test of time and is the most popular astro camera probably of all time and its 11mp.

Greg.
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Old 11-08-2014, 10:44 AM
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The D5200 is a good camera, if available at a good price -- might be another camera you might want to consider.
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Old 11-08-2014, 10:48 AM
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I had a D5200, and am very satisfied with the quality of the pictures. Everything is extremely sharp with superb autofocus. I don't think you can go wrong with either choice http://thedigitalcamera.net/nikon-d5...he-difference/
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Old 11-08-2014, 01:01 PM
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acropolite (Phil)
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I've used a Canon 5DII on my ED 80 and skywatcher reducer (specific to that model) with the special wide t mount and can't recall seeing any vignetting.

FWIW the dedicated Skywatcher reducer screws on to the standard SW dual speed focuser after removing and enables the widest possible imaging path. I can't see any reason for nikon to be any different provided the same focuser, reducer and tmount are used.
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Old 11-08-2014, 01:52 PM
PeterEde (Peter)
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If you can afford FF it's better to have crop some vignetting than not have enough room for the magnification to fit on the sensor whole?
Having said that I use a 60D. I'm not handing out an extra $1000 for a few mm of sensor room. I'd go a 6D but it does not have the flip out screen.
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