SXV-M26C vs Nikon D7000

[MarkS]

I'm very seriously considering a new camera for astro-photography.  The money is there, it's just a question of choice. I definitely want to stick with one shot colour because full colour imaging is definitely my forte (especially with my darkish sky) and in my opinion the convenience of taking all colours simultaneously is ideal in our UK climate where you never know if you'll never be able to finish your image because the clouds came over before one of the channels is recorded.  I also want an APS sized sensor to take good advantage of the Bananascope's flat field.

So I'm seriously looking at the Starlight Xpress SXV-M26C.  The body shape of this camera means I could also use it with a C11 Hyperstar, which is a route I may well choose to go down (this is what Greg Parker does, M26C on Hyperstar).  The QHY10 uses the same sensor and is a bit cheaper, which is also a bit tempting but SX do have an excellent reputation for customer service.  However, in all this there's a big BUT.  

The sensor in both SX and QHY versions is the Sony ICX493AQA (http://www.bythom.com/olddslr.htm) which is exactly the same sensor used in the old Nikon D40x (released in the year 2007).  It is dated SuperHAD technology.  Nikon cameras have advanced by leaps and bounds since then.  The Nikon D7000 (same sensor as Pentax K 5 and Sony A580) uses the Sony IMX071 Exmor sensor which is a far superior chip.
Some info on Exmor sensors:  http://www.sony.net/SonyInfo/technology/technology/theme/cmos_01.html

The Nikon 40x and D7000 can be compared here:
http://www.dxomark.com/index.php/Cameras/Compare-Camera-Sensors/Compare-cameras-side-by-side/(appareil1)/680%7C0/(brand)/Nikon/(appareil2)/514%7C0/(brand2)/Nikon
Go to the measurements section and look at ISO, SNR, Dynamic Range etc.
In a sense, this is a direct comparison between the SXV-M26C and D7000 cameras.

So why buy an astro-cam using 6 year old technology when I could buy a far cheaper Nikon D7000 with a far superior sensor and mod it?  This is the question that really vexes me.  Now if Starlight Xpress built a cooled Sony IMX071 based camera I would already be on the waiting list.  But as it is, I now have an almost impossible decision

I'm beginning to veer toward the D7000.  At around £600 it's a cheap stopgap until the day when hopefully one of the major astro-cam manufacturers decide to build a camera based on a modern chip!

Lots of other useful info on the D7000 in this thread:
http://forum.orpington-astronomy.org.uk/index.php?topic=8805

Thoughts anyone?

Mark

[Carole]

I am not into all the technical stuff, but gut feelings are you could wait forever for the right chip to come along, I would say go for the cooled camera and get the SX one you've been looking at.  Can't see the point in getting yet another uncooled DSLR type camera.  

I sort of agree with the OSC camera principle but I have been amazed at the difference in sensitivity with a Mono and am using the two in tandem.  I have filters too, but as you say not enough nights to do an image, so am saving them for when we get a few clear nights in a row.  

Just speaking as some-one who has recently moved from DSLR to a cooled camera both mono and OSC.  

Carole

[Ian]

If you're going to mod D7000 Mark, there seems to be a reasonable number starting to appear on the used market.

You don't fancy a FX sensor then? D800 is a bit tasty at 36Mpixel...

[RobertM]

That is a dicision and a half.  I myself have been wondering the same thing but with the SXVF-m25c and canon 6d.  There are a lot of advantages to a DSLR, not least being portability and convenience.  Also don't underestimate the effect of dark current as well as read noise.  Also whilst the Hyperstar is a game changer it is not particularly flexible and can be frustrating at times.

You can compare DSLR noise patterns at DPreview.  I believe the Pentax k5 is the best of the current APS cameras (same chip as the Nikon).

Unfortunately there are precious few examples of decent images out there taken with anything other than Canons so it's a difficult choice.

Robert

[RobertM]

I should also add that you can try my M25 for a more direct comparison if you wish.

Robert