Nikon D7000 for Astrophotography

[Mike]

I've decided to give my Nikon D7000 a go for astrophotography. From what i've read about the camera and what i've seen produced so far it should be pretty good. It has very low noise and has a massive advantage of my Canon 1000D in that I can crank the ISO all the way up to 25600 in Live View mode if necessary to enable me to see stars clearly for and focus on them. Live view on the Canon is pretty useless as you have no way of adjusting the gain. It is therefore very dim, making focusing a real challenge. I have found the Canon to be a very frustrating camera to use, especially after being used to a decent quality cooled CCD camera. Another advantage is the HD Video mode, again with manually selectable ISO and shutter speeds, which should also make it useful for planetary imaging.

So, i've bought an adapter from Ian King and will give it a try out the next chance I get to see how it compares with the Canon.

[The Thing]

Don't Nikons have a IR light in the shutter box area for timing the shutter?

[Mike]

Not that i'm aware of. If they do use one it would be on and off for milliseconds and no doubt at a frequency beyond the CCD sensitivity.

[mickw]

If you're using APT for capture with the Canon, you could set up a Plan at max iso for focusing although that would only be 1600 with the 1000D

[MarkS]

Mike,

This thread discusses the internal IR LED and also mentions the Nikon algorithm that "removes stars":
http://forum.orpington-astronomy.org.uk/index.php?topic=7188

I don't know if the D7000 is affected by the IR LED but I guess you are not going to do an H-alpha conversion in any case, so it won't be an issue.  It might also be the case that the D7000 is unaffected by the "star removal" algorithm.

I agree with everything you have said and I have no doubt that the D7000 is capable of producing images as good as the Canons, though I would love to see some hard statistics in terms of read noise, dark current and QE (quantum efficiency).  I'm certainly very interested in how well it might perform for high speed planetary imaging.

The only point I would add is that if you intend to use it for deep sky nebulas then without an H-alpha conversion you will suffer seriously impaired sensitivity to that wavelegth.   For that reason alone my own preferred route is to buy a cheap secondhand Canon which can be modded and used exclusively for astro-photography.

Mark

[Mike]

Mark I have read about the "Star Eater" algorithm, but apparently that has been fixed with the D7000. There is a discussion about it HERE

I am aware it will not be as sensitive to the Ha. I do still plan on getting another cooled monochrome CCD again at some time in the future. If the D7000 works well I can use it as a one-shot colour camera for when time is limited or for none nebulous subjects. The D7000's main use will be for standard photography.

[MarkS]

Really good news on the "star eater" algorithm!

This thread gives the read noise as 3 electrons:
http://forums.dpreview.com/forums/read.asp?forum=1034&message=38180817
It's an extraordinarily low figure!  The equivalent figure for the Canon 350D is 5.3 electrons.

Mark

[RobertM]

I'm sure you're right about the noise reduction as I read the same thing but also about the IR shutter illumination too.

LifePixel does an IR mod service and this is what they say : http://shop.lifepixel.com/1-Convert-your-digital-camera-to-infrared-IR-only-/3-Nikon-DSLR-infrared-conversion-service-p4.html

Nice camera - it would be good to give Canon some competition in this market.

Robert

[MarkS]

LifePixel does an IR mod service and this is what they say : http://shop.lifepixel.com/1-Convert-your-digital-camera-to-infrared-IR-only-/3-Nikon-DSLR-infrared-conversion-service-p4.html

Useful link Robert.  I didn't realise how many Nikon models were affected by the IR shutter illumination problem.

[JohnP]

Well I look forward to results. I just got myself a super cheap 400D with a view to 'modding' it... John

[MarkS]

I just got myself a super cheap 400D with a view to 'modding' it... John

Wow John! 
Multi-megapixel astro-images!

Mark

[Mike]

Look forward to see what you can do with the 400D John.

[mickw]

Lifepixel seem to suggest that the IR LED could cause issues with long exposures or high iso.

Although I would assume that the standard IR cut filter would prevent this

[MarkS]

Lifepixel seem to suggest that the IR LED could cause issues with long exposures or high iso.
Although I would assume that the standard IR cut filter would prevent this

Yes, I'm sure they mean it only happens following the IR mod.

[RobertM]

The internal IR cut filter probably bleeds a little IR light which might show up given a long enough exposure and high enough boost to the signal.  On the other hand it might well 'flat' out if not too bad just like amp glow.  Their statement also seems to indicate that the IR shutter LED is permanently on

I wonder what wavelength light the IR LED emits ... unlikely to be Ha I would have thought.  If that's well beyond 656nm then it could be filtered out so at least you'd get Ha (though not all infrared).

Robert

[Mike]

I did a 5 minute exposure yesterday with the lens cap on and apart from a few hot pixels nothing else showed up at all.

[Mac]

Just a thought,
Nikon use the IR sensor to measure the EXACT speed of the shutter so that the shutter module can calibrate itself.

There is no speed measurement on Bulb, so it might actually turn it off.

I'll have to test my D3 and see.

Fingers crossed they release an updated firmware for the D3 regarding the noise removal.

Mac.

[MarkS]

There is no speed measurement on Bulb, so it might actually turn it off.

Interesting point - it could well be the case ...

[Mike]

Just an update on using my Nikon D7000 for astrophotography.

I have now purchased an intervalometer. It cost £14 on eBay (that is not my hand) :-



I also found some control software called 'Control My Nikon' which was £15 and is similar to APT in some ways. I can do live viewing on the full screen and control exposure, etc. it also automatically downloads any images taken with the intervalometer. So with both of these items I can now focus the Nikon properly and have automated control for long exposures.

Now all I need is a clear night to test it out.

[RobertM]

Looking interesting... http://www.lifepixel.com/infrared-filters-choices

[Mike]

Yes I was looking at that yesterday. They do an astro conversion too. However I did buy this camera specifically for terrestrial imaging so don't have any intention of getting it modded.

Maybe if it turns out to be a nice camera to use unmodded I may consider buying another body and having that converted in the future. However, if I was going to spend that kind of money i'd rather pay a bit more and get a decent high resolution cooled astro-cam.

[mickw]

Certainly looks promising Mike

[Carole]

It will be interesting to see how this performs Mike. 

I agree with you about the Live view on the Canon, it only sees the brightest magnitude stars, so I tend to do my focus on one of my alignment stars and that works, but it's pretty hopeless for anything else except M42 where you can actually see enough to centre the object.  I got quite a surprise when I used my Atik for the first time at how much more I could see.

I've also got one of those remote controllers, I used it in Iceland, but I find it rather piddly to try to programme and difficult in the dark, but I guess practice will make perfect, but it certainly works OK once you've programmed it.

Will watch the progress.

Carole