CMOS or CCD? Nikon/Canon

[The Mekon]

I'm a bit old, but choosing cameras for astro work used to be so easy.
You had to have mirror lock and replaceable screens so it was Nikon, or Olympus.

I am all at sea over this new DSLR business.

Is CCD better than CMOS or the other way around?

I was thinking about a Nikon D90 and then noted someone bagging CMOS. So I started looking at the earlier D80. Now I have seen a thread on another forum promoting CMOS.

What type of chip do Canon use?? it will mean changing my adaptors and lenses, but what are the equivalent Canon models to the above Nikon? Is software availablility a problem for Nikon?

[wasyoungonce]

Well since no replies..I'll have a quick answer...keeping in mid you have an AP130, so, are seasoned. Historically the Canon's have had less noise which made them better for astro-work. Of course cameras like the 300D/350D/20Da helped elevate this status.

Of course other mfgrs make good cameras..of this there can be no question. But it still appears to be the consensus that the canon's still have less dark noise. However, this would not be "the one thing" to make a judgement on what DSLR to buy.

Most DSLR users use the camera at prime focus but if you have a collection of lenses for another type of camera (and want to use them for Astro) then I can understand reluctance to change types, rightly so.

Don't worry about the battle between CCD & CMOS...they both perform well with good designs. Just make sure you get a 16 bit camera..not a 14bit. Gives bigger bit depth resolution!

There are a lot of programs written that support canon features, like: EOS_Movrec (http://sourceforge.net/projects/eos-movrec/files/) (to record video out); APT (http://www.ideiki.com/astro/EOS.aspx) ; blah blah. And ...many DSLR users have their camera front UV/IR filter changed (http://www.alpineastro.com/filters/filters.htm) to allow more "spectrum" thru...makes it more sensitive for Hydrogen gas. This was limited to mainly Canons but I think there are now filters for other types nowdays?

Of course we haven't mentioned probably the most important part...pixel size. (http://www.clarkvision.com/articles/does.pixel.size.matter/) Most modern cameras have around 5.0 microns per pixel, mine is 5.2 micron. Better to maybe have a pixel size of a little larger..lets say 6.0 micron or more. Best to try to match your pixel size to your scope (http://www.newastro.com/book_new/camera_app.php) so you get around 1.5 arc seconds per pixel resolution (or more).

IMHO the larger pixel size cameras give better images than my smaller pixel size camera. I think the mfgrs have been rushing to make larger pixel resolution sensors (for the consumer market) and have to thus make smaller pixel sizes to fit into the sensor size. This does not really fit the requirements we want in a DSLR, for Astro work.

Finally if you do consider a good DSLR for Astro work...maybe you should also consider something like a cooled astro colour camera like QHY8 (http://www.gamaelectronics.com.au/). While DSLRs are good all rounders they cannot match the dedicated cooled astro cameras. Consider a good DSLR costs $1500+ and a QHY 8 ..similar...just a little more.

Anyway...FWIW.:D

[The Mekon]

Thanks wasyoungonce!

I may have found the answer in a preamble to Jerry Lodriguss DSLR book. As you say either type is OK.

You may think I am "seasoned", but not so. As a youth I was into photography and so am familiar with the old SLRs, but aside from a bit of piggy back and eyepiece projection stuff, I have never really put astronomy and photography together.

I must be one of the few A-P owners who does not image! Have had the scope for 19 years now and always just enjoyed visual.

I am leaning heavily to the Nikon D90. (pixel size 5.5 microns and 12.3mb) I have an unsued A-P Nikon adaptor, and a bunch of old Nikon lenses that should be good for both prime focus and piggy back

The D90 can only get cheaper over the next few months as it has just been superceded by the D7000

Thanks again for your input.

John