Correct CCD and Telescope match

[Eris]

Hi everyone. I’m currently doing my homework for an eventual purchase of a CCD imager to be used with my (C11) working in conjunction with a focal reducer of f6.3. I would also like to do wide-angle imaging with some old quality SLR lenses (28, 50 & 135mm) using SBIG’s specified adapter.
Can anyone please tell me what gives the best pixel match and image quality between SBIG’s ST2000XM and ST7XE when imaging through a C11? The ST2000XM has a KAI 2001chip with an imaging array of 1648x1214 at 7.4 microns. The ST7XE has a KAF- 0401E chip with an imaging array of 765x510 at 9 microns.
As mentioned earlier priority will be given to imaging at f 6.3 through the telescope. While I’m told “the ST2000 will give me more bang for my bucks,” I’m more interested in a correctly matched CCD imager for my telescope.

Thanks

[[1ponders]]

I can go one better than that Eris. This program here by Rod Wodaski does all that for you. Select your scope, FR, Camera (or imput your own) and there you are. It's a ripper and saves so much time working it out yourself. I wouldn't be without it

http://www.newastro.com/newastro/book_new/camera_app.asp

[[1ponders]]

The ST2000 will give a resolution of 0.86 arcsec/pixel and the ST7XE gives 1.05 arsec/pixel (with a C11 @ f/6.3). If you can get 1 arcsec seeing you are doing very well.

But with an old 50mm lens @ f/1.8 will give you 36.79 arcsec/pixel.

[RB]

Welcome to the forum Eris.

:welcome:

[ballaratdragons]

Thanks for that link Paul

Now I can see exactly what the size of image I am supposed to be getting on different objects :thumbsup:

Welcome to the forum Eris :)

[Dennis]

You might find this nomogram useful in determining the optimum set up for seeing conditions and subject matter versus focal length and pixel size.

It is a copy of one published in Sky & Telescope.

Cheers

Dennis

[[1ponders]]

We aim to please Ken :D

[JohnG]

Hi

Here is another little program you might want to have a look at:

http://mysite.wanadoo-members.co.uk/astroplover/Main.htm

About halfway dow, under My Freeware, called Astrophotography Settings, you can edit the program to include your own cameras and telescopes, completely stand alone and FREE, there is a screen shot of what it looks like on the website.

Cheers

JohnG

EDIT: Oop's should have checked the link, click on Software.

[[1ponders]]

Thanks John. Another little proggy to add to the desktop :lol:

[rogerg]

I knew how to calculate the right camera for my scope for some time. What I didn't realise is how different my scope's actual focal length was to it's theoretical.

For example at the time I was using a F/6.3 reducer. In theory my scope would've been 1960mm I think??? (hard to remember) .. but in practice it was actually something like 2200!

This is obvious to me now because I understand more and know how changes in the imaging train affects the focal length, but..

My point here is to those who aren't aware, you should perhaps first calculate the actual focal length of your scope so you know that you're using the right input numbers. I did this by taking an image and matching it up in Astrometrica to find my precise focal length - a luxury having already got a CCD. Not sure how you'd do it accurately without a CCD.

[Eris]

Thanks for your help guys.