Meade DSI

doh!! I just got an email saying that Meade don't ship outside of the US!
can't get scope! thanks all for help!

I'm not sure there's a calculation out there that would equate the DSI in a particular scope to a particular eypiece... But there might be!

The usual description for any imager in any OTA is the field-of-view you'll get.

For the DSI and an 8" SCT, the FOV is 10 * 13 arcmin. You'd need a mosaic of about 8 images to cover the full moon.

Thanks all for your help!

Comet hunter you can buy meade products over here. Just not direct from meade.

The two meade dealers in ireland, I know of are andromeda optics and andy mccrea in north down telescopes. There are also many UK dealers who will ship here.

Let me put a bit of perspective around the whole focal lenght thing for you. The important thing about any camera/telescope combination is not about magnification but about how much (in area) of the sky you can fit in and also about the resolution you can acheive. Those factors determine the detail you can expect to acheive in your astro photos.

Let me put some figures behind your meade 8" and dsi example.

The DSI PRO has a sensor which is 510x492pixels in size. That is the image size that will appear on your screen. Now each pixel is 9.6x7.5microns (1/10000s mm) across.

The formula to calucluate how much of the sky each pixel sees is;

Field of View = 3438arcminutes x pixel dimension /focal lenght

Calculating this out you get for each pixel on the dsi
.9902 arcseconds x .7735 arcseconds. So each pixel will see that sized piece of sky. Now that we know that we can see that the entire chip will cover a piece of sky (510x.9902) * (492 * .7735) = 505 x 380arcseconds.

In arcminutes (1/60 degree) thats 8.41 x 6.34 arcmins. Now that is a really small piece of sky.

In practice this means that you would fit in small objects like some, galaxies, planets etc but you wont fit in many of the bigger objects like nebulae and large galaxies. You can get a focal reducer to make the field of view a bit larger but not by much.

So the question you really should be asking yourself is what you want to photograph. If those wide angle images of gas clouds etc are your thing then this is not the right combination, the field of view is too small. However if imaging a faint distant galxy is your thing then it will work well.

I hope I havent confused you even more!!

:oops:

My calc was using a focal reducer to bring the OTA down to F/6.3.

Dave G's calcs are perfectly correct for f/10

Thanks