Attaching a camera to my scope

[jdg600]

Hi,

I'm new here so I hope I'm posting this ion the right place. I'm fairly new to astronomy having been observing for the last year or so with a telescope (Skywatcher ST-80) that my girlfriend bought me as a Christmas present. Anyway, I've now bought myself a Skyliner-150 dobsonian and am keen to try taking some lunar images with it. To this end I am thinking of buying a something like a Praktica MLT SLR as these seem cheap on Ebay but I don't know how to attach the camera to my telescope. The telescope manual says that a SLR can be attached directly to the scope but I assume that some kind of adapter ring is needed.

Any advice would be much appreciated,

John

[RichieJarvis]

Hi John,

Welcome to SGL!

What you need is a way to convert from the Praktica fitting to a standard T-Mount fitting. The T-Mount fitting is a 42mm thread (not to be confused with M42 threads, because the spacing is different) which is what most astro-kit uses. You can buy these for most cameras quite easily - Jessops sold mine in the shop (but I have a Canon!)

You can then use another adaptor to go into the telescope. An example of what I mean is here

This part of the site also lists Praktica fitting to T-Mount fitting here

The way this works is that you remove any lenses from the SLR camera, put the T-Mount adaptor onto the SLR, and then screw the T-Mount nosecone into the front. You can then put the camera into the telescope focuser in place of the eyepiece. This is called 'prime-focus' imaging by the way. Have a look here for a more detailed explanation:

I really would recommend going down the Digital SLR route though - its alot easier than old-style film, as you can see whats going on immediately.

Cheers,

Richie

[jdg600]

Hi Richie,

Thanks for your very helpful explanation of how to attach a camera to my scope. I am hoping to eventually go down the DSLR route but, unfortunately, funds dictate that I use 35mm film for the moment.

I would like to ask one more question if I may. My telescope has a focal length of 1200mm so I think I should get a magnification of 24x when my SLR is connected. Is this correct? and is this magnification high enough to get decent lunar images? Also would it be possible to obtain images of Jupiter with this set up on a dobsonian or would the longer time exposure needed require tracking.

Thhanks,

John

[Cornelius Varley]

Hi Richie,

Thanks for your very helpful explanation of how to attach a camera to my scope. I am hoping to eventually go down the DSLR route but, unfortunately, funds dictate that I use 35mm film for the moment.

I would like to ask one more question if I may. My telescope has a focal length of 1200mm so I think I should get a magnification of 24x when my SLR is connected. Is this correct? and is this magnification high enough to get decent lunar images? Also would it be possible to obtain images of Jupiter with this set up on a dobsonian or would the longer time exposure needed require tracking.

Thhanks,

John

You can work out how big the moon will appear in the camera in millimetres by dividing the focal length of the telescope by 110.

Lunar Photography

Anne Dittmers Lunar Photography

These links will help you on the slippy slope to lunar photography.

Peter

[RichieJarvis]

Hi John,

I thought that might be the case! Be careful, you'll get the bug and end up spending loadsamoney

Yes, the magnification will be 1200mm / 50mm = 24x (Focal Length of Telescope / 35mm Camera focal length @ 1x Magnification)

You will probably find 2 things - firstly, that you get alot of vingetting on the image - this is because the secondary mirror in your Dobsonian won't be large enough to illuminate the whole of the film. You should therefore make sure that the image is as central as possible in the camera viewfinder.

Secondly, at 24x mag, you should get the whole disk of the moon in the picture.

I would expect Jupiter to appear as a small disk. You should be able to see the moons. You will probably need to track for that though.

Hope that helps!

Cheers,

Richie