Can we use Camera Lenses for star gazing

[addy]

Hi

Just now a stupid question poppe up in my mind.. I have a 400mm focal length f/5.6 EOS mount Lens.. Can I use it for star gazing. Its an APO lens and as such it should perform better than my 80mm ST achro.

Can I get some kind of adapters (EF mount to 1.25"/2") so that we can use a diagonal and eyepieces.

Any references or links related to this topic will be highly appreciated.
thanks in advance..

regards
Addy

[blurblock]

Hi

Just now a stupid question poppe up in my mind.. I have a 400mm focal length f/5.6 EOS mount Lens.. Can I use it for star gazing. Its an APO lens and as such it should perform better than my 80mm ST achro.

Can I get some kind of adapters (EF mount to 1.25"/2") so that we can use a diagonal and eyepieces.

Any references or links related to this topic will be highly appreciated.
thanks in advance..

regards
Addy

Don't think there is any kind of adapter to EF mount for your eyepieces.

[weixing]

Hi,
It may be possible if you can get the correct connector.... but I doubt the quality will be better than a 80mm scope... because the camera lens got lots of element, so light lost is higher.

Have a nice day.

[addy]

yes.. it does have more optics than my 80mm achromat.. but on the other hand it has APO glass and so it might give me better contrast and lesser CA... Also it is designed for photgraphy so it might give me a more flatter field.. I can still expect it to perform like a 60-70mm APO ..dreaming too much

I am not so sure about adapters.. I have seen pentax M42 screw mount to 1.25" adapters but have yet to find EF mount adapters..

Steven Mogg has some interesting things... check this out http://webcaddy.com.au/astro/slr_to_web ... ctures.htm

cheers
Addy

[kayheem]

yes.. it does have more optics than my 80mm achromat.. but on the other hand it has APO glass and so it might give me better contrast and lesser CA... Also it is designed for photgraphy so it might give me a more flatter field.. I can still expect it to perform like a 60-70mm APO ..dreaming too much

I am not so sure about adapters.. I have seen pentax M42 screw mount to 1.25" adapters but have yet to find EF mount adapters..

Steven Mogg has some interesting things... check this out http://webcaddy.com.au/astro/slr_to_web ... ctures.htm

cheers
Addy

Hi,

I do believe it is do-able, but it would not be easy. The most difficult part is to get the focal plane far out enough to accommodate a diagonal (assuming you do want to use 1 for comfort).

The next step is to get an end-cap of an EOS-mount lens. Cut a hole in the centre of the cap and super-glue the male end of the diagonal on (after removing the 1.25" barrel).

If you want something more sturdy and more presentable, get a machinist to do the adaptor, modelled after the end-cap.

Do a dry run by mounting the APO lens and use an eyepiece to see where you can come to focus. Unfortunately, the focus travel of a camera lens is extremely limited. What works for 1 eyepiece will not work for another, except if they are very close to being parfocal.

Kay Heem

[Airconvent]

I do believe it is do-able, but it would not be easy. The most difficult part is to get the focal plane far out enough to accommodate a diagonal (assuming you do want to use 1 for comfort).

The next step is to get an end-cap of an EOS-mount lens. Cut a hole in the centre of the cap and super-glue the male end of the diagonal on (after removing the 1.25" barrel).

If you want something more sturdy and more presentable, get a machinist to do the adaptor, modelled after the end-cap.

Do a dry run by mounting the APO lens and use an eyepiece to see where you can come to focus. Unfortunately, the focus travel of a camera lens is extremely limited. What works for 1 eyepiece will not work for another, except if they are very close to being parfocal.
Kay Heem

mm...all this is high academic since no one in his rigtht mind will spend money to degrade an expensive photographic lens just so to do something that it was not designed to do. the resultant scope will lack aperture and probably provide dimmer images due to the additional glasses within.

It would be better to just go and buy an Orion 80ED (maybe cheaper too!.

rich

[kayheem]

mm...all this is high academic since no one in his rigtht mind will spend money to degrade an expensive photographic lens just so to do something that it was not designed to do.

rich

Hi Rich,

That may be true, but it is the tinkering that is half the fun. I do it all the time.


Kay Heem

[MooEy]

i guess what u will need is to machine a piece of aluminum that is exactly the same as the lens cap, maybe with a hole to fit a 1.25inch barlow and diagonal.

~MooEy~