Jump to content

Banner.jpg.b89429c566825f6ab32bcafbada449c9.jpg

400mm Canon lens vs 400mm telescope


Recommended Posts

If I have a 400mm, f/5.6 (72mm aperture) is that "roughly" the equivalent to a refractor with the same aperture, f, and focal length? If so, purchasing a 80mm aperture telescope would be a bit redundant since that size is already covered by my DSLR lens? So, perhaps, I should go to something like 120 - 130mm aperture as my next step? (Astrophotography of galaxies and nebula is the goal).


Thanks, Lloyd

Link to comment
Share on other sites

Quote

 

I guess what I'm asking is that if I already have the 400 mm Focal Length camera lens (with about 1.6 arc-sec resolution), I should not go out and get a 400 mm scope but rather something in the 800 mm focal length range with about 0.96 arc-sec resolution so as to go after smaller objects than I can already to with the DSLR lens. Am I thinking about this correctly?

Link to comment
Share on other sites

very interesting. Being new to this, how would a Canon L series pro photographic lens compare in those areas you mentioned to a telescope lens? I'm sure the answer is "that depends" and then something about quality and price but can any general statements be made? If I have an $1,800USD 400mm Canon lens, would it be significantly worse in those areas than an $1,800 400mm telescope? Or is there just no way of telling?

 

Thanks, Lloyd

Link to comment
Share on other sites

You may wish to establish contact with Stuart 

https://stargazerslounge.com/profile/27141-stuartjpp/

He has produced some sensational images of DSOs using his L Series 600mm lens. He'd be able to describe any field curvature issues encountered. But I've never seen any. 

If he can achieve those results with an L Series lens, I'd say your 400mm (if it is an L series) would be a close match for a 400mm scope. If you are willing to spend, I'd say spend on something that follows your logic and which doesn't duplicate to quite the same degree 

Simon

Link to comment
Share on other sites

I have a cheap 400mm tele and I think the main issues are harder to focus and less light gathering power than most scopes, but it seems to control CA very well and lacks obvious abberations even if it isn't pin-sharp - possibly some of this is because it is relatively slow.

Tele lenses are mass produced compared to scopes so you sometimes get better optics at any given price point with a lens.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.