Jump to content

sgl_imaging_challenge_2021_annual.thumb.jpg.3fc34f695a81b16210333189a3162ac7.jpg

Focal Reducer problem


Recommended Posts

As a newcomer to imaging, I get confused easily. I have been taking images using a Canon 350DSLR at prime focus on my LX90 for a few weeks. I am both frustrated and pleased at the results. Getting sharp focus is SO HARD ! I recently got a flip mirror and all seemed simple. Then, getting ambitious, I splashed out on an f6.3 focal reducer - the idea being lower magnification and wider field. Seemed a reasonable idea to me. But, problem - I can't seem to reach focus with the focal reducer in place.

I seem to remember reading about this being a "back focus" issue. Can anyone enlighten me? Would the problem be solved with an extension tube? Sorry for the stupid questions - but but I need some guidance here. :insects1:

Confused of Glasgow

Link to comment
Share on other sites

Hi Confused!!

It's a killer isn't it! I have the same issue and mine's only a .5 reducer!

The back focus is the problem - which means that the focuser can't travel far enough DOWN for the light to come to focus. This is a problem with the newtonian design.

I have been playing with different optical configurations, but have not yet managed to find one that works... :lol:

Link to comment
Share on other sites

Yes, I have the flip mirror in situ. Order is as follows: Telescope back - f6.3 focal reducer screwed into rear cell of 'scope - flip mirror. No diagonal.

Can't get enough back focus to focue EP on flip mirror. As EP is parfocal with camera focal plane - can't get focus on camera.

Very frustrating. Read the Meade instructions carefully, and down at the bottom of these is a statement that some 'scopes may not be able to achieve focus with both a flip mirror and reducer in place - grrrrrrr.

Can't think of a way around this.

Tom

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • 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.