Jump to content

Angenioux 25-250 mm Lens Focus


Gary Robinson

Recommended Posts

Hi Guys,

I have Angenioux 25-250mm lenses on both my Arri 2b, and BL2. I haven't shot with the BL2 yet, but I noticed that on my BL2 only, when I zoom in and focus, I lose focus when I pull out to 25. Any ideas on why this is happening?

 

Thanks,

Gary Robinson

Link to comment
Share on other sites

Have you checked the flange depth and ground glass on the BL2? With your Angenieux zoom at 250mm the is a less depth of field at the subject and more depth of field with the lens at 25mm, but at the film plane, it is opposite. At the film plane, the depth of focus is much more shallow with the lens set at 25mm than at 250mm! Check your flange depth and ground glass. If it was the lens, it would cause the same problem with both cameras.

 

Hope this helps - it should be cheap to check and fix.

Edited by Frank Cook
Link to comment
Share on other sites

Thanks Frank,

I'll look into it.

 

Have you checked the flange depth and ground glass on the BL2? With your Angenieux zoom at 250mm the is a less depth of field at the subject and more depth of field with the lens at 25mm, but at the film plane, it is opposite. At the film plane, the depth of focus is much more shallow with the lens set at 25mm than at 250mm! Check your flange depth and ground glass. If it was the lens, it would cause the same problem with both cameras.

 

Hope this helps - it should be cheap to check and fix.

Link to comment
Share on other sites

  • 2 weeks later...

notice also that the focus of a zoom is never linear but in an "s" shape

if your focus reference is at the midel you'll be off focus at beguining and end of the lens.

if the mark matches the end you may be way out at the beguining.

 

if the eye focus matches the mesurement focus mark focus on the neg the ground glass will be good.

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
×
×
  • Create New...