Jump to content

Wratten Filters on a Scoopic MS


Will Montgomery

Recommended Posts

  • Premium Member

Should I order Wratten filters from Kodak for the back filter on my Scoopic MS or just go with the screw on type?

 

I have empty filter holders that can be inserted into the camera, just don't know if quality is an issue with this type, and I have no idea costs for ordering a small Wratten filter from Kodak. I need a #85 for sure and probably a few others for b&w.

Link to comment
Share on other sites

  • Premium Member

:) :) :)

Should I order Wratten filters from Kodak for the back filter on my Scoopic MS or just go with the screw on type?

 

I have empty filter holders that can be inserted into the camera, just don't know if quality is an issue with this type, and I have no idea costs for ordering a small Wratten filter from Kodak. I need a #85 for sure and probably a few others for b&w.

Hi Will,

 

Go with the lens front. The filter behind the lens changes the light path and throws the focus off slightly. You could use them, but the flange focal depth would have to be adjusted because of this back focus shift.

I normally glue down the filter holders on the ACLs.....with the owners permission, of course !!

 

Cheers,

 

Bernie

Link to comment
Share on other sites

Go with the lens front. The filter behind the lens changes the light path and throws the focus off slightly. You could use them, but the flange focal depth would have to be adjusted because of this back focus shift.

I normally glue down the filter holders on the ACLs.....with the owners permission, of course !!

 

Does this info apply also to Bolexes? This is the first time I've heard this...

Link to comment
Share on other sites

It would apply to all behind the lens filter systems. This is especially critical with wide angle lenses, as the depth of focus is very narrow, and the focus shift can throw the image off. You can stop down the lens to increase depth of focus, but another problem is introduced: any dirt or scratch on the filter will register on film.

 

On longer lenses above 75-100mm you can use behind the lens filters without the above problems. Depth of focus is large, and the focus shift not a problem.

Link to comment
Share on other sites

  • Premium Member
Does this info apply also to Bolexes? This is the first time I've heard this...

 

Yes, it does. When a filter is used up front on a lens, it does not change the back focus. By putting a filter behind the lens, you reach the most critical point at which the light bundles to a point. The thickness of the filter changes the light path and brings the focus slightly further back.

 

There are three solutions: 1) Don't use behind-the-lens filters. 2) Change the back focal distance of the lens. 3) Change the flange focal depth of the camera.

 

Cheers,

Bernie

Link to comment
Share on other sites

  • Premium Member
Didn't the Scoopic come with three 72mm filters? I've seen sets labeled "For Canon Scoopic only". They were skylight, 80, and 85.

This one didn't, but I didn't buy it new. Getting front lens filters is easy, I can order from B&H no problem.

 

Interesting that Canon would make the system like that without some sort of back focus compensation; maybe they just thought it wasn't that critical for news gathering.

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...