Nikkor APO 480mm f9, quick question

[Eric Rose]

I just received one of these lenses from an APUG member. There is a slider (not the f-stop ring) on the lens barrel. What the heck is it for?

Eric

 

[shutterfinger]

Barrel lens with a slot with sliding cover- used for waterhouse stops or drop in filters, your choice.

 

[tkamiya]

It's probably a flat field correction. I see the lens listed as a copy lens.

 

[Shawn Dougherty]

Barrel lens with a slot with sliding cover- used for waterhouse stops or drop in filters, your choice.

Yep. I used one on 8x10 for several years, great lens. I taped the slot closed, wasn't sure if stray light getting in would cause problems but I was fairly certain it wouldn't help. =)

 

[E. von Hoegh]

It's probably a flat field correction. I see the lens listed as a copy lens.

Most process lenses have this slot for Waterhouse stops used in making halftones.
Flat field correction? hardly. These are already flat-field lenses, apochromatic as well.