[joelovotti]

I have a Pentax-A 28mm f2.8

I understand the hyper focal relationship between the Red 10 foot distance and the Red f.8 but....

The first depth of field mark to the left of the scale is also RED.

What does this represent?

Thanks,
joe

[blackcloudbrew]

It's for IR focusing I believe.

[Just1MoreDave]

The mark above the orange diamond next to the 4? Yep, a mark to aid focusing when you're using an infrared filter.

[stevebrot]

It's for IR focusing I believe.

Ding! The prize goes to the brewster!

The IR mark is present on almost all the manual focus lenses I own. I have never used it, but I imagine the flow would be to establish focus through the viewfinder, apply the offset and shoot.


Steve

[stevebrot]

The mark above the orange diamond next to the 4? Yep, a mark to aid focusing when you're using an infrared filter.

Dave brings up the other good point that the viewfinder can be pretty dim when all the needed filters are in place. I have read of people composing (on tripod), focusing, adjust focus offset, and THEN put the filter on the lens! Long exposure times too.


Steve

[Ex Finn.]

From Super-Program owners manual.

[joelovotti]

Hey, thanks every one. Nothing I will use but at least I understand the lens fully.

Thanks again,
joe