Dear Group,

I am looking for exposure compensation figures for the standard P67 extension tubes set. I just haven't been able to find anything on this and am wondering if anyone has a simple table or something to assist with exposure adjustment for each tube.

Thanks, Gordon

-- Gordon Rogers (rogersg@tpgi.com.au), November 11, 2001

Answers

Pentax has a booklet that covers the subject of exposure compensation with tubes. I would suspect that most national offices of Pentax have it. For the USA it would be the Englewood Colorado office. The name of the booklet is "Auto Extension Tubes- Extension Tubes". The booklet is for the 6x7, 67 and 67II. If you use the TTL, it figures the compensation automatically.

-- Steve Rasmussen (srasmuss@flash.net), November 13, 2001.

Gordon:

My Kodak Professional Photoguide, 1st edition, 1975 printing lists the following formulas:

Exposure factor =(M+1) squared, where M=(image size/subject size)

Exf=(M+1)xf, where Exf=Effective f-number for Extended Lens and f=Engraved f-number on lens.

I hope this will help you.

Mark J.

-- Mark A. Johnson (logic@gci.net), November 21, 2001.