Being new to teleconverters, I have a couple questions. I know that by adding a 1.4X TC to my 500/4.5, I'll lose a stop of brightness; f/5.6 will now be f/8. But I'm confused about the difference between "actual aperture" and "effective aperture." How literally will I have f/8? Will I be receiving only the drawbacks of a smaller f/stop, or also one or more of the benefits? By this I mean:
1. Let's say that without a TC, the lens would deliver 40 lpm of center resolution at f/5.6, 50 lpm at f/8. How much resolution will I have when my aperture ring is set to f/5.6? I always hear that I'll "lose sharpness" with a TC. But if my lens gains sharpness as I stop down, wouldn't that largely compensate? Or is the answer "It doesn't work that way," because the lens diaphragm still opens to f/5.6 so I'm still accepting light from the more distortion-prone edges of the front element? 2. Let's say that without a TC, the lens would deliver 0.5 m of depth of field at f/5.6, and 0.7 m of DOF at f/8. How much depth of field will I have when my aperture ring is set to f/5.6? Paul Franklin Stregevsky 13 Selby Court Poolesville, Maryland 20837-2410 [EMAIL PROTECTED] H (301) 349-5243 - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
