I have an observation to share that I'm sure you have noticed as well. It seems that stopping down is no substitute for having the lens focused to the exact point. Infinity sharpness using hyperfocal settings is just not as good as having an infinity focus. This is noticable on the 200mm, 300mm, 400mm etc. Even when moving the hyperfocal distance closer to infinity, the sharpness at infinity is still not as good as the infinity setting. However, this effect is not as pronounced in the wide lenses as in the telephotos. The 45mm lens does very well with hyperfocal infinity sharpness. The reason is that this lens and other wide 6x7 lense have more DOF inherently than the telephotos. So even at f/4, out of focus subects do not look really soft as they do with the teles. This makes a difference when stopping down. Even a moderate amount of stopping down on a wide lens brings things to sharpness quite easily. With the teles, it's a struggle. I always have to move the hyperfocal point toward infinity to get any kind of decent sharpness at infinity. If I were using a 200mm on a 35mm system, it is really not a problem, but the 400mm on the 67, it is a challenge. I guess that is one reason why MF cameras are so much harder to use than 35mm.

-- Steve Rasmussen (srasmuss@flash.net), October 25, 2001

Answers

Focus on the subject.

Look at a Large format landscape where the photographer used lense tilt to maximize d.o.f. and pay attention to horizon sharpness. Then look at a medium format landscape photograph (Pentax 67 in my case). The only way to get the medium format to look as sharp as the large format at infinity is to focus on infinity, or very close to it. This is with the 45 and 55 lenses. Hyperfocus results in soft horizons every time. Sometimes this is acceptable when the subject is relatively close and the environment is represented but is not required to be in critical focus. My position is if it needs to be in critical focus (sharp sharp at 30x40 inches)then focus directly on it.

Steve Boothe

-- Steve Boothe (boothers@wwdb.org), October 26, 2001.

This problem is, IMHO, the Achilles heel of all rigid 6x7 cameras. On the one hand, you have fairly long focal lengths with restricted DOF, and on the other hand, no movements to counteract this. You're correct about the near-far landscape shots: focus on infinity and forget about hyperfocal. Even with the 75mm, I never got 100% satisfactory sharpness all over using the DOF scale.

No more problems after switching to LF though ;-)

-- Stefan Geysen (stefan_geysen@hotmail.com), October 27, 2001.

Stefan, what does IMHO means in plain english?

Thanks.

J.G.

-- Jean Grothe (jean.grothe@videotron.ca), October 27, 2001.

Jean, IMHO means "in my humble opinion"

-- Stefan Geysen (stefan_geysen@hotmail.com), October 28, 2001.

I find hyperfocal settings in MF to be rather optimistic, even for the 45 mm. Has anyone tried the Zoerk tilt (and shift) systems on a P67?

-- Tony Cunningham (cmserv@wxs.nl), October 28, 2001.