Hassy HC 35mm lens

[Boghb]

My shots with this lens show extreme softness in the corners, even at f8 or f11.  I was never thrilled with my CFE 40, but that one seemed much sharper in the corners.

I would appreciate some feedback from other owners: is there some problem with my lens, or is this lens generally this bad?

[MarkKay]

mine is very sharp but i am using an aptus 65 so it is essentially cropped at the edges

My shots with this lens show extreme softness in the corners, even at f8 or f11.  I was never thrilled with my CFE 40, but that one seemed much sharper in the corners.

I would appreciate some feedback from other owners: is there some problem with my lens, or is this lens generally this bad?
[a href=\"index.php?act=findpost&pid=81473\"][{POST_SNAPBACK}][/a]

[Boghb]

I use mine with the P45, so softness appears at the cropped edges -- not even that far out from the center.  I initially thought it was a focus issue, since I always risk it with hyperfocal to use the largest possible apperture, but my center is sharp.

It also appears that more distant objects get softer as you move away from the center.  Could there be some infinity focus problem that is compounded by edge softness?

[Gary Ferguson]

The British Journal of Photography ran an interesting and scholarly article some years ago about the "shell effect". The shell effect afflicts some (but not all) wide angle designs and it's where the true plane of focus curves progresively back towards the camera as you move away from the centre of the frame. So if you focused in the centre of the frame at a point say 20 metres away the actual point of focus at the edge of the frame might be say 15 metres away. In other words it's the opposite of the flat field, process lenses used for photo/mechanical reproduction.

If you're facing and photographing a flat subject (let's say the facade of a building) it sometimes pays to focus slightly beyond the subject in the centre of the frame so that on average across the frame more of the subject is pulled into the acceptable depth of field. The problem is of course worst when the subject is at infinity, because (unless you're using a view camera) you can't focus "beyond" infinity.

You could easily check with your lens by lining the camera up square on to a wall, focusing exactly at the centre, then progressively focusing slightly farther away and seeing if the edge quality improves.

This is one of the reasons I got a digital back in a Hasselblad V fitting, not because I'm a particular fan of the V system (I'm not, as a digital platform it's in the stone age), but because it has two lenses, the Biogon 38mm and the Planar 100mm, which have particularly flat fields, and are therefore relevant for the architectural photography which is the main part of my work.

[Boghb]

Gary

Thanks much for the reply and your helpful articles on focusing.

[rljones]

This is one of the reasons I sold the H2 system and got an Alpa.

The 24XL is flat across the entire field and yields the AOV across a P45/Leaf 65/75 as the Biogon did across a 6x6 piece of film (about like a 19mm on 135 format).

Further, the 24XL and the 12SWA body weigh about the same as the 35mm HC lens too.

-Robert

[Boghb]

Robert

You are right.  I had the Horseman 24XL combo and am now waiting on my Silvestri and 35XL.  This is far superior to the 35HC.  But it is not perfect, since you are limited to F16, and even at that aperture your DOF is not as much as you'd expect.  And with the Alpa, you can't critically focus, so you need to err on the side of a smaller aperture and reduced sharpness.

[ericstaud]

With the Aptus 75 and the Alpa I can critically focus when working on a tripod.  It just takes several captures checking the screen on the A75 at 100%, or working tethered.  The 24xl digitar does not have a perfectly flat focus plane, but this benefits most pictures because the horizon is often at infinity, and the foreground is often only a few feet away.