Soft around the edges?

[John Brady]

I am looking for some advise on edge softness with my 47 sa xl.
I have noticed that there is noticable edge softness in some of my pictures. It seems to be more noticable in the upper corners than the lower corners. For example the foreground looks fine but tree branches in the upper corners look fuzzy.

I am using an Ebony 45su and I am trying to keep the front and rear standards parallel and level. I think the majority of these shots were at f-22. Some with center filter some without.

Is there a sweet spot aperature setting I should be using? Is it a characteristic of this lens, or is it just my lens?

Thanks in advance for your advice.

jb
(sorry, spell check off)

[Scott Davis]

IIRC, the 47 SA is not REALLY meant for 4x5. While it has sufficient coverage to evenly illuminate the full 4x5 frame, it is really a 6x9/6x12 cm lens. As to why more in the upper than lower corners, the only thing I can think of is you may have applied some unintentional fall, or your lens is not centered vertically on your lensboard.

[Steve Hamley]

Sounds like at least partly a centering problem because the "fuzziness" tends to one side/end. Are you using a centered or off-centered hole in the lensboard?

Steve

[Juergen Sattler]

Also check if there is a little screw on the shutter back - I had that when I got my 65mm Nikkor and I didn;t notice it right away and my pictures had that one-sided fuzzy look to it. Remove the shutter from the lensboard and see if there is this tiny screw on the shutter. Remove the screw or drill a tiny hole in your lensboard to accomodate the screw - personally I'd remove the screw before I'd start drilling holes into lensboards.

[John Brady]

Juergen,
I think you may have diagnosed the problem. I recently tried remounting the lens. I have been using a recessed lens board and I wanted to try using a flat board. The flat board would not focus so I put the lens back on the recessed board. When remounting I noticed how hard it was to line the screw up properly. I began to wonder if I had it mounted flat in the first place. I also checked to see if what I thought was the center position for this lens was correct. I took the back off and measured the position. It does appear to be centered correctly. I have not shot with the lens since re-mounting it, but I will check it out.
Thanks,
jb

[Donald Hutton]

"IIRC, the 47 SA is not REALLY meant for 4x5. "

I have to completely disagree with this - it actually lights up a lot more than the 4x5 frame and allows more movment than the image circle quoted by Schneider suggests. I have seen 40x50 inch prints from chromes shot with this lens and they are awesome - right into the corners. Absolutely the best superwide 4x5 lens I've ever used.