Blurred edges from wide angle for 8X10 -- 150 Super-Symmar XL

[putri]

IM USING A SCHNEIDER 150MM SUPER SYMMAR F5.6 LENS XL ASPHERIC MC 105 DEGREES

AND I GET BLURRED EDGES FROM MY 8X10 CAMERA SHOT WITH NO TILTS OR SHIFTS.

[marionovak]

Hi Russel,

 

Strange, I don't use this lens, however, I'm familiar with it. I went to Schneider site again and I pulled out chart with lens coverages and for this lens image circle is way beyond 8x10 format edges, I ordered this lens, I should have it in a week or so and I will let you know what my results are,

[marionovak]

Schneider tech specs are 375 mm image circle for this lens, which is 14.7"

[kelly_flanigan1]

"Coverage" is less wide open. It is in data sheets usually with a lens stopped down several stops. What F stop do you have your "blurred edges" with?

[putri]

i shot with a small aperture f45!so the coverage of the leans is ok i guess.but what causes

the bluurness on the neg edes?strange.i made sure the back was parellel and even the lens

centred and not shifted up or down.

[kelly_flanigan1]

Try some shots at F22; your corners might be twice as sharp. :) If your lens is sort of diffraction limited at F44 and F22; then F22 will have about twice the resolution.

[putri]

wouldnt that make my foreground blurred then if i need the depth of field?

[michael_briggs2]

<p>Schneider's pdf datasheet specs a 386 mm diameter coverage at f22 (<a href=" http://www.schneideroptics.com/photography/large_format_lenses/super-symmar_xl/">http://www.schneideroptics.com/photography/large_format_lenses/super-symmar_xl/</a>).

Stopping down to f45 would probably reduce sharpness due to diffraction, but I don't think this explains the symptom of edge blurriness -- diffraction would effect the image everywhere.</p>

 

<p>The MTF curves for f22 and infinity show some falloff in image quality at the edge of the coverage (as do all lenses), but they are quite good. They are excellent in the inner 80% of the image circle, which portion will cover 8x10 without movements. So there shouldn't be any edge blurriness in Russel's setup.</p>

 

<p>The Super-Symmar-XL lenses are very sensitive to the separation of the lens cells. I suggest checking that the lens is correctly mounted. For example, if incorrectly installed in a thick lensboard, the lensboard might prevent the rear cell from seating correctly. Has the indexing screw been removed from the shutter? This might tilt the entire shutter.</p>

 

<p>If these easy ideas don't explain the problem, I suggest another test with a flat subject. A good subject is a brick wall. Make sure that the camera is level and perpendicular to the wall. If it still seems that the lens doesn't have the coverage that it should, then probably you should send it to Schneider to be checked (in the US: <a href="http://www.schneideroptics.com/service/">http://www.schneideroptics.com/service/</a>).</p>

[michael_briggs2]

"wouldnt that make my foreground blurred then if i need the depth of field?"

 

Yes, don't let some idea of optimimum aperture re diffraction take over. Generally depth of field is more important to the viewer. They won't have a comparison photo to judge whether a different aperture would have made some objects sharper, but if important objects that you, the photographer want in focus, are out of focus because of dof, the photo won't satisfy you.

 

Of course, you may be able to get the foreground in focus with a front tilt.

[eric_leppanen]

Did you have any type of filter or focusing hood attached to the lens when you took your photograph?

[putri]

there was no hood or filters on the lens.i'll probaby have to check the mounting on the

lens again.thanks!

[roger hein]

Russel,

 

A friend of mine had the 110 SS-XL with the same problem. He returned it to Schneider for

repair. Probably your best bet.

[putri]

thanks for all the help! i figured it out! i didn't mount the lens properly on the lens board

and so it was actually extended out alot!!what a fool!the washer was suppose to support

the board and NOt the back element.!