Crown Graphic images tend to be out of focus on the right side

[trondsi]

I have been using my Crown Graphic on and off for a few years now. I still think it is far more difficult to use than my 35mm and medium format cameras, but it is also very nice to get those huge negatives and positives back. However, I have noticed that my images tend towards softness towards the edges. This is probably a bit because of the nature of the Optar lens (at least this is what I heard), but it also tends to be significantly worse on the right side of the image. Sometimes it is plainly out of focus on the right side, although it is usually not visible to the naked eye (i.e. I have to use the loupe to see it). The film holders do not seem to be the issue here. Any suggestions?

 

[Luckless]

Are you sure everything is in alignment?

First test I can think of would be to rotate your lens and see if the issue rotates with it or remains the same. Rule out a lens issue vs camera alignment issue. If you give the lens a half turn and the softness shifts to the left, then you know the issue is in the lens. If it remains on the right, then something would be misaligned with the camera.

 

[trondsi]

Sorry, I don't have any good scans right now, but I think you can see it in this one, where the upper right gets a bit "mushy".

https://c2.staticflickr.com/6/5629/20674722501_2be10f9c7e_h.jpg

 

[sissysphoto]

Infinity stops unequal, although I don't see what you're talking about.

 

[trondsi]

Are you sure everything is in alignment?

First test I can think of would be to rotate your lens and see if the issue rotates with it or remains the same. Rule out a lens issue vs camera alignment issue. If you give the lens a half turn and the softness shifts to the left, then you know the issue is in the lens. If it remains on the right, then something would be misaligned with the camera.

OK, maybe I can check that. I also thought of something; I wonder if the film holder moves slightly when I pull the dark slide. Not sure if this should bring the image out of focus though.

 

[trondsi]

Infinity stops unequal

Interesting suggestion. Is this a common problem? I suppose I could also mis-align the lens slightly when I secure it in a different position.

 

[shutterfinger]

The front standard tends to swing to the side that the standard lock is set, the harder the lock is to set the greater the swing. I only snug it until its set square then fully lock being careful not to shift it.
I use the depth gauge feature of a digital caliper to measure the distance from the end of the rail to the front standard on each side and check the gg with a loupe when setting infinity stops. Focus tack sharp with the standard square to the rails before setting the stops.
Check the film holder seat for debris in the corners and the light trap grove. Keep them clean.
Which back, spring or Graflok?

 

[sissysphoto]

As for me, I never really lock the front standard tight, as in pushing it the whole 90 degrees or whatever. Even with perfectly set infinity stops, it might cock the front standard a bit. I always just push the lock enough to snug it up a bit, avoiding all that force. And on a Super Graphic, the lock lever is a good bit more flimsy and prone to break off with all that force. It's just not necessary.

 

[shutterfinger]

As for me, I never really lock the front standard tight, as in pushing it the whole 90 degrees or whatever. Even with perfectly set infinity stops, it might cock the front standard a bit. I always just push the lock enough to snug it up a bit, avoiding all that force. And on a Super Graphic, the lock lever is a good bit more flimsy and prone to break off with all that force. It's just not necessary.

Only because its incorrectly adjusted.
Crown and Speed Graphic

Super Graphic

 

[trondsi]

The front standard tends to swing to the side that the standard lock is set, the harder the lock is to set the greater the swing. I only snug it until its set square then fully lock being careful not to shift it.
I use the depth gauge feature of a digital caliper to measure the distance from the end of the rail to the front standard on each side and check the gg with a loupe when setting infinity stops. Focus tack sharp with the standard square to the rails before setting the stops.
Check the film holder seat for debris in the corners and the light trap grove. Keep them clean.
Which back, spring or Graflok?

I didn't know there was a difference here. It looks like this one:
https://proxy.duckduckgo.com/iu/?u=...2013/06/crown-graphic-4x5-details-008.jpg&f=1

 

[shutterfinger]

I didn't know there was a difference here. It looks like this one:
https://proxy.duckduckgo.com/iu/?u=...2013/06/crown-graphic-4x5-details-008.jpg&f=1

That's a Graflok. It should hold a film holder tight but the graflock sliders can be pushed up snug against the holder for extra security if desired.

 

[trondsi]

Thanks shutterfinger!
When using my strongest magnifier on the ground glass, I can see the softness of the lens towards the edges quite clearly (when wide open that is). Looking over my images, only a few are actually certainly more soft on the right than the left, the others are just more soft towards the edge in general. Maybe I should just take extra care that the film holder is tightly in place. I always thought that the Optar lens should go sharp all the way when closed down, but now I think it does not seem to be the case, at least not at f/22. If my images are anything to go by, the photos are always a bit blurry towards the edges.

 

[shutterfinger]

The 135 f4.7 is a Tessar design. It should be sharp edge to edge but due to production tolerances your's may not be. The 135 was standard on 4x5 graphics.
The 127mm f4.7 was made by both Kodak and Wollensak. It is the normal lens for 3x4 format and will just cover 4x5 with no movements and soft corners.
After checking standard squareness to the film plane check the lens for a shifted element. The tessar is 2 airspaced elements in front of the aperture and a cemented pair in the rear. Its possible the lens was disassembled, cleaned and a front cell did not seat correctly.

is a Zeiss tessar, other makes will be similar, only the degree of curvature of the elements and spaces will change.

 

[Dan Fromm]

Back when usenet's rec.photo. was active Richard Knoppow, who knows whereof he speaks, reported several times that an error had been made when Wollensak's Velostigmat Ser. II/Raptar prescription was calculated. Its consequence is that the lenses' off-axis aberrations are less well controlled that those of other tessar types. He reported that to get the same edge sharpness from a Raptar as from the equivalent Kodak Ektar the Raptar had to be stopped down two stops more. This is not because of poor quality in manufacture, rather of poor QC in design. People have forgotten this. Many users rave (positively) about their Raptars anyway.

trondsi, is your Raptar's shutter flush with the lens board. I ask because those shutters were usually delivered with a small screw protruding from the rear. The screw goes into a notch or small hole on the board, prevents the shutter from rotating when being cocked etc. Many people have put lenses on boards with the locating screw in contact with the board. This gives a little unintentional swing, just like misaligned bed stops.

Get an Ektar (there were no 135 mm tessar type Ektars) or a modern lens.

 

[wombat2go]

It is possible , but tedious, to check the parallel alignment like this.
https://app.box.com/s/ph2jel7gupxl1tiifi4flatrv1uvrrrb

A lot easier method is the "Fromm Jigger"
Here is my latest incarnation, but it is for the 2x3 Century, and have not made one for the Speed yet.
https://app.box.com/s/f4mx4n06jpveooq6fksud3i8yv98hlea
This version is adjustable for a range of lenses.

I suspect that some lenses are more sensitive ( blurred) than others to any part of the focal plane being even slightly beyond infinity

So a check for that, is to take some medium distance photos with the front standard extended accordingly.
This is the 2x3 Century with the 65mm Super Angulon at a closer distance and the bed axtended accordingly.
https://app.box.com/s/9qrlw48oqngxx849v6tgrz4l0f129amc
I have similar trouble to trondski's image with this lens set near infinity.

 

[shutterfinger]

This is the 2x3 Century with the 65mm Super Angulon at a closer distance and the bed axtended accordingly.
https://app.box.com/s/9qrlw48oqngxx849v6tgrz4l0f129amc
I have similar trouble to trondski's image with this lens set near infinity.

According to Schneider's information the 65mm f5.6 has 170mm image circle at f22.
https://www.schneideroptics.com/inf...ormat_lenses/super-angulon/data/5.6-65mm.html
The diagonal of 2.25 x 3.25 format is 100.4mm and actual image area a few millimeters less so there should be ample coverage with movements.
I suspect you have incorrectly mounted lens cells, a bent barrel, or other mounting problem within the lens and shutter.

I have had several 135mm Optar's and the one I currently own is tack sharp wide open. None have exhibited edge softness.

 

[wombat2go]

Hi Shutter,
Yes, your comment is possible, and same may apply to trondski's problem, if the camera and lens board are otherwise aligned.
Replacing just the shutter is not worth while in my case.
I have purchased some lower cost b/w 120 rolls to do tests.
I have an open yard with a 20 meter ( 60 foot) steel picket fence on one side and a heavy tripod.
https://app.box.com/s/iada51c2ublkjgznvkcs
(That with a vintage K mount Rikenon XR 50mm f/1.4)
I can test the SA 65mm like that for 10 exposures at various distances, maybe turning the camera 90 degrees too.

 

[shutterfinger]

Pick up one of these
https://www.ebay.com/itm/Digital-El...0.l1313.TR12.TRC2.A0.H0.Xdigital+caliper.TRS0
likely available at local hardware, home improvement, or auto parts store for $20 or less.
Excellent for checking cameras.