Phase One SK 55 LS non blue ring

[MiltReeder]

I just purchased a used 55mm SK LS lens.  I was stunned to learn that at f/2.8, wide open, this lens is unusable.  Very soft.  Only slightly better at f/5.6.  Not until I reached f/8 was the sharpness and definition up to the SK that I would expect.  Is this just a "bad copy" or is this normal?

Looking at other posts, it seems that the optics for this lens have not changed in the new Blue Ring version so I would assume the results would be the same?

Milt

[gagemanning]

I don't think the optics have changed but have read the quality control is better.  I've not had any problems with my blue ring.  Here is pictures from my site using only the 5mm LS blue ring.  Below is an image shot at f5.6.

[MiltReeder]

Well, first off, you're playing unfairly!  That is a very cute image of wonderful little girl.  Thanks for sharing.

I am afraid my example images are much, much more boring.  I've attached 4 images, all cropped at 100% on the IQ1-100 mega pixel back.  They range from f/2.8 to f/8 all shot with the same focus.

[Paul2660]

I just purchased a used 55mm SK LS lens.  I was stunned to learn that at f/2.8, wide open, this lens is unusable.  Very soft.  Only slightly better at f/5.6.  Not until I reached f/8 was the sharpness and definition up to the SK that I would expect.  Is this just a "bad copy" or is this normal?

Looking at other posts, it seems that the optics for this lens have not changed in the new Blue Ring version so I would assume the results would be the same?

Milt

Hi, I looked at your crops, the F2.8 does seem not to be sharp anywhere and the lens may need to be serviced.  You should still have a center sharp spot even at F 2.8.  Curious, have you tried AF only or MF via Live view? or both?  If this is all with AF, you may need to do some AF adjustment which can be done on the XF and DF+.   However best test IMO is MF with Live View which on your back should be possible to get a very good test for good focus. 

The DOF on the 55 is shallow wide open.

Paul Caldwell

[MiltReeder]

These were shot all on manual focus.  The f/8 and beyond are quite sharp so I now it's not the focus issue.  Also, this select is very close to the center of the lens, but not exactly.  All shot on a very sturdy tripod with mirror up so not changes there.

[Christopher]

Looks pretty normal to me. Perhaps not the best copy, but  I would say the the 55 is Phase weakest lens by far.


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[DrakeJ]

I'm quite happy with the sharpness of the 55mm blue ring lens wide open. Perhaps the 55mm benefits from the quality control disproportionally from the other lenses in the SK lineup.

[JoeKitchen]

I too have the 55mm LS, Blue ring version though.  Seeing this conversation, I was curious and did a quick test wide open. 

The center of the image and where focus is achieved is tack sharp, although DoF is nonexistent.  Here are some flowers in my kitchen I quickly snapped, cropped down somewhat. 

If you don't get anything in focus, I would be concerned. 

[Christopher]

Sure the center is ok but on my two 55 and two 55 BR lenses from two dealers 1-2 corners were crap till f8 /f11

No other lens has such big problems. It's time to redo that lens.


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[siddhaarta]

Here are the MTF for different distances and apertures.

Schneider-Kreuznach MTF measure different spatial frequencies, that is 15, 30 and 60 l/mm, as compared to Leica, Hasselblad or Zeiss with 10, 20 and 40 l/mm.

Nevertheless, it seems clear, that this is not a state-of-the-art design.

[narikin]

These were shot all on manual focus.  The f/8 and beyond are quite sharp so I now it's not the focus issue.  Also, this select is very close to the center of the lens, but not exactly.  All shot on a very sturdy tripod with mirror up so not changes there.

Did you focus tethered, using LiveView on Capture One?  (DB version is free if you don't have Pro). Best way to test any lens for focus is live view, or at least work tethered captures on a good monitor.

I was unimpressed with the 55mm Schneider when I tested one, maybe 5 years ago. Quite honestly, you'd be just as well off optically with the older Mamiya 55mm AF lens, it's not so pretty, and doesn't have LS, but optically it's *excellent. Will only cost you a few hundred $ on eBay too! Manual Focus requires setting on the XF camera body, as there's no lens switch/clutch. 

I'd return the LS, if you're unhappy, and get/test a 55mm Mamiya AF.

[Paul2660]

Hi Narkin

Where is the MF Switch on the XF?  I have looked and can't locate it so is it in a drop down menu?

I agree the older 55 AF Mamiya is a great lens but I have not figured out a at to manually focus mine.

Thanks
Paul Caldwell

[Graham Welland]

Pretty certain that the only way to manual focus a clutchless/switchless Mamiya AF lens is to set the AF to rear button and if you want to focus manually you just turn the focus dial and not use AF at all. I haven't found a manual focus mode option other than on the lens.