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Phase One 55mm 2.8 LS

PostPosted: Fri Dec 30, 2011 2:04 pm
by NN159009UL4
Does anyone have experience with this lens? As part of a new P1 IQ160 system I acquired a P1 150 2.8 AF which is tack sharp throughout the center and central edges of the frame, the 80mm 2.8 LS which shows similar image quality and the 55mm 2.8 LS which is totally different story. I have had 3 copies, all showing the same characteristics:
Very poor central sharpness at f2.8 and f4. Satisfactory to excellent central sharpness at f5.6 and up.
Absolutely horrible (and unusable) central edge sharpness at all apertures until f11 when the edges become marginally acceptable. This involves 30% of the frame on the right and 20% on the left and is not meant to include the corners. Noticeable deterioration begin at f16 due to diffraction.
From my perspective, these characteristics make the lens effectively a 1 f stop piece of glass unsuitable for landscapes and group portraiture unless one is willing to perform major cropping. And if such cropping is done, one has to ask why she/he is using a MF rather than D3x or 1DsIII. Moreover, the necessity of using such a small aperture largely negates the advantage of a leaf shutter mechanism. Resolving this issue is another matter, but in the meantime I need a wide angle in the 35-55mm range. Can anyone make a suggestion based on personal experience?

Re: Phase One 55mm 2.8 LS

PostPosted: Mon Jan 02, 2012 8:50 pm
by Stretch
I have used the 55mm on several occassions in the studio at a small aperture. I was not impressed and I have heard from others that it is not great. I primarly shoot with the 75-150 which is a great lens. I also have the 35mm which is ok but not great. The Hasselblad 35mm is much better, but it is twice the price. I recently got the 120mm TS which seems to be very sharp. I have the 45mm on order which is supposed to be very sharp, time will tell. I shoot to a 65+.

Re: Phase One 55mm 2.8 LS

PostPosted: Wed Jan 04, 2012 3:02 am
by Bill9
My 55 LS is my most used lens. It is soft at the corners wide open but by 5.6 it's entirely acceptable and by f8 it's perfect. I used to have the non-LS version - this is way better.

I use it for landscapes typically printed to about 36 inches.

Sounds like you have a bad (de-centered?) copy.

Bill

Re: Phase One 55mm 2.8 LS

PostPosted: Wed Jan 04, 2012 12:37 pm
by NN159009UL4
Bill,
May I ask what back you are shooting the 55mm LS with?

Re: Phase One 55mm 2.8 LS

PostPosted: Wed Jan 04, 2012 10:30 pm
by NN159009UL4
I acquired the Mamiya 55 2.8 AF new from KEH. My preliminary results comparing it with the 55 2.8 LS on the P1 645 DF are, to my eyes, quite remarkable particularly given the $3724 price differential. Center is reasonably sharp @ 2.8 @ infinity and tack sharp by 5.6. Corner and edge sharpness is more than acceptable at f4 and 5.6 and excellent @ f8. I detect no appreciable CA wide open in the center or corners although I have yet to photograph a really high contrast, brightly illuminated subject. Likewise, while a more thorough analysis of field curvature is pending I detect nothing obvious. The performance over the entirely of the frame on my IQ160 already appears to be vastly superior to the 3 P1 55mm 2.8 LS units I examined as far as my needs are concerned.

Re: Phase One 55mm 2.8 LS

PostPosted: Wed Jan 04, 2012 11:08 pm
by NN159009UL4
I should also note that P1 concluded that 2 of these LS units were performing within specifications. I still fail to understand how they came to that conclusion. To any experienced photographer this would seem ridiculous. The issue is only magnified by the price differential. Whatever, I appear to have found a satisfactory replacement.

Re: Phase One 55mm 2.8 LS

PostPosted: Thu Jan 26, 2012 4:48 am
by Bill9
I'm using the IQ180.
Bill

Re: Phase One 55mm 2.8 LS

PostPosted: Thu Jan 26, 2012 1:36 pm
by NN159009UL4
I have noted my experience with 3 different samples of the S-K 55mm 2.8 LS above and compared them to the Mamiya 55mm 2.8 which cost $3724 less. Unless there had been some change in the manufacturing of this lens, I would expect similar performance, particulary at this sensor size (40 x 54). While your needs may differ from mine, I would strongly suggest that you either try a loaner/rental before purchase or receive a writtten assurance that the unit can be returned if it fails to meet expectations based on pre-sales marketing.