I have found that with a (P45+) that both the 35mm AF (not the newer Phase One D) and the 28mm both have issues to consider.
1. Foremost varient differences. I tested 4 35mm AF's 2 used 2 new and ended up with a used one. On the 28mm the only reason I had one was due to the Phase One package that was available when I purchased my back. The 1st 28mm version was totally off on one side and went back to Mamiya 3 times, finally they replaced the entire lens and the new one was much better So you have to first decide, do you need the extra reach, then find a good version.
2. Filters, I use them, the 35mm likes them the 28mm doesn't. I still use a rig on my 28mm that was developed by Tim Ernst, and if you search the forms, you may still find the link. Net, you can adapt the larger Cokin filter system to the outer ring of the 28mm and get by fine. You add a solid glass $400.00 filter to the front of the rig that makes the lens out of balance, but it works. The 35mm just takes any 77mm filter and works fine with them. The rig Tim built up allow you to actually use both a Cokin sheet filter and a CL-PL.
3. Corner sharpness, My 35mm is pretty worthless at below F8 for corners and seems to really shine briefly from F8 to F14, much past that it seems to suffer from other problems. It's so bad at F3.5 that you actually get smeared image material like when you have shifted a lens too far. My 28mm is just a bit better wide open, but really not much, and that is really key. You are paying 3K for a used one and 4K for a new one, where as the 35mm can go for under 800. At F8 the 28mm starts to really shine and then stay that good till around F16, where it also starts to go. The hyper focal of both lenses is very good at F8, the 28mm has just a bit more reach.
4. C/A, can be seen in my 28mm, very dependent on the aperture. So far Capture One does the best job on this and can really help. The 35mm has C/A, but it's not as marked as my 28mm. I use Capture One mostly for images taken with both lenses since the lens adjustment sliders can really help. Especially the corner softness slider.
5. Lens effects, I don't know what the true term here is, but, I the 28mm acts like a 14mm on my 35mm camera, in the way it creates the perspective, seems to push things back and even out/flatten skies. There are times I really like this look, the 35mm seems more like a 24mm lens on my P45+. The outer element of the 28mm is most impressive.
The 28mm is big and heavy, I find now I don't carry it as often as I used to and many times drop back to the 35mm. The 28mm is a firmware lens (it has firmware installed) and you have to send the lens to Phase ONe/Mamiya to get it updated. I bring the 28mm when I know I will need to be more open due to prevailing conditions for shutter speed.
As I move over to a tech camera, the 28mm is one lens I will most likely sell since I feel that the Schneider/Rodenstock options are much better, even though it seems you can't shift them much with a IQ160 back.
Paul Caldwell
http://www.photosofarkansas.com
