I am trying to figure out what is going on with this lens. I often have trouble remembering which lens I was shooting with especially when focal lengths are close, so I shot an entire roll with my Mamiya 105 D, and then an entire roll with my 80mm right after. I developed them, and the results were clear: my beat up chrome 80 was much, much sharper. And more contrast, and higher resolution. Don't get me wrong, my lens isn't put together backwards or tilted or misalgned (I think). I tested alignment with a loupe and ground glass on the film plane and it looked good. But compared to the 80, which is razor sharp, the 105 just isn't. My copy doesn't really catch up until f16. Is this sample variation or a purpose-made portrait lens by Mamiya with a little bit of undocumented softness? Does anyone else have experience with this lens that can comment on it? I'm trying to decide if I should try to get a new one or leave the focal length out of my camera bag.
I have a 105 DS and haven't found it to be lacking in the sharpness department although I don't have the 80mm to compare to. Compared to other 6x6 80mm lenses however it is comparable.
It could be issue with that specific example, eg it is possible for people to swap the taking and viewing lens so someone may have done this in the past.... If you're not sure if it is the newer 5 element version you can check infinity on the focus scale. The 5 element DS required a separate scale from the older 105 due to a different back focus distance and its identified on the scale with DS.
Yeah, I was looking at both finder and ground glass, so I don't think there is an alignment problem. And Flavio, I should have been more clear, what I meant was it doesn't catch up to the 80mm until f16. It is "sharp" at f5.6. Just not razor sharp especially when viewed side by side with the 80mm
Yeah, I was looking at both finder and ground glass, so I don't think there is an alignment problem. And Flavio, I should have been more clear, what I meant was it doesn't catch up to the 80mm until f16. It is "sharp" at f5.6. Just not razor sharp especially when viewed side by side with the 80mm
Apologies if it’s inappropriate to tack this on, but the timing of this post is uncanny: I have a black 55mm lens for my C3, and I noticed today that it’s pretty soft at open apertures (i.e., 5.6 and wider). Anyone else notice this?
There is a lot of sample variation with the 55mm.
The copy i had, was sharp at 5.6.
...the 55mm is the optically the most complex in the C-series line up of lenses - maybe it's just the most difficult to get 'right' at manufacture. I have all the lenses except the 250mm and they are all really good performers - even the 55mm. The only thing you need to careful of is flare. Pointing into the light, the lens easily produces sharply defined pentagons from it's five bladed diaphragm.
Not a real data point from me about the 55, but I've never heard of it being the best lens in the system. It's the only one I have never had in my hands myself. The reason being, I think most people seem to think it is the worst lens in the system, and it's expensive. The lens designs for the TLR series was constrained by the need to make the front element relatively small so two of them could be fit in the inter-lens distance. This made wide-angle design particularly difficult. Take a look at the size of the big honking front element on the Pentax 6x7 55 f3.5, it's like 100mm compared to the dainty Mamiya. I think this was partly counterbalanced by not needing to design around the mirror flopping up as you would in a SLR. But there is still a mirror there for the viewing lens, so still a constraint compared to a rangefinder or view camera. Anyways, I've never heard as much praise for the 55 as I have for the other lenses, so it doesn't seem out of the question that it would be softish up until f8-f11.
Well, considering how much was off with this camera when I bought it, I guess I shouldn’t be surprised I got a bad sample. Not that I mean to complain! I love this camera. And I almost always stop down to 11 or 16, so it won’t derail me too much.
So, the big white elephant in the room is...
Have you repaired the foam that presses the ground glass against its proper seat in the camera?
If not, all lenses will have sharpness problems.
I have a question about that. On my camera, a C330 (non F or S) the foam is between the ground glass/plastic/fresnel piece and the clear glass top that protects it. The ground glass itself rests on three studs rising above the mirror, and that position doesn't seem to change based on the foam. I've seen on other forums, people talk about how the foam can affect focus position but I don't understand how it does. I almost wonder if it's an urban myth. The case I could see it affecting focus is if the foam is dry and gluey, and the screen is glued to the top of the frame instead of being pushed down to the studs. But other than this rare case, is there any other way it can happen?
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