tsdevine wrote:
I've tried about 6 different adapters and 4 different Pentax 28's....while there may have been slight differences in the upper left corner, this adapter gives the best performance across the frame. The "better" adapters seem too thick. The cheaper ones seem to perform better, but then there's probably less adherence to tolerances so I can't rule that out. So far this is the best of the lenses and adapters.
One thing I will say is that I was focused a little short of infinity, and that may be aggravating that upper left corner. I will say that in other shots it's close in performance to the upper right. Although if there was any corner I've thought might be a little worse, that's the one.
Yeah, there are so many variables and the Pentax 28 is not perfect. I have seen the scenario/ effect though where if the adapter is even just slightly tilted and the focus is near infinity, one corner might be oof and the other corner will be noticeably sharper. It's an odd thing about how all of the Pentax 28/3.5's seem to not focus at infinity using the "better" adapter (as my better Rayqual adapter behaves the same but seemingly just with this particular Pentax lens. I use it with all my other Pentax lenses without issue).
As a side note, I have been considering (not because I need it!) picking up the Olympus 28/2 as the price on that lens seems to have dropped a bit lately. It's said to be one of the sharpest Olympus OM lenses.
While perfect corners are obviously desirable, the lens is so good over so much of the frame that it gets down to splitting hairs over how much it matters. If you look at the area that is a little blurred (at f/11), it's so minute it almost seems silly to fault it to much. I've tried so many 28mm lenses (not the Zuiko 28/2 or Leica Elmarit-R 28 II), it just has the best color and sharpness over a majority of the frame. And the build.... I've gotten so fond of it, I'm not sure why I still look around for something better. There's the Nikon 28mm 1.8 thats supposed to be very good too. But it's pretty crazy what a near 40 year old lens can do. I even prefer it over my FE 16-35 for landscape shooting.
I wish the Rayqual (or Kiwi) worked better, but c'est la vie.
tsdevine wrote:
The Pentax doesn't give perfect corners.....but it delivers over so much of the frame I don't care. As you note, the Olympus does well in the corners but doesn't impress as much everywhere else. Could be my copy of the lens, or the adapter I'm using. The lens is a later serial number lens in mint condition, so it could be the adapter. (Or maybe it's just how it performs on the a7r.)
-Tim
Just did a quick test shot and by F11 with the Pentax 28/3.5, the corners look pretty sharp imo...so good that I may end up parting with the 31Ltd at some point (which is about a stop ahead across the frame). This is with a cheap Fotasy adapter. The focus distance is further versus your shot (I focused on the telephone pole in the center) but the dof seems to be fine even covering the bottom, close corners (the dof does seem greater than possible, as you mentioned on one of your copies). Click through to download the full size. Just for reference, the serial on my Pentax 28/3.5 is 5332305. Is that in the same batch as any of the ones you have tried?
Honestly at infinity I don't think my copy is all that much different than yours in this shot. I think there is a little towards the camera field curvature at the corners (or it seems to show a bizarre DoF for a given aperture.) So in the barn shot I wasn't at infinity and the upper left corner is further away than the focus point, sort it's sort of the worst case scenario for this lens.
I've had 2 516 and 2 518 copies...the last one I bought was supposed to be a 534, but when I got it it was a 518. I complained to the seller (never heard anything back), but it turned out it was the best of the 4 copies I had. I noticed the same seller had sold one a few weeks before I had bought mine and it matched my serial number. So some guy got the later one (not matching what was shown) and I got his. I noticed that the higher number serial number copy went up for sale about a week later, so at that point I figured I had gotten the better deal. The guy was selling the 534 for less than he paid for it.
I still keep my eye open for a later copy.....I might pull the trigger one more time. While not cheap per se, you can cherry pick for a good copy more so than lets say a c/y Zeiss 28mm 2.8....jut because of the cost.
By the way, the adapter I found best is a Fotodiox with a funky tripod foot. The Fotasy was close, but not quite as good. I picked up another Fotodiox, but it turned out to be a dead ringer for the Fotasy (exactly the same as a matter of fact.) Bot the Rayqual and Kiwi were worse.
Interesting about the serial numbers on the 28. I have only owned the one copy and was happy enough with the performance that I did not get obsessed about it (as I did with the 31Ltd).
I have owned 2-3 copies of the CY28/2.8 over the years and none of them came close to the Pentax 28/3.5 (and they were used on less demanding bodies with lower MP's). You also mentioned a NIkon 28/1.8. If it's the recent 28/1.8G, it has a lot of field curvature and it's not so hot for across the frame sharpness (I returned mine fairly quickly after testing it on a D800).
Here is what the Pentax 31Ltd can do at F8 with the same scene as above (Rayqual adapter). It's a little sharper than the 28/3.5K (well, this example is) as it does not loose that tiny bit that gets lost at F11 due to diffraction. Btw, exact same processing on all of these (28 vs 31). All were also hand held so will not match exactly but I think there is enough similarity to see what's going on. Pentax31_F8 by tariqgibranstudio, on Flickr
Here it is at F11 (not much improvement in the corners and slightly less fine detail compared to F8 imo). Pentax31_F11 by tariqgibranstudio, on Flickr
Yeah, no argument...the 31 looks great here. I think it was AgeoJO who suggested the 28 1.8 Nikon was great. I did see an ensuing discussion about field curvature though. I've only had one copy of the 28 that was meh. The other two were very good stopped down. This last one was better at wider apertures.
I don't obsess too much...but for some reason I do with this lens. I'm pretty darn happy with this last one. So if I were to pull the trigger again, it would have to be a mint late copy version. Just to try more than anything.
The 31 does look very nice, but shooting mostly landscape it doesn't make enough of a different for me to probably spring for that lens. (And possibly go through the find a perfect copy routine.)
My c/y Zeiss 28m 2.8 is soft in the lower right corner. If I knew it could be easily fixed (or fixed at low cost) I'd send it somewhere for repair. It's in beautiful condition other than that problem. I still don't think it would win over the Pentax though (I know that is blasphemy...)
tsdevine wrote:
Yeah, no argument...the 31 looks great here. I think it was AgeoJO who suggested the 28 1.8 Nikon was great. I did see an ensuing discussion about field curvature though. I've only had one copy of the 28 that was meh. The other two were very good stopped down. This last one was better at wider apertures.
I don't obsess too much...but for some reason I do with this lens. I'm pretty darn happy with this last one. So if I were to pull the trigger again, it would have to be a mint late copy version. Just to try more than anything.
The 31 does look very nice, but shooting mostly landscape it doesn't make enough of a different for me to probably spring for that lens. (And possibly go through the find a perfect copy routine.)
My c/y Zeiss 28m 2.8 is soft in the lower right corner. If I knew it could be easily fixed (or fixed at low cost) I'd send it somewhere for repair. It's in beautiful condition other than that problem. I still don't think it would win over the Pentax though (I know that is blasphemy...)
Yeah, I was surprised at just how different the two mint - and both MIJ- copies of the 31Ltd were. I suppose I was lucky to just have to try two to find a good one (both were good of course, I just mean across the frame - corner to corner).
Tim, are you saying you tried 3 copies of the newer Nikon 28/1.8G? Maybe I just ended up with a particularly bad copy if that's the case. Edit...Nevermind, I take it you were referring to the Pentax 28 with the multiple copies.
tsdevine wrote:
As you note, the Olympus does well in the corners but doesn't impress as much everywhere else. Could be my copy of the lens, or the adapter I'm using. The lens is a later serial number lens in mint condition, so it could be the adapter. (Or maybe it's just how it performs on the a7r.)
-Tim
that's just the way it performs, it's kinda the way all the olympus OM wides perform – sacrificing center sharpness for even performance across the frame.
) picking up the Olympus 28/2 as the price on that lens seems to have dropped a bit lately. It's said to be one of the sharpest Olympus OM lenses. 
