| Author |
Message |
    
John Shriver
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, December 19, 2004 - 07:49 pm: | 
|
I got a real basket case Summar on eBay. (Only $32, so I'm not sore about it.) Worst problem is that the group in the front cell is about 40% decemented. Very obvious ghost image in test shots.
Looking at eBay closing prices on clean Summars, and considering the prices for such repairs at Focal Point or CRR Luton, this lens is clearly not economically repairable commercially.
I have the front cell out of the lens, and the group separated from the front element. But I have no idea which side of the holder (cell) one would remove the group through. There certainly is a residue of glue around the front side of the group, so perhaps it is just cemented in place from the front? In that case, I presume gentle heating would take it apart.
On the other hand, CRR Luton's site (lens polishing page) notes that the front lens element of the Summar is peened in place, by bending over the brass of the lens cell against a spacer ring. It certainly looks like this could be the case as well, looking at the back side of the cell. If that's the case, I'd have to use a lathe (or a file) to remove metal to let the group out. On the other hand, they would be peening the mount directly against the glass, which does sound rather risky, so perhaps that's not the way they did it.
Also, does anyone know how the rear lens cell comes apart? It has obviously been dissasembled before, by brute force, and then assembled with some glue, probably epoxy. There appear to be the remains of a blackened brass ring (possibly a tube) that threaded into the back holding in the rear element. Is that how it goes?
(The only part of this lens that is nice is the focusing mount. I cleaned out the blackened crispy crud, lubed with LaBelle 106 Teflon grease, and it's now quite velvety.) |
John Shriver
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, December 24, 2004 - 05:05 pm: |
|
I will report that heating the cell in a toaster oven to 400 degrees did not allow pushing the group out of the lens cell. So it must indeed be peened over, not just cemented in place.
However, I was pleasantly surprised to have the failed cementing reflow, and get a lot better. It went from 40% de-cemented to about 10% decemented. There are two bubbles in the cemented area, one about 1mm, the other about 2mm.
I reassembled the lens, with as much cleaning as I could muster (some surfaces are inacessible, and dirty to boot), re-painting the edges of the groups, and reassembling the iris (not hard at all).
The results of testing show that the lens is still pretty dreadful. Quite a lot of overall flare, this on a very hazy afternoon with nothing bright in the shot. However, the ghost image that the de-cementing was causing was gone. The sharpness is now respectable, on a par with other 50mm LSM lenses.
Maybe I should call it a Holgar, rather than a Summar? |
John Shriver
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 16, 2005 - 10:54 am: |
|
For the record. I just spotted an auction on eBay (item 6532556871) of a cut-in-half Summar lens for store display. It is quite clear that all four lens groups are peened into their mounts. The peening over is always on the side facing the iris. I'm definitely saving a copy of the picture.
Meanwhile, I solved my problem by getting an optically gorgeous Summar for $111 on eBay. Fun lens. Yes, very soft corners wide open, and it vignettes, too. But it is not at all soft at f:8. I've not had any flare problems, even without a hood, and (of course) an uncoated lens. |
Peter Wallage
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 16, 2005 - 02:28 pm: |
|
Enjoy your Summar, John. I have a Summar on my 1939 Leica IIIb, and IMHO it's very much an under-rated lens even among Leicaphiles. Yes, I too find it a bit soft in the corners at f/2 but I don't get any vignetting (at least not that I've noticed). It sharpens up very nicely at f/4.5, and at f/6.3 is critically sharp. It hasn't got quite the contrast of the Sonnar on my Contax II, but for sharpness there's nothing to choose, judging by 10x8 prints. |
|
