Pherdinand
the snow must go on
Ned - do you really really think it's the lens that does it?
Now honestly. Really?
Now honestly. Really?
PetarDima
Well-known
I just developed one roll of Efke KB 400 * push for 1 f-stop, 15 min, 20 C in Microphen 1:1 ... new Minolta Rokkor shots will be soon 
P.S. Anyone have photos with Rokkor 28mm ???
P.S. Anyone have photos with Rokkor 28mm ???
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hans voralberg
Veteran
ah lovely Im pondering between this and Harris 35mm skopa
Im pondering between this and Harris 35mm skopaEmilGil
Well-known
When I checked my M6TTL + 40mm Summicron-C, it was an almost perfect match with the 35mm frames on distances over a few meters. Closer than 3m or so, you need to frame a bit tighter (but not anywhere as tight as the 50mm frame). Making the 35mm frame show up instead of the 50mm one is pretty simple, just take out a file and remove about 1mm from a flange on the back of the lens.moonwrack said:
BTW, this thread reminds me that I need to send my 40mm for a CLA as the focusing ring is very stiff...
Pherdinand
the snow must go on
EmilGil said:
LOL, maybe because of all the filed-off brass dust falling into the focus helicoid?
EmilGil
Well-known
If it only was that simple, my lens isn't modified!Pherdinand said:LOL, maybe because of all the filed-off brass dust falling into the focus helicoid?
I intend to have it done when I send it to be CLA'd.
foto_fool
Well-known
EmilGil said:
Tight focus ring was a characteristic of the Summicron-C right out of the box. Has anyone else sent theirs to Sherry or Don for this issue? Results?
BTW Ned - great picture. Enough to get me to re-consider selling mine
D just kidding, Roland!) Anyway, it is the shooter as much as the lens. - John
ferider
Veteran
....Enough to get me to re-consider selling mine D just kidding, Roland!) ...
D just kidding, Roland!) ...
palec
Well-known
PetarDima said:
Rokkor 28mm with white spots:
Back to topic, here's Summicron 40mm:
borismach
Established
great shots
great shots
Really great shots! I thought the white spots usually developed on this lens will be harmful to itd optical performance. How come there looks no impact on your photos...amazing!
bm
great shots
Really great shots! I thought the white spots usually developed on this lens will be harmful to itd optical performance. How come there looks no impact on your photos...amazing!
bm
borismach
Established
I just got a Leitz Minolta CL set, with a Germany 40/2 Summicron-C for a few days. Just finished a roll of color neg and have it developed/printed. I find it really sharp...however the red color is a bit exaggerated. Overall it is an excellant lens.
Need to examine more on this lens.
Cheerz-bm
Need to examine more on this lens.
Cheerz-bm
palec
Well-known
borismach said:Really great shots! I thought the white spots ussually developed on this lens will be harmful to itd optical performance. How come there looks no impact on your photos...amazing!
Of those two only the first photo is made with 28mm Rokkor, second is 40mm Summicron. The white spots (more precisely said small bubbles between elements) have impact on performance because of flare problem. If you can evade unsuitable light conditions, you can have nice lens for bargain price. Especially if you like the rough look:
Neopan 400 pushed to 3200 helped, too, of course.
Palaeoboy
Joel Matherson
Yes this is true, I have handled many 40mm Summicrons and they all were very firm with their focus. If you prefer a lighter focus I have found the CLE Rokkors to be very light, it most likely has to do with the different cam designs.
Sorry but this is simply not true. The front glass of the Rokkor 28 is a single element. It does not touch any other elements so cannot be bubbling between elements. The spots start to form on the black paint covered edges of that front element. Because this is not in the optical path it doesn't effect image quality. When the white spots, which I believe to be crystal leaching out of the black paint, find their way on to the rear of the front element it will begin to impact on optical quality.
palec
Well-known
Palaeoboy said:
I haven't seen the lens disassembled only read about this issue - often mentioned as element separation. What I can confirm is that under first glass are small particles which look like bubbles, so you're probably right. i just wonder, why they look sheer if their origin is in black/white paint. Could be these are crystals from glue balsam?
V
varjag
Guest
The "white spots" are sign of separating lens elements in the front group. Normally they are glued together with Canadian balsam (or synthetic substitute), which can deteriorate with time.Palaeoboy said:
PetarDima
Well-known
Here we go! New shots with EFKE KB 400 ( pushed + 1 f-stop, 15 min in Microphen 1:1, 20 C, agitation 5sec. - every 30 sec. ). As usual, I have many
shots underexposed, funny many shots could be done with ISO 100, but I used
this film for hard test: daylight, night, low light. I must say again: I love this extra
sharp lens, but I need something wider - I think that some street shots just ask for
wide and close-up shooting! ... and EFKE, Efke is old school film, pure sadness
All photos are without corrections, only resized.
Cheers, Vlad.
shots underexposed, funny many shots could be done with ISO 100, but I used
this film for hard test: daylight, night, low light. I must say again: I love this extra
sharp lens, but I need something wider - I think that some street shots just ask for
wide and close-up shooting! ... and EFKE, Efke is old school film, pure sadness
All photos are without corrections, only resized.
Cheers, Vlad.
V
varjag
Guest
After some more research, it appears there are 3 theories about the spots: separation, crystalline growth or coating defect. Hard to tell which one is correct without taking a lens apart..varjag said:
Ororaro
Well-known
Good stuff, Petar!
PetarDima
Well-known
Thank you, I've tried to do my best
Palaeoboy
Joel Matherson
As mentioned in my earlier post its impossible for it to be lens separation and deterioration of some cement or balsam as the front group only consists of only one element. (Please see attached lens diagram)
The white spots start at the rim of the lens not in the optical path where it is coated in black paint to reduce internal refections. At this stage it appears as a ring of while spots. (You can see the flat sides in the lens diagram where the white spots begin.) The fact that it starts here at the sides means it cannot be a coating flaw (for only the spherical/optical side are coated) or glue from elements glued together as there are no other elements.
The crystal theory is the only valid one. The crystals leach out of black paint and begin to form around the edges. If not cleaned and allowed to continue they become so abundant they dislodge from the edges and find their way onto the inner surface of the front element. At this point they can etch into the coating. (this is where the faulty coating myth comes from) At this stage it does effect image quality and is irreversible in its damage.
The last myth with regards to the white spots is that if it hasn't happened now it never will. Not true either. One 28mm Rokkor I had only last year that showed no white spots at all and I took it out on a very hot Australian summer day, by the time I got home there was a ring of the white spots, clearly leached out by excessive heat. So keep those 28mm Rokkors cool boys and girls especially if you have only one or 2 spots appearing. If it hasn't progressed to the lens surface get the edge of the front element cleaned and repainted.
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