M-Rokkor 28/2.8: Spots, Schneideritis, Haze - How can I decide, what's what?

jsrockit said:
Is there a huge difference from before?
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Not sure, if the difference is 200 Euros big, but there is a difference. I think, I will try to make some tests on the weekend to see, how contrast improved.

At least a visible foggy spot in the center of images is gone. I don't know, if this is simply caused by cleaning the lens or by the spot-repair.

I was happy with the image-quality of the lens before, though, but a little bit unsure.
 
That looks great, I haven't seen any ill effects in the rolls I've shot with the lens thus far, except maybe some strange smudgelike flares in the bottom when shooting against the light. And ofcourse some pretty low contrast. But I will be sending in my lens as soon as I get the money to do it, very nice results from the service. Do you know if the white spots have a tendency to return after service?

Thank you for remembering to share your experiences by the way!
 
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back alley said:
big difference in the looks of the lens...very curious to see what the difference in images might be like.
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Well, it's not that much of a difference. As I wrote before, I had a small foggy spot in the center of the image, which is gone now. But the lens was good before, so I expect only small differences, like improved contrast and less flares. Since I really like that lens, I think, it was worth the money.
 
the rokkor 28 is a great lens...i sometimes think of looking for a good copy so i might have a faster 28 than the cv 3.5 but one that is still just as small.
 
Another one...

Another one...

Got this week my CLE with 28/2.8 back from Will van Manen.

CLE got CLA; new light seals, "flickering LED syndrome" repair...
Rokkor: white spots removed; mount changed to bring up the 28mm frame at the M

rokkor.jpg


Unfortunately, a previous owner clean the coating off the frontlens...:)
 
I had the spots in mine repaired by John Van Stelten at FocalPoint in the USA. It was great for a while, but then the lens developed haze in the front element group. DAG was not able to completely clean it out (but he did modify the mounting flange to bring up 28/90 frame lines on a Leica M camera, as well as mill 6-bit coding into it). The haze results in flare when pointed toward the sun, and maybe a bit lower contrast overall.

I don't really use the lens anymore since buying an Elmarit-M Aspherical 28/2.8, but in some ways I liked the M-Rokkor better.

::Ari
 
Anyone knows where these bubbles develop? Is it between a glued lens group or just on the surface of one element? If it's not in between it might be worth trying doing it yourself. Got one for $300 5 min ago and I must do something even if pics come out good...
 
micromoogman said:
Anyone knows where these bubbles develop? Is it between a glued lens group or just on the surface of one element? If it's not in between it might be worth trying doing it yourself. Got one for $300 5 min ago and I must do something even if pics come out good...
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The front glass of the Rokkor 28 is a single element so its not a glue or separation problem. The white spots are crystals that leech out of the black paint that coats the side rim of the element painted on to reduce internal reflections. Thats why the appear as a perfect circle around the lens when you look at it straight on. The process is accelerated by heat. The crystals can continue to form until they break off and find their way onto the inner surface of the front element whereby they can etch into the lens coating itself. Not all go that far. Most never get past the rim which has little effect as its not in the optical path. Its fixable but the hard part is that the front element is difficult to remove from the element tube. It may be more than a do it yourself job.
 
kermaier said:
I had the spots in mine repaired by John Van Stelten at FocalPoint in the USA. It was great for a while, but then the lens developed haze in the front element group. DAG was not able to completely clean it out (but he did modify the mounting flange to bring up 28/90 frame lines on a Leica M camera, as well as mill 6-bit coding into it). The haze results in flare when pointed toward the sun, and maybe a bit lower contrast overall.

I don't really use the lens anymore since buying an Elmarit-M Aspherical 28/2.8, but in some ways I liked the M-Rokkor better.

::Ari
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Ari: Wasn't your lens without the white spots at first?
 
raid said:
Ari: Wasn't your lens without the white spots at first?
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It had a variation on the white spots theme: translucent spots in a similar uniform pattern. John at FocalPoint said the cause is the same -- condensation interacting with metallic compounds in the coatings to produce crystalline bubbles.

I'm still planning to send it back to John to see if he can get rid of the garden-variety haze it currently has. Then I'll have to decide which of the M-Rokkor and the Elmarit-M stays and which goes....

Cheers,
Ari
 
It so strange that this phenomena doesn't affect the image. Are these spots visible if you let the light come through the lens and get focused on a white paper? They must be visible at some point of focusing distance...not necessarily within the range in the camera. Also worse with small aperture?
Might it be possible to keep the front glass in the barrel and clean it from the inside? Dismantle aperture blades and the other lens groups. Just thoughts...
 
micromoogman said:
It so strange that this phenomena doesn't affect the image. Are these spots visible if you let the light come through the lens and get focused on a white paper? They must be visible at some point of focusing distance...not necessarily within the range in the camera. Also worse with small aperture?
Might it be possible to keep the front glass in the barrel and clean it from the inside? Dismantle aperture blades and the other lens groups. Just thoughts...
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I think your misunderstanding where the spots are in the early stages. They are not on the optical front and rear of the element, they are on the side of the element which is painted black to prevent internal reflections. They are visible because of the way the sides are angled that permits you to see them as a ring. But in the early stages its not on the optical path and therefore doesnt have any impact on image quality. In the later stages however the crystals break off and then find there way onto the rear surface of the front element. Its at this point it does affect lens performance and can etch into the multicoatings of that element. For some reason only a few get to this later stage. Maybe the paint where the crystals leech from was applied thinner so there isnt enough to create large enough crystals to get to the damaging phase. The phenomenon is not unique to this lens. I have photos of Schnider, Zeiss Hologon and Elmarit lenses that have had the same problem, its just the instances with the Rokkor are more frequent.
 
Thanks for clarification. I have those bubbles on a Zuiko 50/1.4 too, but those are clearly limited to the outer region of the lens element/group, these are all over. These also look more like micro spots than transparent bubbles.
Shouldn't every "bubble" create a lens in itself, changing the path of the rays of light?

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My Rokkor has very few white spots. In fact, I sold the lens at RFF as not having any white spots, but the buyer sent the lens back because he found white spots. I am a very happy dude that I got my lens back. On the EP-2, it is a normal lens with 2.8 max aperture.
 
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