testing an M-Rokkor 28mm

[bkrystad]

I found one of these locally and have two weeks to try it out. It was priced reasonably well for having the white spots around/on the front element. I've got a roll of HP5 that I put through my CLE with the 28mm yesterday drying in my darkroom right now. I'm interested in anyone's experience with the following:

1. What should I look for in the exposures to indicate that the white spots are interfering, if they are?

2. I have some frames shot wide open, some frames shot closed; would the spots be more evident in one type of shot than the other? (I risked flare on purpose in some of them as well, heard someplace that they show up with flare.)

3. Has anyone sent their lens to a reputable shop to make the fix that Minolta used to do at the factory for this problem? I'm wondering if this is safe or risky for the integrity of the lens, reasonable or expensive compared to waiting for a clean lens to show up at twice the price, or other experiences.

[chambrenoire]

I have the M-Rokkor 28mm f/2.8 - ofcourse with a lot of very fine, small white spots.

I have never seen any indications that they have disturbed my pictures or anything, fully open or at f/22. It's a real nice lens and I really like the pictures I've taken with it.

[Ronchnam]

I use a 28/2.8 Rokkor with white spots on my epson R-D1. Not interfering.

[roundg]

No worry on the white spots. No effect on pictures at all. I tried all kinds of shoot with it.

[raid]

I have such a lens myself. There were no white spots for 15 years, and suddenly there are spots. I sold the lens and it was returned to me because of the white spots. Maybe I am lucky that I got back my lens?

I have lowered the asking price by $125 now.

It is a fine lens, as you know.

[f16sunshine]

I had the lens and sold it with much regret. The white spots had no effect in any way to the IQ.
We speak of tiny white spots that have a quite distinct size and pattern correct?

[kermaier]

3. Has anyone sent their lens to a reputable shop to make the fix that Minolta used to do at the factory for this problem? I'm wondering if this is safe or risky for the integrity of the lens, reasonable or expensive compared to waiting for a clean lens to show up at twice the price, or other experiences.

I contacted John Van Stelten at FocalPoint to ask about repair of the spots. He charges $250 and has only a 75% success rate, as sometimes the coating damage has resulted in etching of the glass. (If it turns out he can't fix it he only charges $75.) He said the reason it's so expensive a repair is that the front element of the M-Rokkor 28/2.8 is machined into the lens barrel, and so it can't be removed by simply unscrewing a couple rings like most lenses.

FWIW, I'm the one who bought Raid's lens (thinking that it was spots-free) and returned it. The spots issue just makes me uncomfortable, having read about it's potential to progress from the edge toward the center until it becomes a problem for picture taking. After reading the testimonials from all of you here, perhaps I'm being foolish.

Cheers,
Ari

[bkrystad]

Thanks, everyone, great input.

I just spent thirty minutes in my darkroom looking at negatives from my test roll projected on a clean sheet of white paper under the enlarger at f/2.8 (bright). I can't identify any consistent (or even varying) aberrations on the negatives, even in flared shots where I would expect some refraction or ghosting from the crystals on the lens surface. Though I'm only partly sure what I would be looking for on the negative if any defects were indeed present.

I agree that if the spots progressed and occupied more of the lens surface than the edge, that would be frustrating. Hearing from Raid that the spots can suddenly appear on a previously clean lens makes me think waiting for a clean one might not be worth it. And $250 is an awfully expensive repair for a lens that only fetches at most twice that when mint.

Hmm. I'm on the fence. I'm going to print some of my test frames next week and scratch my head some more. I'll post some scans on this thread when I have them.

[Beemermark]

I have the white spots and in the 10 years or so I've owned I haven't noticed any growth. In the last year or so I picked up a nice 28 Elmarit and I can tell no difference in identical pictures taken with the two lenses. The white spots are a non-issue, just like bubbles in the glass and dust specs on the inner elements.

[LChanyungco]

could someone post a photo of the spots ? thanks.

[raid]

I contacted John Van Stelten at FocalPoint to ask about repair of the spots. He charges $250 and has only a 75% success rate, as sometimes the coating damage has resulted in etching of the glass. (If it turns out he can't fix it he only charges $75.) He said the reason it's so expensive a repair is that the front element of the M-Rokkor 28/2.8 is machined into the lens barrel, and so it can't be removed by simply unscrewing a couple rings like most lenses.

FWIW, I'm the one who bought Raid's lens (thinking that it was spots-free) and returned it. The spots issue just makes me uncomfortable, having read about it's potential to progress from the edge toward the center until it becomes a problem for picture taking. After reading the testimonials from all of you here, perhaps I'm being foolish.

Cheers,
Ari

Ari,
Are you getting second thoughts!:D:angel:

[bkrystad]

Photo of the lens I'm testing (which shows I need to clean my lenses better!) attached.

[raid]

The spots do not seem to impact the image qualities at all based on what I have read online. My photos with my lens always came out great, even though I never saw before any spots until Ari told me about them.

[raid]

Here are some images taken with the Rokkor.

http://photo.net/photodb/folder?folder_id=605103

[kermaier]

Ari,
Are you getting second thoughts!:D:angel:

Raid, I believe it was you who posted in a similar thread a couple of years ago that you would never consider buying one of these with spots! :o

But seriously, I think I would only buy one with spots if the price were quite low, such that the cost of having it repaired wouldn't end up making the total price too outlandish. Just my current feeling on the subject, which could change.

::Ari

[Krosya]

I dont understand - why play game and gamble when there are so many other good 28mm lenses out there that dont have any spots problems?

[raid]

Raid, I believe it was you who posted in a similar thread a couple of years ago that you would never consider buying one of these with spots! :o

But seriously, I think I would only buy one with spots if the price were quite low, such that the cost of having it repaired wouldn't end up making the total price too outlandish. Just my current feeling on the subject, which could change.

::Ari

Ari,
I had the "spotless " lens at that time. I may have been mistaken in thinking that the spots cover up the area through which the light goes through.

[raid]

I dont understand - why play game and gamble when there are so many other good 28mm lenses out there that dont have any spots problems?

The spots seem to be harmless.
The Rokkor-M is of equal quality as a Leica 28mm lens of its time.
The built quality is excellent too.

[Krosya]

The spots seem to be harmless.
The Rokkor-M is of equal quality as a Leica 28mm lens ot its time.
The built quality is excellent too.

That MAY be true, but I'd prefer a "spotless" lens. ;)

[kermaier]

I dont understand - why play game and gamble when there are so many other good 28mm lenses out there that dont have any spots problems?

Well, I don't think there's any other 28mm out there to match the particular characteristics of the M-Rokkor, those being:


Size - The CV Skopar 28/3.5 is smaller, but it's not as sharp across the field at wider apertures, and it's a half-stop slower.

Speed - The Konica M-Hexanon is an f/2.8 lens also, but it's twice the size, and usually 1/3 more expensive. The Leica Elmarit is an f/2.8 lens, but at least 50% larger and 2-3 times the price.

Performance - The older Elmarits are no better than the M-Rokkor. The M-Hex is probably sharper and more contrasty (more modern manufacture and coatings, of course).

Cost - M-Rokkors go for $400-$600, Elmarits for $800-$1200, M-Hex for $500-700, Skopar for $300.


The combination of size, speed and performance at moderate cost makes it a very attractive lens, in theory -- if only one can be found with it's front element not a slowly ticking bomb. So, there are those who keep using a spotty M-Rokkor and hope to find a clean one, and those who give up and just get an M-Hex (or an Elmarit if they've got deeper pockets). I'm on the fence.

::Ari

[Krosya]

You left out CV 28/2 lens which seems to be a good one. Plus I believe that Rokkor brings out wrong frames on most leicas. - correct me if I'm wrong here , as I never had one.

[kermaier]

You left out CV 28/2 lens which seems to be a good one. Plus I believe that Rokkor brings out wrong frames on most leicas. - correct me if I'm wrong here , as I never had one.

Yes, I left out the CV 28/2 and 28/1.9, which are in a whole 'nother size class; and I left out the Summicron 28/2 which is in a whole 'nother price class. The f/2-ish lenses aren't really appropriate comparison points, IMO.

And you're right: The M-Rokkor brings up the 35mm frame lines on Leica bodies, which is a non-trivial usability issue. It didn't occur to me, because I use an R-D1 which has manual frame selection (like the CV Bessas, et al.) Anyway, I think there are a number of the usual suspects among repair shops that are competent to make a simple modification to the mount to bring up the 28mm frame on a Leica.

::Ari

[raid]

The Rokkor is now on sale for $450.
First come, first served.

[Palaeoboy]

There are a few different stages to the white problem but the first stage is where the white spots form on the sides of the front lens element. Because it its not in the optical path most dont see any degradation in their pictures. The problem arises from crystals forming from the black paint that was used as anti reflection blackening. It is heat activated, so you may have a lens with no spots whatsoever and you take it out on a hot day in the car or something and get home and there they are! The fix is a matter of having the front element removed, cleaned and the sides repainted, but as someone mentioned before the lens cell is difficult to dismantle but not impossible. If the crystals get really bad then they break off and move onto the lens surface and sometime etch the coatings, its this stage where it can affect image quality but most dont seem to get to this stage fortunately.

[Palaeoboy]

OK I used to own one, and it was spotless, but that was years ago, when I had CLE's.

What are the spots? I assume they are deterioration of the coatings, how can they be removed without damage to the coatings? Or are they fungus?

Minolta recognised the problem early on and fixed alot of them under warranty, they even did the fix outside of warranty for alot of people. So yours may well have been cured of the problem and would never arise in that lens.

The spots arent a deterioration of the coating as they dont start on any lens optical surface. The spots occur on the sides of the front element. (Please see diagram) When looking into the lens front on they appear in a ring.

The spots are in fact small crystals that leech out of the black paint that was used to coat the sides of the lens element to prevent internal reflections. The leeching and crystal formation process is accelerated by heat. One example I purchased was new in box from the UK where it was probably kept at a reasonable temperature but I took it out on a hot sunny day here in Australia and when I got home there was the ring of white spots!

Where the white spot problem gets bad is when the crystals get so large they break off and get onto the rear surface of the front element and they begin to etch into the coating. To be honest though I havent seen many get to that stage and with age the offending paint has largely dried out anyways. I think most should find the spot problem remain localised to the sides outside the optical path.

I avoided the lens for many years even after being heavily into CLE's but I tried one when it came up cheap and I was amazed how good the lens really is. I am also a fan of the Skopar 28 f3.5 but the older Rokkor does have the edge on it in performance. Quite impressive when you consider its nearly 30years old.

[DougFord]

Mine had started to develop the dreaded white spotted disease so I sent it off to John Van Stelten.
He had a hell of a time getting mine dismantled. But persistence and perhaps a few choice cuss words later he had it apart and was able to commence with the repair. The lens is compact and light weight. I ultimately chose the rokkor over an elmarit 2.8 asph that I had at the time. Very different rendering/performance between these lenses. Both are excellent.

[bkrystad]

Spent some time in the darkroom making straight prints of some frames from my test roll that I thought might push the boundaries of the lens. These two are flare tests.

The first one is the only frame I found on the roll that I thought might have a ghosting/flare artifact from one or more white spots (circled in red in JPG).

The second shows flare where you would expect it (no hood, straight into direction of sun), but I don't see any candidates for artifacts, maybe the very upper-right corner by the boat railing?

[bkrystad]

Now, here are a couple prints from frames made with the M-Rokkor 28mm that gave me a good feel for the lens, one in a contrasty setting, the other wide open indoors with shallow depth of field.

I think after evaluating this test roll I'll go ahead and keep the lens (good price compared to other white-spotted M-Rokkor 28mm sales in the past few months) and I might consider the fix with John Van Stelten at some point.

Disclaimer: I'm generally a sucker for Rokkor glass. I wouldn't suggest everyone should be. But I'm enjoying the prints I'm getting with this and other lenses from the same era.

Thanks again to all for your input and information! Great stuff!