Minolta Rokkor 28mm 2.8 M Mount -Opinions?

[Thea]

Hi,
Please can I have some opinions on using this lens which is a Leica M mount on Leica's as compared to other makes of 28mm Lenses for the M Mount?
Thanks alot 🙂

 

[mac_wt]

Good lens, but with a tendency to develop white spots inside, that eventually will have effect on the pictures. This can easely be seen from the front of the lens as an allmost symmetrical ring of white spots (different sizes possible) towards the edges of the glass elements.
I haven't seen a definitive explanation (is it separation between two elements?) or a solution. There have been instances of spots disapearing and reapearing.

If the lens has spots but if they are not to big, you can do a bargain. If the condition of the lens can not be checked, it's your call. If the lens is guaranteed spot free, it might be expensive.

Edit: forgot to add that I own one with a neat circle of spots, but that still produces some good pictures.

 

[Tom A]

The white spots that are so common are signs that the balsam glue in the lens is deterioating. As long as it stays on the black mount part, there is no visible problem with using it, but it also weakens the lens. A sharp rap on the lens can get it to come apart. It is quite common with older lenses (I had a Hologon 15f8 where this was a problem!). It can be fixed, but it is fairly costly to do so.
My biggest problem with the Rokkor 28 was the fact that the hood always came off!
The performance of the Rokkor is good, but I think you are better off with a used Elmarit 28f2.8 (preferably a post 1980 lens). The other alternative is a Voigtlander 28f3.5, which although a bit slower, is a better performer. It is out of production now, but Camerquest or Photovilla might still have stock.
The Rokkor was very compact and if that is a point for you, the VC 28 is about the same size. The Elmarit 28 is a bigger lens and due to the M8 it has become more expensive used and a bit difficult to find.

 

[mac_wt]

I forgot the most elementary problem (even more common than the white spots 😉 ): it doesn't bring up the 28mm frame on an M-mount camera with automatic frame selection, other than the Minolta CLE.

 

[KoNickon]

Or, if you find one (and mine's not for sale!) the Kobalux 28/3.5. Screw mount lens, extremely compact, excellent optically.

 

[Doug]

...it doesn't bring up the 28mm frame on an M-mount camera with automatic frame selection, other than the Minolta CLE.

True, it brings up the 35mm framelines on other cameras.

But the reverse situation is better: The Leica and ZM 28mm lenses bring up the 90mm frame on the CLE but that doesn't matter since it's so small anyway, and the 28mm frame always remains visible in this camera.

So other 28mm lenses are conveniently usable on the CLE, but the CLE's 28 can a bit awkward on other bodies with auto frame selection.

 

[raid]

I have a Rokkor 28mm/2.8 that did not develop white spots. Its strength is its small size, along with good sharpness.

 

[sepiareverb]

I have a Rokkor 28mm/2.8 that did not develop white spots. Its strength is its small size, along with good sharpness.

I wonder if your nice humid weather down there has anything to do with it? TomA mentions this being repairable but expensive- I assume the whole lens comes apart and gets reglued? Sounds very expensive.

 

[raid]

I would not get a Rokkor with white spots. Period. If it had not developed spots by now, it may never happen in the future.

Here are some images taken with the Rokkor:

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

Here are four more:

http://photo.net/photodb/folder?folder_id=606480

Raid

 

[erikhaugsby]

It's a great little gem. I don't care about the white spots, because, frankly, they don't do anything noticeably detracting to my pictures; and not pixel-peeping doesn't hurt, either.

 

[Thea]

Thanks for the comments, I didnt realise this lens wouldnt bring up the 28 framelines. Appreciate your help.
Thea

 

[40oz]

does anybody have any imput on how expensive "repairable but expensive" actually is? And who would do such repair? I was planning on finding one to buy, but want some pespective when comparing "perfect except for a few small white spots," to "not perfect cosmetically, but lens is clear with no spots."

Thank you in advance.

 

[dberger]

The white spots are definitely not lens separation or lens element cement deterioration; the spots form on the rear surface of the front lens, which is a single element.

Explanations that I have read relate to either bad coating on the rear of the front element or something in the black paint they used to coat the lens edge that interacts with the lens surface (or coating) to cause spots. The latter makes more sense to me.

For what it's worth, my M-Rokkor 28 has what I would call a mild case of the spots that does not seem to have any ill effects when compared to a spotless M-Rokkor 28mm and other 28mm lenses. Also, unlike Tom's hood, mine bayonets on snugly and does not come loose.

Cheers,

David

 

[Never Satisfied]

Your other option is the M Hexanon 28mm f2.8 that rates as well as the pre ASPH Leica; it's M mount and doesn't have white spot issues and is way cheaper than a Leica 28mm.

 

[mac_wt]

does anybody have any imput on how expensive "repairable but expensive" actually is? And who would do such repair? I was planning on finding one to buy, but want some pespective when comparing "perfect except for a few small white spots," to "not perfect cosmetically, but lens is clear with no spots."

Thank you in advance.

If you manage to get the element out of the mount, an option might be Arax Photo (http://www.araxfoto.com/). They work on lens glass, including recoating and reglueing, but explicitly state that they prefer to receive the bare glass and that they don't work on 35mm lenses (I imagine that once you have bare glass, there isn't much difference between 35mm glass and medium format glass, but that offering to repair 35mm lenses is like opening a can of worms). I don't know of other options.

Wim

 

[Palaeoboy]

The white spots that are so common are signs that the balsam glue in the lens is deterioating. As long as it stays on the black mount part, there is no visible problem with using it, but it also weakens the lens. A sharp rap on the lens can get it to come apart. It is quite common with older lenses (I had a Hologon 15f8 where this was a problem!). It can be fixed, but it is fairly costly to do so.
My biggest problem with the Rokkor 28 was the fact that the hood always came off!
The performance of the Rokkor is good, but I think you are better off with a used Elmarit 28f2.8 (preferably a post 1980 lens). The other alternative is a Voigtlander 28f3.5, which although a bit slower, is a better performer. It is out of production now, but Camerquest or Photovilla might still have stock.
The Rokkor was very compact and if that is a point for you, the VC 28 is about the same size. The Elmarit 28 is a bigger lens and due to the M8 it has become more expensive used and a bit difficult to find.

I rarely disagree with Tom but I do on this occasion in some respects. I have been an advocate of the Voigtlander 28mm f3.5 since it came out and without doubt it is definitely a great lens. However it does not outperform the Rokkor. I have both lenses and at f4 the Rokkor is clearly sharper at the outer edges. At 5.6 the difference is slight but still visible to the Rokkors favour and at f8 they are the same. At f11 however the Rokkor starts to fall off yet the Voigtlander maintains its performance. The Voigtlander is smaller than the Rokkor in length but its heavier due to its brass construction. The black finish of the Rokkor is also better than the Voigtlander. The Voigtlander wears far to easy (Probably my biggest complaint for this lens). Photo magazine reviews at the introduction of the Rokkor claim its performance as good as the Elmarit of the period. I believe this to be true as I compared the Voigtlander when it first came out with the (E49) Elmarit and the Elmarit had the same slight advantage at the edges as the Rokkor did in the later test. Unfortunately I sold the Elmarit before I purchased the Rokkor so could never do a 3 way test)

It is true as Tom mentions that the Hologon is known for the white spot problem that develops with age but the Rokkors developed theirs within months in some cases under warranty so I believe their causes to be quite different.

The white spot problem is definitely not lens separation. ( I have attached a lens diagram. There is only one element up front where the white spots occur). The spots originate on the black paint on the edges of the front element. If you look at the lens diagram you can see the sides of the front element where the white spots develop. Front on they appear as a perfect ring around the lens but are not in the optical path so don't effect picture quality in the early stages. I believe that the spots are white crystals that leech out of the black paint when subjected to heat. One Rokkor I have didn't have a single white spot, then I took it out on a hot Australian day in the car and when I got home there was a ring of white spots. This was only a year or so ago too. So it can still happen. Where the white spots become a problem is if they are allowed to continue to grow and the white crystals break off and fall onto the face of the element and then etch the coating. (This is how the assumption that its a coating flaw occurs which is reasonable if you didn't realize the source). So if the white spots are in the early stage and just on the non optical edges of the front element then its worth getting it cleaned and repainted. If its spread to the inner surface of the front lens element its not worth fixing, just use it while you can.

Several years back the cost of the Rokkor was exceptionally high, almost the cost of the (E49) Elmarit so it wasnt that good value in the past but it was the only compact 28 for a time. There are now a few choices and prices are a half to a third of a few years ago so its worth a look when considering 28's.

*Curious Note* One user who attempted to get their white spots cleaned reported that it could not be cleaned by their repairman because the front element could not removed separately. This is odd because Minolta did replace the front elements under warranty as the white spot problem developed early. Most likely its just that the repairman couldn't take on the job but I put it out there in case some lenses have sealed optical units as a possibility.

 

[lic4]

Reviving an old thread--
I believe John Van Stelten knows how to service these; he also says that the problem is from moisture--I would venture to believe him. This is from a posting of his on another site:

"Actually, I deal with this problem often and these white spots are from moisture getting under the antireflective paint and causing it to lift, creating an air bubble which appears white. The reason it show up as a spot/dot is because the paint (just as coating) has pores and the moisture can only reach the glass surface via the pore. The paint must be removed and replaced but it is a big job because the front element is machined into this conical mount in the front and a small cemented doublet (next to the aperture) is machined into the rear smaller conical end. Minolta (with this design) created an airspace that is difficult for the moisture to evaporate from. On the other hand condensation can get into almost any space even under the tightest seal. This lens will often also have spots in the coating because of moisture getting thru the coatings pores and that is even more of a problem to repair"