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Vivitar - Kiron 2/24mm Be Careful!
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PostPosted: Sun Jun 27, 2010 4:47 pm    Post subject: Vivitar - Kiron 2/24mm Be Careful! Reply with quote
Yes, i loved specifications and reviews were good. Sadly after disassembled 3 pcs all had one (the same) back element deteriorated. This element can't be cleaned.

Some of you might be familiar with Japanese 400 and 500mm generic lenses sold under Travenar, Hanimex, Rubimat, Beroflex and some other labels that have nearly always one back element hazed irreversible in similar way (well this element is pretty basic and big and optic store nearby made me replacements for 20 EUR/pc).

Anyway before buying Vivitar - Kiron 2/24mm look through lens carefully and buy only if bright and clean.


PostPosted: Sun Jun 27, 2010 5:11 pm    Post subject: Reply with quote
Hi,

Many thanks for the hint, i was just thinking about one of these ...

Do you have an idea about the fact that the rear element cannot be cleaned ?

Cheers


PostPosted: Sun Jun 27, 2010 5:16 pm    Post subject: Reply with quote
I guess strange kind of soft glass (just this particular element - 3rd or 4th from the back). Vinegar acid 5% eat it badly in half an hour.


PostPosted: Sun Jun 27, 2010 6:00 pm    Post subject: Reply with quote
Mine has some haze on the rear element too (Kiron made too). But I see no sharpness/contrast lost, and I don't want to sell it, so I see no reason to clean it Smile


PostPosted: Sun Jun 27, 2010 7:26 pm    Post subject: Reply with quote
CarbonR wrote:
Mine has some haze on the rear element too (Kiron made too). But I see no sharpness/contrast lost, and I don't want to sell it, so I see no reason to clean it Smile


There *is* loss of contrast. You could easily see it by shooting the same scene before and after the cleaning. I cleaned a Vivitar S1 135/2.3, and the difference was obvious. Here are my test pictures: http://forum.mflenses.com/lens-haze-effect-on-picture-quality-t19581,highlight,haze.html


PostPosted: Sun Jun 27, 2010 8:46 pm    Post subject: Reply with quote
I've got the Komine made Vivitar 24mm F2....No problems with my version


PostPosted: Sun Jun 27, 2010 9:59 pm    Post subject: Reply with quote
I wonder if this is also a problem with the Kiron 28/2?

Last edited by jjphoto on Sun Mar 10, 2013 9:50 am; edited 1 time in total


PostPosted: Sun Jun 27, 2010 10:19 pm    Post subject: Reply with quote
jjphoto wrote:
I wonder if this is also a problem with the Kiron 28/2?

I've recently purchased a Kiron 28/2 and found it's contrast to be lower, but not poor, compared to the Contax Distagon 28/2.8. It was fairly noticeable at wider apertures but much improved when stopped down. STill quite a sharp lens, in the central area anyway. I just wonder if it has the same kind of glass in it as the 24/2.

JJ


Hold the lens to a light and look through it, you will soon see if there is a problem with one of the elements as it will look dull Wink


PostPosted: Sun Jun 27, 2010 10:52 pm    Post subject: Reply with quote
ManualFocus-G wrote:
jjphoto wrote:
I wonder if this is also a problem with the Kiron 28/2?

I've recently purchased a Kiron 28/2 and found it's contrast to be lower, but not poor, compared to the Contax Distagon 28/2.8. It was fairly noticeable at wider apertures but much improved when stopped down. STill quite a sharp lens, in the central area anyway. I just wonder if it has the same kind of glass in it as the 24/2.

JJ


Hold the lens to a light and look through it, you will soon see if there is a problem with one of the elements as it will look dull Wink


It looked OK when I first looked at it but I'll have a closer look when I get a chance.

JJ


PostPosted: Tue Jun 29, 2010 3:39 pm    Post subject: Re: Vivitar - Kiron 2/24mm Be Careful! Reply with quote
Pancolart wrote:
Yes, i loved specifications and reviews were good. Sadly after disassembled 3 pcs all had one (the same) back element deteriorated. This element can't be cleaned.


This is a well known problem :

Some kiron lenses had a coating deterioration problem ( certainly a over-normal sensibility to fungus)..
This mean that ALL kiron and kiron made (vivitar) CAN have a coating deterioration problem

Last edited by PBFACTS on Tue Jun 29, 2010 4:03 pm; edited 1 time in total


PostPosted: Tue Jun 29, 2010 3:59 pm    Post subject: Reply with quote
If it is a coating deterioration problem, can you remove the coating to make the lens usable again? Question


PostPosted: Tue Jun 29, 2010 4:30 pm    Post subject: Reply with quote
Nope. That was my initial post. And it's not coating.


PostPosted: Wed Jun 30, 2010 3:15 pm    Post subject: Reply with quote
Pancolart wrote:
Nope. That was my initial post. And it's not coating.


it sounds as if you are referring to the lubricants breaking down and "outgassing" leaving a fine film of lubricant on one or more elements. The Kiron lenses are known for their superb coatings.


PostPosted: Wed Jun 30, 2010 4:06 pm    Post subject: Reply with quote
Nope. It's glass deterioration. I am referring only to this particular model. I love Kirons by the way. If i find healthy 2/24mm i will still buy it.


PostPosted: Wed Jun 30, 2010 4:16 pm    Post subject: Reply with quote
Pancolart wrote:
Nope. It's glass deterioration. I am referring only to this particular model. I love Kirons by the way. If i find healthy 2/24mm i will still buy it.


Interesting. This is the first I've heard of Kiron glass deterioration. You'll love the Kiron 24mm f/2 lens. My Panagor (Kiron) 24mm f/2.5 and 21mm f/4 lenses are also stellar performers.







PostPosted: Wed Jun 30, 2010 5:49 pm    Post subject: Reply with quote
made me check my Vivitar - Kiron f2/24. looks clear to me, and I like it quite a lot, it is my most used wide angle lens.


PostPosted: Tue Jul 06, 2010 11:05 pm    Post subject: Reply with quote
I have several Vivitar 28's (and 24) of different makes and find the Kiron made f/2.0 to be my least favorite. The aperture blades were all gummed up and even now still move slowly and inconsistently. Also, I see a number of bubbles or blisters in the elements; at first i thought this might be element separation but i don't know for sure.
I will see if i can get a pic of this issue.

It was a $15 lens, so i am not too broken up about it but so far find the Kiron version to be highly disappointing.
By contrast i find the Tokina and Komine variants to be just stellar.


PostPosted: Wed Jul 07, 2010 2:08 am    Post subject: Reply with quote
That's too bad to hear that. I just checked my Kiron 24/2 by Kino Precision of Japan and all looks good.



PostPosted: Sat Jun 30, 2018 4:00 am    Post subject: Reply with quote
aoleg wrote:
CarbonR wrote:
Mine has some haze on the rear element too (Kiron made too). But I see no sharpness/contrast lost, and I don't want to sell it, so I see no reason to clean it Smile


There *is* loss of contrast. You could easily see it by shooting the same scene before and after the cleaning. I cleaned a Vivitar S1 135/2.3, and the difference was obvious. Here are my test pictures: http://forum.mflenses.com/lens-haze-effect-on-picture-quality-t19581,highlight,haze.html


I can tell the difference. Interestingly enough, today one of my recently purchased lens arrived. Right after I put on the camera, I can see the contrast is very low. I had thought it is the lens' design. Upon close inspection, I find there is haze on the inner element. Haze does reduce the contrast dramatically. It is the first time I see haze in a lens. I guess because it is a really beaten-up one. Time for me to do some DIY...


PostPosted: Mon Jul 02, 2018 6:28 am    Post subject: Reply with quote
It is very likely glass corrosion.
Different glass has different chemical resistance. Some glass types have no problem with longer humidity and for example acid substances, other glass types detoriate fast. It is like with the wineglass in the dish-washer, they get tarnished after many dishwasher runs.
AR coated glass is normaly much better than uncoated glass in this regard, but given the age of these lenses it seems not good enough.

I have a big Tessar lens and a Meostigmat with the same problem. Up to now my lens polishing experiments did´t help there. Too much of the material is detoriated.


PostPosted: Thu Nov 11, 2021 1:30 pm    Post subject: Reply with quote
Sorry for dragging that old thread back on top of the forum again, but I want to know what we´re talking about. Here´s my issue of that lens in the manifestation of a Vivitar.




Is that it? The hindmost element of soft glass deteriorated due to oil dust from the aperture blades or similar, or am I looking at a different phenomenon here that is probably remediable?







PostPosted: Thu Nov 11, 2021 7:12 pm    Post subject: Reply with quote
According to these photos it looks quite good and imho no reason to worry.


PostPosted: Thu Nov 11, 2021 7:50 pm    Post subject: Reply with quote
Could also be haze in the cemented element (if it has one)


PostPosted: Fri Nov 12, 2021 1:46 am    Post subject: Reply with quote
Seems like it could be cleaned. No way to know until you try. Haze from evaporated lubricants is common. I have also run into uncleanable haze in a few cases. In those it seems like the glass was etched somehow. That problem, IMHO, is not limited to any given lens, I have noted it in several makes.


PostPosted: Fri Nov 19, 2021 5:27 pm    Post subject: Reply with quote
Yes the haze looks rather minor. It´s difficult to photograph the phenomenon properly. From close-up examination I can tell it´s not a split or broken glass. I only fixed a lens once, a really good Zuiko with stuck aperture, but that was simple because the previous owner had the aperture control button inserted wrongly and the procedure was simple. I´m a bit worried doing more harm than good by opening up an otherwise perfectly fine lens. Well, I probably know more when I tried it on a full frame camera, just waiting for the adapter to arrive.

Thank you for your answers.
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