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10-18-2011, 05:09 PM   #1
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Old prime lens Haze problem

i have the following lens SMC Pentax-M 50mm 1:1.7 prime lens that i purchased second hand and at the time it had some fungus and dust inside the lens.
As i did not pay much for it i decided to take it apart and clean the fungus from the optics using lens cleaner and alcohol with good success.
I have now had the lens apart a number of times because it appears to produce a smokey haze in certain light conditions - see attached photos.
It only happens in certain light and does at times produce very good clear and sharp photos.
Is this a fault of the lens or my lack of knowledge of photography and how to use a fast prime lens in difficult light?
please help!!!

Attached Images
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PENTAX K-r  Photo 
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PENTAX K-r  Photo 
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PENTAX K-r  Photo 
10-18-2011, 05:31 PM   #2
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Are you using a lens hood? It may not be the only problem, but it should help cut down on some of that glare. Not so much in the third pic, where you're shooting right at a bright light source.
10-18-2011, 05:37 PM   #3
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i just need to know if this is normal for a lens like this or if it is a fault or lack of cleaning the lens optics properly.
If it is a problem with the lens i will replace it with another of the same series but i do not want to purchase another only to find it will be the same
10-18-2011, 08:23 PM   #4
dms
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I have this lens I don't see anywhere near such flare. You were not using a filter were you?
It appears to be from lights in the picture so hood would not eliminate it. IMO your fungus has actually etched the glass surface--removing the glass coating--resulting in internal reflections and thus flare. That is an educated guess as I don't have any lens that had fungus issues, in so far as I know. But the picture exhibits a lot of flare.
In any event, as I said above, it is not what I believe I would see with my M50 f1.7 lens.

10-18-2011, 08:58 PM   #5
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This is very helpful dms
It seems as i suspected that the lens is damaged or not performing as it should due to me taking it apart to clean it.
I would grab a filter but being that the cost of replacing this lens would be not much more than the price of a good filter i think i will track down another one through eBay.
Thanks for your help
10-18-2011, 09:07 PM   #6
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No, when I asked about the filter I was concerned you used one and thus it complicates the analysis.
A filter adds one additional glass surface (the inner surface) for possible additional reflections.
10-18-2011, 09:10 PM   #7
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ok now i understand - i have just removed the filters from my zoom lenses after i had some nasty reflection issues when doing night shots.
10-18-2011, 09:34 PM   #8
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QuoteOriginally posted by spike62002 Quote
ok now i understand - i have just removed the filters from my zoom lenses after i had some nasty reflection issues when doing night shots.
Echoing that the lens probably has been damaged from the fungus eating it. You can possibly check by shining a flashlight through it and looking. If its etched, you should see it.

10-18-2011, 09:39 PM   #9
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i don't see any etching as such but looking through the lens it does look smokey and not clear as i believe it should, this is what has led me to pull it down and clean it several times .
10-18-2011, 10:14 PM   #10
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I've got a similar lens with the same problem. The haze on mine appears on the inner element of the back group, and from what I could establish is due to lens seperation. I am now trying to get hold of some Canadian balsam to try and re-cement it. The following article (it is in English) might explain it better.
Fotomozaic.ro - despre si pentru fotografie
10-18-2011, 10:36 PM   #11
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that is a very insightful article and i believe explains what has happened to this lens in a past life.
When i first got the lens it had obvious signs it has been opened before.
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