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08-21-2018, 11:06 PM   #1
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Question on Lens Front Coating Damage

Hello,

While I am here in China for the summer, I acquired two lenses: a Rikenon P 28-100/4 for my ME Super, and a Nikkor AF-D 28-105/3.5-4.5 for my FE2. I acquired both lenses rather cheaply (for its Chinese market price) because both of them have some marks on the front element. However, I have confirmed that the markings only consist of coating damage but not actual scratch on the elements.

However, the marking patterns are somewhat different. There are quite a few markings on the Rikenon, and they seem to spread out, much like cleaning marks. But the marking are not pronounced at all and can only be seen if I shine light directly onto the element and observe from an oblique angle. The markings on the Nikkor are more pronounced and can be seen without shining light onto the element. They are also larger but are concentrated in several small spots. But the rear elements on both lenses are in pristine condition.

I would like to know how these different coating damage patterns would affect image quality. I understand that coating damage on the front element would not affect IQ mostly, but I would like to know when these damages might be a problem and how they might show up.

I would also like to have someone recommend a hood for my Rikenon. I was able to get a compatible aftermarket bayonet hood for my Nikkor, but I can't find a compatible hood for my Rikenon except generic ones.


Sincerely

08-22-2018, 12:49 AM   #2
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If you were able to take some photos it would help. Are you sure the marks are on the outside of the element because some of those spots you describe sound like they could be fungus.

If the damage is just the coatings (like so called "cleaning marks") then its unlikely to have much effect on the performance on the lens - potentially it might be a little bit more prone to flare but otherwise probably not noticeable in your photos.
I like this post on how extreme the damage needs to be, in order to be readily noticeable: How Dust and Damage on Lenses Affect Image Quality
08-22-2018, 02:19 AM   #3
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QuoteOriginally posted by kiwi_jono Quote
If you were able to take some photos it would help. Are you sure the marks are on the outside of the element because some of those spots you describe sound like they could be fungus.

If the damage is just the coatings (like so called "cleaning marks") then its unlikely to have much effect on the performance on the lens - potentially it might be a little bit more prone to flare but otherwise probably not noticeable in your photos.
I like this post on how extreme the damage needs to be, in order to be readily noticeable: How Dust and Damage on Lenses Affect Image Quality
I've sent my Rikenon out for adjustments along with my ME Super, because of some tolerance issues the lens can't reach infinity at the 100mm end (but has no problem on my MZ-M), and my ME Super deserves a good CLA. I've asked the technician to watch out for fungus, but I am absolutely sure the things are cleaning marks - they are identical to the ones on my Helios-81H which has very soft coating, but only much less visible, and I am sure they are not on the inner surface and does not look like fungus (I've had fungu growing in one lens or two so I know how they look like).

I'll post the marks on my Nikon later when I get back home.

通过我的 moto x4 上的 Tapatalk发言
08-22-2018, 06:08 AM   #4
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I think you'll be fine. The sample Kiwi posted is just what I was looking for. I have a Pentax A 1.2/50 I picked up off eBay, and it has a couple very minor cleaning marks you have to hold the lens just right to see. I've taken a ton of shots trying to make it exhibit something I can see, and I can't. I'd say use them and enjoy.

08-22-2018, 10:34 AM   #5
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They can be just watermarks. A bead of saltwater or with heavy mineral content (even pool water with all that chlorine) that dries (it can happen really fast in a warm sunny, windy day) on a lens can leave a mark on the coating (even more so if it reacts chemically).
08-25-2018, 09:45 PM   #6
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Even scratches to the rear element have less influence than you might think. I have a Tamron 28-75 with light scuffs on the front and rear element. Tested against a 28-75 mounted on a Nikon, the contrast and flare were very similar, only a slight loss in detail (probably due to assembly differences).
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