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Please help me identify these spots in my lens.
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PostPosted: Thu Aug 16, 2018 3:04 pm    Post subject: Please help me identify these spots in my lens. Reply with quote
Recently purchased this Minolta Rokkor-PF lens, ad said no fungus but bits of dust. But this doesn't look like normal dust to me (the spots with clear rings around them). I am wondering if they could be fungus spores or if the lens has some haze and the spots are condensation or some other liquid which clears the glass around the spots? I have Googled it and been through all the images but can't find anything similar.

Any thoughts will be most appreciated as I don't want to store it with other lenses if it could be fungus, plus that will affect resale price. Might buy a mint copy as it's gets very sharp stopped down to f8 and I assume all the crap inside is harming it when open at f1.7 and smaller. Thanks.







PostPosted: Thu Aug 16, 2018 3:29 pm    Post subject: Reply with quote
It seems like it is on the external surface of the rearmost element. I would give it a wet clean using a lens tissue moistened with a drop of lens cleaner, twice, and then see if it improves.


PostPosted: Thu Aug 16, 2018 5:50 pm    Post subject: Reply with quote
Seele wrote:
It seems like it is on the external surface of the rearmost element. I would give it a wet clean using a lens tissue moistened with a drop of lens cleaner, twice, and then see if it improves.


It is not on the outside, it is probably the next piece of glass though. I gave it a quick clean with water and an ear bud before posting, which didnt make any difference. Thanks anyway.

I have just booked to have a lens dealer coming on Saturday so will see if he will take it and a few others for a reasonable price, unless someone else knows what it is. I would like a better copy anyway as it is so sharp at f8. Not been lucky recently: sending a Canon 50mm f1.4 back to Japan tomorrow as it doesn't focus to infinity and I just put 2 cheap Industar lenses up for sale as they have loads of scratches on front element which makes images hazy, it's like they have been cleaned with sand paper Laughing But I love a couple of other recent buys.


PostPosted: Thu Aug 16, 2018 6:36 pm    Post subject: Reply with quote
Probably haze, probably helicoid-lubricant related.


PostPosted: Thu Aug 16, 2018 6:49 pm    Post subject: Reply with quote
Gardener wrote:
Probably haze, probably helicoid-lubricant related.


These days I am making a point to service my lenses to get rid of the early, unstable grease inside and replace with the more stable modern grease; I am still feeling my way though, but I can say I have figured out how to work on a few German - mainly Meyer - lenses so far.


PostPosted: Thu Aug 16, 2018 7:48 pm    Post subject: Reply with quote
Gardener wrote:
Probably haze, probably helicoid-lubricant related.


Thank you, that is helpful


PostPosted: Thu Aug 16, 2018 8:08 pm    Post subject: Reply with quote
The spots definitely look like they are probably oil-based. Thus, plain water most likely would have little effect, or could leave marks of it's own on drying. I use ROR (residual oil remover) as my go-to lens cleaner. Used with a clean micro fiber cloth or Kimwipes, it's safe and easy to use. I spray it right on the lens.

Here's the cleaner:

https://www.amazon.com/ROR-Optical-Cleaner-Spray-Bottle/dp/B0002HMRF2/ref=sr_1_1/139-4563556-1824464?ie=UTF8&qid=1534449771&sr=8-1&keywords=ror+lens+cleaning+solution

These are good wipes:

https://www.amazon.com/dp/B077Q2JV1W/ref=sspa_dk_detail_3?psc=1&pd_rd_i=B077Q2JV1W&pf_rd_m=ATVPDKIKX0DER&pf_rd_p=a54d13fc-b8a1-4ce8-b285-d77489a09cf6&pf_rd_r=TQ33XQKR2CWFXB3QMZFW&pd_rd_wg=ZmAKs&pf_rd_s=desktop-dp-sims&pf_rd_t=40701&pd_rd_w=vk7uL&pf_rd_i=desktop-dp-sims&pd_rd_r=5dcd48df-a18f-11e8-b894-65785e22d3f3

Best,

Paul


PostPosted: Fri Aug 17, 2018 4:48 am    Post subject: Reply with quote
pdccameras wrote:
The spots definitely look like they are probably oil-based. Thus, plain water most likely would have little effect, or could leave marks of it's own on drying. I use ROR (residual oil remover) as my go-to lens cleaner. Used with a clean micro fiber cloth or Kimwipes, it's safe and easy to use. I spray it right on the lens.

Here's the cleaner:

https://www.amazon.com/ROR-Optical-Cleaner-Spray-Bottle/dp/B0002HMRF2/ref=sr_1_1/139-4563556-1824464?ie=UTF8&qid=1534449771&sr=8-1&keywords=ror+lens+cleaning+solution

These are good wipes:

https://www.amazon.com/dp/B077Q2JV1W/ref=sspa_dk_detail_3?psc=1&pd_rd_i=B077Q2JV1W&pf_rd_m=ATVPDKIKX0DER&pf_rd_p=a54d13fc-b8a1-4ce8-b285-d77489a09cf6&pf_rd_r=TQ33XQKR2CWFXB3QMZFW&pd_rd_wg=ZmAKs&pf_rd_s=desktop-dp-sims&pf_rd_t=40701&pd_rd_w=vk7uL&pf_rd_i=desktop-dp-sims&pd_rd_r=5dcd48df-a18f-11e8-b894-65785e22d3f3

Best,

Paul


I think Paul is right. I had a lens show up with similar oil spots. They weren't there is sale pictures. I suspect rough treatment enroute to me caused the oil to scatter from its source.


PostPosted: Fri Aug 17, 2018 11:34 am    Post subject: Reply with quote
Much appreciated, thank you all.

I think this puts the lens 2nd, slightly ahead of my beloved Super Takumar 55mm f1.8, for sharpness. Maybe the Tak can claw it back in the character test. The super tak 50 1.4 is solidly in 1st place out of 15 cheap manual lenses, but may get challenged when my broken canon 50 1.4 nFD is replaced.


PostPosted: Fri Aug 17, 2018 4:38 pm    Post subject: Reply with quote
Which Rokkor PF is this lens? I don't recognize that lever on the outer perimeter.


PostPosted: Sat Aug 18, 2018 5:08 am    Post subject: Reply with quote
woodrim wrote:
Which Rokkor PF is this lens? I don't recognize that lever on the outer perimeter.


One of the early 55/1.8's.


PostPosted: Sat Aug 18, 2018 9:42 pm    Post subject: Reply with quote
Like this:

Early Auto Rokkors have this Aperture preset lug.


PostPosted: Sun Aug 19, 2018 12:30 am    Post subject: Reply with quote
Thank you! Like 1 small
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