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Danger of G lenses?

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ToothyWeasel View Drop Down
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Post Options Post Options   Quote ToothyWeasel Quote  Post ReplyReply Direct Link To This Post Topic: Danger of G lenses?
    Posted: 23 October 2023 at 17:19
I was browsing macro lenses, looking at the 100mm lens and the 200mm G lens. Thats when I was told about an issue with G lenses and their grease having hardened over the years to the point it’ll actually break your cameras AF drive. My question is there anyway to test a lens for the hardened grease without risking your camera?
 



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addy landzaat View Drop Down
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Post Options Post Options   Quote addy landzaat Quote  Post ReplyReply Direct Link To This Post Posted: 23 October 2023 at 18:23
Who told you?
Why would G-lenses be different?
The only reference of something slightly similar is grease becomming gummy which is hard on the focus drive. Never heard it broke the camera (but if anybody has, it would be interesting to hear about it)

How to check? Turn the focus ring. When it focusses easy in manual focus, it should be fine with autofocus.
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Post Options Post Options   Quote neilt3 Quote  Post ReplyReply Direct Link To This Post Posted: 24 October 2023 at 01:15
Who told you that ?

I've most of the Minolta lenses from the start of A-mount in 1985 , including quite a few G lenses .
200mm f/2.8 , first version , mid 80's . 300mm f/4 H/S and 300mm f/2.8 , first version , 400mm f/4.5 , 80-200mm f/2.8 G , white version . 85mm f/1.4 RS , early 90's .Sony 35mm f/1.4 G , 2006 onwards .
The grease is spot on in all of them .
I've never heard of the grease drying out in any Minolta AF lens .

I've a lot of manual focus Minolta SR mount lenses , and all of them focus correctly , non are stiff or with dried up grease .

The only lenses I've got that have had problems with their grease are some FSU lenses , who probably used some form of axel grease to lube them with .

With regards to A mount macro lenses , I've the Minolta 1-3X Macro zoom lens , the Minolta 50mm f/3.5 , Minolta 50mm f/2.8 RS , 50mm f/2.8 D and Sony 100mm f/2.8 ( same as the Minolta 100mm f/2.8 D ) and a Sigma 180mm f/3.5 .
All focus as intended and work well with all my A mount cameras , Minolta and Sony .

I've never heard of Minolta A mount lenses grease drying up and breaking the cameras AF . Can you provide a link to where you've read this ?


Edited by neilt3 - 24 October 2023 at 01:22
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ToothyWeasel View Drop Down
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Post Options Post Options   Quote ToothyWeasel Quote  Post ReplyReply Direct Link To This Post Posted: 24 October 2023 at 15:47
This was mentioned to me in a Minolta discord server while discussing potential lenses I was looking at, that’s why I was asking as I had never heard that before. There’s some posts on here from around 2016 talking about how the grease gets pretty gummy and strains auto focusing motors like in this thread: https://www.dyxum.com/dforum/minolta-2870-g-ageing-issues-needs-replacement_topic123348_page1.html
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Post Options Post Options   Quote neilt3 Quote  Post ReplyReply Direct Link To This Post Posted: 24 October 2023 at 16:46
Originally posted by ToothyWeasel ToothyWeasel wrote:

This was mentioned to me in a Minolta discord server while discussing potential lenses I was looking at, that’s why I was asking as I had never heard that before. There’s some posts on here from around 2016 talking about how the grease gets pretty gummy and strains auto focusing motors like in this thread: https://www.dyxum.com/dforum/minolta-2870-g-ageing-issues-needs-replacement_topic123348_page1.html


I've only read the first few posts, but the opening post of that thread has nothing to do with what you asked .
It's talking about a sticking aperture .
Nothing to do with focus , be it AF or MF .

There should be no oil or grease on the aperture to go hard in the first place .
A sticking aperture won't damage your camera or lens as as it just fails to stop down correctly giving overexposed images .

Oh and two other G lenses I have I forgot to mention were the 28-70mm f/2.8 G in that thread and the 17-35mm f/3.5 G .
Both of which also work fine .

I did have a 28-70mm who didn't focus to infinity , but clearly someone previously had had it apart and put it back together wrong .
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addy landzaat View Drop Down
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Post Options Post Options   Quote addy landzaat Quote  Post ReplyReply Direct Link To This Post Posted: 24 October 2023 at 20:41
It is the same thread I linked to and the second post mentions: "If you're having a focus ring stiffness issue, then the AF drive from the camera can indeed play a factor. [...] The old grease gets gummy and makes the ring turn very stiff, which is hard on a camera motor." Like I said, that does not mean it breaks the camera. It is very unlikely and I suspect the camera has a slip thingy (can't remember the proper term) that prevents the motor from getting burnt (or something similar).

Also, if this happens with G-lenses, it surely also happens with non-G screw drive lenses like that 100mm Macro....

But like I said, if it focusses fine by hand, it will focus fine with the camera.

And discord is "random guy on the internet" - not a reliable source.
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addy landzaat View Drop Down
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Post Options Post Options   Quote addy landzaat Quote  Post ReplyReply Direct Link To This Post Posted: 24 October 2023 at 20:45
Oh, and if you're still uncertain, pick up a el-cheapo Dynax/Maxxum 3, 4 or 5 - if that can drive the lens, your Dynax 9 for sure will.
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Post Options Post Options   Quote Dotsch Quote  Post ReplyReply Direct Link To This Post Posted: 27 October 2023 at 17:29
I had never any grease or issues with all my ten Minolta screw drive lenses, mostly build in 1985 to 1987, including the 100 Macro. The mostly in hobby use since 20 to 35 years and working fine.

The only issues I had was a lose gearwheel in the Minolta 20mm, which I as able to repair and a liquid grease of the aperture of the 50 1,7 which ran between the two lenses of the front element.
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Post Options Post Options   Quote Snegren Quote  Post ReplyReply Direct Link To This Post Posted: 27 October 2023 at 22:20
Grease drying out is an issue with pre-80s lenses with organic grease. It can go solid and freeze focusing helicoids. The mineral grease used by Minolta, even in the early SR days, should last for centuries.
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