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Legacy Lenses Discuss the use of older lenses, using adapters, from the Olympus OM system, Leica M and R-series, and the millions of others too.

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Old 13th April 2017
RobEW RobEW is offline
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Unexpectedly good way to inspect lens

Hi. I'm not sure whether this is well known or a novel idea. I happened upon it by chance.

I have an old Olympus Four thirds 12-60, bought used, and was pleasantly surprised to see that, as well as its other useful attributes, it can also focus very close. I happen to have the EX-25 extension tube so I thought I'd try it, to see if it provided even better macro capability.

The results?

Firstly the bottom of the viewfinder display shows "-.-" instead of an aperture, and the camera calculates exposure wrongly. I guess this is Olympus refusing to recognise this combination.

Secondly I can't get it to focus on anything (neither AF nor MF) at focal lengths of 12-50, and between 50 and 60 using MF when the focus ring indicates infinity the actual focus is 1.5 inches or less (say 4cm or less) from the front of the lens. This perhaps should have been foreseeable.

But thirdly an unexpected and potentially useful result. When zoomed to between 50 and 60mm, by adjusting the focus and when in certain lighting conditions (good light from the side, but a dark background in view) I can focus on the filter, the front element or even (I think) some internal elements, and see clearly (or even photograph) images of (and reflections from) specs of dirt and dust etc.

It looks horrendous, and I'm amazed I get decent images from it at all. (Maybe when focussed at more normal distances, these specs have little impact). Obviously my lens and filter need cleaning. Maybe some of those bright reflections are from internal dust which would need professional efforts to remove if it's worth it.

Anyway, I wonder whether this is a recognised way to inspect certain lenses? It shows up a lot that's not easily noticed by other methods.
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Old 13th April 2017
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benvendetta benvendetta is offline
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Re: Unexpectedly good way to inspect lens

I am surprised there is no indication of a connection between the lens and the body as there are contacts in the EX25.
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Old 13th April 2017
RobEW RobEW is offline
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Re: Unexpectedly good way to inspect lens

Same EX-25 works fine on my 50-200.
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Old 13th April 2017
Ulfric M Douglas Ulfric M Douglas is offline
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Re: Unexpectedly good way to inspect lens

Quote:
Originally Posted by RobEW View Post
... I can focus on the filter, the front element or even (I think) some internal elements, and see clearly (or even photograph) images of (and reflections from) specs of dirt and dust etc.

It looks horrendous, ...
Take off the filthy filter.
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Old 13th April 2017
RobEW RobEW is offline
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Re: Unexpectedly good way to inspect lens

I've cleaned it. Lens pen is very effective.

While I was peering through the system with the EX-25 on, I had the filter slightly loose, so I could twist it to see which of the marks would move. That's how I could distinguish between when it was focussed on the filter and when on the front element.
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