Everything I know about OM Zuikos

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Is there a thread or link to the best OM Lens to M4/3 adapters?
I've had fairly good luck with the cheapest stuff I could find on evilBay.

Sometimes, they need some help. The hole for the latching pin might not be deep enough. I got one bunch that was missing the radial screw that stops it from turning too far, and you could turn it past the locking pin if you had the button down for some reason.

If you get a bad one, throw it in the junk box, and you're only out $10-$15 or so.

That said, the ones that have worked well say "FOTGA" on them, but I have one that works particularly well that has no name on it anywhere. The ones I've had problems with say "DOLLICE" on them, but at least one of those works fairly well. It seems to be a crap shoot.

Generally, the µ4/3rds end is milled out of aluminum, and they're pretty similar.

The OM end varies in quality. There are two general sorts: one has a bit of springy metal riveted to the stainless or brass mount, the other has thin slots in the bayonet flanges to create a friction fit. While I feel the first type is higher quality and manufacturing cost, the second type can be "tuned" by changing the thickness of the slot. Squeeze it with some pliers if the fit is too tight, or stick a screwdriver in the slot and widen it by twisting if the fit is too loose.

Both the Dollice and Fotga ones have the separate springy metal, while the no-name one has the slotted flange. I've "tuned" it fairly tight, and use it with my 180/2.8, the heaviest lens I use regularly.
 

John King

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John ...
Adding to the excellent info Mark provided in his OP, people may find the following PDF files useful. I uploaded them to my FTP site this morning.

I'm just trying to figure out the FTP access ATM. I will notify the user credentials when I have them worked out.

AFAIK, these documents are no longer available anywhere, and they shouldn't be lost ...
 

barry13

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Adding to the excellent info Mark provided in his OP, people may find the following PDF files useful. I uploaded them to my FTP site this morning.

I'm just trying to figure out the FTP access ATM. I will notify the user credentials when I have them worked out.

AFAIK, these documents are no longer available anywhere, and they shouldn't be lost ...
Hi, Google Drive or Dropbox could be good options.
 

barry13

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Thanks for the suggestions, Barry.

I really do need to work out how to grant read only access to my own FTP server.
Chrome and Firefox will both be removing ftp very soon. They were going to do it already but decided to hold back to give IT departments more time because of the pandemic.

If you have a web server, a browsable folder is an option.
 

John King

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I think I have worked this out ...

The URLs from which I have aggregated this info over the years is shown on the documents (many years ago as of today).
I do not believe that any of them are still available, so hard to obtain permission to use them. The last time I checked for availability was about 7-10 years ago, and none were still available then.

My purpose is merely to propagate them so that they are not lost.
ALL credit for the contents must go to the original authors.

Files are available as PDFs here:

https://canopuscomputing.com.au/Downloadable_Files/OM_Lenses_Info/OM_Lens_Chart.pdf
https://canopuscomputing.com.au/Downloadable_Files/OM_Lenses_Info/OM-System_lensterms.pdf

{OM_Legacy_Lenses.pdf}
This link to A. Wrotniak's site is still alive, but dates from 2005:
https://www.wrotniak.net/photo/quest/q08.html

This file should be read and understood before reading the Olympus_OM_System_Lens_Tests.pdf file, otherwise the lens test file could be misleading.
https://canopuscomputing.com.au/Downloadable_Files/OM_Lenses_Info/OM_Lens_Tests_Method.pdf

The following file is about 116 pages long, and needs to be evaluated with care.

https://canopuscomputing.com.au/Downloadable_Files/OM_Lenses_Info/Olympus_OM_System_Lens_Tests.pdf

Hope that this is of benefit to people.
 
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junkyardsparkle

haunted scrap heap
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John King

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I've done a meta-analysis of the Gary Reese tests, which is also on-line.

I took his "A-F" grading system and translated it to numerical numbers, and grouped everything by aperture relative to wide open, to make comparisons easier.
Jan, that's as massive an amount of work as Gary's original, almost. Well done.

It is a good thing that knowledge is replicated. Us humans are exceptionally good at forgetting what is well known.

Look at the history of Tourette's syndrome, forgotten about for about a century!
 

Danny_SWE

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What a thread!! Massive research there MarkRyan!

I found this on a local selling site, so many goodies...
OM.png
 
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