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Re: [OM] C-U Lens follies

Subject: Re: [OM] C-U Lens follies
From: Moose <olymoose@xxxxxxxxx>
Date: Fri, 6 May 2016 16:18:15 -0700
On 5/6/2016 3:18 PM, Mike Gordon via olympus wrote:
There are several sites summarizing the achromatic diopters available.  I am 
slightly puzzled as to why they are not all that readily available in lower 

I think when these things were the rage, there weren't many common longer teles and zooms. Appropriate C-U lens diopters and extension tube lengths vary widely with FL.

That's a reason why µ4/3 extension tubes aren't as useful as one might like. OM users may be especially spoiled, with an unusual 7 mm Auto Tube. On a 50 mm lens, it adds 14% extension, just right for modest close focus range improvement.

The typical 12 mm 'short' tube adds 24%. But the short tube in µ4/3 is 10 mm, adding 40%, which is more than is needed or useful for modest C-U. But put it on a really long lens, and it's not enough.

Same thing with C-U diopters. Add +1 to a 50 mm lens, and nothing much happens, 
whereas +1 or less is right for a long tele.

I like this  site:


Thanks!. I had a couple, but not that one. Seems more complete and less out of date. Last update 2010, so doesn't, for example include the Oly MCON P-01 and P-02

Not sure where Moose found the Minolta one, but these are not that easy to find.

The 'Bay, where else? There were several of the No. 1 & 2s, at least a couple No. 0s. I picked the set of three for less than any of the lone No. 0s. Just about to set up to test it. Mint condition, older single or early multi coatings.

It's All in the Math Moose

What if the Hokey Pokey *IS* what it's all about?

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