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All Ektars are not equal !

 
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pv17vv



Joined: 22 Dec 2001
Posts: 255
Location: The Ardennes, Belgium

PostPosted: Sat Dec 12, 2009 6:14 pm    Post subject: All Ektars are not equal ! Reply with quote

I own two 127 Ektars in factory-fitted Synchro-Compur shutter, both built anno 1956 assumingly by the same workers.
Recently #1 was away beeing CLA'd so I used #2.
I discovered Infinity Stops tuned for #1 were completely off for #2, so much I reflexedly checked if they were still solidly in screwed in place.
They were.
When the image on the GG was sharp at infinity, the arrow was in front of 50 ft on the focus scale.
Really a big difference...
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45PSS



Joined: 28 Sep 2001
Posts: 3229
Location: Mid Peninsula, Ca.

PostPosted: Sat Dec 12, 2009 10:18 pm    Post subject: Reply with quote

No two lens coming off any manufacturers line are the exact same. There will be slight differences to large differences depending on what tolerance the manufacturer is using.
Kodak ran good quality control but I do not know what tolerance they used. Using the cam list for the Pacemakers as a guide it appears to be 1.5% which results in a range of focal lengths from 125.095 to 128.905 for the 127mm Ektar assuming they used the same variance percentage for over and under.

Measure the actual rail movement from one lens at infinity to where the other is at infinity in Milli meters and that will be the difference in actual focal length of your lens.

When you adjust your side rangefinder you are adjusting it to you lens, not the labeled focal length so you are effectively measuring the lens actual optical length.
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glennfromwy



Joined: 29 Nov 2001
Posts: 903
Location: S.W. Wyoming

PostPosted: Sun Dec 13, 2009 10:24 pm    Post subject: Reply with quote

Lens manufacturers also use shims to adjust the lenses when fitting them to shutters. I know Kodak used this practice, though I've never run across one with shims. The shims bring the focus into tolerance. Reference material, such as the 1944 edition of Graphic Graflex Photography, et al, states that Ektar lenses should NEVER be removed from their shutter. That is probably due to the shims being lost. You can find out how much the one that's short is off compared to the long one by simply screwing out the front cell until it matches. That would be the thickness of the shim that doesn't exist. It really doesn't matter, though. choose one and adjust the rangefinder to suit. Put the other one on something else.
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Glenn

"Wyoming - Where everybody is somebody else's weirdo"
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pv17vv



Joined: 22 Dec 2001
Posts: 255
Location: The Ardennes, Belgium

PostPosted: Tue Dec 15, 2009 6:20 pm    Post subject: Reply with quote

Thank you for your replies.

Quote:
It really doesn't matter, though. choose one and adjust the rangefinder to suit. Put the other one on something else.


Glenn, this is exactly was I intended to do. The lenses will be carefully packed and stored and the shutter will be put in reserve until I find something to screw into it.
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Mike1234



Joined: 10 Jan 2010
Posts: 12
Location: South Texas

PostPosted: Sat Feb 06, 2010 7:40 pm    Post subject: Reply with quote

I'll bet someone switched the wrong FL elements on the rear of one of the lenses.
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Dan Fromm



Joined: 14 May 2001
Posts: 1887
Location: New Jersey

PostPosted: Sat Feb 06, 2010 9:35 pm    Post subject: Reply with quote

Hmm. Why oh why oh why did Graflex supply more than one focusing scale for lenses of the same make, model, and nominal focal length?

Rhetorical question. Actual focal length = nominal +/- as much as 5%. That's why.

The difference in flange-to-film distance between "focused at infinity" and "focused at 50 feet" isn't very large.

Cheers,

Dan

Oh, yeah, I've told this story before but I'll tell it again. I once bought a bunch of aerial cameras that held, between 'em, 20 38/4.5 Biogons. These lenses' engraved focal length is 38 mm. Nominal, per Zeiss' documentation, is 38.5 mm. The camera manufacturer had measured, marked each lens with its actual focal length. The range was 38.3 - 38.8 mm. And these were very expensive lenses made about as precisely as possible for a highly exacting application.
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pv17vv



Joined: 22 Dec 2001
Posts: 255
Location: The Ardennes, Belgium

PostPosted: Sun Feb 07, 2010 7:37 am    Post subject: Reply with quote

Thanks for this precision Dan, very interesting as usual.
To close the topic, this lens #2 is at home on camera #2 and everything is OK, normally no need to put it on camera #1.
Georges
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