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Mareklew
Tinkerer
Username: Mareklew
Post Number: 67
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, May 02, 2010 - 02:29 pm: | 
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Hi,
Short: can I take the taking/viewing lens pair from a Yashica Mat (original) and put them in a Yashica 124G? Are threads and general flange distances same (I know I will need to adjust the viewing lens for focus)?
Long version:
I have here a Yashica Mat, my favourite travel companion with an exceptionally sharp copy of Yashinon taking lens. Unfortunately, it has hit ground and focusing rails aren't straight anymore.
I also have a mint-looking Yashica 124G with an ordinary run-of-the mill lens. Mechanically perfect, but each time I see the photos next to my old ones I see they're less sharp. I could set off and buy another 124G, but they are all old, and this one is mechanically tip-top. So I wonder, could I swap the lenses?
I don't want to 'just try' it, because (literally) screwing focus adjustment and having to re-do it from scratch isnt' exactly my favorite pastime and I'd rather avoid doing it if somebody knows for sure the lens wont' fit.
Also, I have an unfinished roll of film in 124G now.
Thanks for any input,
Marek |
Scott
Tinkerer
Username: Scott
Post Number: 101
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, May 02, 2010 - 02:53 pm: |
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It's Yashinon lenses in both cameras, right? I assumed that all of the Yashinon lenses in all of the Yashica TLRs were the same, and could be swapped for another Yashinon lens without the need for adjustments
Do your two taking lenses actually have different specifications? Or is one of them damaged by cleaning marks or something else that might be affecting the sharpness?
Also, am I correct in believing that the only method of focus adjustment on a Yashica TLR is the shims between the lensboard and the shutter unit? |
Mareklew
Tinkerer
Username: Mareklew
Post Number: 68
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 03, 2010 - 07:18 am: |
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Well, all lenses are Yashinon, but what I wondered is, whether their mounts are same.
What makes me feel extra strange is, that my 124G has a lens with no serial number on it, while Mat has one engraved.
As to the lenses on the 124G: they look perfect, not a single scratch. The focus adjustment is done by screwing the viewing lens in and out of its thread, there's a setscrew to fix it in place. The problem is, this screw bites into the thread directly, so it doesn't rotate smooth anymore after being fixed once. I have no idea how to check focus plane alignment (Scheimpflug error), besides checking the focus in the center.
Marek |
David_nebenzahl
Tinkerer
Username: David_nebenzahl
Post Number: 286
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 03, 2010 - 06:04 pm: |
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Isn't Scheimpflug only relevant when a camera has tilts or swings (i.e., when the focal plane isn't parallel to the plane of the lens)? You may be overthinking this a little. If you adjust for sharp focus in the center, you should be good. (Can't help you with the 124G/Mat issue, unfortunately.) |
David_nebenzahl
Tinkerer
Username: David_nebenzahl
Post Number: 287
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 03, 2010 - 06:06 pm: |
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Oh, you're saying how do you determine if the focal plane is parallel to the lens plane, right? Sorry, can't help you there either (except to assume it is unless the camera has been dropped or otherwise subjected to shock). |
Mareklew
Tinkerer
Username: Mareklew
Post Number: 70
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 04, 2010 - 05:12 am: |
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Exactly. I suspect my camera might have an unwanted tilt or swing built in. A tilt would be extremely bad, as it makes taking and viewing lens shift focus at different 'speed', i.e. equal displacement against infinity position results in different displacement of focus plane.
I started meanwhile to rebuild my old Yashica, stripped it totally down, found no apparent bends in the focusing rails, so it colud be good after adjusting focus retract "bumpers" to zero play. What remains an unknown is, however, whether the lens plane and film plane are still parallel and stay parallel when focusing. I'm a bit puzzled as to how to check this.
Also adjusting infinity focus of the taking lens seems to need some kind of a trick I haven't come across yet.
greets,
Marek |
Glenn
Tinkerer
Username: Glenn
Post Number: 773
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 06, 2010 - 01:31 pm: |
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The answer is VERY simple - Get yourself a proper focusing target sheet, remove camera back and place ground glass/Scotch Tape over film aperture, place camera on tripod and focus on target. View the image on the focus screen and the ground glass/tape under high magnification - compare the sharpness of the two images at their top and bottom edges. Do this at various distances and see what happens - it soon becomes apparent if there is a problem with a bent lens board. |
Chiccolini
Tinkerer
Username: Chiccolini
Post Number: 98
Registered: 06-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, May 30, 2010 - 03:02 pm: |
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Marek, how did this turn out for you? Do you now have one good camera and one parts camera or ?
Do you have the rear lens of the 124G? I need one. Mine is "etched" (the coating and grease from the shutter got together to form something unremovable). |
Mareklew
Tinkerer
Username: Mareklew
Post Number: 85
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 31, 2010 - 03:11 am: |
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I bit the bullet and restored the crashed Yashica (the one with perfect optics) to original working condition. The casing is dented and bent, but the focusing rails are realigned and sharpness across the image plane is as-new or better. The lens hits in the center at f:8 resolution limit of FP4+ enlarged with Componon-S 50mm lens (I know its 24x36 lens, that's why I checked center-field only). Good enough for me.
I have also adjusted my 124G to provide acceptably good sharpness throughout the image, which is not much worse than the old one.
I have, however, switched to a Rolleicord Vb for now, equipped with RB67 focusing screen it makes a better all-rounder as it is easy to focus (custom screen), has a very good lens and the shutter needs not be cocked while the film is advanced already (no risk of triggering shutter while in bag).
Marek |
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