bluesun267
Well-known
Thanks, that's what I thought! Your scans mirror my experience exactly.
Leicaflex SL Summicron-R 50mm vs M3 Konica M-Hexanon 50mm
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bluesun267
Well-known
I don't believe this.
I noticed the poor sharpness in various shots between 15' and infinity. Getting better as you focused closer.
shawn
Veteran
I just put the lens on three RF cameras (M3, CLE, M240) and at the lens infinity position all the RFs agreed with being at infinity, no overshot. If all the lens were built wrong then that would certainly be impacting the infinity scans I posted and would just be dumb on a system that doesn't focus optically through the lens. Esp. for anyone calibrating a Hexar RF they would be putting the lens on, setting it to hard infinity and then calibrating the RF to that.
Even still, doesn't change the closer in differences.
Shawn
Freakscene
Obscure member
Don’t believe me. Take a KM lens apart and check, and carefully measure mtf as you move out to infinity focus. I have three of the KM 50/2s and one each of the 28, 35 and 90. None if them has an infinity stop on the helicoid and all the 50/2s focus past infinity. I really love the lens, you just need to learn how to use it.
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das
Well-known
I bet that the M-Hex's mentioned above may front focusing a little bit, which is what the focusing error usually is when used on Leica M cameras, and which cannot be immediately diagnosed on a film camera. A mirrorless camera would be the best way to test (with liveview critical focusing to ensure that infinity is actually reached).
bluesun267
Well-known
Your claim is quite outrageous: A manufacturer who has been in business for many decades, and has made RF lenses for a good chunk of that time, suddenly can't calibrate infinity. And worse, builds it into one model lens as a 'feature'.
I don't have a lens anymore to disassemble and I'm not sure what you mean by an infinity stop "on the helicoid". I work on RF lenses all the time and there are quite a few different ways the various manufacturers place limits on the focus travel. Very few of which could be considered part of the helicoid itself (if we are using the same terminology here--I consider the word helicoid to refer to the interior threaded part only, usually made of brass). Furthermore if your lenses are focusing past infinity I would look toward adding a shim before messing with the hard stop. But again I don't have the lens in front of me.
I did check my copy at the film gate of my Hexar RF when I bought it and was satisfied it agreed with the rangefinder @ infinity along with all my other lenses of various brands.
Another reason I don't believe your claim is that we really are pixel peeping here. Pitting a really exceptional lens against an average one. In practical use, the Hexanon is still a very good lens with beautiful character. I don't believe the samples here point to a manufacturing defect which would cause the Hexanon to have to employed in a manner different than every other lens of its kind in order to get adequate results. And it just doesn't look like a focus problem to my eyes. So I'm going with the simple explanation, rather than the extraordinary one you propose.
das
Well-known
Many 50mm M-Hex's shipped from the factory early on were calibrated to a different backfocus distance than Leica, enough to throw off the focus. This was apparently to account for film depth/flatness issues between a Leica M and a Konica Hexar RF. Later M-Hex's were shipped all in Leica spec. I had to get my early 50mm Hexanon professionally realigned to get it to work right on Leica Ms. The M-Hex has two adjustments for this, one is a glued-on ring on the back of the lens under the lens mount and another is an adjustment at the center of the lens barrel. This is all very well-documented. The M-Hex should be 96-98% of the lens of a V4 M-Summicron. If it is not, then there is a problem with the lens.
raid
Dad Photographer
Using a Leica M10 or M11 with a Visoflex finder can resolve the raised issues here. Focus manually and then use the finder. Are you getting identical distances ?
shawn
Veteran
It is possible the infinity is off. If anyone has a site explaining how to take apart the M-Hexanon to adjust it I would be willing to try it. If it is focusing past infinity the optics need to move out but the RF cam needs to stay where it is as it is correct for infinity. I could shim the mount and then shim the cam but it would be easier to just move the optics if that is possible. I tweaked the cam on my 90mm to match the optics (which were fine).
A mirrorless camera would be a way to make sure infinity is focused but it would NOT be the best way to determine if the lens is properly calibrated for infinity. Pretty much every M mount adapter I have used on mirrorless cameras has been too thin. Actually common for most adapters as manufacturers make them that way to make sure a lens can hit infinity.
On a digital camera the SLR lens is going to have an advantage over a M mount lens.....
Shawn
shawn
Veteran
That assumes the RF is calibrated correctly. Two other ways that don't need the rangefinder, focus to hard infinity on the moon and take a shot and then focus a little closer and shoot again. I will try this on my M240 with the Hexanon. Or put ground glass in the M3 with a piece of tape on it with an X and then use another camera focused at infinity to look through the Hexanon (at infinity) and see if the X is sharp. Could set this up easily enough as this is how I calibrate Kraken's.
Having said all that the Summicron-R is dead on at infinity at its stop.
Shawn
raid
Dad Photographer
I have never had problems with RF in my M3, M6, M8, M9, M10.
Freakscene
Obscure member
Take one apart and check before making any accusations. As has been outlined by several others, the back focus on the Hexar RF was calibrated using differently, and the lenses were not built with an adjustable infinity stop. I am not and have not suggested that it was a feature. It is simply how they were built.
I have also been assuming that your lens was calibrated for Leica standard back focus. If you have an early lens that is not, all sorts of interesting things happen when you use the RF to focus. But when you get it working on a Leica rangefinder, there is no way to adjust where the lens travel stops, and they focus incorrectly when put hard against the infinity stop.
KoNickon
Nick Merritt
I'm not really sure what to think of all this -- seems like ground that's been trod before: Some of the early M-Hexanons were built to wider tolerances than Leica M lenses were. Whether Konica later tightened the tolerances, I don't know, and if so, I don't know as of what serial numbers that occurred. (Does anyone have this information?) But given all this, wouldn't the true test be to see whether the 50 Hex being tested focuses correctly on a Hexar RF?
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