Friday, January 1, 2010

Lens mount study---150mm lenses

Each lens on Byron needs to be measured for its infinity stop, that is why I asked my clients to ship their lenses planning to use on Byron to me.
Byron is handmade converted, and the lenses are in different shutters, these variations bring great differences within lenses in same focal length.
Recently I measured 12 Byrons for their 4.7/127 Ysarex, to engrave their infinity stops. I found out that i.stop location changes within 4mm range, specific camera should paired with specific lens, no lens/camera switches allowed.
And on 150mm lens, I got 7 lenses this time, all in different type, although they are marked 150mm, but by their i.stop location, I'm sure some lenses are far less than 150mm.
Another BIG brother is a 2.8/150 Xenotar, I put a 127 Ysarex with it as comparison, you can see its size!! In  #3 shutter! Jesus Christ!
We will discuss each lens one by one, for future references.
Rodenstock Geronar 6.3/150 in #0 shutter
This lens got the shortest i.stop distance among other 150 lens, I doubt it is far less than 150mm, but found no data to prove it.
It doesn't need extruding lens board, normal board is good enough, and best of all, this lens can stay in camera when fold up, its tiny size and light-weight feature is great for travel and pack-carry, all these make this lens highly recommended for Byron.
Voigtlander Heliar 4.5/15cm in #1 shutter
This vintage lens is rather fast--4.5, and needs a extruding lens board, for its exceeding i.stop, and for its #1 shutter.
Fujinon.W 5.6/150 in #0 shutter--older version
Fuji 150 lens on normal lens board, can be directly mounted on, that is, no need to unscrew the rare element first. Compared with newer version, this lens is rather small in size, and quite easily mount/unmount.
CM Fujinon.W 5.6/150 in #0 shutter--New Version
I don't understand why Fuji made this version in such a big size, much bigger then previous version, but the lens are all in same size, a lot of space is wasted on its "bowl", front and rare, brings troubles when mounting on Byron.
two versions compared in size.
Infinity stop moves further a little bit, compared with old version, so it needs an extruding lens board. And the rare element is bigger than 48mm in diameter, must be taken off when mounting, then re-screw it on, that makes this lens the least choice for Byron, take my word, choose that old version.
Schneider APO Symmar 5.6/150 in #0 shutter
I was hoping to mount this lens directly, according its rear size in 47mm dia. smaller than Byron front standard lens hole 48mm, but because of extruding lens board, it only allow for in-directly mounting, very disappointed.
So there are two options:
1. installed with extruding lens board, and in-directly mount the lens.
2. installed with normal lens board, directly mount the lens, but rail extends about 2mm.
I will take option 2, for 2mm of rail movement loss cause focus range from 5 feet to about 5.3 feet, and I think I seldom to use a 150 in such close distance.
Pity, this is my favorite lens, but I can't make it perfect fit on Byron.
Fujinar 6/3/15cm vintage lens in #0 shutter

This tiny lens takes extruding lens board for its 3mm exceeding i.stop, other than that, no problem on mounting/un-mounting, very light-weight, a great lens for travel and trekking, but front element is little bit high, preventing it staying in camera when fold up.
Seikosha-Rapid shutter got a funny long release arm, so it can be released by Byron's sliding release, another weird plus.
Rodenstock APO Ronar 9/150 in #0 shutter
This lens takes extruding lens board, it is tiny, light-weight, easy to mount/un-mount, and very sharp. Though it is not a fast lens, but you can pick it in very reasonable price, and thinking of we always take pictures in rather slower aperture, like f/11or f/16, it is actually a good candidate for rangefolders.
(to be continued.....)

150mm lenses Recommendation List to fit Byron:  
tiny, light weight and stay in fold up
1. Rodenstock Geronar 6.3/150mm

directly mount, take off when fold up
1. Fujinon.W 5.6/150 (old version)
2. Fujinar 6.3/15cm
3. Voigtlander 4.5/15cm (in #1 shutter)
4. Rodenstock APO Ronar 9/150

Better NOT!!
indirectly mount, take off when fold up
1. Fujinon.W 5.6/150 (new version)
2. Schneider APO Symmar 5.6/150

Don't Even Think About It!!
1. Xenotar 2.8/150 in #3 shutter
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