Group: Moderator
Post: 2,040 (562 liked)
Join date: April 2014
Status: Long, long time Contax and Yashica user; glad to be here and hope to contribute.
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on Oct 15, 2021 11:07:45 GMT
Posted: Oct 15, 2021 11:07:45 GMT
This is one of the most difficult cameras to find, especially outside Japan: Yashica's Pentamatic II. This camera was manufactured in September 1960 and production only lasted 4 months.  Pentamatic II 5.8cm f1.7It is shown here with its classic accompaniment, the Auto Yashinon 5.8cm f1.7 lens with its ten, curved aperture blades and smooth bokeh. The lens is a stunner. It is unusual in having a dof stop-down button near the top centre of its mount as well as a sliding lever just below it to re-open the aperture. There is strong speculation from Chris Whelan (of yashicasailorboy fame) that this lens was actually manufactured by Zunow who also went on to produce a number of lenses for Yashica's 8mm movie cameras. I have pictured the camera with its rewind crank extended but it can tuck away such that it lies flat and forms part of the base of the cold shoe; it's a neat design. The Pentamatic II offers shutter speeds from 1s to 1/1000s plus B and the X flash sync of approximately 1/60s. Unfortunately, despite employing every tool at my command, I am unable to remove the attached filter which is rather frustrating; hopefully I won't have to resort to breaking its glass to gain access to the front of the lens. |
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Join date: August 2016
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on Oct 15, 2021 21:49:34 GMT
Posted: Oct 15, 2021 21:49:34 GMT
That 5.8cm f1.7 sure does look a lot like the Zunow 5.0cm f1.8 of 1958 -- the ribbing on the focusing ring is the giveaway. They also made a 5.8cm f1.2 at the same time. I assume their lenses had a proprietary bayonet mount, but that's just a guess.
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Group: Administrator
Post: 1,370 (301 liked)
Join date: February 2017
Status: Failed treatment for L.B.A. and G.A.S,
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on Oct 16, 2021 9:38:01 GMT
Posted: Oct 16, 2021 9:38:01 GMT
Unfortunately, despite employing every tool at my command, I am unable to remove the attached filter which is rather frustrating; hopefully I won't have to resort to breaking its glass to gain access to the front of the lens. I have a pair of pliable filter wrenches that squeeze to cover 52mm to 58mm. They can grip both the barrel end piece and the filter (one, each), and most times that's sufficient when the filter is a little over tightened - however - I've had luck with a couple of techniques when that method fails. Mine are the plastic type wrenches and do start to slip if the filter is really stubborn, so I have several strips of both leather and rubber that I can slip between one wrench and the filter to give it some extra gripping power. If there's no way to get all of that in place, or there's grit/grime locking everything in place and that still doesn't offer enough leverage... I have a couple of leather and/or rubber pads that I can lay out flat on a table to flip the lens onto them in perpendicular fashion, and twist the whole lens counterclockwise, so that either the rubber or leather pad grabs the edge of the filter ring all at once. If the edge is knurled, it's an even better grip and less likely to slip while turning. That gives maximum force with downward pressure to (hopefully) break whatever hold the filter has on the threads. There are two more ways to ratchet up the aggressiveness if none of the above works, but either one are last resort methods before I start hacking away at the glass and remaining filter ring. 1. Put a skillet on the stove and get it faily hot, but not 'cooking temp' hot. Flip everything perpendicular again, and set the whole of the filter ring edge onto the skillet to rapidly heat up just the ring. Once hot, go back to the leather pad method to again flip/twist the whole thing and unscrew the filter. Too hot and it may melt rubber, so best to stick to the leather pad only. 2. Caution! this is messy and ruins the filter permanently. Cut 2 slots into the filer's front ring edge - one at 12 o'clock and one at 6 o'clock - that are wide enough to place a straight edge of a metal ruler into both slots, just like a huge straight-blade screwdriver fits into a screw head. Twist to break the seal. The one complication might be where the lens would normally be disassembled by unscrewing the whole front optical block. If the filter is almost welded into place, it may end up pulling the whole block with it as you turn. |
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on Oct 16, 2021 23:16:07 GMT
Posted: Oct 16, 2021 23:16:07 GMT
I certainly never thought of the #2 approach. Sure it's drastic, but sometimes that's what it takes.
I have the plastic wrenches two, but have not had much luck with them. A similar approach is a rubber, flexible wrench. This is basically a large, thick rubber on the end of a stick. They are available at hardware stores and used by plumbers. They grip really hard and should get anything off -- plus they are handy for pipes, automotive car filters, etc.
A similar approach is to wrap a thick robber band around the recalcitrant filter -- for a better grip.
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Group: Moderator
Post: 2,040 (562 liked)
Join date: April 2014
Status: Long, long time Contax and Yashica user; glad to be here and hope to contribute.
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on Oct 17, 2021 1:24:37 GMT
Posted: Oct 17, 2021 1:24:37 GMT
Hi everyone,
Thank you all for the suggestions on getting rid of that reluctant filter.
It looks to have become corroded over the decades in storage - in trying to turn it, all I've succeeded in doing is wrenching the lens barrel by about 20 degrees. I think I may have simply to cut it off - sacrificing a 60 year-old filter is not a problem. It's just important not to nick the lens in the process. Wish me luck...
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