Komura or Toyo 7 element 2X TC??

[sarah_fox]

<p>Hi all,</p>

<p>Well, my original post is probably buried and forgotten. It turns out the 7-element Komura 2X TC I ordered has a split thread. Ever see this happen?</p>

<p><img src="http://www.graphic-fusion.com/miscpics/komura.jpg" alt="" /></p>

<p>The vender says he has a 7 element Toyo he can send me instead. Any thoughts on a Toyo?</p>

 

[JDMvW]

<p>That's a new one for me.<br>

Puzzling about how it happened. <br>

I think a mismatch with a T-mount (M42x0.75, instead of the 42x1.0 of normal M42) would have stripped inwardly, not spread the threads.</p>

<p>Or could this one be a teleconverter made directly for a T-mount pitch (I have a couple of these that came with Spiratone's 400mm lens) and the 42x1 spread it? I'd guess then that the split would be longer, anyhow. The fact that the fail is only at the automatic aperture pin, suggests maybe something happened there?</p>

[john_shriver]

<p>Komura had their own T-mount-like system, the "Unidapter", and there was a 2X teleconvertor that would fit between the lens and mount adapter. The one I have is specifically engraved "for Unidatper". Doesn't look like what you have.<br>

This teleconvertor be used (ridiculously) to make my Komura 100/1.8 into a 200/3.6. Only advantage that stack-up has over my 200/3.5 Komura is that it focuses closer.</p>

 

[sarah_fox]

<p>The pin is actually a Fujica lens mount latch pin, not the auto aperture pin. (The seller said this TC was a Pentax configuration, but really it was Fujica.) I'm guessing someone got the pin stuck and forced the lens loose. (This is supposedly a NOS TC, BTW.)</p>

<p>Any thoughts about swapping for a Toyo 7 element TC? Should I take a refund and wait for another Komura? (I probably paid a bit too much for the thing anyway.)</p>

[JDMvW]

<p>I'd take the refund, if the Komura is what you want. For all I know the Toyo is as good or better, but I know nothing. If it's worse, you'd kick yourself.</p>

[sarah_fox]

<p>Well, here's a related question:</p>

<p>Would all 7-element 2X teleconverters have essentially the same optical design? In other words, would the differences be mostly in quality of manufacture?</p>

<p>And then...</p>

<p>Is/was Toyo a decent manufacturer?</p>

[rick_drawbridge]

<p><strong>Sarah</strong>, "Toyo" is as common a brand in Japanese as "Alpha" or "Apex" is in English, and it's consequently almost impossible to determine who the manufacturer of a "Toyo" product was unless there are a few more clues available. The best known Toyo is a manufacturer of large format view cameras, but I've read that they did not ever manufacture 35mm lenses or accessories. As for the design, I guess there could be great variation in the arrangement of seven elements....</p>

[sarah_fox]

<p>Thanks, Rick. I'll pass on it, then. I'm sure the right TC will come along if I wait.</p>

 

[profhlynnjones]

<p>In my experience they were similar in performance. However, the Komura was the first of the 7 element tele extenders as I recall it. B&J/BBOI imported Komura lenses in the US with whom I was associated for some time. Interestingly Komura made both a 4 element and a 7 element, for shorter FL lenses the 7 element worked best but with long telephotos the 4 element worked best, no I have no idea why, but it was decidedly true.<br>

Lynn</p>

[sarah_fox]

<p>Thanks, Lynn! :-)</p>

[sarah_fox]

<p>Thanks, Lynn! :-)</p>

[sarah_fox]

<p>Good news! I was able to buy another Komura TC for much less money than the original one. (I was the only bidder.) I'll just ask for a refund after all.</p>

<p>On another front, I had ordered a Kenko multicoat green filter from filterhouse.com for this same project. They contacted me and said they no longer carry many of the Kenko filters they offer on their website, generously offering to substitute their prestigious Kokonor brand for the same price. Kokonor?! What the heck is that?! So I've not had much luck these days. An order to Adorama fixed that problem -- $2 cheaper than B&H. Hey, a buck is a buck, and two bucks make an alternative couple. That's how I figure it.</p>

[bob_miller4]

<p>Some M42 versions of the 7-element Komura Telemore95 II teleconverter were made for Fujica M42 cameras and have some extra protrusions that cause mounting problems on some non-Fujica M42 camera flanges. These TC's are marked "F". I think the ones for plain vanilla M42 were marked "P".</p>

<p>By the way, any TC marked Telemore95 without the "II" has only four elements.</p>

[sarah_fox]

<p>Thanks, Bob! Well, I guess the one I have on order (due any day now) is the earlier 4 element design, which according to Lynn works better on long telephotos than the 7 element design. I hope it's true.</p>

<p>Funny story about the green filter, BTW: Adorama shipped everything but the green filter, which was on back-order. However, filterhouse came through with the Kenko MC green for me after all. I'm looking forward to trying it out.</p>

<p>I also made a pentapod -- a tripod with a bipod attached to it at the feet. (Bipod = tripod with one leg amputated.) The bipod supports and stabilizes the camera body, keeping the whole rig from rotating and wobbling, so I can shoot at substantially slower shutter speeds now.</p>

[bob_miller4]

<p>I recently tried using a Komura Telemore95 II 2X made for for the Fujica-type M42 mount, just like the one pictured here. I was chagrined to find that plain vanilla M42 lenses I had (including Super Takumar 55mm/2 original version) would not screw in all the way and therefore did not give a proper infinity focus. So I inspected its threads carefully. Lo and behold! The threads had a split like that in the picture here but less pronounced. The moral is to beware of this 2X variant since Komura had problems machining it. I checked eBay for a true non-Fujica M42 version and saw one that looked like the Fujica type but it was not identified as such. Caveat Emptor.</p>