Hi

My question about thies lens is the following.The lens has 2 focal lengs 210mm and 370mm but for 370mm I have to use only 1 part of the lens and need a bellows lengs of about 430mm so I have to buy a other bellows for my Arca and also a loger monorail bevor I can use it! 1. Question: Is it sharp enough to use it with todays films on the 370mm version! 2. Question: Witch part has to be removed to get the 370mm version?

The 210mm version is take sharp and the lens is in a very good condition!

Thanks for help

-- Armin Seeholzer (armin.seeholzer@smile.ch), March 05, 2001

Answers

The lens is good at the 210mm length. You have to remove the front element to convert it to the 370 length (but as you point out the bellows draw required is more than 370mm because the lens nodal point now lies behind the lensboard - the 430 mm sounds about right). Performance isn't as good at the converted length since by removing the front element, some of the corrections designed into the lens are removed as well. Performance can be improved by using a strong monochromatic filter, which reduces chromatic aberrations. If it needs buying a longer monorail, it might be worth checking out other lenses as well. Alternatively, do not buy the longer monorail but try cobbling together an extension lensboard. I'm quite happy with this lens, even at the converted length but different folks have different demands. I even use it as a wide angle on my 8x10 (oddly enough, it covers, although specs say it shouldn't - the edges are soft but I don't need to splurge on a 210 SA). Good luck. DJ

-- N Dhananjay (ndhanu@umich.edu), March 05, 2001.

I agree and by coincidence tested mine out over the weekend to see how sharp it was using the rear element. I was very pleased with it, and the other convertibles I have used and often use (the 180/315 and the 150/265) seem plenty sharp as converted lenses to make prints in the 11X14 range. I assume the points about focus shift and the yellow filter are valid (most people posting responses seem to know much more than I do about such things) but I've used the 180 converted to 315 with no allowance for focus shift and no filter and have been very pleasantly surprised with the results. I do stop the converted lens down all the way. From reading Ebay ads it appears that 99% of the people selling these lenses think the front lens alone is the way to get the longer focal length, and the buyers probably follow that advice. I've told sellers they have it backwards and they lecture me on how long they've been in the business... It seems to make sense that you'd take off the rear one since the idea of going around with bare aperture blades exposed seems kind of weird. I did try a negative using the front element alone, the exposure seemed correct using the aperture scale for the converted lens, and you get a focal length not so long as the rear element. People will correct me, no doubt, pointing out that this lens is by design symmetrical, but I'm looking at three negatives I shot yesterday and the front isn't as long as the back. So try it and see what you think, the rear alone may be satisfactory, it just depends on how big you like to make your prints. If it satisfies you, then you've got a big savings in $$ and weight.

-- Kevin Crisp (KRCrisp@aol.com), March 05, 2001.