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#1
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lens progress
On Thu, 17 Mar 2011 08:06:27 -0700 (PDT), Cheesehead
wrote: I was able to pick up a Fujinon-W 300/5.6 in a Copal 3 for a really good price. It was really good since the rear cell has some separation beginning out at the edges. It will be a while before it affects the image (it's just out on the edges right now), but the price was good enough that I normally I would have gotten the shutter alone for the price paid. I'm going to use it for a while and enjoy it while keeping my eyes open for two sets of cells 1) 450/9 nikkor-m 2) 240/5.6 nikkor-w And maybe a replacement Fujinon rear cell, if one shows up somewhere. Looks like an apug.org post is in order. Mind if I ask what you paid for it? I have a similar Fujinon-W with beginning separation, totally obscured by f/11 so not a problem in practical situations. I'm considering selling it since it's too heavy for the front standards of any of my cameras. Thx. Agree 100% with the suggestion of 250/6.7 Fujinon. It's also a lot smaller than the Nikkor, being in a Copal 1. |
#2
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lens progress
Cheesehead wrote (in part):
A front cell without a rear is worthless, ... Why is that? I have a Wisner convertable plasmat set that has 5 cells in 4 focal lengths (450mm, 400mm, 350mm, and two 250mm). These cells can be used alone or in pairs, giving 11 focal lengths. When used in pairs, focal lengths from 152mm to 258mm are obtained. I tend to use them in pairs, especially 52mm, 182mm, 212mm, and 258mm. If single cells are used, the lateral chromatic aberration is not corrected. If shooting in Black and White, a deep yellow filter can hide it. Ron Wisner allegedly made a zero-power corrector lens for this, which I ordered, but he never supplied me with one. -- .~. Jean-David Beyer Registered Linux User 85642. /V\ PGP-Key: 9A2FC99A Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 11:40:01 up 14 days, 19:41, 4 users, load average: 4.40, 4.54, 4.52 |
#3
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lens progress
Cheesehead wrote:
On Mar 18, 11:54 am, Jean-David Beyer wrote: Cheesehead wrote (in part): A front cell without a rear is worthless, ... Why is that? I have a Wisner convertable plasmat set that has 5 cells in 4 focal lengths (450mm, 400mm, 350mm, and two 250mm). These cells can be used alone or in pairs, giving 11 focal lengths. When used in pairs, focal lengths from 152mm to 258mm are obtained. I tend to use them in pairs, especially 52mm, 182mm, 212mm, and 258mm. If single cells are used, the lateral chromatic aberration is not corrected. If shooting in Black and White, a deep yellow filter can hide it. Ron Wisner allegedly made a zero-power corrector lens for this, which I ordered, but he never supplied me with one. I was arguing something specific, not something general. After all, my other lens is the Protar VII. Now, if you have some info on solo use of the Fujinon-W 300/5.6 front cell, I might have good use for it. If I had one, I would, at least try it. First, behind the shutter if the threads permit. It might be usable. -- .~. Jean-David Beyer Registered Linux User 85642. /V\ PGP-Key: 9A2FC99A Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 13:50:01 up 14 days, 21:51, 4 users, load average: 5.05, 4.86, 4.56 |
#4
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lens progress
"Jean-David Beyer" wrote in message ... Cheesehead wrote: On Mar 18, 11:54 am, Jean-David Beyer wrote: Cheesehead wrote (in part): A front cell without a rear is worthless, ... Why is that? I have a Wisner convertable plasmat set that has 5 cells in 4 focal lengths (450mm, 400mm, 350mm, and two 250mm). These cells can be used alone or in pairs, giving 11 focal lengths. When used in pairs, focal lengths from 152mm to 258mm are obtained. I tend to use them in pairs, especially 52mm, 182mm, 212mm, and 258mm. If single cells are used, the lateral chromatic aberration is not corrected. If shooting in Black and White, a deep yellow filter can hide it. Ron Wisner allegedly made a zero-power corrector lens for this, which I ordered, but he never supplied me with one. I was arguing something specific, not something general. After all, my other lens is the Protar VII. Now, if you have some info on solo use of the Fujinon-W 300/5.6 front cell, I might have good use for it. If I had one, I would, at least try it. First, behind the shutter if the threads permit. It might be usable. I don't know for certain what the Fujinon is because Fuji used the same name for an entire line of lenses. But, from its speed and focal length I would guess it to be a Plasmat type. The single cells of Plasmats are useable as longer focal length lenses, but, of course, without the correction of the complete lens. This is true generally of "convertible" lenses. While the theoretical performance may be better behind the iris it may actually not make much difference and the bellows draw necessary will be less when its in front of the shutter. This is not just the physical displacement of the lens but because of the location of the rear principal point of most convertible type lenses. If the lens is a Tessar the front element is useless by itself because it is a negative lens and will not form an image. The rear element of a Tessar _will_ form an image but of rather low quality because most of the correction is in the front half of the lens. In general lenses of symmetrical or nearly symmetrical form are "convertible" in the sense that either cell can be used alone, although with some, perhaps considerable, reduction in image quality. -- -- Richard Knoppow Los Angeles, CA, USA |
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