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Can the Koni Omega 58mm F/5.6 Hexanon Lens cover 4x5?


bobpeters

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Can the Koni Omega 58mm F/5.6 Hexanon Lens cover 4x5? I have the lens, and I installed it into a regular Copal # 0 shutter for my Pressman Model C. I got a Toyo Field 45A and a Deep recessed lensboard, and installed the lens in that temporarily. I have no idea what the F stops are, as the shutter has a scale for a F5.6 150mm lens. I can see clouds kind of dimly in the bottom of the ground glass when I have the lens wide open and the camera level.
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If you want to know what a lens covers take a large piece of white cardboard. Turn off all the lights in your room. Close the drapes. Now open the lens wide open. Point the lens out the widow at a distant object. Hold the cardboard behind the lens and move it towards or away from the back of the lens till you see a sharp image. Now measure the size of the image circle that you see on the cardboard. That is what your lens will cover at infinity wide open. Since you are using a wide angle lens for a 67cm camera it is very doubtful that it can cover a 45" piece of film.

Go pick up a lens designed to cover 45.

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I installed it as it was the only Copal #0 lens I had, and was curious. I noticed that it was brightest in the 6x7/6x9 Grid Lines, but I noticed clouds in they sky, on the bottom of the ground glass, which is why I asked, Is in any larger stopped down?
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Almost any lens will cover more when stopped down, but I would be surprised if this lens covered 4x5 adequately since it was designed for a rangefinder camera without camera movements. Extra covering power always costs more money, and there would have been no need for it with the camera this lens was designed for.
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Almost any lens will cover more when stopped down, but I would be surprised if this lens covered 4x5 adequately since it was designed for a rangefinder camera without camera movements. Extra covering power always costs more money, and there would have been no need for it with the camera this lens was designed for.

The lens' rear tube is relatively long and its rear element is relatively small. Mechanical vignetting limits its coverage.

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I just checked it again today, and wide open (Above f5.6 on a 150mm lens, as that is the scale on the shutter). I think it covers the entire ground glass. I check again tomorrow or the day after, as I'm not completely sure, and the light has to be really bright.. It's on a recessed lensboard, if that matters.
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I did a test this morning and it does show some vignetting in the corners, but it's raining and cloudy outside so the light isn't optimal for a test. I can't tell if it's vignetting, or it just the falloff being too much. Edited by bobpeters
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Bob, I'm blind -- most recent measurements 20/15 -- or you're hallucinating. I just put my 58/5.6 KH on my 4x5 Cambo. At infinity at f/5.6 it barely puts light in the corners of the 6x9 grid on the GG. This isn't just optical vignetting (cos^4). Cos^4 puts 6x9's corners 1.6 stops down from the center, 4x5's 2.8. To which you can add the effects of mechanical vignetting.

 

I understand "covers x" to mean "puts good image x/2 off axis," not illuminates x. The only way to find out whether a lens covers a format is to shoot it and examine the negative closely.

 

"Covers at certain focal distances" is weaseling. The circle covered expands the closer a lens is focused. That's nice, and a big "so what?" for the lens' general usability.

 

If the lens did cover 4x5, you'd need to use a center filter with it.

 

What does the lensboard have to do with coverage?

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Bob, I'm blind -- most recent measurements 20/15 -- or you're hallucinating. I just put my 58/5.6 KH on my 4x5 Cambo. At infinity at f/5.6 it barely puts light in the corners of the 6x9 grid on the GG. This isn't just optical vignetting (cos^4). Cos^4 puts 6x9's corners 1.6 stops down from the center, 4x5's 2.8. To which you can add the effects of mechanical vignetting.

 

I understand "covers x" to mean "puts good image x/2 off axis," not illuminates x. The only way to find out whether a lens covers a format is to shoot it and examine the negative closely.

 

"Covers at certain focal distances" is weaseling. The circle covered expands the closer a lens is focused. That's nice, and a big "so what?" for the lens' general usability.

 

If the lens did cover 4x5, you'd need to use a center filter with it.

 

What does the lensboard have to do with coverage?

Would a shallow lensboard make the coverage bigger? I figured that a center filter would be needed, as its a lot brighter in the center, that it is at the top, bottom and sides. I know most 47 and 58 lenses need center filters. I'm using a Toyo Field 45A with the deeper of the two Toyo lensboards, if that makes a difference. It does fade into the corners at infinity. Could it be used as a "cheap" wide angle for close but wide applications? So you can't figure out coverage from the glass? I'm doing this partially for kicks, as I had the lens in the Copal shutter for a Pressman Model C, and to see if it would actually work, and that I wouldn't need another 58mm.

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It is a matter of personal preference. Most users find a center filter necessary for lenses shorter than around 90 mm on 4x5.

 

All that a recessed board does is increase the length of bellows needed to focus at a given distance. Since movements are difficult with a compressed bellows, using a recessed board with a short lens often makes good sense. The only thing that changes coverage is magnification.

 

The typical ground glass is quite coarse, therefore has low resolution and gives a poor indication of what resolution on film will be. You can see serious fuzziness on the GG but not sharpness.

 

The lens won't cover 4x5 on a Pressman C either.

 

Y'know, these lenses and their 60/5.6 brothers aren't that expensive. No one uses them on 4x5 cameras. There's a reason. Its the same reason why no one uses 65/6.8 Angulons and Raptars/Optars on 4x5. They don't cover.

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It is a matter of personal preference. Most users find a center filter necessary for lenses shorter than around 90 mm on 4x5.

 

All that a recessed board does is increase the length of bellows needed to focus at a given distance. Since movements are difficult with a compressed bellows, using a recessed board with a short lens often makes good sense. The only thing that changes coverage is magnification.

 

The typical ground glass is quite coarse, therefore has low resolution and gives a poor indication of what resolution on film will be. You can see serious fuzziness on the GG but not sharpness.

 

The lens won't cover 4x5 on a Pressman C either.

 

Y'know, these lenses and their 60/5.6 brothers aren't that expensive. No one uses them on 4x5 cameras. There's a reason. Its the same reason why no one uses 65/6.8 Angulons and Raptars/Optars on 4x5. They don't cover.

The Pressman C is the 2.25" x 3.25" model, the Model D is the 4x5. Could you use the lack of coverage, as an artistic effect, or doesn't it work that way?

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