Viewfinder question

Gerry M

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• Aug 18, 2019

• #1

For a medium format (120) body with a: 62mm, f5.6 lens and a 6X7 film gate of approx 56mmH X 68mmL X 88mm diagonal, what would be the closest aux VF to cover this FOV? I hope I have worded this properly. Any input would be appreciated.

Thanks,

Gerry

 

xya

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• Aug 18, 2019

• #2

if you calculate the diagonal and we presume that the standard for 24x36 is 50mm, it's 35mm equivalent. if you want to take into account that 24x36 is a 2:3 ratio, 56x68 is close to 4:5 ratio, it becomes more complicated...

 

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Gerry M

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• Aug 18, 2019

• #3

Maybe about 31mm at the 6X7 ratio? Might have mask off a larger format (Gaoersi) type.

 

Dan Fromm

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• Aug 18, 2019

• #4

88 mm is normal for 6x7. 43 mm is normal for 24x36. If you don't believe me, do the calculation. The two formats have different aspect ratios so an exact match is impossible.

If you want to match diagonals, (62/88)*43 = 30.

If you want to match horizontals, (62/68)*43 = 39

Horseman Convertible?

 

xya

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• Aug 18, 2019

• #5

Dan Fromm said:

88 mm is normal for 6x7. 43 mm is normal for 24x36. If you don't believe me, do the calculation. The two formats have different aspect ratios so an exact match is impossible.

If you want to match diagonals, (62/88)*43 = 30.

If you want to match horizontals, (62/68)*43 = 39

Horseman Convertible?

Click to expand...

43mm is normal, that's easy to calculate, but the industry made 50mm the standard focal length (sometimes 45mm in the early days). that's what we are used to. 35mm wouldn't b a bad match...

 

mshchem

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• Aug 18, 2019

• #6

Gerry M said:

For a medium format (120) body with a: 62mm, f5.6 lens and a 6X7 film gate of approx 56mmH X 68mmL X 88mm diagonal, what would be the closest aux VF to cover this FOV? I hope I have worded this properly. Any input would be appreciated.

Thanks,

Gerry

Click to expand...

Linhof has made a really nice variable viewfinder forever. I found one in a thrift shop for 25 bucks. Dial it in to match your setup.

 

mshchem

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• Aug 18, 2019

• #7

Also used Fotoman finders?

 

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Gerry M

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• Aug 18, 2019

• #8

Dan Fromm, Yes, I believe you as mine measures 88mm. Yes, a Convertible.

I'll keep a watch for used LF vf and mask to fit.

 

Dan Fromm

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• Aug 18, 2019

• #9

Gerry, does your Convertible's body have a nominal 6x7 gate or did you measure the roll holder? I ask because I've always understood that the Convertible is natively nominal 6x9 (56 mm x 82 or so mm) body with a Graflok back. It accepts nominal 6x7 and nominal 6x9 Horseman roll holders. Which do you have?

Here https://www.rangefinderforum.com/forums/showthread.php?t=165096 are some sample shots that clearly aren't approximately 6x7. 2x3 is more like their aspect ratio.

If you have a nominal 6x9 roll holder (diagonal ~ 100 mm) the 24x36 equivalent focal length is .43 * 62 = 27 mm. A 28 mm finder should suit.

 

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Gerry M

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• Aug 18, 2019

• #10

Dan, I have a 6X7 220 and a 6X9 120 back, both Horseman. the 6X7 is 88mm and the 6X9 is 100mm. I can't get a ruler into the body gate, but by ruler & eyeball, it looks to be about 82mm. I tried a 25mm Voigtlander with the 6X9 back and it wasn't too far off. I just put a roll of 120 in the 6X7 back today and used the wire frame finder. Still have 6 frames left on that roll.