f number is the ratio of the focal length to the entrance pupil (aperture). But the important thing to do is to measure the aperture as it appears through the front element of the lens NOT the physical aperture (I've made this mistake). Place the lens mounted in the shutter on a light table and from above looking down into it from arms length hold some measuring callipers close to the front element and measure the size of the aperture as it appears. If you measure 19mm and it is a 150mm lens that is 150/19 = 7.89 call it f/8. Try it out on a lens that you know has the correct scale to make sure you are doing it right. Using this technique you can make your own scale quite easily. It will be somewhat approximate. I wouldn't go burning lots of Velvia purely on the basis of home calculate f-stops before you have done some exposure tests! On the other hand going through the process makes you wonder how accurate the real scales are. We often get a bit to prissy about exposure when the +/- half a stop if fine. en.wikipedia.org/wiki/F-number
great video Nico, but an extension to this, I have a Linhof 5x7", it has a dial_set shutter, linhof branded (with the engraved edges)- a 150, 210 and a 360; is it OK to switch this to a sinar board ( an f2 with 4x5" format back standard)?, aka drill the holes to fit the nut to screw it onto this board. ( on this shutter the nut is a flange which is screwed onto the lens board, and the shutter and lens just screw on, no need to remove the rear element), this is NOT the standard linhof tech board you show on your channel, not offset, just large and flat.
Interesting video, but how does changing the shutter alter the focal length of the lens ? Changing the shutter doesn't(or shouldn't) alter the position of the lens elements. And how does one actually change the shutter? Your video doesn't show that .
Thanks, Nicolas, this has solved a potential issue I've been thinking about concerning foldable medium format cameras as well. Verdict: Better stick to the same brand and stick to the focal length / shutter combo.
Hi Nicolas, love your videos. Is that the Rodenstock 210mm macro lens on the table. I would be very interested on you doing a show on large format macro lenses. I wonder since the cameras have a bellows, all normal lenses could be used for close up, so why the need for a macro lens. I have this lens, but im not sure if im using it correctly. There is very little info out there on these lenses.
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f number is the ratio of the focal length to the entrance pupil (aperture). But the important thing to do is to measure the aperture as it appears through the front element of the lens NOT the physical aperture (I've made this mistake). Place the lens mounted in the shutter on a light table and from above looking down into it from arms length hold some measuring callipers close to the front element and measure the size of the aperture as it appears. If you measure 19mm and it is a 150mm lens that is 150/19 = 7.89 call it f/8. Try it out on a lens that you know has the correct scale to make sure you are doing it right. Using this technique you can make your own scale quite easily. It will be somewhat approximate. I wouldn't go burning lots of Velvia purely on the basis of home calculate f-stops before you have done some exposure tests! On the other hand going through the process makes you wonder how accurate the real scales are. We often get a bit to prissy about exposure when the +/- half a stop if fine.
en.wikipedia.org/wiki/F-number
great video Nico, but an extension to this, I have a Linhof 5x7", it has a dial_set shutter, linhof branded (with the engraved edges)- a 150, 210 and a 360; is it OK to switch this to a sinar board ( an f2 with 4x5" format back standard)?, aka drill the holes to fit the nut to screw it onto this board. ( on this shutter the nut is a flange which is screwed onto the lens board, and the shutter and lens just screw on, no need to remove the rear element), this is NOT the standard linhof tech board you show on your channel, not offset, just large and flat.
Interesting video, but how does changing the shutter alter the focal length of the lens ? Changing the shutter doesn't(or shouldn't) alter the position of the lens elements. And how does one actually change the shutter? Your video doesn't show that .
Thanks, Nicolas, this has solved a potential issue I've been thinking about concerning foldable medium format cameras as well. Verdict: Better stick to the same brand and stick to the focal length / shutter combo.
Hi Nicolas, love your videos. Is that the Rodenstock 210mm macro lens on the table. I would be very interested on you doing a show on large format macro lenses. I wonder since the cameras have a bellows, all normal lenses could be used for close up, so why the need for a macro lens. I have this lens, but im not sure if im using it correctly. There is very little info out there on these lenses.