If I want to hand hold a camera I want results Identical to the tripod. Certainly many famous hand held photographs are blurry and that is fine. This discussion is just about photographs in which being blurry would detract from the image.
EI 200 film in a 35mm camera in bright sunlight gives me 1000th to 500th at F8. I cannot detect if the camera is on the tripod or not. This is great. This my be the reason 35mm was so popular for hand held photography.
What about other cameras? Well I suspect many think the lighter the camera the easier to hand hold but (flame suit on) that is incorrect. Heavy is better. Lets look at the extremes. Little MINOX is a problem in that it is so light. As an example, imagine that the camera was so light that the mass of the camera and the mass of the shutter release button were the same. Now when you squeeze the camera between you thumb and index finger the button would move down toward the camera just about the same distance as the camera moves up toward the button. If the release mechanism is super feather light, the camera and button can be made to move toward each other slowly with less blurring of the resulting picture. If the shutter button is stiff, then the camera and button will jerk toward each other rapidly and cause more blurring. The MINOX is 'wide open' all the time and this helps one use the fastest shutter speed possible.
What about a hand-held view camera. I have a Horseman 6x9 so I'll use that as an example. On a bright sunny day I could possibly use F8 at 1000th (assuming the shutter went that fast) but I don't want to use F8 with the Horseman. I'll explain why.
Rule of thumb for determining best aperture: I have many many lenses and cameras with various formats from 8mm movie cameras and MIINOX, to view cameras. How can I easily determine the best aperture? I know almost all my lenses will have aberrations that will improve with smaller f numbers. I also know that diffraction will increase as I stop down. So I need an F number that is a good compromise between improved aberrations and diffraction.
Using a combination of personal experience and historical precedent I came up with the following:
We know Oscar Barnack thought F11 was a good compromise for a 35mm Leica. My experience is that F8 is a little better if one is scrutinizing the photographs close up. F8 gives an aperture diameter about 6mm (I can't do a lot of math in my head but in the field I go like this for a 50mm lens: F1 = 50mm, F2 is half (25mm), F4 is half again (12mm) and F8 is half again (6mm)). F11 gives an aperture about 5mm. So somewhere around 5 to 6 mm is the smallest one wants to go.
We know that Walter Zapp put a f3.5, 15mm on his cameras and he knew that this lens should not be stopped down any further. So that works out to F1 = 15mm, F2 = 7.5mm, F3.5 about 5 to 6mm. (Other subminis like the Yashica Atron have smaller apertures but ..'blury is as blury gets...')
For my Horseman 6x9, I calculate F1=100mm, F2 = 50mm, F4 = 25mm, F8 = 12mm, F16 = 6mm. Therefore without having to do a lot of tests, I use F16.
If I had an 8x10 camera I would calculate F1 = 360, F2 = 180, F4 = 90, F8= 45
, F16 = 22, F32 = 11 and F64= 5.5
I think most photographers have their favorite F-number memorized for their favorite format. (I suspect that anyone that knows anything about the history of photography knows "F64 Group"). 4x5 use F22, Rolleiflex use F16, etc.
So this 5 to 6mm thing is for lenses with focal length similar to diagonal of film plane (the so called 'normal' lens) What about long focus, telephoto and wide angle lenses?
Without going into calculations and tests the easy way I think about it is that "Wide angle lenses MINIMIZE diffraction effects" and I conceptualize this as the wide angle lens shrinking the subject and also shrinking the little circles of confusion. Therefore one can get away with aperture diameters smaller than 5-6mm. Since a 25mm lens makes things 1/2 the size on the film plane (compared to a 50mm lens) we can figure a 3mm aperture would be OK. So this would be F1 = 25mm, F2 = 12mm, F4 = 6mm, F8 = 3mm.
So the short story is F8 to F11 is still good with the wide angle lens (on 35mm camera).
The telephoto and long focus lenses behave the same way in that a 100mm lens magnifies the effects of diffraction, so an aperture of 12mm is needed. We can figure F1 =100mm, F2 = 50mm, F4 = 25mm, F8 = 12mm.
Again I can just assign F8 to F11 as the optimum for all the lenses used on the 35mm camera.
I suspect this may not seem 'right' to many or others do it differently or some may come up with math to show how this cannot possibly be correct, but this is just the way I do it and it keeps my brain happy to organize things this way as I skip around between formats.
Now the big, big, big thing we come to next is that not only does this 6-5mm rule of thumb help figure out how much diffraction we can tolerate, it also lets us compare the depth of field between formats.
The bottom line is that 6 to 5mm aperture size on ALL formats (with 'normal' lens as described above) with have the same depth of field.
Here are some additional SYNONYMOUS statements:
1) At aperture sizes 6 to 5mm the foreground objects will all have the same level of fuzziness when focused at infinity for all camera sizes with the 'normal' lens
2) At aperture sizes 6 to 5mm the ability to Zone focus or estimate focus will be the same for all formats with normal lens. So, if you are good at guesstimating focus with your MIINOX you will be just as successful guesstimating focus with your homemade 8x10 camera with it's F65 lens! Since you may have made this camera out of steel and it 'weighs a ton' it you may be able to hand hold it at 1/30 of a second with i.e. 200 or 400 film in bright daylight. Of course if you tried to make it "as light as possible" it may not be usable.
EI 200 film in a 35mm camera in bright sunlight gives me 1000th to 500th at F8. I cannot detect if the camera is on the tripod or not. This is great. This my be the reason 35mm was so popular for hand held photography.
What about other cameras? Well I suspect many think the lighter the camera the easier to hand hold but (flame suit on) that is incorrect. Heavy is better. Lets look at the extremes. Little MINOX is a problem in that it is so light. As an example, imagine that the camera was so light that the mass of the camera and the mass of the shutter release button were the same. Now when you squeeze the camera between you thumb and index finger the button would move down toward the camera just about the same distance as the camera moves up toward the button. If the release mechanism is super feather light, the camera and button can be made to move toward each other slowly with less blurring of the resulting picture. If the shutter button is stiff, then the camera and button will jerk toward each other rapidly and cause more blurring. The MINOX is 'wide open' all the time and this helps one use the fastest shutter speed possible.
What about a hand-held view camera. I have a Horseman 6x9 so I'll use that as an example. On a bright sunny day I could possibly use F8 at 1000th (assuming the shutter went that fast) but I don't want to use F8 with the Horseman. I'll explain why.
Rule of thumb for determining best aperture: I have many many lenses and cameras with various formats from 8mm movie cameras and MIINOX, to view cameras. How can I easily determine the best aperture? I know almost all my lenses will have aberrations that will improve with smaller f numbers. I also know that diffraction will increase as I stop down. So I need an F number that is a good compromise between improved aberrations and diffraction.
Using a combination of personal experience and historical precedent I came up with the following:
We know Oscar Barnack thought F11 was a good compromise for a 35mm Leica. My experience is that F8 is a little better if one is scrutinizing the photographs close up. F8 gives an aperture diameter about 6mm (I can't do a lot of math in my head but in the field I go like this for a 50mm lens: F1 = 50mm, F2 is half (25mm), F4 is half again (12mm) and F8 is half again (6mm)). F11 gives an aperture about 5mm. So somewhere around 5 to 6 mm is the smallest one wants to go.
We know that Walter Zapp put a f3.5, 15mm on his cameras and he knew that this lens should not be stopped down any further. So that works out to F1 = 15mm, F2 = 7.5mm, F3.5 about 5 to 6mm. (Other subminis like the Yashica Atron have smaller apertures but ..'blury is as blury gets...')
For my Horseman 6x9, I calculate F1=100mm, F2 = 50mm, F4 = 25mm, F8 = 12mm, F16 = 6mm. Therefore without having to do a lot of tests, I use F16.
If I had an 8x10 camera I would calculate F1 = 360, F2 = 180, F4 = 90, F8= 45
, F16 = 22, F32 = 11 and F64= 5.5
I think most photographers have their favorite F-number memorized for their favorite format. (I suspect that anyone that knows anything about the history of photography knows "F64 Group"). 4x5 use F22, Rolleiflex use F16, etc.
So this 5 to 6mm thing is for lenses with focal length similar to diagonal of film plane (the so called 'normal' lens) What about long focus, telephoto and wide angle lenses?
Without going into calculations and tests the easy way I think about it is that "Wide angle lenses MINIMIZE diffraction effects" and I conceptualize this as the wide angle lens shrinking the subject and also shrinking the little circles of confusion. Therefore one can get away with aperture diameters smaller than 5-6mm. Since a 25mm lens makes things 1/2 the size on the film plane (compared to a 50mm lens) we can figure a 3mm aperture would be OK. So this would be F1 = 25mm, F2 = 12mm, F4 = 6mm, F8 = 3mm.
So the short story is F8 to F11 is still good with the wide angle lens (on 35mm camera).
The telephoto and long focus lenses behave the same way in that a 100mm lens magnifies the effects of diffraction, so an aperture of 12mm is needed. We can figure F1 =100mm, F2 = 50mm, F4 = 25mm, F8 = 12mm.
Again I can just assign F8 to F11 as the optimum for all the lenses used on the 35mm camera.
I suspect this may not seem 'right' to many or others do it differently or some may come up with math to show how this cannot possibly be correct, but this is just the way I do it and it keeps my brain happy to organize things this way as I skip around between formats.
Now the big, big, big thing we come to next is that not only does this 6-5mm rule of thumb help figure out how much diffraction we can tolerate, it also lets us compare the depth of field between formats.
The bottom line is that 6 to 5mm aperture size on ALL formats (with 'normal' lens as described above) with have the same depth of field.
Here are some additional SYNONYMOUS statements:
1) At aperture sizes 6 to 5mm the foreground objects will all have the same level of fuzziness when focused at infinity for all camera sizes with the 'normal' lens
2) At aperture sizes 6 to 5mm the ability to Zone focus or estimate focus will be the same for all formats with normal lens. So, if you are good at guesstimating focus with your MIINOX you will be just as successful guesstimating focus with your homemade 8x10 camera with it's F65 lens! Since you may have made this camera out of steel and it 'weighs a ton' it you may be able to hand hold it at 1/30 of a second with i.e. 200 or 400 film in bright daylight. Of course if you tried to make it "as light as possible" it may not be usable.
