Closeup Working Distances Table for 8x10
A little table I've worked up in Excel. I *think* it's accurate, following the formulae available online for bellows factor, bellows extension, and total working distance.
B = total bellows extension
W = working distance
T = total distance from subject to film plane
dimensions in inches at top are subject size dimensions.
I've already used this successfully once so it's pretty good I think.
Why is this useful? Because working out lens choice and setup for large-format closeup work can be tricky, especially if you don't have a tape-measure with you (but no self-respecting large-format photographer should be without one of those, surely??). Depending on whether a given camera front focuses or back focuses or both, setup can be time-consuming.
Using this table, I first figure out roughly what the subject dimensions are, then figure out roughly where I am in terms of magnification and which vertical part of the column I'm on. Depending on how much working distance I want or have available, I would then work down the list of lenses and select the lens I need (or indeed have) and set up the camera roughly according to the total distance indicated. Some adjustment is required for in-between magnifications, but that's much better than wasting half an hour guessing and getting frustrated.
Measurements with underlines are amounts of bellows extension where I would need to use the extension board for my Chamonix 810V (without extension, bellows is limited to 680mm; with extension board, this extends to 850mm). I haven't therefore included bellows lengths that would exceed 850mm.
Having a reasonably long QR plate on the camera also helps. I use a Wimberley P50 on both 8x10 and 5x4, which is 167mm in length.
For time to add, I use the reciprocity timer app for consistency with bellows extension calculations. It automatically calculates reciprocity time and adds this too, according to its own formulae.
Closeup Working Distances Table for 8x10
A little table I've worked up in Excel. I *think* it's accurate, following the formulae available online for bellows factor, bellows extension, and total working distance.
B = total bellows extension
W = working distance
T = total distance from subject to film plane
dimensions in inches at top are subject size dimensions.
I've already used this successfully once so it's pretty good I think.
Why is this useful? Because working out lens choice and setup for large-format closeup work can be tricky, especially if you don't have a tape-measure with you (but no self-respecting large-format photographer should be without one of those, surely??). Depending on whether a given camera front focuses or back focuses or both, setup can be time-consuming.
Using this table, I first figure out roughly what the subject dimensions are, then figure out roughly where I am in terms of magnification and which vertical part of the column I'm on. Depending on how much working distance I want or have available, I would then work down the list of lenses and select the lens I need (or indeed have) and set up the camera roughly according to the total distance indicated. Some adjustment is required for in-between magnifications, but that's much better than wasting half an hour guessing and getting frustrated.
Measurements with underlines are amounts of bellows extension where I would need to use the extension board for my Chamonix 810V (without extension, bellows is limited to 680mm; with extension board, this extends to 850mm). I haven't therefore included bellows lengths that would exceed 850mm.
Having a reasonably long QR plate on the camera also helps. I use a Wimberley P50 on both 8x10 and 5x4, which is 167mm in length.
For time to add, I use the reciprocity timer app for consistency with bellows extension calculations. It automatically calculates reciprocity time and adds this too, according to its own formulae.