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Archive 2006 · DOF and slide rules

  
 
Rhys
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p.1 #1 · DOF and slide rules


I've been playing around with PDA-based DOF calculators and find pretty much they're a PITA to use because they're on a PDA rather than being card slide-rules.

Thus far I have found only DOF Master (which produces circular slide rules) for DOF slide rules.

Does anybody know of any downloadable free depth of field slide rule that I can simply print out with a linear format rather than circular?



Jul 23, 2006 at 04:49 PM
waileong
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p.1 #2 · DOF and slide rules


Why? With digital, DOF is now a lot more than before, and LCD preview lets you know immediately after every shot.


Jul 24, 2006 at 04:00 AM
Rhys
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p.1 #3 · DOF and slide rules


It's easier to get it right first time. I don't have time nor inclination to muck about with a tiny LCD screen. I've also seen how that tinly LCD screen makes the most yucky out-of-focus photo look sharp.


Jul 24, 2006 at 07:13 AM
Osai
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p.1 #4 · DOF and slide rules


Have you ever thought of using the DOF preview button


Jul 25, 2006 at 06:30 AM
Rhys
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p.1 #5 · DOF and slide rules


Lol. DOF preview buttons are not that reliable - especially with dim viewfinders in dim environments.


Jul 25, 2006 at 11:22 AM
Osai
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p.1 #6 · DOF and slide rules


Rhys wrote:
Lol. DOF preview buttons are not that reliable - especially with dim viewfinders in dim environments.


Not reliable? Stopping the lens down with the DOF button shows you exactly what you'll get when you press the shutter.



Jul 25, 2006 at 11:28 AM
Ken Tanaka
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p.1 #7 · DOF and slide rules


Stopping down the iris with the DOF preview button is as reliable as its gets with ttl dslrs. As for dimness while stopped down, simply close your left eye and let your right eye's iris adjust to the dimmer viewfinder for a few seconds.

If you can't bring yourself to do that, simply aperture-bracket scenes that require focus field precision.



Jul 25, 2006 at 12:02 PM
Rhys
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p.1 #8 · DOF and slide rules


I have never found DOF preview levers to be all that effective in analysing DOF. I can see what's massively out of focus but when it's slightly out - no way. I need more accuracy than this. I don't chimp because I can't blow the image up large enough to check everything properly.

I found a couple of nice ideas though for generating DOF scales though. I enclose links to two.
http://www.cameraguild.jp/nekosan/topcon/card.htm
http://www.photocritique.net/dof.html

I might now generate my own since the formula is very simple:
http://en.wikipedia.org/wiki/Depth_of_field#Depth_of_field_formula

I like the idea of a simple card or even a pack of cards of most used focal lengths.



Jul 25, 2006 at 02:11 PM
EB-1
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p.1 #9 · DOF and slide rules


waileong wrote:
Why? With digital, DOF is now a lot more than before, and LCD preview lets you know immediately after every shot.


For me DOF is less than before because I shoot 24x36mm and print larger than ever. LCD body displays are useless for judging DOF of Canon RAW files.

EB



Jul 25, 2006 at 07:34 PM
Rhys
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p.1 #10 · DOF and slide rules


EB-1 wrote:
For me DOF is less than before because I shoot 24x36mm and print larger than ever. LCD body displays are useless for judging DOF of Canon RAW files.

EB


I agree. The display is good for the histogram and showing you whether you have the picture or not. It's not much good for anything else. Even zoomed in to the max I can't tell if a photo is in focus or not. I took a photo of a woman at her hen party and it looked fine on the LCD. WHen I saw it on the computer screen, it was unusable. I couldn't even sharpen it enough to be recognisable as a 6x4!

I can't guarantee to see what I'm supposed to see, looking through an already tiny and dark viewfinder in candle-light - it's just too dark to use a DOF preview. On my 35mm SLR I find the viewfinder darkens too much for depth of field preview to be much help. On my 35mm cameras though, there's a depth of field scale that I can use and have used with great success. On my EOS lenses, this scale is missing so I'm having to work through various methods of calculating DOF from distance.

Thus far I've decided that a series of cards - one for each of the following focal lengths: 17, 28, 50, 75, giving for each aperture from f2.8 to f22 at 1 meter intervals from nothing to 10 meters. I don't see much need for DOF calculations beyond 5m really but I'll do for 10 just for a round figure. It's a case of sitting down with a calculator to work it all out. Rather than calculating the range I'll calculate the hyperfocal for the distances.



Jul 25, 2006 at 08:18 PM
Osai
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p.1 #11 · DOF and slide rules


Rhys wrote:
I have never found DOF preview levers to be all that effective in analysing DOF. I can see what's massively out of focus but when it's slightly out - no way. I need more accuracy than this. I don't chimp because I can't blow the image up large enough to check everything properly.

I found a couple of nice ideas though for generating DOF scales though. I enclose links to two.
http://www.cameraguild.jp/nekosan/topcon/card.htm
http://www.photocritique.net/dof.html

I might now generate my own since the formula is very simple:
http://en.wikipedia.org/wiki/Depth_of_field#Depth_of_field_formula

I like the idea of a simple card or even a pack of cards of most used focal lengths.



So can we assume then that you will bring a tape measure wherever you go and measure everything in the scene Come on now.



Jul 25, 2006 at 08:59 PM
dennyf
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p.1 #12 · DOF and slide rules


Try this one..

http://www.dofmaster.com/dofjs.html



Jul 25, 2006 at 11:22 PM
Rhys
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p.1 #13 · DOF and slide rules


Osai wrote:
So can we assume then that you will bring a tape measure wherever you go and measure everything in the scene Come on now.


No. I check the distance on the lens, when it has focussed. Plus, the further away the subject is, the greater the depth of field so minor miscalculations don't matter so much. I have my ideas now. I shall commence designing.



Jul 26, 2006 at 07:39 AM
MadHatter
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p.1 #14 · DOF and slide rules


Rhys wrote:
No. I check the distance on the lens, when it has focussed. Plus, the further away the subject is, the greater the depth of field so minor miscalculations don't matter so much. I have my ideas now. I shall commence designing.


Then why do you have to be so exact that you need a calculator?



Jul 28, 2006 at 08:44 AM
Rhys
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p.1 #15 · DOF and slide rules


Because the closer you are to the subject the more critical the calculations are. Generally in the range 1-20 feet is the critical range.


Jul 28, 2006 at 10:37 AM
Osai
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p.1 #16 · DOF and slide rules


If you're that close, then you can use the DOF preview button.


Jul 29, 2006 at 06:53 AM





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