Looking for Different Depth of Field Calc

tom_berkowski · March 6, 2011

I have seen depth of field calculators and find them useful. However, I'd like one that does not make me enter distance from subject. I am terrible at estimating distance, and my camera does not do that for me.

Let me know if something like this exists:

- Enter lens: say 100mm

- Enter height of subject: say I'm shooting a 5'7" model, so I have approximately 6" vertical in frame.

- Calculator automatically calculates how far I am from the subject using 100 mm's angle.

- Then everything else acts normally like DoF calculators I've seen. Say I want 1.5" DOF, it gives me apeture.

For this example, I my guess from experience would say at least 2.8 but probably between 2.8 and 4.0. I'd like to accelerate my learning, though, so a calculator would help.

Thanks.

tom_berkowski · March 6, 2011

I meant 2.5 feet DOF as desired, not 1.5".

john_a5 · March 6, 2011

Consider investing in a tape measure or maybe one of those laser measuring devices--you have to at least guesstimate distance and after awhile, it is easy.

htarragon · March 7, 2011

Your camera DOES do that for you. When you focus on your subject the distance markings on your lens should be able to let you know the distance from camera to subject.

About the laser distance finder, since photographers try to focus on the subject's eyes - DO NOT POINT A LASER AT A SUBJECT'S EYES or FACE - EVEN FOR A SECOND. Lasers can damage or destroy retinas in a very short amount of time.

If your camera is on a tripod measurement by measuring tape should be easy, if using the laser, tell the subject to turn 180 degrees away from the camera or use an inanimate object in subject's place.

William Michael · March 7, 2011

What Camera?

Do you require a practical DoF mechanism to be used mainly for Portraiture / People Photos?

WW

tom_berkowski · March 8, 2011

I am using a Canon 5D. Yes, I'm interested in DOF primiarily for portrait work.

Yes, the lenses do have marking showing distance. I meant after the fact. My 5D does not give distance in the exif data.

I don't have a computer (or iPhone for that matter) in the field with me. I am looking for an online DOF for times I'm not in the field, just to accelerate my desk learning to put to use in the field.

I think all parameters are there, so if I were better with math and had more time, I could just do it myself. I figure something like this exists, though. Even rules of thumb? Something like: "working w/tall female model in a flat pose, for shallow DOF, set to 100 mm lens to 2.8." (I'm guessing again.)

William Michael · March 8, 2011

I am using a Canon 5D. Yes, I'm interested in DOF primiarily for portrait work. Yes, the lenses do have marking showing distance. I meant after the fact. My 5D does not give distance in the exif data.

</blockquote>

Thanks for answering.

Not sure how useful the Distance Scales are on the lens’ turrets anyway – mine are pretty useless apropos any DoF calc.

If you want to work out the DoF AFTER the fact then all you need to do is pump in the FoV(h) which is the (approx) length of the longer edge of the frame at the point of focus and work backwards from there. But I don’t really understand why you would want to do that. The only time I do that is for technical analysis of Photographs – not usually mine.

***

I don't have a computer (or iPhone for that matter) in the field with me. I am looking for an online DOF for times I'm not in the field, just to accelerate my desk learning to put to use in the field.

</blockquote>

If you want to use something in the field then I suggest you stop attempting to memorize a truck load of stuff and just use or memorize these:

<a href="http://d6d2h4gfvy8t8.cloudfront.net/12793235-lg.jpg"><img src="http://d6d2h4gfvy8t8.cloudfront.net/12793235-lg.jpg" alt="" /></a> WW’s DoF 135 Format Cheat Sheet – Portrait

***

<img src="http://d6d2h4gfvy8t8.cloudfront.net/12793234-lg.jpg" alt="" width="500" height="700" /> WW’s DoF 135 Format Cheat Sheet – Landscape

Note the number patterns – quite suitable to locate DoF for: F/2; F/4 and F/8.

WW

tom_berkowski · March 8, 2011

WW,

That is excellent, exactly what I'm looking for. Do you know how I convert that to a 100 mm lens (my lens of choice for portraits)?

William Michael · March 9, 2011

Do you know how I convert that to a 100 mm lens (my lens of choice for portraits)?

</blockquote>

You don’t.

It is.

That is my cheat sheet for A 135 FORMAT Camera.

That is why I asked what camera you used – the 5D is 135FORMAT.

I have DoF Cheat Sheets for all the format cameras I use: APS-C; 135; 645; 6x7; 5x4.

My Cheat Sheets are based upon the Axiom of DoF viz.:

For any Camera Format, for any Aperture, for any Framing: the DoF will remain the same.

This Axiom will hold true for Shooting Distances within the Portrait Range and be accurate to within fractions of inches.

The Axiom is not applicable to Macro shooting.

The Axiom wanders a tad beyond the Hyper-focal Distance.

My Cheat Sheets have a little safety factor in them.

WW

tom_berkowski · March 9, 2011

Thanks, WW! I thought your 135 reference was to a 135mm lens. Thanks very much for this. Rule of tumb was all I was looking for, not exact calc, so this is perfect.

William Michael · March 9, 2011

You are welcome.

Yes I understood you thought "135" was a lens's Focal Length.

The Axiom is stronger than a mere Rule of Thumb - I have just rounded the figures such that they have a little safety latitude and are easy to commit to memory

WW

tom_berkowski · March 14, 2011

WW,

One final (I think) question. Total DOF is what you list on this sheet, correct? It's not DOF behind the subject, is it? I remember from back of my very old version of Canon Lens Works that 1/3 of DOF is in front; 2/3 behind. In practical application, I assume you focus on eyes, pick apeture to achieve total DOF that gets entire pose and desired props in focus.

This is very helpful, thanks.

William Michael · March 14, 2011

"Total DOF is what you list on this sheet, correct?"

</blockquote>

Yes. Correct. TOTAL DoF.

Yes a rule of thumb is 1/3 in front 2/3 behind the Plane of Sharp Focus.

And the DoF is rounded down.

And my cheat cards use conservative CoC figures (Circle of Confusion).

That is to say if the DoF calculator gives me "three feet, two and three eigth inches" I will note "3ft". On the other hand, if the DoF calculator gives me "two feet ten inches" I will note 2ft 6inches.

I do this rounding also to make the number patterns easier to remember.

Look at the top chart - the numbers are 2ft; 4ft; 8ft . . .

Hence F/4 = 3ft and F/8 = 6ft

AND hence - F/1.4 = 1ft

And F/2 = 1ft 6inches

When I developed the system years ago I planned to ALWAYS memorize ONLY three Apertures: F/2.8; F/5.6 and F/11 . . .

All I need to remember is the phrase: "35mm camera - Full Length Vertical - two four eight"

</blockquote>

WW

William Michael · March 14, 2011

"In practical application, I assume you focus on eyes, pick apeture to achieve total DOF that gets entire pose and desired props in focus."

</blockquote>

Yes: in the theory sense of you statement. But not necessarily in practice.

Apropos DSLR: I use Canon DSLR and the AF is interesting. It works on contrast and often the eye is not the best. I work a lot in AL (Available Light) and without a Flash Mounted (Flash Assist Focus). I shoot often Indoors and at Night both indoors and outdoors. Some lenses are better at AF that others. Some DSLRs are better for MF than others. Most Photographers I have spoken with over the past 10 years do not have ANY MF technique perfected whatsoever.

Examples: <img src="http://d6d2h4gfvy8t8.cloudfront.net/12793893-md.jpg" alt="" /> 5D + EF85/1.8 F/1.8 @ 1/80s @ ISO400 HH

AF did lock on the leading eye – and I F&R using that: Next option the bridge of the nose where there are specula highlights,; next option the line of cleavage, lower toward the breast bone, such that the AF is nearer to the same plane as the eyes. ***

<img src="http://d6d2h4gfvy8t8.cloudfront.net/12593632-lg.jpg" alt="" /> 504470v04 5D+85 F1.8 @ 1.125s @ ISO400 HH Manual I nailed her left arm. ***

<img src="http://d6d2h4gfvy8t8.cloudfront.net/12474013-md.jpg" alt="" /> 5D + EF50/1.4 The AF was having difficulty locking on her face anywhere, because of the shadows I expect. The line of braiding and yellow on her right Breast. Her head was a swivelling, anyway – often the head is moveing – the chest area is often better – for men the line of the coat across the white shirt for women the line of the dress near the bust line. ***

<img src="http://d6d2h4gfvy8t8.cloudfront.net/12000375-lg.jpg" alt="" width="700" height="500" /> 5D + 135/2: F/2 @ 1/400s @ ISO800 HH Manual Bridge of nose - that was easiest.

***

Very rarely is the subject 90 dgrees front on to the camera, so there will be a point on the Chest Area that lines up with the plane of focus of the eyes.

In really dark environs I have used the sparkle / reflection of room lights from the shoes.

I use centre point focus only.

WW

tom_berkowski · March 15, 2011

Very helpful, WW. I see the pattern in the results, which makes it a lot easier than having too many numbers to try to keep in my head.

I like your focus examples. I also use canon. I have lately been doing this: 1) Getting exposure using Av and center focus point. 2) Switch to M, setting apeture and shutter speed. Switch to other focus point on eyes. (On 5D which meters off center focus point, I can't use Av and switch to another focus point.)

This works most of the time, but AF doesn't always work on eyes, especially for focus point other than center. I sometimes use other focusing techniques including using AF center point, shifting to MF on lens, recomposing. This sometimes works, sometimes not. I also sometimes use CF4 with various focus points to basically keep camera in MF until I want to switch it. I have my C setting set up with M mode/CF4-1 for this purpose.

None of my techniques are completely foolproof, so I'll also try yours.

All of this has been extremely helpful to me.

Thanks,

Tom

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