How come no DOF info on view finder??

I must be missing something... why is it that Canon (don't think Nikons either) doesn't display DOF field depth calculation on the view finder? It would be GREAT to be able to see what the resulting DOF (both front of and behind the subject focus) as you compose the shot.

Since the camera has ALL the information, focal length, subject distance, and aperture, this should be a relatively a no-brainer to implement. The DOF Preview button is pretty useless for smaller aperture settings!

This would completely eliminate any guesswork around how much DOF you will end up with in the resulting shot. Is there some patent issue I'm not aware of??? Or am I the first to think of this??

That would be a great addition I think.

I suspect that like all things "computer" what sounds easy would be very hard to implement economically.

What I reallly miss is that my old EOS 650 circa 1987 had a 'control' settings where you wished to ensure DoF subjects in focus ~ you viewed the nearest object and half pressed the shutter, then recomposed to get the furthest object and press again, then recomposed to get the mid 'zone' and took the shot - the camera selected the aperture and consequent shutter speed to "do it".

The current A-Dep mode which I have never used sadly does not do the same thing AFAIK.

Box Brownie wrote in post #3978293
I suspect that like all things "computer" what sounds easy would be very hard to implement economically.

Nah, I am a programmer myself and it wouldn't take more than 10 lines of code to do this...

DOF formula

But DOF depends on more than the aperature you are using. Sounds like it would be a complicated calculation. And how would the info be displayed to you? I doubt telling most people distances would help much. I like the DOF preview button myself.

that would be a cool feature, to be able to see what your DOF is based on the focal point and aperature selected....I would think it wouldnt be hard to program into the camera...

bbbig wrote in post #3978630
Nah, I am a programmer myself and it wouldn't take more than 10 lines of code to do this...

DOF formula

I bow to your experience as a programmer but as I see it the modern dSLR is comprised of fixed programming in the various onboard ic's and the variable stored programming in the firmware and though it may only take 10 lines of code the fixed (hardwired) programming may not be able to be so integrated with the changes in the firmware.

On the face of it there is more computing power in the dSLR than was on the early Apollo missions (probably an incorrect statement but just to get my 'idea' across) and even that had problems even with all the error trapping they used by having 5 'voting' computers.

gasrocks wrote in post #3978726
But DOF depends on more than the aperature you are using. Sounds like it would be a complicated calculation. And how would the info be displayed to you? I doubt telling most people distances would help much. I like the DOF preview button myself.

The display would be something like:

[Inches or feet front of the subject] / [Inches or feet behind the subject]

indicating everything in between will be in focus. See my previous post and hyperlink - the formula isn't all that complex, and yes you do need more than the aperture info, however all that information is available to the camera when it's shot.

DoF also depends on the distance from the subject to the camera, so closer you get, shallower DoF; further away, deeper DoF.

How will the (dslr) camera know how close it is to the subject?

Also, isn't what you are suggesting a variation on hyperfocal distance? (i.e. it's what those markings on your lens barrel are for)

qtaran111 wrote in post #3978882
How will the (dslr) camera know how close it is to the subject?

The camera would know how far the subject is, by getting the focus information from lens.

qtaran111 wrote in post #3978882
DoF also depends on the distance from the subject to the camera, so closer you get, shallower DoF; further away, deeper DoF.

How will the (dslr) camera know how close it is to the subject?

From the focus information, perhaps?

-js

This presupposes that the distance is actually being measured by the lens and can be transmitted to the camera processor.

Somewhere I saw a Canon lens list that showed which lens could transmit the distance info for use with the ETTL-II flashguns and it was very few of them!!! Distance being very important when doing flash exposures.

I have set up the DOF calculations in a spreadsheet, and there are just three equations (plus some simple unit conversions) and they aren't particularly difficult. The only "trick" in a spreadsheet is to use the "IF" operator to recognize and display Infinity (when Hyperfocal Distance is less than the Focus Distance).

http://www.dofmaster.c​om/equations.html

For anyone doing macro or landscape work, this would be more useful than Auto Focus.

The first manufacturer to add this feature (provided it works) may well have me as a customer.

EDIT: I have seen so many threads on this forum where the OP's real problem was DOF, not focusing. Most of them don't have an inkling about DOF (and it takes twenty inklings to make a clue ). These people could benefit from DOF display - if they could understand it.

I'd kill to have this feature.

You can upload a jar file to your (compatible) phone that will do it. You take your phone with you everywhere right?

bbbig wrote in post #3978913
The camera would know how far the subject is, by getting the focus information from lens.

number six wrote in post #3978921
From the focus information, perhaps?

How? The camera only knows/records the focal length not distance to subject.