Tips Please for Finding DOF w/ Digital

[tradesmith45]

I'm a recent convert to digital. W/ all my film gear, figuring out DOF is pretty easy. I'm having plenty of problems w/ my OMD & (w/ one exception) lenses w/ no focus scales.

I've used the "preview" button but the small electronic finders are rarely adequate to see acceptable DOF. My biggest problems occur w/ very long FL & macro.

After reading all the criticisms of Mu43 as having too much DOF, I was not expecting the have this problem.

I see plenty of great shots on this forum so please tell me what you experienced hands are doing to get adequate DOF?

Thanks much!

 

[Dave in Wales]

You could always try the OM-D's 'Test Picture' page 94.

 

[meyerweb]

I'm not sure exactly what your problem with DOF is. My suggestion would be to take a bunch of test shots with the lenses you use, at different distances and f-stops, and learn how the camera responds.

You mention tele's, so perhaps the issue is that you're not used to the effective focal length (more properly called "crop factor.") If you're using, say, the 100-300 lens, that's "equilvalent" to a 600mm lens on the long end, so DOF may be shallower than you're expecting from the lens / aperture combination.

 

[flash]

For a given angle of view, distance and aperture a 4/3 shot will have double the DOF of a 35mm shot. (because your halving the focal length to get the same angle of view - ie: COC is bigger). So if you are comfortable with what you'd get in 35mm, 4/3 is twice that. For example if your shooting on 35mm with a 50mm lens and getting DOF of 10cm. The same shot with the 25mm equivalent on m4/3 will give you a DOF of 20cm.

The problem you have with no DOF scales exists on most AF lenses for 35mm as well. Very few have DOF scales anymore. I do carry a DOF calculator on my smart phone as a rough substitute.

Gordon

 

[arad85]

(because your halving the focal length to get the same angle of view - ie: COC is bigger).

I agree with everything you say, except CoC is smaller with the smaller focal length (sorry, just being pedantic :smile: )

 

[tradesmith45]

For a given angle of view, distance and aperture a 4/3 shot will have double the DOF of a 35mm shot. (because your halving the focal length to get the same angle of view - ie: COC is bigger). So if you are comfortable with what you'd get in 35mm, 4/3 is twice that. For example if your shooting on 35mm with a 50mm lens and getting DOF of 10cm. The same shot with the 25mm equivalent on m4/3 will give you a DOF of 20cm.

The problem you have with no DOF scales exists on most AF lenses for 35mm as well. Very few have DOF scales anymore. I do carry a DOF calculator on my smart phone as a rough substitute.

Gordon

S how often do you use the DOF calculator?

 

[tradesmith45]

You could always try the OM-D's 'Test Picture' page 94.

Thanks, been doing that some but it sure does slow you down. Was hoping for faster options.

 

[tradesmith45]

Tanks for the suggestions. Been thinking about this more & think a couple things are going on. One is the use of modern hi- res monitors including a Retina display. These are so much better than contact sheets & wet prints. I' just not use to how revealing the LED monitors are. Which may mean the standard COC valuse should be revised down.

I think the problem I'm having @ 300mm is accuracy of the AF not DOF. Aperture will show the focus point used in the photo & the distance. I've used my DOF app to calculate the actual DOF & find there should be enough to have the whole subject in focus. But it isn't. Other elements in the frame are in focus so I think I need to rely less on the AF at 300.

But there are so many other reasons to have focus scales on lenses. Two Olys, the newest Fuji X & some Pentax Limited lenses have them. With digital, I've fallen in love w/ moon & star lit landscapes. Seeing DOF in the dark is problematic using test shots due to the noise. And even using that you have no way to focus the lens at the hyper focal distance to maximize DOF.

The O12mm with its focus scale makes all this easy - set the focus to the hyper focal distance for the aperture & shoot. But that means I have to do all such shots w/ the 12. We need most primes to work like this.

 

[flash]

I agree with everything you say, except CoC is smaller with the smaller focal length (sorry, just being pedantic :smile: )

I blame the coffee.

Gordon

 

[flash]

S how often do you use the DOF calculator?

Ive been doing this for 20 years. I don't need it terribly often. I know that I'll start a head and shoulders portrait at f4 (my preferred look) on 35mm and go from there. I like full length portraits at about f2.4 etc. etc. etc.

But I do a couple photo sfaris a year and I use a DOF calculator and the Photographers Ephemeris quite a lot. Im too lazy to remember all the hyperfocal distances.

Gordon

 

[speedandstyle]

I think the problem I'm having @ 300mm is accuracy of the AF not DOF. Aperture will show the focus point used in the photo & the distance. I've used my DOF app to calculate the actual DOF & find there should be enough to have the whole subject in focus. But it isn't. Other elements in the frame are in focus so I think I need to rely less on the AF at 300.

What mode of AF are you using? I use center spot for everything but fast action. This works especially well with tele lenses if your subject isn't moving too much. Center the lens on your subject and focus then recompose and take the shot. You can find infinity and closest focus with m4/3 lenses - simply turn them till they reach it. All of my lenses are at their limit by 1 to 1 and a half revolutions.

 

[EasyEd]

Hey All,

With my XE-1 I use the DOF ribbon in the display or the old rule of thumb - focus a third of the way "into" (up from bottom of) the image and you probably are in the neighborhood of hyperfocal distance.

-Ed-

 

[arad85]

I blame the coffee.

Wine is my normal excuse

 

[tradesmith45]

What mode of AF are you using? I use center spot for everything but fast action. This works especially well with tele lenses if your subject isn't moving too much. Center the lens on your subject and focus then recompose and take the shot. You can find infinity and closest focus with m4/3 lenses - simply turn them till they reach it. All of my lenses are at their limit by 1 to 1 and a half revolutions.

I do something similar, use S-AF+MF. For birds, I use the smallest AF target the OMD will give. This all works great for all my teles except when the O75-300 is >250mm. Even at 300mm, the AF works pretty well in strong lighting. But through in a brightly colored bird like scarlet macaws or medium to low light & the OM-D struggles - both AF & IBIS.

As I think I mentioned earlier, I have the focus peaking hack set up on the OM-D and now rely heavily on it to make sure I've nailed the focus before tripping the shutter.

 

[tradesmith45]

Hey All,

With my XE-1 I use the DOF ribbon in the display or the old rule of thumb - focus a third of the way "into" (up from bottom of) the image and you probably are in the neighborhood of hyperfocal distance.

-Ed-

Thanks for reminding me of the 1/3rd rule. Unfortunately, it very hard to use for super tele or macro shots because its often so hard to tell what part of the subject is closest/furtherest.

I'm trying to develop some kind of standard workflow for DOF. Having exceptions to a workflow makes it harder to remember all the steps for each situation. Well, that's no different than an exposure workflow & I'm having few problems in that area. So along with all these suggestions, I'm sure I'll eventually get my DOF workflow successfully going!

Thanks much!

 

[tradesmith45]

Hey All,

With my XE-1 I use the DOF ribbon in the display or the old rule of thumb - focus a third of the way "into" (up from bottom of) the image and you probably are in the neighborhood of hyperfocal distance.

-Ed-

Tell us about the DOF ribbon, please.

 

[tradesmith45]

The EXIF data displayed in Aperture includes the focus distance. Wish there was a way to get that info to display on the camera real-time. But not sure if it is accurate enough for setting the hyper focal distance.

 

[JoeV]

The problem when talking about DOF is always quantifying it into some useful format.

Back "in the day," DOF scales on lenses were only a starting point. The assumptions that determine where the manufacturer puts those markings on the lens might not match your needs or wants. Are you posting 800 pixel-wide images to the Internet, or printing to 18"x24"? Obviously, those two needs will require entirely different DOF parameters. The problem with lens DOF scales is they only can provide guidance for one condition, the assumptions that the manufacturer built into the scale.

There are similar set of assumptions built into DOF calculators, online, BTW.

Common practice, if more strict DOF were required, was to fudge the scale - like shooting at f/8 but using the DOF scales for f/5.6, for instance.

And, relatedly, the so-called "hyperfocal distance" is only valid for those assumptions the lens scale markings were based upon. If you're printing large files, you might want to use a tighter set of f-stops on the scale.

In practice, I rarely if ever use DOF scales or focus scales, whether they be adapted MF lenses or system AF lenses. I focus via EVF upon my principal subject of interest and choose aperture according to my subjective feelings about how much or how little DOF the image needs, not based upon numerology or scientifically sound optical rigor, but upon creative gut feel. It's a picture, not a spreadsheet.

 

[tradesmith45]

The problem when talking about DOF is always quantifying it into some useful format.

Back "in the day," DOF scales on lenses were only a starting point. The assumptions that determine where the manufacturer puts those markings on the lens might not match your needs or wants. Are you posting 800 pixel-wide images to the Internet, or printing to 18"x24"? Obviously, those two needs will require entirely different DOF parameters. The problem with lens DOF scales is they only can provide guidance for one condition, the assumptions that the manufacturer built into the scale.

There are similar set of assumptions built into DOF calculators, online, BTW.

Common practice, if more strict DOF were required, was to fudge the scale - like shooting at f/8 but using the DOF scales for f/5.6, for instance.

And, relatedly, the so-called "hyperfocal distance" is only valid for those assumptions the lens scale markings were based upon. If you're printing large files, you might want to use a tighter set of f-stops on the scale.

In practice, I rarely if ever use DOF scales or focus scales, whether they be adapted MF lenses or system AF lenses. I focus via EVF upon my principal subject of interest and choose aperture according to my subjective feelings about how much or how little DOF the image needs, not based upon numerology or scientifically sound optical rigor, but upon creative gut feel. It's a picture, not a spreadsheet.

After playing around w/ the camera some today to figure out more about DOF, I'm back on this topic again.

Much of what is said above is equally applicable to exposer. The exposure reading is only a starting point, its subjective, we adjust it to get the artistic result we want, etc. etc. etc.....

Our modern cameras now give a ton more information about exposer than we ever had w/ film but they give us zilch about DOF. However imperfect it was, what our old cameras gave us about DOF (focus scales, ground optical view screens) has been removed. What's with that? As consumers, we ought to be demanding better. Isn't the AF system really a range finder?

So today, I was trying out the DOF alternatives using my OMD w/ 14-42mm II R on a scene in my garden that goes from about 10 to 30' - pretty simple right? I'd like to shoot the scene w/ as long a FL as I can so the stuff in front & in back are not so different in size. I try the Preview button, a test photo magnified, a manual DOF calculator & LensLab on my iPad.

So I start @ 42mm FL. I try several apertures w/ the Preview & test photo & nothing seems to work but I'm not sure because when I get down to f22, everything is a bit fuzzy. Try focusing @ several distances into the scene too - still not sure. I get out the calculators & immediately discover, getting that much DOF @ 42mm isn't possible since the lens only goes to f22. Remembering Mu43 hits diffraction limits at relatively large f, I conclude I'll have to use 25mm or shorter to maybe have enough DOF in the f11 range.

But a simple focus scale would have shown me this in 1/100th of the time!

Of course this experience is now filed in the old memory bank so I won't make that particular mistake again but this was an easy example. When you start doing long tele or macro scenes, there are a 100 variations that will challenge your knowledge bank.

We need a DOF tool in our cameras that works as well as exposure. for example, I've implemented the "focus peaking" hack found on this forum. If it could be used during Preview, we'd have a great DOF tool.

In the mean time, I'll work on adding to my experience bank & keep my calculators handy.