rehess Loc: South Bend, Indiana, USA

Honestly, this is a hold-over from film cameras, when you had to develop the film before you could see the actual results.

Personally, I've never made much use of this capability simply because I developed a style dependent on context, so I use "comfortable" apertures like f/5.6, where exact DOF is less important.

SteveR Loc: Michigan

You didn't quite get what I was trying to say. It didn't dim when using my f1.8 lens. Perhaps it was because of its light gathering capability. I don't know. Even when I would close the aperture down using the d.o.f. lever it did not go dark as it does on my D7100. It might have "dimmed" but it didn't go dark.

Tallyann

That's what happens to me with the D7100 which prompted my question. At F16 plus the preview is a dark or black view that shows nothing. What is this telling me? At f3.5 the view dims very little, if any. I wasn't sure if the button if working properly or I just don't get it the purpose of it.

bobmcculloch Loc: NYC, NY

Good answers as far as I read, I could never see much difference when pushing the button so I didn't and don't use it, besides something always moves while I'm doing the looking, funny how things move even in a landscape if in doubt start doing 3 shot bursts, one will be better than the others, Bob.

jackm1943 Loc: Omaha, Nebraska

To make it much easier to use, I set one of my back buttons to do DOF Prevue. The standard button is not easy to reach on my Canon. I use it frequently now.

rehess Loc: South Bend, Indiana, USA

Normally you are looking through the lens wide open.

When you have the lens set at f/3.5, pressing the button closes down from wide open to f/3.5, so it dims a little.

When you have the lens set at f/16, pressing the button closes down from wide open to f/16, so it dims a lot.

Bob Boner

What Bob Malarz said.

bkyser Loc: Fly over country in Indiana

I can't tell you what happened with your film camera, , my view has always dimmed x amount based on the F-stop chosen with with film as well as digital when the DOF preview button was pressed. Maybe your DOF button wasn't actually working on the film camera?

Bob Locher Loc: Southwest Oregon

Really, that is one of the advantages of mirrorless cameras. The Electronic View Finder (EVF) compensates for how much light is available so you get the same brightness in the EVF regardless of the aperture. Which means it really is WYSIWHG - what you see is what you get. Meaning: the depth of field and the focus in the View Finder are at the actual shooting aperture, NOT the wide open until shooting image of the DSLR with the shallow depth of field.

pesfls Loc: Oregon, USA

That is correct. I recently got my first mirrorless (PEN F) and noticed this right off. I had to fiddle with it at first because the lack of dimming threw me for a loop after decades of using SLR's. I like that feature. But I still use it all the time on the older style bodies.

speters Loc: Grangeville/Idaho

E.L.. Shapiro Loc: Ottawa, Ontario Canada

It can come in handy under certain conditions. Of course, it dims the viewfinder image as you stop down the aperture and it is difficult to actually preview depth of field, especially in low light conditions. In the studio where there is ample artificial light from continuous sources or the modeling lights in studio flash equipment, you can actually and precisely observe depth of field. The same apples to out of doors environments in bright conditions.

It is not necessarily practical to preview depth of field in shooting on the fly situations, however, if the camera is mounted on a tripod and you have plenty of time to work, your DOP preview feature may be helpful. I oftentimes use it in the studio when doing still life work were deep depth of field or selective focus is critical. I also use it to make certain that deep lens shades or filter adapters are not vignetting which becomes more apparent in the viewfinder when the lens is stopped down.

If you don't care to use it, that is not a problematic issue in that it does not take up much space on your camera's array of controls and it won't interfere with other operations or cause problems if left dormant.

On my digitized and film medium format cameras, the DOP preview control can remain in stopped down position until it is manually released, I use it in conjunction with the mirror lock up feature in critical long exposure situations to prevent additional mechanical vibration.

I do miss depth of field scales on lenses- they are handy when determining hyperfocal distances whe scale focusing.

SteveR Loc: Michigan

Yes, it was working, because by selecting different f stops I could how they affected the depth of field. The d.o.f. lever on my f.t.b. taught me how to use d.o.f. Remember, though, an f1.8 lens itself is designed to gather more light. It's not just that the aperture is 1.8 at the widest. If you look at an f1.4 lens, the front lens is even bigger. Back in film days, those were the cool lenses to have just because they looked so monstrously big.

Photocraig

If the Single Lens reflex camera was invented in the digital era, only, there would never have been a DOF preview button. It is a vestige (as am I to an extent) of the film era when you could not evaluate the overall effect of DOF on a particular image before exposure. When I used them on my various film cameras, I found they were ONLY effective when I was shooting wide open or close to it. After f4 and smaller, the image is too dim to effectively analyse.

However, given the very shallow DOF of lenses wide open, the ability to check DOF, a portrait assuring the eye's iris and lashes are, at least, in focus. Or eye dead on and ear and tip of the nose with acceptable sharpness. It is truly a vestige of the film days when we were shooting without the instant feedback of the LCD screen.
PS: that's what Polaroid backs were used for--hard to imagine I wanted one--duuuhhh.

As Bob relates, and I think of it that way, the DSLR allows for preview and review of images to an even greater extent than even his Ground Glass screens at full image size on view cameras.

However, when we get wrapped up around Depth of Field, apparent focus, circles of confusion etc. In any given image--including mental ones through your eyes-- at any moment, it is important to point out that there is ONLY ONE plane of (exact) focus in the image. All the rest is determined by the Physics of optical characteristics of lenses and light. Somewhat complex formulas, algebra, etc. Maybe even into Calculus for the lens design stuff.

Practically, for making images of large scenes, including landscapes, DOF can be estimated and carefully worked into the set up. It is those very large "f1 Point something" apertures that can cause us a problem. Also the other extreme is extreme magnification with Macro and long telephoto lenses.

I bless my stars that digital has allowed me to set exposure with different characteristics and evaluate the results on a scene instead of waiting for the darkroom results and missing the photograph I was trying to make in the field or studio. Add the ability to wirelessly control and tether your camera to a phone, tablet or computer with a BIG screen and as an image maker, this is what hog heaven was about.

Short answer: DOF Preview button? FuggettabOUt it!
C

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

The button is in a great position. I have reprogrammed it on my D800 and D810 to turn on the Virtual Horizon feature in the viewfinder.