DOF preview button question

SloYerRoll

I know what it's supposed to do.
But it seems to my untrained eye that even w/o the DOF preview being used. I have a decent idea of what is inside my DOF. i.e. I look at an image and focus on it. I can tell whether the b/g is in focus or not. Or am I not looking at this correctly?:dunno

Why use the DOF button then?

Richard

SloYerRoll wrote:

I know what it's supposed to do.
But it seems to my untrained eye that even w/o the DOF preview being used. I have a decent idea of what is inside my DOF. i.e. I look at an image and focus on it. I can tell whether the b/g is in focus or not. Or am I not looking at this correctly?

Why use the DOF button then?

Without the DOF button, you see the frame as it would be with the lens wide open. The DOF button closes the iris to the selected aperture, which will increase the DOF. Since it also darkens what you see in the viewfinder, it takes a bit of practice to notice the difference.

SloYerRoll

Thanks Richard,
As I said though. I know what it does. I just haven't been able to find a practical use for it. What do you use the DOF preview button for?

jeffreaux2

SloYerRoll wrote:

Thanks Richard,
As I said though. I know what it does. I just haven't been able to find a practical use for it. What do you use the DOF preview button for?

Im with you on not having a practical use. In addition it always kinda starles me when I accidentally get into it with my fingers!!!

I would think that it might be useful for someone doing product type photography with bright constant light sources.....maybe.

LiquidAir

The handy thing about DoF preview is you can hold it down while you adjust the apeture. Its a really quick way of getting a rough aperture value when DoF is an issue. A simple use for it is a portrait where you want to blur the background. Often the best choice in that scenario is to stop down as much as you can while maintaining blur in the background and DoF preview is a quick way to find that point.

KED

rsinmadrid wrote:

Without the DOF button, you see the frame as it would be with the lens wide open. The DOF button closes the iris to the selected aperture, which will increase the DOF. Since it also darkens what you see in the viewfinder, it takes a bit of practice to notice the difference.

Which explains why, if you shoot wide-open, it does nothing, correct? I had originally mistaken it for sort of a boteh preview, but I now think it's exactly the opposite.

SloYerRoll

LiquidAir wrote:

The handy thing about DoF preview is you can hold it down while you adjust the apeture. Its a really quick way of getting a rough aperture value when DoF is an issue. A simple use for it is a portrait where you want to blur the background. Often the best choice in that scenario is to stop down as much as you can while maintaining blur in the background and DoF preview is a quick way to find that point.

That's the answer I was looking for! Now I have a a reason to really get the "feel" of the DOF preview button..
Thanks Ken, and everyone else

Cheers,
-Jon

LiquidAir

KED wrote:

Which explains why, if you shoot wide-open, it does nothing, correct?

Yes.

Normally the aperture is left wide open when focusing; the DoF preview button stops the aperture down to the radius which will be used when the photo is taken. So, yes, if you shoot wide open it does nothing because the shooting aperture and the focusing aperture are the same. Where the DoF preview button comes in handy is when you have an f/2.8 lens on the camera, but you want to see the scene at f/5.6 through the viewfinder.

KED wrote:

I had originally mistaken it for sort of a boteh preview, but I now think it's exactly the opposite.

It depends on what you mean by boteh preview. The DoF preview button shows you what the sensor will see when the picture is taken. However, it will never make the background focus softer than what you see while focusing. What you see while focusing is always the shallowest DoF the lens is capable of delivering which is good because it both makes your view brighter and makes it easier to focus precisely.

evoryware

I use the button when I want to find distractions etc and I have my lens stopped down. So before I shot this waterfall picture, I wanted to make sure there were no more distracting tree branches in the frame in front of the fall. The camera is showing at f/2.8, wide open. I don't see any branches. I had my camera set to shoot at f/11 though. When I hit the DOF button at F11, I saw branches in front of the waterfall come into focus, I knew I had to change my position to get the branches out of the shot! Actually quite effective once you learn how to use it.

Richard

I mostly do street shooting, so I don't use it much. But if I'm shooting something up close like flowers, I use it to see what's going to be sharp and what's not.

KED

LiquidAir wrote:

It depends on what you mean by boteh preview.

Well what I meant, of course, was "bokeh" preview. A typist I am not!

SloYerRoll

KED wrote:

Well what I meant, of course, was "bokeh" preview. A typist I am not!

If it wasn't for spell check. My posts would look atrocious! They look bad enough even WITH spell check

KED

SloYerRoll wrote:

If it wasn't for spell check. My posts would look atrocious! They look bad enough even WITH spell check

Unfortunately, spell check doesn't know "bokeh" any better than "boteh"!

SloYerRoll

KED wrote:

Unfortunately, spell check doesn't know "bokeh" any better than "boteh"!

That's why they made "add to dictionary"

Unfortunately I've accidentally clicked mispelled words into the dictionary. So my spell check is all buggered up!

KED

SloYerRoll wrote:

That's why they made "add to dictionary"

Unfortunately I've accidentally clicked mispelled words into the dictionary. So my spell check is all buggered up!

True story: I recently sent someone an e-mail which, after hitting "send", I discovered to be kinda full of typos including some of the type that S/C won't catch -- "tow" instead of "two" for example. My recipient gave me some good advice: "Slow down".

LiquidAir

KED wrote:

Well what I meant, of course, was "bokeh" preview. A typist I am not!

Sorry. I wasn't making a comment about your spelling. Since the word comes from Japanese I don't think it has a standard English spelling.

What I meant by my comment was that there the term "bokeh" gets used in a number of different ways. Personally I do think of the DoF preview as a bokeh preview because it lets me see how much the background will be blurred in the actual shot. I often like to blur backgrounds enough to provide separation without blurring them so much that they are unrecognizable. DoF preview helps me zero in on the aperture which gives me the effect I want.

KED

LiquidAir wrote:

Sorry.

No reason at all to be sorry - it took me about 24 hours to realize my typo, is all. Your posts on this have been really informative. This is somewhat foreign to me as I almost always shoot wide open, but am interested in checking it out now that I understand it better.