DoF Preview Button

viper_biker

viper_biker

Suspended / Banned
Messages
550
Name
Gareth
Edit My Images
Yes
Reading through 'Understanding Exposure' at the minute and I'm reading about the DoF button. Now, for me, it's really of no use, but it got me wondering, does anyone use it, and if so, under what circumstances?
 
yep i use mine from time to time to check what my backgrounds look like when i use a smaller aperture.
 
I use mine when I'm using the Raynox for Macro, very handy.
 
stan the man said:
but how does it work :shrug:
Click to expand...

Know what ya mean. I could never see what I was supposed to be seeing on the 400D. Never use it now, and not even sure if I have one.
 
I don't know about the A700, but on the 450d, when I press the button, the lens stops down to the aperture set and I can get an idea of what the image DoF is going to be like, it gets harder to see as it's darker of course..
 
It is the same for all cameras, you can see how it works by setting the aperture to f/11 and then looking through the lens and pressing the DOF preview button, you will see that the aperture will get smaller.
 
If you look through the front of the lens, rather than the viewfinder it should be clearer as to what is happening.
 
stan the man said:
yeah,as i change the aperture,then press the button...what i see just gets darker,and cannot make sense of it all to be honest.like you,i don't bother to use it anyway..
Click to expand...
Best way of rectifying that is to shut your eyes for a few seconds so they are more accustomed to the lower levels of light.

Makes 'seeing' the changes with the DoF preview button a much more enjoyable and useful experience.
 
Mike.P said:
Thats all very well but if you cant see whats happening through the viewfinder then whats the point?
Click to expand...

Hi Mike

I don't really use it either! but if I understand the question correctly? then I would say that if you allow your eyes a few seconds to get used to the darker view! then what you can see in the lighter areas through the viewfinder will be the part of the shot in sharper focus :) It does take a bit of getting used to and I hope I explained that OK, but try it and take a few test shots to see what I'm ramblin on about :thumbs:
 
I always use it when photographing a static subject that will look best with the background out of focus. It is good for that purpose.
 
68lbs said:
Never use it now, and not even sure if I have one.
Click to expand...

You do, it's the big button under the lens release.

I've used it very rarely. In most of the situations I shoot in, I've a pretty good idea of what DOF I'm going to get at any given aperture. Handy for macro though, as said.

Use it for flash preview / modeling lamp from time to time, also.
 
Mike.P said:
Thats all very well but if you cant see whats happening through the viewfinder then whats the point?
Click to expand...


I think he means just to demonstrate the function of the button, not that you use it in this way.

Look through the lens from the front, press the button and you'll see the shutter close depending on what aperture you have selected.

To use it practically, you do of course need to be looking through the viewfinder with the camera pointing at the subject.
 
I use mine, again mainly for static subjects.

To see what it actually does, go OUTSIDE in DAYLIGHT (to get the best effect and be able to see the effect) and pick a subject to focus on, but ensure there are other subjects in the background, as per my lovely diagram below...

You______Subject(car)___________Other background subject (house)

Focus on the car and notice how out of focus the house is. Now set your aperture to f16(ish) or less (higher f number) and press the DoF button. You'll see the whole image in the viewfinder becomes darker, but with that - the house has become more in focus, while the car is still also in focus.

This is the focus levels you would expect to see in the final image, but by using a longer shutter speed it won't be so dark....
 
Shine On said:
I think he means just to demonstrate the function of the button, not that you use it in this way.

Look through the lens from the front, press the button and you'll see the shutter close depending on what aperture you have selected.

To use it practically, you do of course need to be looking through the viewfinder with the camera pointing at the subject.
Click to expand...

Yes I understand the fact you can see what happens when you look through the lens (and I already knew what was happening) but what I was saying is what point is there knowing what is happening if, when you use the viewfinder all you see is it getting darker.

I will try getting my eyes adjusted first as others have recommended. :)
 
Mike.P said:
if, when you use the viewfinder all you see is it getting darker.
Click to expand...


I think that's the point. That isn't all you should see. You should be able to better judge differential focus and depth of field. As it gets dark, items in the blurred background should jump into focus (depending on how stopped down you are)

Paul
 
When I first got the camera I could not see the point of the DOF button, but now I do use it for two thing, 1) Backgrounds when shooting Macro, and sometimes 2) to check shadows when using off camera flash.
 
There have been discussions here recently about Hyperfocal Distance, and about how difficult, not to mention impossible, it is to use this technique with zoom and other lenses which don't have depth of field scales on the barrel.

With a little knowledge of what the hyperfocal distance is likely to be, you make a guesstimate, and then use the depth of field preview button to check.

As a rule of thumb - focus about one third of the way into the picture, and then check. As has been pointed out 1/3rd of the way in is unlikely to be exactly correct, but it will often be near enough for starters.

What I often do after checking is switch to manual focus and adjust the focus manually, if necessary, then check again using the DoF preview button.

:)
 
DoF buttons were useful in the film days where you had no idea or way of assessing the DoF until the print came back to show you you were wrong :lol:

Today, it's a total waste of time as chimping the shot tells you far more than looking through a darkened viewfinder ever can - especially in macro work and using flash ;)

All IMHO of course :D

DD
 
Jayst84 said:
Preview button's quicker than chimping. :p
Click to expand...

For the subjects that have been suggested time isn't an issue - and it's far more accurate

Have you looked through the viewfinder on a dull day at f22 - it's too dark to see anything useful

Chimping is best - period :D

DD
 
Jayst84 said:
:thinking: Ok.. ;)
Click to expand...

Conceded a bit quick there m8 :lol:

Going back to the film days, I used the DoF button often - as a beginner - but soon got used to what each aperture gave me on what lens, and in those latter film years I didn't use it at all - but it was a great learning tool

Today, thanks to digital, I still rarely use chimping as a means of assessing DoF as I just know' what I'm getting anyway - but as a learning tool, and especially for macro & flash, chimping is a much much better way of assessing the shot than darkening your viewfinder with the DoF button

DD
 
Don't use mine...
I use instinct instead:lol:
After taking photographs with all formats for 60 years I am rarely surprised.;)
 
viper_biker said:
Reading through 'Understanding Exposure' at the minute and I'm reading about the DoF button. Now, for me, it's really of no use, but it got me wondering, does anyone use it, and if so, under what circumstances?
Click to expand...

I use it for macro work - very useful.
 
I agree with Dave, I rarely use the DoF button, either judge the DoF or just guess and check the LCD after, far faster IMO.
 
You must log in or register to reply here.
Back
Top