Depth of field preview?

Lacock Abbey detail

A
Lacock Abbey detail

  • 0
  • 1
  • 21
Tyndall Bruce

A
Tyndall Bruce

  • 0
  • 0
  • 39
TEXTURES

A
TEXTURES

  • 4
  • 0
  • 65
Small Craft Club

A
Small Craft Club

  • 2
  • 0
  • 60
RED FILTER

A
RED FILTER

  • 1
  • 0
  • 51

Recent Classifieds

Forum statistics

Threads
198,905
Messages
2,782,826
Members
99,743
Latest member
HypnoRospo
Recent bookmarks
0

clwyd

Member
Joined
Feb 21, 2008
Messages
46
Location
Welshpool, W
Format
35mm
Can someone please tell me how to interpret the depth of field preview on my lens? When the button is press the lens stops down to the set aperture but what does this tell me???

Thanks Chris.
 

David A. Goldfarb

Moderator
Moderator
Joined
Sep 7, 2002
Messages
19,974
Location
Honolulu, HI
Format
Large Format
Look at what's in focus with the lens wide open, and then what's in focus with the lens stopped down.

If you're focused on a distant scene, you might not notice too much, but try focusing on something fairly close to the near focus limit of the lens. As you stop down, more will be in focus. You might even focus on a ruler parallel to the lens axis and measure how much is in focus. Once you see what's going on, you'll notice more at greater distances.
 

jd callow

Moderator
Moderator
Joined
Jan 31, 2003
Messages
8,466
Location
Milan
Format
Multi Format
It tells you what parts of the image will be in focus and what parts will be out of focus. It is most easily appreciated when there is a good deal of distance between the point that is in focus and the other areas of the image. Such as a face in focus and the other objects in the frame being very near and or very far away.
 
OP
OP

clwyd

Member
Joined
Feb 21, 2008
Messages
46
Location
Welshpool, W
Format
35mm
Thank you both, because the screen was darkening i hadn't noticed the background coming into focus as i stopped the lens down. Regards Chris
 

Anscojohn

Subscriber
Joined
Dec 31, 2006
Messages
2,704
Format
Medium Format
Chris,
That's a great little device for taking people pictures, especially outside. Compose that luverly picture; then press the DOF preview, and, lo !! a potted plant, or a telephone pole, or some such object seems magically to grow out of the person's head that you did not notice at wide open aperture.
 
OP
OP

clwyd

Member
Joined
Feb 21, 2008
Messages
46
Location
Welshpool, W
Format
35mm
Hi John, I never thought about that , but yes I can see the advantages.
Thanks Chris
 

CBG

Member
Joined
Nov 21, 2004
Messages
889
Format
Multi Format
Especially valuable when using long fast lenses. Or when focusing extremely close up. The image in each of those changes the most when stopping down. You will see far less change when stopping down a slow short lens.

C
 
Joined
Jul 1, 2008
Messages
5,462
Location
.
Format
Digital
In a nutshell, your image should be composed such that a third of the image in front is in focus when the depth of field preview is operated, with focus extending two-thirds to the rear from the point of focus. You will see the difference by stopping your lens down (DoF preview) at f5.6, compared to, for example, f11 to f16. In small formats like 35mm, anything above f16 can result in softening of the image as light is being bent around the aperture blades in the lens (defraction). Like CBG says above, DofF needs to be critically evaluated with long/telephoto lenses, but it's less of a concern with ultra-wide angle lenses (17 to 24mm) as those lenses have inherently great depth.
 

Martin Aislabie

Subscriber
Joined
Nov 17, 2007
Messages
1,413
Location
Stratford-up
Format
4x5 Format
The second advantage is it also has the advantage that it raises apparent contrast – useful if taking photos of people outside

Suddenly deep shadows around the eyes and/or under the chin magically pop out of nowhere.

A touch of fill-in flash will cure the deep shadows and add a key-light in their eyes.

I use depth of field preview all the time on 35mm

Have fun

Martin
 

nemo999

Member
Joined
Jul 20, 2008
Messages
277
Format
35mm
Can someone please tell me how to interpret the depth of field preview on my lens? When the button is press the lens stops down to the set aperture but what does this tell me???

Thanks Chris.

Theoretically it shows you the precise depth of field you will get at a given taking aperture. In practice, it shows you that the focusing screen gets darker as you stop down and, since the screen has been optimized for a large aperture, you can hardly see what's sharp and what isn't. DOF preview is a very dubious benefit - to maximize its usefulness, it's good to put a plain (non-fresnel, non-microprism) screen in your camera if this has interchangeable screens. The only really accurate way to know what will be sharp is to use the DOF markings on your lens mount (if present) or else use DOF tables.
 

pentaxuser

Member
Joined
May 9, 2005
Messages
19,975
Location
Daventry, No
Format
35mm
Thank you both, because the screen was darkening i hadn't noticed the background coming into focus as i stopped the lens down. Regards Chris

I am using Chris' quote because as I understand it, this is the drawback with DoF preview. Are there any "tricks" to be used which gets you the real picture of DoF when things darken or is it simply a question of being aware that things are happening which aren't obvious unless you concentrate on looking for the info.

Does a Beattie Intenscreen or equivalent work here, albeit at a price?

Thanks

pentaxuser
 

eddym

Member
Joined
Jan 22, 2006
Messages
1,924
Location
Puerto Rico
Format
Multi Format
I am using Chris' quote because as I understand it, this is the drawback with DoF preview. Are there any "tricks" to be used which gets you the real picture of DoF when things darken or is it simply a question of being aware that things are happening which aren't obvious unless you concentrate on looking for the info.

Does a Beattie Intenscreen or equivalent work here, albeit at a price?

Thanks

pentaxuser

Well, you could use the view camera trick of a dark cloth. By shutting out all the ambient light, your eyes will adjust to the darkened view in the finder and you will be able to see details better.
 
Joined
Jul 1, 2008
Messages
5,462
Location
.
Format
Digital
The Beattie IntenScreen is "probably" available (I can't be sure); it provides a 1-1.5 stop brighter than that fitted to many SLRs as standard. The drawback however was the introduction of metering errors which were often overlooked, thus resulting in confusion and guesswork with metering, especially those with matrix/evaluative systems. As I understand it, Canon advised users against employing a Beattie screen, both for the EOS focusing point matrice and difficulty in fitting. These screens can be extraordinarily expensive (more than US$190 or AUD$200)... e.g. http://www.camerascreens.com/35mm_Intenscreens/35mm_Format.htm . Normally, as irritating as it can be, you really do have to concentrate when the viewfinder brightness drops, but this will also bring detail into sharp relief and tweaking the focus while activating DoF preview will allow you to see just where the start and finish of the range of acceptable focus (Depth of Field's correct term) is. Rather than make it a half-second affair, allow your viewing eye to adjust to the darker condition over a longer few moments.
 

pentaxuser

Member
Joined
May 9, 2005
Messages
19,975
Location
Daventry, No
Format
35mm
Thanks. I had already assumed that the user and certainly it's true for me, has an eyecup which shuts out all ambient light. There is no DoF button on my MZ7 so I have no experience of using one but maybe with a proper eyecup on a 35mm camera the darkening problem isn't a problem

pentaxuser
 
Photrio.com contains affiliate links to products. We may receive a commission for purchases made through these links.
To read our full affiliate disclosure statement please click Here.

PHOTRIO PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Ilford ADOX Freestyle Photographic Stearman Press Weldon Color Lab Blue Moon Camera & Machine
Top Bottom