DOF Preview

Shutter_to_think

I have the Nikon D700. My favorite lens, the Nikon 70-200/2.8.
One frustration I am having is being able to preview DOF.
When I'm looking through the viewfinder on A-Priority and change the aperture, why doesn't the DOF change so I can see what the picture will look like? Am I missing something?

pathfinder

Originally 70 years ago, lenses had to be manually stopped down to the appropriate aperture before tripping the shutter, and manually re-opened to the maximum aperture for reflex viewing with a single lens reflex camera. This obviously made for slow shooting. SO manufacturers introduced automatic aperture lenses - lenses that allowed viewing and focusing with the aperture wide open, that then quickly shut down when the shutter was pressed and the exposure made, and then automatically re-opened for viewing again. This is how modern lenses work on an SLR camera. Choosing Aperture priority does not stop the lens aperture down until the shutter is pressed.

What you want to press, ( not the shutter button ) is the depth of field preview button which is usually on the left side of the camera body by the lens mount. This will stop the lens aperture down to your selected aperture to allow you to see how the chosen aperture affects the depth of field. I use this technique frequently. Be aware, that if you are viewing through an f 2.8 aperture lens, and you stop it down to f11, 4 full stops, you will have 1/16th as much light coming through the lens and it will look much, much darker - this is normal - give your eye 10 - 15 seconds to adjust to the lower light level and you will begin to see again and can evaluate the dof then.

Pixoul

Shutter_to_think wrote: »

why doesn't the DOF change so I can see what the picture will look like? Am I missing something?

To expand on pathfinder's great explanation, once you start using the DOF preview button, you'll see exactly why modern lenses don't automatically change the aperture while you're composing the photo. Stopping down during composition will let less light in making it difficult to focus and see your subject.

craig_d

Pixoul wrote: »

To expand on pathfinder's great explanation, once you start using the DOF preview button, you'll see exactly why modern lenses don't automatically change the aperture while you're composing the photo. Stopping down during composition will let less light in making it difficult to focus and see your subject.

Well, nobody in his right mind composes and focuses while stopped down. If you don't have an automatic aperture lens, you compose and focus on your primary subject with the lens wide open, then stop down, check DOF, set shutter speed, and finally shoot. This is what I have to do when I use old Nikon MF lenses on Canon DSLRs.

time2smile

First of all Welcome...

The old DOF button, she aint what she used to be.
Its there, try it, you will end up using LV or just calucate it...

good luck

Shutter_to_think

Thanks for all the help. I tried it. and boy..... does that ever suck.
It gets so dark, you can't even see.
So I guess it comes down to learning DOF more than by adapting it.
I have the iPod app called "DOF Master". It works great but it's still something you have to calculate instead of doing it on the fly.
Thanks again.

chrisjohnson

Shutter_to_think wrote: »

Thanks for all the help. I tried it. and boy..... does that ever suck.
It gets so dark, you can't even see.
So I guess it comes down to learning DOF more than by adapting it.
I have the iPod app called "DOF Master". It works great but it's still something you have to calculate instead of doing it on the fly.
Thanks again.

I share the frustration.

On my Canon 40D there is a handy creative mode called A-DEP - probably Nikon has something similar. It uses all the focus points to recommend an aperture. It is not a precision tool but serves me as a useful sanity check when wandering around with a telephoto.

JohnBiggs

Shutter_to_think wrote: »

Thanks for all the help. I tried it. and boy..... does that ever suck.
It gets so dark, you can't even see.
So I guess it comes down to learning DOF more than by adapting it.
I have the iPod app called "DOF Master". It works great but it's still something you have to calculate instead of doing it on the fly.
Thanks again.

Wow. If it gets too dark to see, you have to wonder about shutter speed.

Btw, the darkness is related to the aperture you select.

pathfinder

You're right, John, if it is that dark then the shutter speed is not going to be very short either.. But DOF preview is much easier to do with a camera on a tripod, than hand held generally.

I did emphasize that one MUST wait 10 - 15 seconds, at least, to allow ones eye to begin to adjust to the much lower light levels........ I thought that it was apparent that the amount of darkness is a function of the chosen aperture too.

Folks can be so impatient these days, apparently.

I suspect most pros just have a feel, and idea, of how the various aperture affect DOF and go with that rather than hauling out a DOF calculator.

I do have a DOF calculator for my Droid and for my iPad, but rarely use them, unless I want a specific number for the hyperfocal distance.

LiquidAir

pathfinder wrote: »

I suspect most pros just have a feel, and idea, of how the various aperture affect DOF and go with that rather than hauling out a DOF calculator.

I find that getting a feeling for DoF is easier if you shoot with primes. That said, when shooting I rarely try to finesse the DoF. Rather, if I want everything in focus I immediately stop down to f/11 (or f/16 if I think f/11 won't be enough). When shooting hand-held in low light where f/11 is not an option I make sure to choose my focus point in such a way that shot still works if the DoF is very shallow.

Snowgirl

pathfinder wrote: »

I do have a DOF calculator for my Droid and for my iPad, but rarely use them, unless I want a specific number for the hyperfocal distance.

Quick question: what's the name of the iPad app?

pathfinder

I have DoFC on my iPad. - just search for depth of field or photography at the App store and you should see several choices. Mine may not be the best, it is actually an iPhonebapp, but it works.

On my Droid it is Depth of Field Calculator, and it seems well executed, as it allows me to choose my own Circle of Confusion. Sounds funny to say it that way, though, doesn't it?

pathfinder

LiquidAir wrote: »

I find that getting a feeling for DoF is easier if you shoot with primes. That said, when shooting I rarely try to finesse the DoF. Rather, if I want everything in focus I immediately stop down to f/11 (or f/16 if I think f/11 won't be enough). When shooting hand-held in low light where f/11 is not an option I make sure to choose my focus point in such a way that shot still works if the DoF is very shallow.

I agree. I shoot landscapes mostly at f8, unless I have a specific reason to shoot at a different aperture. I do shoot shallow dof shots, as well, always with a single AF point precisely placed, if possible.

divamum

LiquidAir wrote: »

I find that getting a feeling for DoF is easier if you shoot with primes. That said, when shooting I rarely try to finesse the DoF. Rather, if I want everything in focus I immediately stop down to f/11 (or f/16 if I think f/11 won't be enough). When shooting hand-held in low light where f/11 is not an option I make sure to choose my focus point in such a way that shot still works if the DoF is very shallow.

Exactly. I shoot a lot at f4 and below, and thus try to make it habitual to pick the appropriate focus point and be as accurate in placing it as I can. I have my camera is set to single-point focus as the default.

hgernhardtjr

Maybe I'm thinking of the wrong lens (I shoot Canon), but doesn't that lens have a depth of field scale indicator engraved on/built in to its barrel?

chrisjohnson

hgernhardtjr wrote: »

Maybe I'm thinking of the wrong lens (I shoot Canon), but doesn't that lens have a depth of field scale indicator engraved on/built in to its barrel?

Depends which lens. In the old days a DOF engraved indicator on the lens was a useful feature. I suppose with A/F zoom lenses it has become very difficult to implement. It would be a nice feature to have the hyperfocal distance pop up in the viewfinder - seems easy for the manufacturers to calculate approximately and would save us relying on memory or looking stuff up.

Otherwise I confess my approach is similar to LiquidAir and Pathfinder.

michswiss

I'm working a lot on manual focus techniques these days and getting a feel for hyper-focal length takes practice. I pretty much shoot with primes, all of which have an aperture ring so I still have the scale engraved on the lens which helps. Btw, the DOF preview button on the D700 is defaulted to the front upper right button next to the lens barrel.

Given that i shoot wide open a lot, I'm like Divamum in only using a single autofocus point. But, I'm curious why you would use AF shooting a landscape shot on a tripod?