Help needed with dof - DPChallenge Forums

Canon EF 70-300mm f/4.5-5.6 DO IS USM

04/08/2008 12:34:19 PM · #3

For one, the macro lens is going to give you the slimmest DOF even at f18.

For max DOF you need to shoot at the widest angle possible with the lens closed down as much as you can get it. That means focal length 18 and f18 using the figures you've posted so far.

Even though zooming will give a compressed effect, it also lessens the DOF.

Message edited by author 2008-04-08 12:35:09.

chris48083

Pentax K10D

Pentax DA 18-55mm f/3.5-5.6 AF

04/08/2008 12:38:10 PM · #4

Originally posted by cpanaioti:

im confused, if you compress DOF wont that effectivly do the same as making it deeper??

cogerox

Nikon D850

Nikon AF-S Micro-Nikkor 105mm f/2.8 VR

04/08/2008 12:44:41 PM · #5

So, closer with the zoom at the widest and stopped down the maximum? Won't that also reduce sharpness?

cpanaioti

Canon EF 70-300mm f/4.5-5.6 DO IS USM

04/08/2008 12:45:04 PM · #6

Originally posted by chris48083:

Originally posted by cpanaioti:
For one, the macro lens is going to give you the slimmest DOF even at f18.

For max DOF you need to shoot at the widest angle possible with the lens closed down as much as you can get it. That means focal length 18 and f18 using the figures you've posted so far.

Even though zooming will give a compressed effect, it also lessens the DOF.

im confused, if you compress DOF wont that effectivly do the same as making it deeper??

No. I've given a very simplistic analogy. There's a formula to determine the field of focus based on the focal length and f stop.

Try this:

Using a zoom lens - broader range the better and use the lens at a mid focal length like f8 or f11.

Frame a shot at both the short and long end of the lens. Using the same point to focus on (about 1/3 into the scene)

Remember what's in focus is 1/3 in front of the focus point and 2/3 behind.

cpanaioti

Canon EF 70-300mm f/4.5-5.6 DO IS USM

04/08/2008 12:46:39 PM · #7

Originally posted by cogerox:

So, closer with the zoom at the widest and stopped down the maximum? Won't that also reduce sharpness?

You wanted to know what would give the most DOF and that's what will. It won't be the sharpest though. You need to shoot at about f8 - f11 to get the sharpest but that won't give you the deepest DOF. It's a tradeoff.

Nikon AF-S Micro-Nikkor 105mm f/2.8 VR

04/08/2008 12:50:06 PM · #8

May be helpful -
//www.dofmaster.com/doftable.html

cogerox

Nikon D850

04/08/2008 12:57:04 PM · #9

Originally posted by pointandshoot:

May be helpful -
//www.dofmaster.com/doftable.html

That is helpful. Thanks. And, that brings up my next question which is...should I focus at the front edge, the center or the distant edge to get the greatest dof?

Bugzeye

Fisher Price Kid-Tough Digital

04/08/2008 01:14:39 PM · #10

I have read that you should do that in 3rds, one third in or 2 thirds in depending on subject.

04/08/2008 01:51:13 PM · #11

Originally posted by cogerox:

...should I focus at the front edge, the center or the distant edge to get the greatest dof?

The near side of center, but center is probably close enough depending on what scale you are working with. Use the largest number f/stop (f/22) of your lens to start. If the near and far subjects are still OOF then move further from the setup and try again. If you have to, go to your 18mm lens which has an extremely wide DOF. Generally, the typical DPC voter will vote down a photo if the subject closest to the lens is OOF but are kinder if only the background is OOF.

Message edited by author 2008-04-08 14:01:21.

CarpeLumen

Canon EF 100mm f/2.8 Macro

05/01/2008 12:35:18 PM · #12

Actually the correct area to focus is 1/3 into the desired field since the DOF is shorter in front of the foci than behind it.

Spork99

OM System OM-1

05/01/2008 01:12:24 PM · #13

Originally posted by FourTDSean:

Actually the correct area to focus is 1/3 into the desired field since the DOF is shorter in front of the foci than behind it.

That's a good guesstimate/starting point, but to really maximize DOF, set the focus at the hyperfocal distance.

05/01/2008 01:16:15 PM · #14

Originally posted by FourTDSean:

Actually the correct area to focus is 1/3 into the desired field since the DOF is shorter in front of the foci than behind it.

The fraction of the depth of field which is in front of and behind the focus distance changes with focal length. With a 50mm lens it is 46% in front and 54% behind (at 3 feet). It is even closer to 50/50 with longer lenses.

ETA focus distance

Message edited by author 2008-05-01 14:44:18.

Spork99

OM System OM-1

Sony 24-70mm F4 Vario-Tessar T* FE OSS

05/01/2008 01:19:18 PM · #15

Originally posted by pointandshoot:

Originally posted by FourTDSean:
Actually the correct area to focus is 1/3 into the desired field since the DOF is shorter in front of the foci than behind it.

The fraction of the depth of field which is in front of and behind the focus distance changes with focal length. With a 50mm lens it is 46% in front and 54% behind. It is even closer to 50/50 with longer lenses.

That's why you use the hyperfocal point and the DOF calculator.

Bear_Music

Samsung Galaxy S24 Ultra

05/01/2008 01:46:21 PM · #16

Originally posted by pointandshoot:

And the closer you focus, the more DOF shifts towards the rear. That's why the 1/3 rule of thumb is so useful; the closer you get, the more critical is the precise location of the DOF.

R.

05/01/2008 02:22:25 PM · #17

Originally posted by Spazmo99:

Originally posted by pointandshoot:

Originally posted by FourTDSean:
Actually the correct area to focus is 1/3 into the desired field since the DOF is shorter in front of the foci than behind it.

The fraction of the depth of field which is in front of and behind the focus distance changes with focal length. With a 50mm lens it is 46% in front and 54% behind. It is even closer to 50/50 with longer lenses.

That's why you use the hyperfocal point and the DOF calculator.

The OP was asking about macro. Rarely would the hyperfocal point apply.

05/01/2008 02:24:43 PM · #18

Originally posted by Bear_Music:

Originally posted by pointandshoot:

Originally posted by FourTDSean:
Actually the correct area to focus is 1/3 into the desired field since the DOF is shorter in front of the foci than behind it.

The fraction of the depth of field which is in front of and behind the focus distance changes with focal length. With a 50mm lens it is 46% in front and 54% behind. It is even closer to 50/50 with longer lenses.

And the closer you focus, the more DOF shifts towards the rear. That's why the 1/3 rule of thumb is so useful; the closer you get, the more critical is the precise location of the DOF.

R.

And that is why the 1/3 rule applies for landscape but not macro. It becomes closer to a 1/2 rule for macro.

Spork99

OM System OM-1

05/01/2008 02:24:46 PM · #19

Originally posted by pointandshoot:

Originally posted by Spazmo99:

Originally posted by pointandshoot:

Originally posted by FourTDSean:
Actually the correct area to focus is 1/3 into the desired field since the DOF is shorter in front of the foci than behind it.

The fraction of the depth of field which is in front of and behind the focus distance changes with focal length. With a 50mm lens it is 46% in front and 54% behind. It is even closer to 50/50 with longer lenses.

That's why you use the hyperfocal point and the DOF calculator.

The OP was asking about macro. Rarely would the hyperfocal point apply.

No, but the DOF calculator still applies and will give more precise answer than the 1/3 rule or the 1/2 rule.

Message edited by author 2008-05-01 14:25:24.