Controlling depth of field

System

Hi, I'm new to this whole macro thing in that I have never used a "true" macro lens for macro style photography. Generally in the past I've used a long zoom lens to get close to small subjects. Recently I've purchased a Canon 100mm EF Macro lens and have been playing with it's very close focusing abilities.

I'm having some trouble with the depth of field when I'm close focusing on a subject. I'm using a Canon ring flash and a 40D body with a tripod.

What I'm wondering is if there is a depth of field guide out there somewhere that will help me learn the more complex aperature/focusing distance/DOF relationship with a true macro lens?

silversx80

http://www.dpreview.com/learn/?/Glossary/Optical/Depth_of_Field_01.htm

GOLDENORFE

Hi MagicKiwi, iv got that lens, the pics in my butterfly eyes post were all taken at f6-f9 single shots,no focus stacking.
always try to focus on the eyes,thats the main focal point of the subject. you dont realy need to go lower than f11.
manual focus much better than auto!
post some photos soon,we can comment better then.
phil.
http://www.flickr.com/photos/goldenorfe/

System

GOLDENORFE wrote:

Hi MagicKiwi, iv got that lens, the pics in my butterfly eyes post were all taken at f6-f9 single shots,no focus stacking.
always try to focus on the eyes,thats the main focal point of the subject. you dont realy need to go lower than f11.
manual focus much better than auto!
post some photos soon,we can comment better then.
phil.
http://www.flickr.com/photos/goldenorfe/

I may just do that, but I have to admit that I am the worst person in the world for posting photos. Nothing I have seems to be good enough for others to pass their critical eye over Not to mention where I am in the world it's still pretty much winter so there's little opportunity to get out and about with the gear.

Skippy

MagicKiwi wrote:

Hi, I'm new to this whole macro thing in that I have never used a "true" macro lens for macro style photography. Generally in the past I've used a long zoom lens to get close to small subjects. Recently I've purchased a Canon 100mm EF Macro lens and have been playing with it's very close focusing abilities.

I'm having some trouble with the depth of field when I'm close focusing on a subject. I'm using a Canon ring flash and a 40D body with a tripod.

What I'm wondering is if there is a depth of field guide out there somewhere that will help me learn the more complex aperature/focusing distance/DOF relationship with a true macro lens?

Hi MagicKiwi, any reason why your using a tripod?
If your using a Flash you should be able to shoot Handheld.

I use a 40D as well, but rarely ever use the tripod.

Some folks stack their shots in order to give the more depth,
the Master of this technique is Lord V.

I usually have my camera in MANUAL MODE.
ISO 200
Speed 200-250
and shoot between F8-F11-F14

I usually have to tone the Flash unit down a bit.

Tell us a little more about how you set your camera up if you would

.... Skippy
.

Lord Vetinari

Dof when shooting macro is dependent on the magnification and the aperture. Unfortunately smaller than about F11 at 1:1 you start getting noticeable diffraction softening of images which can be a problem.
You can get more DOF at a given aperture by shooting at a lower magnification and cropping, or by careful use of shooting angle (see exercise here
http://www.digitalgrin.com/showthread.php?t=58028 )
or by focus stacking.
Many photographers take advantage of the shallow DOF to take more abstract pictures of subjects.

Brian V.

System

Skippy wrote:

Hi MagicKiwi, any reason why your using a tripod?
If your using a Flash you should be able to shoot Handheld.

I use a 40D as well, but rarely ever use the tripod.

Some folks stack their shots in order to give the more depth,
the Master of this technique is Lord V.

I usually have my camera in MANUAL MODE.
ISO 200
Speed 200-250
and shoot between F8-F11-F14

I usually have to tone the Flash unit down a bit.

Tell us a little more about how you set your camera up if you would

.... Skippy
.

Thanks for the advice so far everyone. It has been helpful.

I generally use a tripod for nearly everything I shoot, even if it's people, sports, landscape etc. I shot manual with no flash for the first 15-20 years I owned a camera so the only way I could keep from spoiling my frames (I also treated film like it was gold since it could cost me most of my spending money for a week) was to use a pod. Old habits die hard they say and I don't think I'm in a hurry to let this one go even though I've gone digital.

I am interested in hearing more about how to stack shots with different DOF or focus points. I imagine this would only be useful with a flash unit or frames shot within a couple seconds of each other.

Also I've been trying to aim for my lens' "sweet spot" which I understand is usually a stop or two back from wide open. Do other people try for this or is it something I shouldn't bother with?

Lord Vetinari

MagicKiwi wrote:

Thanks for the advice so far everyone. It has been helpful.

I generally use a tripod for nearly everything I shoot, even if it's people, sports, landscape etc. I shot manual with no flash for the first 15-20 years I owned a camera so the only way I could keep from spoiling my frames (I also treated film like it was gold since it could cost me most of my spending money for a week) was to use a pod. Old habits die hard they say and I don't think I'm in a hurry to let this one go even though I've gone digital.

I am interested in hearing more about how to stack shots with different DOF or focus points. I imagine this would only be useful with a flash unit or frames shot within a couple seconds of each other.

Also I've been trying to aim for my lens' "sweet spot" which I understand is usually a stop or two back from wide open. Do other people try for this or is it something I shouldn't bother with?

There's a tutorial here on focus stacking http://www.wonderfulphotos.com/articles/macro/focus_stacking/

Don't think most people use the sweet spot of a lens in macro- you are either shutting the lens down to get reasonable DOF or using the lens wide open to get dreamy abstracts. Might be worth trying though for some natural light shots.

Brian V.

Robinivich

MagicKiwi wrote:

Also I've been trying to aim for my lens' "sweet spot" which I understand is usually a stop or two back from wide open. Do other people try for this or is it something I shouldn't bother with?

Someone who actually owns the lens feel free to step in here, but as far as I know from reading reviews, the "sweet spot" of the 100mm macro is the entire frame, at all focus settings and all apertures up to f16, and it ain't easy to find a higher quality lens...

That's a nice lens you've got there

With a lot of lenses, for a lot of different kinds of photography, stopping down to the "sweet spot" is a darned good idea, but macro lenses are typically so sharp and contrasty that it makes little difference, and macro photography makes more demands of depth of field than of anything else.

Lord Vetinari

Robinivich wrote:

Someone who actually owns the lens feel free to step in here, but as far as I know from reading reviews, the "sweet spot" of the 100mm macro is the entire frame, at all focus settings and all apertures up to f16, and it ain't easy to find a higher quality lens...

That's a nice lens you've got there

With a lot of lenses, for a lot of different kinds of photography, stopping down to the "sweet spot" is a darned good idea, but macro lenses are typically so sharp and contrasty that it makes little difference, and macro photography makes more demands of depth of field than of anything else.

Think sweet spot can mean different things but I normally assume it's where the lens is sharpest which is normally in the range F5.6 to F7.1 for virtually all lenses including macro ones.

Brian V.

System

Lord Vetinari wrote:

Think sweet spot can mean different things but I normally assume it's where the lens is sharpest which is normally in the range F5.6 to F7.1 for virtually all lenses including macro ones.

Brian V.

Bingo, that's the one I meant.

I've tried some shots using the input I've read in this thread and for some reason I'm still blowing the DOF... I've got the smallest sliver of sharpness and the rest goes as blurry as Lindsay Lohan at a drinking contest.

Well practice makes perfect and I'll try to post something when I have a few frames that are worthwhile for C&C.

Robinivich

Lord Vetinari wrote:

Think sweet spot can mean different things but I normally assume it's where the lens is sharpest which is normally in the range F5.6 to F7.1 for virtually all lenses including macro ones.

Brian V.

No argument from me, this is where the closed down aperture bypasses most of the imperfections visible at larger apertures, and before diffraction starts to reduce the resolution of the lens. I believe this is why photojournalists have the expression "F8 and be there" because it's a safe bet that this is where your lens has the best quality, so don't worry too much about it.

What I meant earlier is that macros tend to be sharp enough that the difference is miniscule. Here's a test of the 100mm macro:

http://www.photozone.de/Reviews/Canon%20EOS%20Lens%20Tests/167-canon-ef-100mm-f28-usm-macro-test-report--review?start=1

You'll notice that F2.8 is very slightly lower resolution (still better here than a lot of lenses) at f4 through f8 it produces practically uniform sharpness, then at f16 it starts dropping due to diffraction. For the difference between f4 and f8, or even f11 (though obviously no results at the link to compare) you're better off worrying about having enough depth of field, rather than finding ideal sharpness.

So my point with the sweet spot was that when you've so little depth of field, even a not quite optimally sharp image at f16 can beat a razor sharp sliver of image at f5.6, and even then, the quality of most macros is so uniform there's no huge reason to worry.