Greater Depth of Field

[dougolupski]

Hi All,

I have been trying to find out if Canon or another third party makes a prime or zoom with a F32 or physically smaller

aperture. I really want a sharp ultra deep depth of field. I have see some software solutions and have heard the

macro 100 f2.8 has f32 but is there anything out there lens wise that doesn't look like junk stopped all the way down.

Thanks for your help.

[sheldonnalos]

The reason things look like junk stopped all the way down is because of diffraction. You can't get around it. As

a lens aperture is closed down, the maximum possible resolution is restricted. Most lenses on 35mm digital are

best at around f/8 or f/11. By f/16 you start to see degrading effects from diffraction and at f/22 it is quite

noticeable.

 

There is no such thing as anything being sharp at f/32, regardless of what lens you use. Any lens will be pretty

much equally bad as another.

[geoffs1]

The wave nature of light: it's not just a good idea, it's the law!

[dennisgg]

Your best bet is probably a tilt-shift lens for increasing DOF.

http://www.outdoorphotographer.com/community/op-editorial-blog/ultimate-depth-of-field.html

 

Dennis

[bobatkins]

This series of images shows you why you really don't want to use f32 - http://www.bobatkins.com/photography/technical/diffraction.html

 

All lenses will be pretty much the same stopped down that far. There's no simple way to get lots of macro DOF and sharp images, Stacking a bunch of images at different focus points and combining them in software is your best bet. A tilt lens can tilt the focus plane for landscape shots.

[dougolupski]

I dont think blanket answers work all that well. I shoot regulary past 32 on my 4x5 and while I get a minor amount of difraction I am still capable of 7 foot prints without any notice. Apples and oranges I know but I just wanted to here what is available for eos mount bodies. I do understand light and difraction but in most cases including this one there is exceptions. There may just not be one for a 35mm camera.

Dennis I have toyed with the idea of a TS and will more than likely make the plunge since my work has me going in that direction.

 

Thanks for the responses.

[dougolupski]

Thanks Bob, you beat me to my response. I am heading into a TS since carrying my 65lbs large format kit isn't always an option.

[pjmeade]

Can you not get sufficient depth of field using hyperfocal depth of field at arounf f16 to f22?

 

Experimenting with a Tamron 28/3.5 and a K1000 (in 1980) I managed very pleasing results from about 1m to infinity.

 

P

[colin carron]

The Canon Macro 100 /2.8 will not give you best results at f/32. If you look at the MTF curves you will see resolution drops sharply after f/11.

 

http://www.photozone.de/canon-eos/167-canon-ef-100mm-f28-usm-macro-test-report--review?start=1

 

If you really want a big depth of field you could :

 

1) stop down to f16 - f22 as in Peter Meade's post and see what results you get

 

2) try a software merge of two or more images with far and near focus.

 

3) try larrge format film camera where the plane of focus can be placed where you want it from near objects to the horizon.

[alan_myers]

Look for articles by George Lepp (Outdoor Photographer magazine) about merging multiple images into a single one with ultra deep depth of field. There's a software designed to do this that he's been trying out.

[j_smith6]

Maybe something simple like using shorter focal length will help.

[KenPapai]

"Look for articles by George Lepp (Outdoor Photographer magazine) about merging multiple images into a single one with ultra deep depth of field. There's a software designed to do this that he's been trying out."

 

PS CS4 will stack 5 photos or so and merge the sharpest of each into one image -- Jeff Schewe talks about this in his overview of PS CS4 in Digital Photo Pro, Nov. 2008.

[sarah_fox]

This technical problem can be addressed with software like PhotoAcute, by which you can combine multiple frames of differing focus into a single frame with augmented DoF (called "focus stacking"). I don't know what the technical limitations of this method are, since the magnification of the image really depends somewhat on focal distance. However, I've seen some pretty impressive results.

[martin-s]

<p>I used to rely on the DOF scales of my MF film gear in the past, but after going digital, that became a lot

more difficult. Modern AF zoom lenses generally don't have DOF scales anymore and when eye-balling the hyperfocal

distance, I was often dissapointed with sharpness at infinity.</p>

 

<p>I found <a href="http://www.trenholm.org/hmmerk/DOFR.html">this article</a> enlightening.</p>

 

<blockquote><i>“Before I describe the solution, let me say what's wrong with the existing philosophy. There's

nothing wrong with the logic or the math. It's the basic assumptions that have been surpassed by technology. The

starting point of the existing theory was that there is a limit on the resolving power of films and lenses. That

limit was said to yield a smallest spot having a diameter equal to one-fifteen-hundredth of a normal lens's focal

length. Thus the maximum permissible "circle of confusion" is 1/30 mm in diameter for a 35 mm camera with its 50

mm standard lens.<br /><br />

 

The problem is that today's films and lenses are capable of achieving a resolution standard at least five times

as stringent, and maybe more. But if one enters that revised standard into the formulae, depth of field just

about disappears. And that doesn't square with experience either.”</i></blockquote>

[JDMvW]

Excuse me, help walk me through this. I'm too tired out to research this myself and I know you all already know the answers to these questions

 

Isn't it true that the f/stop is a ratio of the aperture diameter to the lens diameter?

 

Isn't diffraction effect caused by the absolute diameter of the aperture as related to the properties of light?

 

So... wouldn't f/32 on a really big diameter lens still be large enough to give depth of field without any serious problem with diffraction? Isn't this why the "f/32" school of view camera users was in fact so good at producing great depth of field AND sharpness?

 

Could you use, say, a 6x6cm-format lens on a EOS body at f/32 and avoid the diffraction effect?

 

Or am I just whistling Dixie?

[sheldonnalos]

There is no way to avoid the diffraction effect, at least not with available lens technology.

 

Using an aperture of f/32 works fine on a 4x5 camera but only because you are enlarging the film much less than from 35mm. An aperture of f/32 allows for roughly 30 lp/mm to get to the film or sensor. If you figure that a print needs to have roughly 5 lp/mm for critical sharpness (250 dpi) then you can pull off a 6x enlargement at f/32 without losing much resolution to diffraction. A 6x enlargement from 4x5 is a 24x30 print, where a 6x enlargement from 35mm is just a little larger than a 5x7 print.

 

Diffraction is based on aperture, not focal length. This is primarily because with a longer lens, while it does have a larger physical diameter aperture, the aperture is farther away from the sensor/film and the light waves have more distance in which to spread out (diffract) before hitting the film/sensor. The increased diameter is offset by the greater distance.

 

But you know the truly best way to get more depth of field?

 

Small prints. :-)

[richard_oleson]

Hi JDM:

 

You're right, diffraction is the result of absolute aperture diameter, which gets larger at a given f/stop as the focal length increases.

 

However, depth-of-field does the same thing.... f/32 on a long lens has shallower DOF than on a short lens, because the absolute aperture diameter is larger.

[geoffs1]

Just to re-iterate/expand Sheldon Nalos and richard oleson's remarks...

 

JDM: "Isn't it true that the f/stop is a ratio of the aperture diameter to the lens diameter?"

 

No. The f-stop is the ratio of focal-length to aperture diameter (ex. "f/32" is an aperture diameter 1/32 of the focal-length of the lens). That's why a 300mm f/2.8 lens is so much larger diameter than a 30mm f/2.8.