close-up work maximum depth of field

Hello. I am shooting a close-up photo with a 4x5 sinar. I have a choice of 3 lenses, 90, 150 and 210. I need to fill the frame with an object roughly the size of an orange and I want to get as much depth of field from front to back on all sides of the object (so tilts and swings are irrelevant as far as I can tell.) I can shoot f64 since I am working with strobes.

I am TRYING to avoid using the 90mm. since I want to minimize distortion as much as possible.

As far as I can tell from using a depth of field calculator: http://www.rbarkerphoto.com/DOF2.html (pretty great resource) I essentially have less than an inch of DOF with any of my lenses.

Are there any tricks or advice on this or am I limited by the nuances of the medium?

Many thanks as usual for your thoughts on the matter.

Best,
Serge

Are there any tricks or advice on this or am I limited by the nuances of the medium?

No, you are limited by the laws of physics.

There are a number of things you can to do get a more acceptably sharp print. You can back off and not fill the frame (that is, get farther away from a 1:1 magnification). You can use smaller apertures (DOF will improve, but sharpness will actually decrease). You can print smaller. Etc.

It won't matter which lens you use - at a given magnification, DOF will be the same for all lenses as you found from the DOF calculator.

Without knowing more about what you are trying to acomplish, that's about all I can tell you.

if the object is a cube then tilts and swings are not irrelevant.
If you can only see one face of it then required dof would be very little.
if the object is a sphere then the dof only needs to be 1/4 the diameter of the sphere, unless the object is transparent (glass).

i.e. the shape and substance of this theoretical object may well require less dof than you think and tilts and swings may well help out but without knowing then all advice is guess work.

So what is it?

Bruce said it.

I gather you want to shoot a relatively deep object at a magnification on the order of 2:1. Short answer, as Bruce said, you can't get it all in focus and stopping down to f/64 will lose more sharpness than it gains.

For a longer explanation of what can and can't be done and how to do what's possible, buy a copy of Lester Lefkowitz' book The Manual of Closeup Photography. Out-of-print, available used through, in alphabetical order, www.abebooks.com, www.addall.com, www.amazon.com.

it occurs to me that the effective aperture will be vastly reduced at 1:1 magnification. Question is, will this increase effects of diffraction? Probably. Since f64 will be closer to the optimum sharpness of a 210 lens than a 90 lens, then the 210 may give better actual dof rather than theoretical. I'm just thinking aloud here so anyone with better lens theory than me might like to comment. They might also like to comment on whether the dof field calculator includes that in the maths.

Do you actually need to fill the frame? Remember, you have a tremendous amount of film here. If the final result will be printed, then don't bother filling the frame, just go for best sharpness.

Serge:

If the object you're photographing is opaque, you might consider scanning light photomacrography (a.k.a. "zero-perspective" imaging). You get high resolution and unlimited depth of field by passing the subject through a narrow beam of light while the shutter is open. There used to be an expensive commercially available system for this kind of illumination called the Dynaphot, but some people have improvised their own; see

http://www.modernmicroscopy.com/main.asp?article=60

I have read descriptions of using three Ektagraphic projectors with slit apertures for light, and a relatively cheap motorized stage to move the subject through the light beam. It requires some trial and error, but the results can be spectacular (see the fly head photograph near the end of the Modern Microscopy link).

Good luck.

-- J. Packer

If anyone can tell me how to get dof figures out of this software I would appreciate it.

www.winlens.de/en/wl43_intro.html

thanks

Found it. Its part of "show extra information" . i.e. check box for this should be on.

you can also shoot several sheets at different distances from the object, then scan them, put each in a separate PS layer and erase all the out-of-focus portions from each image. It is important that you move the entire camera-set-up (or your orange), and do not change focus on the camera. There is also a program called auto-montage, not cheap (3 grand or so), that does the same thing. I think there are also routines for NIH image to do that kind of a thing on the cheap side.

Daniel

Rob is right, at 1:1 magnification the 64 aperture will become effective 128 aperture! The diffraction will be as a normal 128 aperture too = awful.

My experience indicates that depth of field is a solely a function of image size (at the same f-stop).

Blowing a 3" orange up to 4" will result in exactly the same depth of field, no matter what lens focal length you use.

Three factors come to mind when chosing a lens focal length:

First, a short lens may be required if you have a limited bellows draw. To be set up properly, many macro shots require a second set of monorail camera bellows, a third standard and extra rail extensions. Sometimes two tripods.

Second, a longer lens is helpful to get the camera back from the subject, out of the way of the lighting equipment.

Third is perspective, as a function of point-of-view. In the case of a sphere, for example, the farther away the lens is, the more surface area can be seen. Moving closer results in a view of much less than 180 degrees of the peel. Same thing happens to (round) faces in portraiture.

Mr. Geiger's suggestion is something I worked with a few years ago. There was a paper (darned if I can find it at the moment) done about ten years ago by a PhD candidate that gives the method and formulas for calculating camera distance for each shot to accomodate focal length changes. It is tedious and not all subjects are particularly susceptable. Erasing differential layer parts is not quite the way to go, but it points in the right direction.

But my guess is that your application is not high-stakes enough to warrant the time and money to pursue the infinite DOF approach. Correct? (There is, or was, a tentative product from Sweden that included the specialized focusing camera and software but it's all little digital format stuff.)

using the Linos(Rodenstock) software I gave the link for, here's what you get for 90mm and 210mm lenses.

www.visualperception.co.uk/lfpf

in both cases I have set the aperture to f32 since setting it smaller causes the coc spec of 0.1mm to be broken, i.e. coc becomes larger because of diffraction( although thats probably not the correct terminology)

note also that in both cases the effective f no is f64.

so to answer the original question, your are correct, what you are trying to do is limited by the physics of the lenses and you will get very narrow dof, around 13mm for a coc of 0.1mm.

I have placed this graph on a temporay web site ; when the link expires in 3 weeks, please e-mail me for a copy.

http://cjoint.com/data/iDsNwDEFwU_pd...90-150-210.png

Comparison of total depth-of-field for 3 different focal lengths of 90, 150 and 210mm
with the same numerical aperture and same magnification ratio same circle of confusion, 100 microns

Basically for a given magnification and same numerical aperture, classical DOF models tell us that DOF is the same better than within 10% for a 90, 150 and 210 as soon as the magnification ratio is bigger that 1/10. Or as soon as the objet is located at a distance closer than 10X the focal length.

Some additional info
- up to f/32 (effective f/64 at 1:1) geometrical DOF des not change by more than 10% for the 90, 150 and 210 as soon as the object is closer than 10x the focal length; and at f/45 (effective f/90 at 1:1) the 10% change in DOF is reached at 1:5 for the same set of lenses... provided that diffraction is negligible... whihc is no longer the case.
- at 1:1 ratio no need for any software, total geometrical DOF is simply 4.N.c ( plus or minus 2 Nc) where c is the CoC (say : 100 microns) and N the numerical aperture as engraved and valid at infinity.

Well, as usual, everyone's knowledge is extremely impressive and I can't thank you enough for the concerted effort you have put into this. While I take my work EXTREMELY seriously and I expect and hope this body of photography will eventually be exhibited, my technical acumen is limited and a lot of the terminology being used is well over my head. I assume it would be worth it to me to eventually learn a bit more.

For now, I wonder if anyone can reduce all of this great information to tell me what my best option is? My inclination again is to shoot with the 150 or the 210 so that I can maintain a distance from the subject. Is it best to assume that I should use less of the total area of the film (i.e. move further away from the subject so that it doesn't fill the frame) and shoot at f45 or f32 so that I can maximize the lens quality while also getting more depth of field?

I apologize that I can't communicate on the level that most of you are able to and hope that it can be reduced a bit for me.

MANY thanks.

Sincerely yours,
Serge

According to Leslie Stroebel's book, as I remember, you are better with a somewhat smaller image on film, and then enlarging it to whatever print size you need. Within 'reasonable' limits. Diffraction, as a factor limiting image quality, will be somewhat less this way.

by installing the predesigner software I gave you a link to, you can calculate the optimum distance to give you the maximum magnification within your dof limits.

All you need to do is to set it up with same parameters as in the following img and then adjust "object distance" and/or "stop radius" to get the maximum maginification available within your criteria.

n.b. without knowing the actual dof required and the height of the object it is impossible for anyone to give you an accurate answer. The software allows you to calculate it exactly by palying with only two parameters. Pay attention to the infinity fno since that is what you have to set on the camera so it must be available on your lens. If coc gives a red error message then you know your into diffraction problems and will lose sharpness. You can also play with coc if you choose to.

the following gives the lens to object distance of 630mm which provides 0.5x magnification and 54mm of dof if you set you your fno to f45

http://www.visualperception.co.uk/lfpf/210mm_2.gif

get your ruler out and have fun.

p.s. I would allow at least 20% margin of error if I were you, since your particular lens design plus film flatness etc etc all come into play.

Rob, was your example just an example or were you seriously suggesting that an 0.1 circle of confusion is appropriate?

Assuming no defocus blur, that allows separation of details no closer than 0.2 mm apart on the subject. Serge might be better off with a Pen F than with a Sinar.

N.B. if image in previous post is not visible then email me and I will send it to you.

It's an example but of course what you need depends on the enlargement you want in the print and we haven't been told that.

However, one of the original responses gives a link to another dof calculator which quotes
coc for 4x5 = .094mm Only 6 thou of a mm difference.

Another oft used figure is focal length /1720 = 0.122mm

take your pick.

Serge, to reduce all this great information as you requested: put on the 210mm lens, fill the frame and shoot at f/64. (It was good enough for Ed Weston)

If you can't hold enough depth of field to suit you, back out a little bit and shoot with a smaller image on the ground glass.

If you find you haven't enough bellows to get the thing in focus at all, switch to the 150 as a last resort.

As someone who has always had a too short commercial deadline and a too small budget, that is exactly my approach to this type of practical problem. Those with more time and money to study, re-study and theorize about all aspects of every issue tend to approach things differently, of course.

John, whether Serge is practical and just shoots or theorizes and then shoots, basically he's toast. Can't get where he wants to go from here, practically or in theory.

Cheers,

laugh... well, toast may be a bit strong. I feel that the abundance of thought that went into all of these answers have given me some very strong ideas of how to proceed without having to reinvent the... studio camera... per se.

cheers,
Serge

I think the question was what is the optimum achievable.
if Serge would tell us what he is photographing and/or how much dof he needs then maybe we could give a more explicit answer.

I agree with all the math/physics talk here but there's one thing that I don't get. I remember seeing a Brett Weston picture of a barrel cactus shot from the top, it filled the frame except it trails off at an angle - all of it was sharp - all of it... maybe my memory is bad... but I'm pretty sure that all of it is in focus. How did he do it? I'll look for the pic and get back to you. ..,.. OK i just found it. I'll post it when I get home.

Here's that Brett Weston shot:
http://www.artnet.com/artwork/424202860/brett-weston-santa-barbara.html

Looks like he somehow cheated physics to me. Maybe it's a really small cactis? Maybe get a small orange? Or maybe there is another secret technique?

Weston didn't cheat physics. The spines are in fact in a fairly narrow range close to a single plane of focus. You can see that by looking at the lower right and left and also the "hole". The image is clearly going out of focus as you move a small distance from the plane of focus.

I'm sure this is not a route that you want to take, but I thought I'd mention it anyway.

There is another option which involves using several images taken at different focal points, and then combining the resulting image stack with some software.

http://www.heliconfilter.com/pages/focus_overview.html

I have absolutely no idea if this will work for your situations, but it may be worth exploring.

Paul

Backing off won't help either. If you keep the film CoC the same it will appear to add DoF, but if you (much more reasonably) use final print CoC the change in magnification will cancel this out.

Basically, assuming that you're constrained to a given CoC and s given diffraction-limited resolution at a constant final print size, there's nothing you can do. Not smaller format (which is what "backing off" really is), not different lens length, nothing.

The only possible improvement is stacked images in Photoshop. Or, of course, print smaller.

I think you are using the wrong media. This sounds like a job for a holograph. You could probably take the bellows off the sinar and turn it into an optical bench, and lasers are cheap these days. All you need then is a beam splitter and some Polaroid film to work out the exposure.