Ideal Macro Lens Advice

[cmoore]

Hello all,

What an amazing resource these forums are. I've spent many hours looking through the forums so I hope I haven't missed this being specifically dealt with elsewhere. I'm photographing small, flat objects about the size of a postage stamp on a Sinar P. The object is kept about 2 - 3 mm from the background. The background is a textured paper and appears in the frame. Obviously, I would like the object to be as sharp as possible but I also want the texture of the background paper to be defined.

Now, working at approximately 10:1 I know that the depth of field will be very small. The first time I did this, I used a 150mm f5.6 Sinaron reverse mounted. Shot at f22 I got acceptable depth of field but overall the image is quite soft. I've also used a 80mm nikkor enlarger lens. Reverse mounted again, shot at f22 again and the object is noticeably sharper but the background paper is softer - apparently less depth of field.

My question is this: at this magnification of approx 10:1 and hoping for 3mm depth of field, am I best off with a macro lens (reversed/not reversed), a reversed enlarger lens or a reversed copy lens? (all shots will be black and white)

Or am I chasing something that can't be done? Am I just toast?

Thanks in advance for any advice!

Cheers

Casey

[Mark Woods]

Hello Casey,

What are you focusing on? If it's the small object, you're wasting part of your DOF on the air in front of your object. The way DOF works, is whatever you focus on, 1/3 in front and 2/3 behind is in "focus." This depends on Circle of Confusion, size of enlargement, etc. On the Sinar P, the focus scale puts you in the middle (if I remember correctly). Look at the image focus & the BG and shoot a test with the focus set a little less than 1/3 behind the FG object.

Hope this helps.

[Jim Michael]

You could set a small reticle at a 45 degree angle and determine what setting provides acceptable dof.

If you end up scanning the negatives would focus stacking be a solution?

[Jeffrey Sipress]

Macro lenses are optimized for 1:1 reproduction. At 10:1 I have no idea about performance!

[Joshua Dunn]

Casey,

I have shot with a Nikkor 120mm AM on a Sinar system but never at 10:1. It’s a fabulous Macro lens and can usually be found priced quite reasonably. I doubt if you can get 10:1 out of it. Any Marco lens is going to be sharper than enlarging lenses or using lenses with the cells reversed. Schneider and Rodenstock have made 180mm Macro lenses and all three have made a 210mm Macro lenses. Sadly I have never shot with one.

If quality is of real concern get a good Macro lens. It sounds like you need a 210mm Macro lens to pull off what you are trying to accomplish, however if you can make a 180mm work it would help with the depth of field you are looking for. What Mark said is right regarding depth of field, as well as making sure the lens plane is square (meaning at the exact same angle) as the item being photographed. Either one of these will yield you better depth of field.

Does anyone near you rent large format lenses? I did a quick Google search and found Tempe Camera (I know nothing about this company and have never used them) that rents a 210mm Macro Sironar-N (Rodenstock). Maybe you should rent one first before investing in one. Or just rent it as needed if you only need it a couple of times a year. Most businesses that rent equipment will ship it as well if they are not near enough to you to pick up.

Hope this helps.

-Joshua

[Dan Fromm]

Hello Casey,

What are you focusing on? If it's the small object, you're wasting part of your DOF on the air in front of your object. The way DOF works, is whatever you focus on, 1/3 in front and 2/3 behind is in "focus." This depends on Circle of Confusion, size of enlargement, etc. On the Sinar P, the focus scale puts you in the middle (if I remember correctly). Look at the image focus & the BG and shoot a test with the focus set a little less than 1/3 behind the FG object.

Hope this helps.

Mark, that's the conventional wisdom for shooting at moderate distances.

It is wrong for distant subjects, where more than all -- that's what infinite means -- of the DoF is behind the subject and for closeup, where DoF is symmetrical about the subject. If you don't believe me, do the arithmetic and then test it by shooting.

[Dan Fromm]

Casey, you want a lens designed for photomacrography and optimized for around 10:1. These lenses are diffraction-limited wide open and stopping them down only decreases DoF.

Candidate lenses include 25/2.5 Photar, 35/4.5 or 65/4.5 Macro Nikkor, 25/3.5 or 40/3.5 Luminar. All of these are designed to be used with front facing the subject. If you want relatively inexpensive and easy-to-find, a reversed 55/2.8 MicroNikkor shot at f/4 or a 25/1.9 Cine Ektar II reversed and shot at f/2.8 are competitive with the others. Given unlimited budget, I'd use the 25/2.5 Photar. Given limited budget, I'd probably take my 25/3.5 Luminar out of the drawer.

If you want reasonable image quality in the background, place the stamp closer than 3 mm to it. You'll have to experiment a little to find the distance that gives results that please you.

You may want to read the macro lens section of my lens diary. It is at http://www.galerie-photo.com/1-lens-6x9-dan-fromm.html (English) and http://www.galerie-photo.com/1-optiq...dan-fromm.html (French).

Something -- I've never understood what -- about closeup work makes people stupid and elicits flagrantly bad advice. There are good books on the subject whose authors understand closeup technique very well. Here are two that I own and recommend:

Bracegirdle, Brian. 1995. Scientific PhotoMACROgraphy. Bios Scientific Publishers. Oxford. 105 pp. ISBN 1 872748 49 X

Lefkowitz, Lester. 1979. The Manual of Close-Up Photography. Amphoto. Garden City, NY. 272 pp. ISBN 0-8174-2456-3 (hardbound) and 0-8174-2130-0 (softbound).

Bracegirdle is more specific about lenses than Lefkowitz. Buy both. They're focused on your problem.

[cmoore]

Hi guys,

Thanks for the input. I'm not scanning these negs but printing them myself about 33"x27" in the darkroom so small improvements will make a big impact on the final image.

I understand that macro lenses vary but that most are optimised for somewhere between 1:4 and 4:1. At 10:1 the logical thing to do would seem to be use an enlarger lens reversed. My object is near enough the same size as a 35mm neg and I want to get that image on to a 5x4 sheet of film. Or perhaps a copy lens would be the way to go?

Does depth of field increase with increase in focal length? This would seem logical as the subject to lens distance increases, so does the depth of field. So using a 80mm lens I only needed about 14" of bellows but had just 6 inches between subject and lens. Using 150mm I needed more like 30" of bellows but the subject was about 12" from the lens.

Due to their design, which of the 3 (macro, enlarger, copy) types of lenses will minimise diffraction at this magnification, or is design irrelevant and simply a function of bellows extension/focal length.

Thanks again.

Casey

[cmoore]

Thanks very much Dan, just seen your post after writing mine. I have ordered Lester Lefkowitz's book but wasn't aware of the other. I'll get my hands on that one too. Will read your diary and do some research into those lenses you recommend.

[Justin Cormack]

Depth of field only depends on magnification not focal length so the only solution is to move the background closer or to change its texture to look better defined.