Mega Macros

David · Expire: 2013-01-25

Today (and for a week or so) I've been playing with mega macros to see how much I could magnify something. This week I've been reverse-mounting various lenses. With my Canon FD 24mm 2.8, I obtained about 3.2X magnification. I was pretty pleased with that, but I wanted to go further. Tonight I tried two new lenses: Nikon 24-120mm and Samyang 18-28mm.

With the Nikon 24-120 reverse mounted on my K=7 I obtained 5.2X magnification. I measured this by putting a millimeter ruler in front of the lens. Vertically, the 15.6mm (high) sensor showed three full millimeters. Now, this is a plastic ruler, so who knows if it's perfectly calibrated (not likely.)

That 5.2 magnification looked like this:

Part of the issue with such extreme macros is that the DoF is shallower than the distance from the top to the bottom of the millimeter ridge. And any movement throws it out of focus. The exposure times, even wire open, are more than a second.

Thinking that I could do better than 5.2X magnification, I put the Samyang on backwards and took this photo of a U.S. quarter:

That's the "R" in "America"

The DoF is so shallow that the top of the letter is in focus, the bottom is not. In fact, in order to fine-tune my focus, I have to insert and remove sheets of paper behind the subject. This is great except for one problem -- the paper is too thick to fine-tune the focus enough! I have to over-shoot the thickness by a few sheets and then put weight on my platform (a note pad over to stacks of blocks) to push the subject back into the focal range. This process introduces a lot of room for error.

For a comparison to the first image, here's the millimeter rules again with the Samyang:

The sensor is 23.4mm wide. I count that as 4.25mm for about 5.5X magnification. Right now that seems to be my limit. And taking actual photos at the magnification poses difficult technical challenges. However, once I work out a better work flow, I suspect that mega macro work will be easier to do with high-quality results.

nurkov · Expire: 2014-03-09

amazing magnifications, at this point you have to stack photos in order to get any sensible dof

visualopsins · Expire: 2025-04-11

Thanks David for real world results. I was going to suggest to another member switching to a microscope for magnifications higher than 2X, just to get finer focus control than is possible with bellows. Your experience here confirms -- dof get real shallow!

Now I wonder how your gigapixel scanner technique results compare with lens-bellows results -- is "enlargement" from dense scan results better than with lens-bellows? and how do those compare with microscope results?

twinquartz · Expire: 2013-10-29

ForenSeil · Joined: 15 Apr 2011 Posts: 2726 Location: Kiel, Germany.

Pics are all looking a bit out of of focus

I've also played a little with high magnifications
Here at about 8:1
Notice small DOF Smile

Size comparision
http://t1.ftcdn.net/jpg/00/25/97/50/400_F_25975091_Acn8QJytRXL9WIGPVpAQpHdGmPfzNvRN.jpg

Many reversed small format lenses (D-Mount etc.) are working pretty nice for around 10:1 imo - and most of them cost a fraction of what you pay for microscope or other native high magnification lenses

David · Expire: 2013-01-25

@Nurkov: Yes, DoF is so thin that without stacked images the results will be effectively unusable. Unfortunately, that also means subject-film distance adjustments measured in a few dozen microns. So I think I need to get a copy stand for future mega macros.

@Eugene: Yes, a microscope does make more sense. I have one, but it's got a mirror to reflect light and not a light bulb. It may also not have been made for any adapters. As for comparing this to the gigapixel scans, I think the scans offer a much greater DoF but at lower resolution and with less quality when compared at the same size. I could print that "R" at 300 dpi on a 16X20 canvas with no image loss. I'd have to enlarge a scanned version beyond its scanned size to achieve that. And my K-7's sensor is returning vastly improved results when digitizing images compared to scanning them.

@twinquartz: That's a great idea I'd not thought of. I imagine that SF has a printer somewhere. But my current thinking is that I'll get a copy stand and use that. Can I focus that with enough precision for the DoFs shown here? I don't know. But an old broken Repronar ought not to cost more than about $25, so it would be a worthwhile investment on the chance that it works.

@forenseil: Yeah, the two millimeter measures are WAY out of focus. I had to flex the pad of paper with my fingers to get them in focus, and then the exposure was some 1.3 seconds, and the pad was jiggling. As for the coin, the image would have been sharper, I think, had my dogs not been walking around the house. Yes, the DoF is that thin that vibrations from my dogs or the upstairs neighbor throw off the focus.

David · Expire: 2013-01-25

@Nurkov: Yes, DoF is so thin that without stacked images the results will be effectively unusable. Unfortunately, that also means subject-film distance adjustments measured in a few dozen microns. So I think I need to get a copy stand for future mega macros.

@Eugene: Yes, a microscope does make more sense. I have one, but it's got a mirror to reflect light and not a light bulb. It may also not have been made for any adapters. As for comparing this to the gigapixel scans, I think the scans offer a much greater DoF but at lower resolution and with less quality when compared at the same size. I could print that "R" at 300 dpi on a 16X20 canvas with no image loss. I'd have to enlarge a scanned version beyond its scanned size to achieve that. And my K-7's sensor is returning vastly improved results when digitizing images compared to scanning them.

@twinquartz: That's a great idea I'd not thought of. I imagine that SF has a printer somewhere. But my current thinking is that I'll get a copy stand and use that. Can I focus that with enough precision for the DoFs shown here? I don't know. But an old broken Repronar ought not to cost more than about $25, so it would be a worthwhile investment on the chance that it works.

@forenseil: Yeah, the two millimeter measures are WAY out of focus. I had to flex the pad of paper with my fingers to get them in focus, and then the exposure was some 1.3 seconds, and the pad was jiggling. As for the coin, the image would have been sharper, I think, had my dogs not been walking around the house. Yes, the DoF is that thin that vibrations from my dogs or the upstairs neighbor throw off the focus.