Canon 200mm Prime as a Rail.

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JKT
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Re: Canon 200mm Prime as a Rail.

Post by JKT »

Those are quite nice. Note the radial streaks - something needs cleaning and likely that something is your camera sensor.

jsp
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Re: Canon 200mm Prime as a Rail.

Post by jsp »

It's looking as though x10 is maybe the sweet spot for depth and focus, given what I am trying to do.

Maybe I will work on optimising that and figure out how to pose hairs vertically.

jsp
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Re: Canon 200mm Prime as a Rail.

Post by jsp »

JKT - I'm glad you like them. I'll do a test on the sensor in a bit. Thanks :-)

jsp
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Re: Canon 200mm Prime as a Rail.

Post by jsp »

I just tested my x50 and x20 on plant hairs and it was really no use as the hairs never sit vertically, so there is always quite a lot of depth in the photo, even for a tiny hair.

I think I will have to stick to x10 even for my tiny subjects.

jsp
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Re: Canon 200mm Prime as a Rail.

Post by jsp »

I just tried photographing hairs with my 10x lens. There are very large hairs in the photo, but it is the tiny ones that are relevant to me because they are the size of the ferns that I am trying to photograph.

In the big stacked image the big hairs are not actually that clear, but the tiny ones can at least be seen clearly. The images are not perfect, but the hairs can at least be seen.

The tiny hair in the bottom photo is one tenth of a millimetre tall-ish.

These hairs are on a leaf of a plant called Green Alkanet here (Pentaglottis sempervirens).
Attachments
Full stack
Full stack
interesting tiny hair
interesting tiny hair
tiny hair enlarged
tiny hair enlarged

jsp
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Re: Canon 200mm Prime as a Rail.

Post by jsp »

These two hairs were photographed with 100mm macro zoom and 10x Mity.

I figured out that the problem with the 100mm lens before was that it had a UV filter on, and with that removed, the lens now works fine.

The frame is not filled by light but the circle in the frame that is lit is 50/100ths mm across. This is compared to a full frame image width of about 35/100ths mm on the 200mm prime.

The 100mm zoom length has a lot more DOF in the full stack (really a lot) but the 200mm prime is more magnified. So the 100mm zoom is only useful if we can use a much higher magnification Mity lens and still get good stack DOF.

I need to do some measurements to see if it is worth it. (Magnification v DOF for the two Canon lenses)
Attachments
tinyhair2small.jpg
tinyhair1small.jpg

jsp
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Re: Canon 200mm Prime as a Rail.

Post by jsp »

Here the specs of my various setup possibilities:

Canon 200mm prime + 50x Mity: Only one black line on the micrometer can be brought into focus. Working distance (WD) is 12.5mm.
Canon 200mm prime + 20x Mity: stack DOF 1/100th cm. Image width 18/100ths cm. WD 15mm.
Canon 200mm prime + 10x Mity: stack DOF 4/100th cm. Calculated image width 35/100ths cm. WD 32mm.
Canon 200mm prime + 5x Mity: stack DOF 17/100th cm. Measured image width 70/100ths cm. WD 34mm. Image width 70/100ths of a centimeter.

Canon 100mm macro + x10 Mity: Stack DOF 33/100ths cm, image width 60/100ths cm
Canon 100mm macro + x20 Mity: Stack DOF 9/100ths cm, image width 31/100ths cm
Canon 100mm macro + x50 Mity: Stack DOF 1/100ths cm, image width 9/100ths cm

So for my purposes the best options are:

200mm prime + 10x. stack DOF 4/100th cm. image width 35/100ths cm
100mm Macro + 20x. stack DOF 9/100th cm. image width 31/100ths cm

Going by the numbers, the 100mm zoom lens looks better, but the 200mm prime is easier to set up quickly, for a number of very small practical reasons. It seems as though either would be good though.

Chris S.
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Re: Canon 200mm Prime as a Rail.

Post by Chris S. »

Jen,

Fascinating pictures! These plant hairs, in some ways, resemble stinging the nettle trichomes I've looked at. (I realize these species are quite distant from one another--but they could experience convergent evolutionary pressure.)

The base of the hairs you've shown seems quite different from nettle trichomes--much less hinge-like or sack-like.

But did you note the bright line roughly half-way up the hair-shaft? This looks very much like the (toxic) liquid-fill level I've seen in nettle trichomes. And some of the tips of your plant hairs appear spherical; nettle trichomes also have spherical tips. Some have attributed this tip structure, in nettles, to silicate translocation, and thought this tip to be silicaceous. My impression differs: I think these hair tips are more like un-burst bubbles--mostly liquid inside, with an outer membrane.

So I wonder: If you stick a few of these hairs into your hand, can you feel any temporary irritation? And can you obtain images of the spherical tips, before, during, and after perturbation? (I've been meaning to investigate this for years.)

--Chris S.

jsp
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Re: Canon 200mm Prime as a Rail.

Post by jsp »

Hi Chris,

It's really intresting to know all that. I didn't know it before. The hairs are definitely "stingy" on the hands. I'm not completley sure what the plant is because there are two wild plants in our garden that look very similar in winter and I can't entirely remember which one this is. It definitely hurts when I pick the leaves though.

I'm trying to think what other tiny things I could photograph in the coming weeks. I think it would be great to photograph loads of things as actually posing the speciment is one of the hardest parts, so I hope to practise a lot as I wait for my ferns to be ready.

Thanks for looking.

Jen

jsp
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Re: Canon 200mm Prime as a Rail.

Post by jsp »

This is another hair on the same plant, but with the 200mm prime and the 20x Mity.

The whole focus stacking thing just stopped working this time in many different ways. I just couldn't get it to work.

Partly the leaf kept gradually changing shape under the lights. Then I couldn't seem to get the starting point right and kept getting muddled between whether to move the camera forward or backwards, or focus to infinity or the other way to get the stack to start in the right place. Then I suspect maybe movement of the leaf again was messing with my distance. Then when I finally got it sorted out and ran the stack, 35 slices came out exactly the same with no movement through the subject.

However, at this magnification and for the size of hair that I was photographing, a single shot is actually pretty good. This is exactly the size and shape of the fern that I am aiming to photograph, though the fern is much more delicate and wouldn't put up with the amount of faffing that it took to take this shot.
Attachments
bulbous-hair.jpg

jsp
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Re: Canon 200mm Prime as a Rail.

Post by jsp »

This is a hair photographed with the 200mm prime and the 50x Mity lens. I'm not convinced that moving up to the 50x really has any great advantages with my particular photographic subject, given how much harder it is to work with, and how much shallower the depth of field is. The hardest part of this shoot was getting the photo while the leaf was melting in front of the torch. The hair was literally moving across the frame so fast that I had to be quick to catch it before it went out of the shot.
Attachments
50x.jpg

jsp
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Re: Canon 200mm Prime as a Rail.

Post by jsp »

This one was taken in front of a fluorescent tube light box with no flashes and no torch for positioning. The second leaf that I tried did still wilt dramatically while I was working, just because it had been picked from the plant. The light wasn't even hot.
Attachments
stacksmall.jpg
small-setup-bright.jpg
small-setup.jpg

jsp
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Re: Canon 200mm Prime as a Rail.

Post by jsp »

This is my chart, in case it's useful for anyone else.

The equipment is:

Canon 5d MkII (full frame)
Canon EF 200mm f/2.8L II USM

Mitutoyo M plan Apo 5x / 0.14 infinity / 0 f=200
Mitutoyo M plan Apo 10x / 0.28 infinity / 0 f=200
Mitutoyo M plan Apo 20x / 0.42 infinity / 0 f=200
Mitutoyo M plan Apo 50x / 0.55 infinity / 0 f=200
Attachments
chart6.jpg

Chris S.
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Re: Canon 200mm Prime as a Rail.

Post by Chris S. »

Jen,

Like you, I've had trouble with plants wilting and moving during a photo session.

To avoid wilting, I've made small vases to hold water for plant cuttings. These vases are short lengths of brass tube crimped and bent on one end to create a seal, epoxied to a small magnet. (My subject stage is steel, so the magnet sticks). Also, to avoid creating an air gap to interfere with the plant's vascular system, I try to cut the stem under water and not expose the cut end to air.

For nettle trichomes--which rapidly loose their liquid if internal pressure is not kept up--I leave a leaf on the stem I'm photographing, and keep continuous light shining on the leaf. Under bright light, transpiration restarts--the stomata open and the cutting consumes a notable amount of water. If I get it right, the tricomes stay full of liquid. In fact, seeing a liquid-air line part-way down the trichome, as you've documented, is a sign that I'm not keeping the cutting's fluid pressure up.

To avoid movement, I try to immobilize the cutting as much as possible. In the case above, I tape the remaining leaf to a large microscope slide, and mount this slide in a clamp next to the tiny vase. Sometimes I tape portions of the stem to thin rods or wires, also epoxied to the base.

The vase, rods, and clamp for the slide all end up attached to the magnet. It can be a real Rube-Goldberg assembly. I keep a box of aluminum and brass stock around, as well as epoxy and magnets, for making subject holders like this on an ad hoc basis.

With many interesting macro subjects, it seems as if figuring out how to hold the thing in place is the greater part of making the photograph.

--Chris S.

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Re: Canon 200mm Prime as a Rail.

Post by rjlittlefield »

Chris S. wrote:
Thu Feb 17, 2022 9:11 pm
The vase, rods, and clamp for the slide all end up attached to the magnet. It can be a real Rube-Goldberg assembly. I keep a box of aluminum and brass stock around, as well as epoxy and magnets, for making subject holders like this on an ad hoc basis.

With many interesting macro subjects, it seems as if figuring out how to hold the thing in place is the greater part of making the photograph.
Yes! Often I think it would be helpful if we had some sort of thread specifically for documenting various Rube-Goldberg arrangements.

As I type, my own rig is 20X photographing a couple of wings of a tiny wasp. The wasp is Bondic'd to a hair from the back of my hand, which is Bondic'd to a balsa stick, which is pinned to a small block of balsa, which is epoxy'd to a steel ball, which is stuck to a washer on a magnet, which is stuck to my positioning stack, the subject being backlit by an electronic flash that is diffused through a piece of printer paper.

The whole setup would look quite baroque, if the interesting bits were large enough to attract attention at all.

--Rik

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