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More on petals under high magnification in UV

Conical Cells
31 replies to this topic

#21 JCDowdy

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Posted 20 August 2014 - 22:28

A cooler, ingenious! It follows then that UVIVF filters on those flash guns would cut out much radiant heat.
You are making good progress.

#22 Akira

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Posted 21 August 2014 - 06:50

Ah, yes, "Velcro" makes perfect sense!

#23 nfoto

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Posted 21 August 2014 - 14:31

Today has been spent with a Sneezewort Achillea ptarmica. Again I'm struck with the wide diversity of cell shapes on the floral parts. This species, a member of the Daisy Family Asteraceae, has rather small flower heads with white-coloured ray florets ("petals") and pale yellow disk florets. The rays are sterile. In UV, the entire capitulum appears quite dark, but the presence of conical cells on the rays is evident and shown by the usual mottling pattern. The corolla of the disc flower is very UV-dark and conical cells there are not apparent.

Here is a crop (100%) of a ray at 10.1X magnification, inclination angle 60 degrees.. Again, the Canon 20 mm f/3.5 macro lens was pressed into service for this capture with the D600 (modified) and the Baader U2" (Venus) filter rear-mounted in a Teleskop-Service filter box. Two Broncolor studio flashes (uncoated Xenon tube) provided the illumination.

I shot stacks comprising 20-30 frames. However, I processed shorter segments, 4-6 frames, for better output quality. Stacking was conducted with the latest version of Zerene Stacker.

Attached Image: DSC_61998_2014-08-21-11.42.26 ZS PMax UDR_100pctcrop.jpg

The conical cells for this species are hexagonal with a wart-like protrusion. The surface looks strikingly like the foundation plates for Lego bricks used by my kids in their Lego peak days.

#24 Andrea B.

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Posted 21 August 2014 - 14:44

Have you tried the stacking machine for this? The name escapes me right now.

This is a really good one. It is really clear that these cells are rounded.
Andrea G. Blum
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#25 nfoto

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Posted 21 August 2014 - 14:58

You mean Stackshot? Not yet. I need to find out how to mount the flower on the rail instead of the camera :D

My earlier success with that contraption was limited. Too much vibration was introduced. Maybe I have to go through the *very* terse manual again to find a better way of programming it.

Back to the A. ptarmica: yes, the cells are rounded and they sit in a hexagonal base pattern. However, other captures indicate they are rounded with a flatter top and striations coming out from that point. The Canon lens runs out of power before these phenomena can be resolved I'm afraid.

#26 nfoto

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Posted 21 August 2014 - 15:04

By the way, the water reservoir/cooler system worked well. The Al block was just lukewarm and plenty of water left after the shoot had completed. So the flowers hardly were impacted and kept from wilting.

#27 Andrea B.

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Posted 21 August 2014 - 16:58

I've been using my granite rock with the drilled hole for water.
The flowers hold up pretty well. However I usually don't make 40 shots of them. "-)
But I'm thinking Al might be a better cooler.

QUESTION: Are all surface cells on flower petals considered Conical Cells? We know that Conical Cells are not always conical. But how do we know that these cells we are photographing are Conical Cells?
Thanks.

I simply must try this. It is so cool what you are showing us!!!

I think maybe my UV-Planar would be good for the effort.
I also have a Schneider-Kreuznach M-Componon 28/4.0 which Klaus very kindly gave me that would be good for this if I could figure out a good way to mount the filters. Can't hold them in front by hand for 40 shots.
Andrea G. Blum
Often found hanging out with flowers & bees.

#28 nfoto

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Posted 21 August 2014 - 17:41

Not all epidermal cells on floral structures are conical cells, far from it. I've seen figures indicating about 80% of flowers have this feature, but to tell the truth, we really don't know yet. Thus, it is a fact that conical cells only may appear on parts of the corolla and hence one really needs UV photography combining wide coverage and high resolution to observe and verify their presence. SEM photomicrographs of course are superb in showing conical cell structures in all their splendour and glory, with far superior resolution than we UV enthusiasts ever can dream of achieving. However, if the SEM sample is taken in a region where there are no such cells, even SEM won't show them.

The conical cells clearly are shaped so as to interact with incident light. In order to accomplish this they have 3-D shapes creating reflections (particularly in UV apparently), or act like spectral gratings to create iridescence. The 3-D shape also acts to increase traction, thus the assumption pollinators get a better grip (the 'Velcro' hypothesis). Another assumption is the conical cells alter the 'wettability' of the petals and other floral parts so the flowers are less adversely impacted by rain.

For the Achillea ptarmica, conical cells are only seen on the ligulate (ray) flowers. I just commenced shooting Campanula persicifolia, which has a highly UV-reflective corolla, but so far I haven't seen any conical cells here at all. The corolla epidermis of C. persicifolia all comprises flat 2-D surfaced cells which also are much smaller than the conical cells I have documented so far.

For the practical shooting: you definitively need to use a filter box to hold your filter. There is no way you can succeed using hand-held filters!

Your 28 mm lens could (and should) be reverse-mounted on a bellows or focusing helicoid.

#29 JCDowdy

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Posted 21 August 2014 - 19:13

Andrea,
Does your M-Componon have front threads?

#30 nfoto

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Posted 21 August 2014 - 20:05

"I've been using my granite rock with the drilled hole for water.
The flowers hold up pretty well. However I usually don't make 40 shots of them. "-)
But I'm thinking Al might be a better cooler."


Consider I'm using multiple 600 W/s studio units at full power and fairly close range (about 20 cm). You can almost fry eggs with that output. Then, repeat 40-50 times with just a few secs interval.

I really need to find a better lens for this line of work. The Canon is too little responsive in UV and besides needs to be stopped down to a nominal f/5.6 in order to give adequate sharp images in UV. Needless to say, at 10X we are travelling way inside the domain of diffraction.

#31 enricosavazzi

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Posted 22 August 2014 - 14:24

View PostAndrea B., on 21 August 2014 - 16:58, said:

[...]
I also have a Schneider-Kreuznach M-Componon 28/4.0 which Klaus very kindly gave me that would be good for this if I could figure out a good way to mount the filters. Can't hold them in front by hand for 40 shots.
[...]
At magnifications above 1x, this lens probably performs better reversed. It also makes sense to place UV filters between lens and camera in this case. In practice, if you have filters in 52 mm diameter mounts, a relatively simple solution is using extension tubes with 52 mm threads at either ends, which lets you place the filter wherever you want along the stack of tubes (I don't think it makes a real difference though where you place the filter, as long as it is not close to the sensor). Old Nikon and Nippon Kogaku extension tubes have 52 mm threads, and other types/brands may also be available with this size of threads.

The problem will be to connect the filter mount of the lens (if there is such a thing, otherwise it might be time to epoxy a step-up filter adapter into this end of the lens barrel) to the extension tubes. So-called "reversing rings" can also come in handy.

If you already have M42 or other types of extension tubes or bellows, it is probably possible to mix-and-match adapters from eBay to connect all pieces together.
-- Enrico Savazzi

#32 Bill De Jager

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Posted 30 August 2014 - 05:37

View Postnfoto, on 19 August 2014 - 09:44, said:

Yes, visit http://www.teleskop-express.de/shop/ which is their online shop. I think the site is in German only, but the pictures are self-explanatory. Besides, German is not that difficult to understand.

Just click the British/American flag near the upper right corner and you'll get it in English. Lots of goodies on the site and excellent service.

Bjørn, thanks for explaining about the filter boxes. I have not used mine yet, and I was thinking I'd have to use multiple adapters at both ends which would be too bulky. Now I know better. Gee, I just should have tried a step-up ring to see if the thread pitch is compatible!