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Three Sunflowers - Three Filters [BaaderU, KolariU, StraightEdgeU]

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#1 Andrea B.

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Posted 03 April 2017 - 01:03

Finally a sunny day! The Solarmeter was reading 3.2-3.5 mW/cm2 during my shooting. That is fairly respectable for a spring day.

The Whole Foods grocery was offering 3 different types of sunflowers (Helianthus spp.) in their flower area so I thought 'oh well, why not?' given that I'd already broken the bank by shopping at this expensive store. I was hoping that there would be some differences in the Helianthus's UV signatures. There was. Cool.

The test filters today were the new KolariU from Kolari Vision, the StraightEdgeU (379BP52) released by UVR Optics last year and the BaaderU from Baader Planetarium. I wanted to shoot in sunlight with no boost from my modded UV flash, the SB-14. So the exposures in this test are a bit longer than usual when I shoot UV at ISO-400 with a flash boost.

Results:
It's always good to get back outside in the springtime and start shooting. I get very rusty over the winter break and must review all my shooting protocols and get them back up to speed. For example, I kept forgetting to re-focus when I changed UV-pass filters. Differences between the three filters in substrate, thickness and coatings (or not) make re-focus imperative. So I'm not totally pleased with focus in these photos.

All three filters gave excellent results. The KolariU (KU) and the StraightEdgeU (SEU) were slightly slower than the BaaderU (BU). The raw composite photos (before white balance is applied) from the KU and BU were very similar. The SEU, of course, has a peak around 380nm which provides a slightly different false colour set when viewing its raw composite. The finished photos from all three filters were almost identical. This can be dependent on the subject being photographed, so I would not always expect this to happen.


Optimal Exposure:
f/11 @ ISO-100 with varying speeds
To obtain optimal exposures I used a Black & White setting and increased exposure time until the right-hand portion of the B&W histogram was as near the edge as I could get. I'm not entirely sure what to call this histogram -- the luminosity histogram? the brightness histogram?

Shooting to the right in B&W will almost inevitably over-saturate (blow out) a colour channel. Usually the red channel blows when shooting UV. Sometimes the blue channel. But the colour version of the photo is easily brought under control in an app like Photo Ninja or some other app which handles highlights well.

Baader UV/IR-Cut :: Optimal Exposure
Attached Image: helianthusThree_visSun_20170402wf_413pn.jpg

BaaderU :: Optimal Exposure
Attached Image: helianthusThree_uvBaadSun_20170402wf_434pn.jpg

KolariU :: Optimal Exposure
Attached Image: helianthusThree_uvKolariSun_20170402wf_455pn.jpg

StraightEdgeU :: Optimal Exposure
Attached Image: helianthusThree_uvStraightEdgeSun_20170402wf_475pn.jpg


Raw Composite:
The photos were opened in Raw Digger and exported. There are no edits or sharpening.
The StraightEdgeU records more in the Blue channel, so its raw composite shows lots of magenta tones. The BaaderU raw comp gives more orange tones. The KolariU raw comp is very much like the BU, but may have slightly more magenta. Not so much as to put it 'in between' the BU and the SEU. The KU stays closer to the BaaderU.

Baader UV/IR-Cut :: Raw Composite
Attached Image: helianthusThree_visSun_20170402wf_413_nef.jpg

BaaderU :: Raw Composite
Attached Image: helianthusThree_uvBaadSun_20170402wf_434_nef.jpg

KolariU :: Raw Composite
Attached Image: helianthusThree_uvKolariSun_20170402wf_455_nef.jpg

StraightEdgeU :: Raw Composite
Attached Image: helianthusThree_uvStraightEdgeSun_20170402wf_475_nef.jpg


Final Photo:
These were converted and edited in Photo Ninja. They were cropped, resized, labeled and converted to JPGs in Photo Mechanic. White balance was made on the same area of the brick (bottom of photo) in all three photos in order to bring out (minor) differences in false colour. Using white standards and colour profiling might give a slightly different result.

Baader UV/IR-Cut :: Finished
Attached Image: helianthusThree_visSun_20170402wf_413pnFinal.jpg

BaaderU :: Finished
Attached Image: helianthusThree_uvBaadSun_20170402wf_434pnFinal.jpg

KolariU :: Finished
Attached Image: helianthusThree_uvKolariSun_20170402wf_455pnFinal.jpg

StraightEdgeU :: Finished
Attached Image: helianthusThree_uvStraightEdgeSun_20170402wf_475pnFinal.jpg
Andrea G. Blum
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#2 Andy Perrin

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Posted 03 April 2017 - 02:15

Ooh. Is it me, or is there a literal bulls-eye pattern (alternating rings of color) in the bottom left sunflower? Referring to the center, not the petals. It seems particularly apparent in the final edit of the StraightEdgeU.

Edited by Andy Perrin, 03 April 2017 - 02:16.


#3 Cadmium

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Posted 03 April 2017 - 02:49

Your Baader U and Kolari U seem to be sharper throughout compared to the Straight Edge U.

Generally, using the same RAW camera white balance, you will see the same RAW colors from Baader U and U-360 stacks, which is what I see above,
however your final individual white balance of those two are much different, which is usually almost identical between Baader U and U-360 stacks.

An example of Baader U vs U-360 stack white balance comparisons, RAW and individual.
Attached Image: BaaderU_LaLaU_SOOC_RAWwb_1280.jpg

Compressing names might mess up Google searches? Not sure.

Edited by Cadmium, 03 April 2017 - 03:05.


#4 igoriginal

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Posted 03 April 2017 - 11:31

View PostAndy Perrin, on 03 April 2017 - 02:15, said:

Ooh. Is it me, or is there a literal bulls-eye pattern (alternating rings of color) in the bottom left sunflower? Referring to the center, not the petals. It seems particularly apparent in the final edit of the StraightEdgeU.

Look closer. That bluish-tinted "ring" in the center of the sunflower head is due to a patch of ripened (fully-formed) seeds, as opposed to the still immature seeds within the remaining part of the head. I suspect that when the rest of the seeds within the head catch up, then this will no longer be a "ring pattern." It's just temporary, and incidental, due to one section of seeds developing ahead of the others.

Curiously, though, one can infer that mature seeds appear to reflect UV at different wavelength peaks compared to immature seeds. It would be an interesting experiment if someone removed the seeds, and obtained a close-up (macro) UV image of a mature and immature sunflower seed, side-by-side.

EDIT: Upon even closer inspection, the immature seeds still have their individual florets present at their tips (whereas, mature seeds are bare, and the florets have fallen off). It is the discrepancy between these two stages of seed development (immature seeds with remaining floret tips, versus mature and bare seeds) which appear to elicit slightly different UV-reflectivity peaks. But again ... as soon as the remaining seed-head section of the flower catches up with its ripening (all of the individual seeds will eventually lose their florets), this temporary "ring pattern" will vanish.

Edited by igoriginal, 03 April 2017 - 11:45.

Igor Butorsky

#5 igoriginal

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Posted 03 April 2017 - 11:31

Beautiful comparison photos, and interesting ones at that, Andrea.
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#6 nfoto

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Posted 03 April 2017 - 14:40

As the site botanist, I can offer a much simpler explanation of the "ring" pattern. This is simply a wave of development of the disc florets from bud to opening in the male stage then ending in the female stage with the styles exserted. No seeds. They come much later if they develop at all in those cultivars.

The structure named "petals" here is the ligulate or ray flowers: a speciality in the Daisy Family (Asteraceae). The ligulate florets are often monoecious and can be either male or female, the first kind perhaps being most common. Most disc florets are dioecious meaning they have male and female structures.

#7 Andy Perrin

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Posted 03 April 2017 - 15:34

Thanks, nfoto, and a good effort, iggy!

#8 Andrea B.

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Posted 03 April 2017 - 15:35

For whatever reason, known only to the sunflower, the flower on the bottom left has open disk florets on the inner and outer circles. Between the two, the disk florets are closed.

Let me see if I can get a close up for everyone.
Andrea G. Blum
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#9 Andrea B.

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Posted 03 April 2017 - 15:36

Your Baader U and Kolari U seem to be sharper throughout compared to the Straight Edge U.

The focusing errors seem to be mine.
Andrea G. Blum
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#10 Andrea B.

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Posted 03 April 2017 - 15:52

wait for the labels........

Helianthus sp.
D750 + 60/2.8G Micro-Nikkor
f/11 @ ISO-400 with varying exposure times.

Open outer disk florets with some closed mid-disk florets.
Attached Image: 750_9029pn.jpg


Open inner disk florets with some closed mid-disk florets.
Attached Image: 750_9032pn.jpg


The seeds lurk under the florets and will only appear when the spent florets have fallen off. Here I peeled back a phyllary to show the future seed. (I do not know if the seeds would actually develop in these cultivars.)
This highly cropped photo also shows a bit of shutter clack even though I was using mirror-up while on tripod.
Attached Image: 750_9034pn.jpg


Florets in several stages of opening.
And the omnipresent lint which wastes no time in leaping onto any flower being photographed.
Attached Image: 750_9035pn.jpg
Andrea G. Blum
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#11 Andrea B.

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Posted 03 April 2017 - 17:27

well, that was kinda interesting.....here's some more

Cutaway
It appears that each disk floret has its own little phyllary like bracts.
BTW, clearly oversharpened. Sorry 'bout that. I was shooting JPGs and cannot go backwards.
Attached Image: 750_9041pn2uvp.jpg

Clump of disk florets
Attached Image: 750_9043v2pn.jpg

One disk floret
On the right is the ovary which becomes the sunflower seed.
Attached Image: 750_9048pn2uvp.jpg
Andrea G. Blum
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#12 Andrea B.

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Posted 03 April 2017 - 17:37

I am sooooo rusty. Accidentally shot JPG. What's the first rule of business when setting up a shoot? Check your settings. Then I blew my protocols and didn't check focus between sets and shots. Then I got impatient and din't want to slooooooow count 1-2-3 between mirror-up and shutter release.
Oh well.
I'm sure it will all come back to me now that I've had a practice run on these patient Helianthus.
:rolleyes: :lol: :lol: :lol:
Andrea G. Blum
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#13 nfoto

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Posted 03 April 2017 - 17:38

Nice extractions, Andrea.

To be studied with a reference (Wikipedia or similar) to the composite flower structure of Asteraceae. These compacted inflorescences have so intricate structure with convoluted nomenclature that I ever so often need a refresher course myself :D

#14 Andrea B.

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Posted 03 April 2017 - 17:42

Thankee.

Flowers are incredibly intricate and complex. I never tire of them.
Andrea G. Blum
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#15 Mark

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Posted 06 April 2017 - 22:58

Those macro shots are fantastic! Like looking at mysterious alien life forms.