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Myosotis sp. [Forget-Me-Not]: Stacking a Tiny Flower


ulf

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Wilhelmson, U. (2020) Myosotis L. sp. (Boraginaceae) Forget-me-not. Stacked photo in reflected ultraviolet light. https://www.ultravio...-a-tiny-flower/

 

Reference:

1. Wikipedia (08 Dec 2020) Myosotis. Wikimedia Foundation, San Francisco, CA.

 

Comment:

For my my first test stack trying my Milar 6.5cm/4.5 I used a very small ForgetMeNot that has been kept reasonably fresh in my fridge for several weeks.

The flowers are very tiny, only a bit more than 1mm in diameter.

 

The stack is made from 24 images with a UV-pass filter stack: S8612, 2mm + U-360, 2mm.

 

The magnification is 2.4x on the sensor.

post-150-0-53444900-1594729969.png

 

 

A closer crop with no additional sharpening.

post-150-0-68840600-1594730037.png

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Thank you.

With some sharpening it gets even better, but the non focussed areas becomes noisy and some stacking artefacts more visual.

The sharpening has to be done selectively. I have to learn more about how to do that well.

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A sharpened part at 100% that looks mostly good:

post-150-0-80401000-1594732370.png

I now realise that the image above wasn't at 100%. This is.

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I think the flower is a Myosotis Stricta.

I picked a tiny bouquet of them in mid May.

This last individual survived at least partly for many weeks in my fridge.

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Is this snip about 2mm across ?

The full image at the top of the thread covers 10 x 15 mm => ca 3.3mm if I do the calculation right.

My guesstimate was slightly off in the first post.

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That is the big question, especially as it looks like the active parts are hidden further down in flower.

Here is a VIS stack from the same bouquet when it was fresh back in May, when I was relearning the craft of stacking:

post-150-0-75642400-1594734992.png

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So we need to take over the fridge with subjects as well as the house with photo gear. I will have to remember that.

 

These are amazing. Excellent.

 

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As Myosotis is not 'fauna' by any stretch of imagination, I took the liberty of moving this topic into the Botanical section ....
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Aha, another reader of that sci-fi classic The Day of the Triffids -- excellent. John Wyndham had the ability to make believable post-apocalyptic narratives, for sure. In my view, better than 'The Kraken Wakes which followed it.
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Editor's Note: For a topic to be in this section, it must have a searchable title else it breaks my indexing algorithm.

 

Old Title: Tiny ForgetMeNot

New Title: Myosotis sp. [Forget-Me-Not]: Stacking a Tiny Flower

 

****

 

Excellent stack! The details are fascinating.

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Andy Perrin
It's fantastic work. I do have a question, though: what is that almost "foggy" appearance in the UV photos? I have seen this in some of mine, but I don't know the cause of it, and it's not with every lens.
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It's fantastic work. I do have a question, though: what is that almost "foggy" appearance in the UV photos? I have seen this in some of mine, but I don't know the cause of it, and it's not with every lens.

I don't see the "fog" in this photos, but my idea is that the glass the lens is made of fluoresces. Some lenses may fluoresce less than others.
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Andy Perrin
No, it’s not fluorescence because that would be in visible light. This is in the UV photos around highlights and specular reflections.
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Visible light from fluorescence can reach the sensor if the filter is not rear mounted (if you screw it in front of the lens). The only other thing I can think about the lens are coatings. You said that it doesn't happen with all lenses, so the origin of the problem should be in the lens. Bright objects can maybe produce reflections inside the lens, as the coatings are not optimized for UV.

 

Does the problem disappear or is mitigated if you mount the filter in the back of the lens?

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Some of that "glow" or "fog" could be from stacking? A specular reflection does not necessarily bounce in the same direction each time. (Not sure if I said that correctly?) One would have to ensure the lighting was precisely in the same place for each shot in the stack. And you could still get differently directed specular reflections because the flower might "breathe" also on the cellular level. I've had some flowers which just flat out move when the UV flash hits them.

 

Or specular reflections could induce a bit of flare? Or the camera in use may not handle specular reflections/highlights well resulting in some pixel "bloom" -- like, spillover into another pixel?

 

So there's 3 guesses. Anything sound reasonable? :grin:

 

Thought of a 4th possibility.

UV photos take longer to expose. So the time spent making a UV stack is quite a bit longer than it takes to make a Visible stack. The slight wilting or organic movement of a flower during the UV stack making could contribute to a kind of stacked motion blur (not sure what to call it) because the stacking softwre cannot completely resolve the match up of the tiny details.

 

Still a spec-tacular result though!

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Andy Perrin

Yeah, so I was assuming that the glow in this case was the same as the problem I had in my old El-Nikkor but you may be right that it’s from something else stacking-related. I suppose the question could by answered by looking at an individual frame or two of the stack.

 

I don’t think it’s caused by movement. It looks pretty much like my old problem with the flare. But I don’t get why some lenses do it and not others.

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