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Papilio ulysses
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Guppy



Joined: 20 Dec 2010
Posts: 103
Location: Switzerland

PostPosted: Wed Feb 26, 2020 10:36 am    Post subject: Papilio ulysses Reply with quote

Hi

What should you do if it snows all day outside?
Stack what it takes!
Wing scales with the NIKON M Plan, 60/0.7 ELWD, 210/0.



http://files.homepagemodules.de/b649264/f7t3438p26625n2_znqSYKuw.jpg

Kamera: Nikon D810
Objektiv: NIKON M Plan, 60/0.7 ELWD, 210/0
Belichtungszeit: Blitz
ISO: 250
Beleuchtung: 4 Blitzgeräte
Aufnahmedateiformat (RAW/JPG): RAW
Beschnittsbetrag in % (Breite u. Höhe): 3.5, 8
Stativ: Reprostand
Aufnahmedatum: 22.01.2020
Herkunft: Nachlass
Artenname: Papilio ulysses
Multishot-Technik: Focus Stacking
Stacking Software / - Methode: Zerene Stacker / PMax
Abbildungsmassstab: 60:1
Objektseitige Bildbreite (mm): 0.58
Stacktiefe (mm): 0.064
Anzahl Stackschritte: 129 (pro Schritt 2 Bilder = Total 258)
Stackschrittgrösse (mm): 0.000496

Kurt
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JH



Joined: 09 Mar 2013
Posts: 1277
Location: Vallentuna, Stockholm, Sweden

PostPosted: Wed Feb 26, 2020 12:50 pm    Post subject: Reply with quote

Nice picture. Your webpage, made me remember that it was your pictures that was one of the main reasons that I wanted to photograph butterfly scales.

Best regards
Jörgen Hellberg
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kutilka



Joined: 04 Feb 2010
Posts: 39
Location: Czech republic

PostPosted: Thu Feb 27, 2020 3:17 am    Post subject: Reply with quote

Super!
Why 2 pictures per step?
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Guppy



Joined: 20 Dec 2010
Posts: 103
Location: Switzerland

PostPosted: Thu Feb 27, 2020 6:54 am    Post subject: Reply with quote

Hi kutilka

look here:
https://www.photomacrography.net/forum/viewtopic.php?t=40955&postdays=0&postorder=asc&start=0

0.000496mm is the shortest step (theoretically) that the StackShot can take.
The steps are measured very unevenly (in practice) and sometimes they go back.
Since I work for photography on the repro stand and not on the microscope, I have tremors. Even if the StackShott doesn't take a step, the focus changes.
If I take several pictures in one step of the StackShot, they are not identical.
If I take 2 pictures, or more with each step of the StackShot, the step size is smaller.
This does not increase the resolution, but the picture becomes sharper and clearer.

For me it is primarily interesting how big the steps are at home and not in the laboratory.
As mentioned, there is vibration at my repro stand, which can be responsible for a back.
Even if the StackShott doesn't take a step, the focus changes, + - 0.0002mm.
If someone closes a door in the house or a truck drives past, it can be up to + - 0.001mm.

As you can see in the picture, none of this is a problem

Kurt
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Lou Jost



Joined: 04 Sep 2015
Posts: 4269
Location: Ecuador

PostPosted: Thu Feb 27, 2020 7:43 am    Post subject: Reply with quote

These are especially interesting because some people report that scales shouldn't be photographed with flash, because of scale movement due to thermal shock causing turbulence. You must be using fast enough flashes (or rigid enough scales) that this doesn't cause problems.
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Guppy



Joined: 20 Dec 2010
Posts: 103
Location: Switzerland

PostPosted: Thu Feb 27, 2020 8:46 am    Post subject: Reply with quote

Hi Lou

I don't have this problem!
I illuminate with 4 flash units (YONGNUO YN560 III).
The output is reduced to 1/128, 1/64 or 1/32.
In the flash units, the diffuser is folded down.
Around the object is one or two white plastic drinking cups.
Distance flash unit to white plastic drinking cup approx. 5mm.
Distance of white plastic drinking cups to the object (scales) approx. 20-30mm.

Kurt
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rjlittlefield
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Joined: 01 Aug 2006
Posts: 20652
Location: Richland, Washington State, USA

PostPosted: Thu Feb 27, 2020 9:28 am    Post subject: Reply with quote

A beautiful image!

One more question: how do you have the subject mounted for photography?

--Rik
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Guppy



Joined: 20 Dec 2010
Posts: 103
Location: Switzerland

PostPosted: Thu Feb 27, 2020 9:52 am    Post subject: Reply with quote

Hi Rik

The wing lies on a black background and is weighted with a big washer.



Kurt
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rjlittlefield
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Joined: 01 Aug 2006
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PostPosted: Thu Feb 27, 2020 10:25 am    Post subject: Reply with quote

Guppy wrote:
The wing lies on a black background and is weighted with a big washer.

Excellent, thank you for the detail.

Lou Jost wrote:
some people report that scales shouldn't be photographed with flash, because of scale movement due to thermal shock causing turbulence.

I have recently been doing some controlled tests of flash-induced blurring. My read is that the problem is far less serious than some discussions might suggest.

In particular, I've had no trouble photographing even the black scales of Urania ripheus at NA 0.75, when I took care to use proper flash technique as Guppy has illustrated: constrain the wing membrane, use speedlight at low power to get short flashes, and place some semi-rigid diffuser around the subject.

On the other hand, I can have almost arbitrarily bad flash-induced blurring by deliberately making mistakes such as holding the moth's body and leaving the wings free, using flash at high power / long duration, and using no decent diffuser.

The message I take away is that flash-induced blurring is a real thing to be aware of and take steps to avoid, but that except for very difficult subjects such as long flexible fibers, flash-induced blurring is much less of a problem than environmental and equipment-induced vibrations are likely to be.

--Rik
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Lou Jost



Joined: 04 Sep 2015
Posts: 4269
Location: Ecuador

PostPosted: Thu Feb 27, 2020 12:12 pm    Post subject: Reply with quote

Quote:
The message I take away is that flash-induced blurring is a real thing to be aware of and take steps to avoid, but that except for very difficult subjects such as long flexible fibers, flash-induced blurring is much less of a problem than environmental and equipment-induced vibrations are likely to be.


I've never knowingly experienced it, but those who have noticed it have also shown that the effect is not eliminated by diffusers. Obviously Kurt has no problems here! I suspect very fast flash pulses are the key. The solid mounting can't hurt either (except that the washer must wreck the scales beneath them, no?)
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rjlittlefield
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PostPosted: Thu Feb 27, 2020 2:28 pm    Post subject: Reply with quote

There are at least two distinctly different causes for flash-induced blurring:
  1. Impact by a sound wave that originates at or near the flash unit --- the "sound wave effect"
  2. Local heating of the subject and surrounding air caused by absorbing energy from the flash --- the "radiometer effect".

It's a safe bet that in some cases, flash-induced blurring is caused primarily by the radiometer effect. The one that comes to mind is Chris S.'s report of flexible glass fibers that either blurred or not, depending on whether they were black or clear.

But it is not a safe bet to assume that the radiometer effect dominates all the time just because it does in specific cases.

In my own experiments, when I've taken care to reduce or eliminate the sound wave effect, the remaining amount of flash induced blurring has been negligible.

As you say, very fast flash pulses can be one key. If the light pulse stops before the sound wave arrives, then the sound wave won't matter.

Looking at Kurt's description, I notice that he says
Quote:
Distance flash unit to white plastic drinking cup approx. 5mm.
Distance of white plastic drinking cups to the object (scales) approx. 20-30mm.

Noting that speed of sound in air is about 350 meters per second, and assuming 35 mm from flash to subject, this suggests that a flash duration of less than 1/10,000 second should eliminate all or most of the sound wave effect. At flash powers of 1/32 and less, I'm guessing that Kurt's Yongnuo units are working in that regime.

Quote:
except that the washer must wreck the scales beneath them, no?

The scales themselves are pretty tough. I would worry more about dislodging them. That said, standard practice for mounting lepidoptera is to press the wings against a spreading board so that their position is fixed by friction. It's not clear to me that Kurt's washer, placed gently, would be much more damaging than that.

--Rik
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Lou Jost



Joined: 04 Sep 2015
Posts: 4269
Location: Ecuador

PostPosted: Thu Feb 27, 2020 4:24 pm    Post subject: Reply with quote

I imagine that even a thermal effect must take a bit of time to move the scale, so even in that case, there might be some sufficiently fast flash that would keep it from affecting the photo. But I have no quantitative feel for how fast that would have to be. What flash duration was Chris_S using?

I recall from my bird photography days that the flash duration of my Vivitar 285 flashes at lowest power was very short indeed. Internet says 1/30000s at 1/16 power. The Yongnuos at 1/128 power might be an order of magnitude faster. That's pretty fast.
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mawyatt



Joined: 22 Aug 2013
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Location: Clearwater

PostPosted: Thu Feb 27, 2020 5:30 pm    Post subject: Reply with quote

Lou Jost wrote:
I imagine that even a thermal effect must take a bit of time to move the scale, so even in that case, there might be some sufficiently fast flash that would keep it from affecting the photo. But I have no quantitative feel for how fast that would have to be. What flash duration was Chris_S using?

I recall from my bird photography days that the flash duration of my Vivitar 285 flashes at lowest power was very short indeed. Internet says 1/30000s at 1/16 power. The Yongnuos at 1/128 power might be an order of magnitude faster. That's pretty fast.


Lou,

I measured some of these speed lights way back and they were in range of 50~100us at 1/128 power, but that was just a quick test to evaluate the relative speeds of various flash sources, from speed lights to strobes.

Best,

https://www.photomacrography.net/forum/viewtopic.php?t=29729&postdays=0&postorder=asc&highlight=waveform&start=0
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rjlittlefield
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Joined: 01 Aug 2006
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PostPosted: Thu Feb 27, 2020 6:22 pm    Post subject: Reply with quote

Lou Jost wrote:
I imagine that even a thermal effect must take a bit of time to move the scale

Yes, but it's not clear that this means a faster pulse would help.

The catch is that in order to get a good exposure, you have to deliver a certain amount of total energy. Shorter flash duration then means you have to deliver the energy proportionally faster, for example by moving the flashes closer or using more of them. There are reasonable assumptions where everything works out to be a wash in this scenario.

in my own experiments with black scales of Urania ripheus, the most important bit of technique was just to stabilize the wing membrane, very much as Kurt has done except that I used paper strips pinned into a slab of balsa as if I were mounting the specimen. With the wing membrane stabilized at that coarse level, and with a stiff tracing paper diffuser wrapped around the objective and almost touching the subject, the remaining flash-induced blur was so small that I was hard pressed to do better with continuous illumination. I finally was able to get what I think was a slighter sharper image with continuous illumination, but only under stringent conditions: no traffic, no wind, no equipment or HVAC fans, nobody moving in the house. Even so, that slightly sharper result came at the cost of hot pixel trails due to long exposure times. The whole experience would have made a very bad advertisement for the idea of "don't use flash".

--Rik
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Guppy



Joined: 20 Dec 2010
Posts: 103
Location: Switzerland

PostPosted: Fri Feb 28, 2020 4:10 am    Post subject: Reply with quote

The pressure wave from the lightning can be measured with a microphone and recorded on a channel with Audacity.
At the same time, the flash is measured with SIEMENS Silicium-PIN-Photodiode with short circuit time SFH 203
http://www.focus-stacking.ch/html/flash_burning_time.html
and records this on the second channel.
Then you can see the timing in Audacity.

Kurt
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