Flash(es) recommendation

[Macrero]

I've been always working with continuous light, but I will be shooting scales at high magnification (20-50X+) where vibrations are virtually impossible to avoid completely.

So I am looking for at least a couple of flashes. I am considering the Godox T350S + X1T trigger, but I am not sure those will have enough power for high magnification work.

Any suggestions are welcome.

Best,

- Macrero

[Chris S.]

Macrero,

Butterfly and moth wing scales, in my experience, tend to be violently jolted by flash, to the extent that they often seem impossible to photograph sharply in any lighting paradigm other than continuous light.

This being the case, I'd suggest you work instead on making your continuous light setup robust enough to permit you to work confidently at 20-50x under continuous light.

Best,

--Chris S.

[Macrero]

Hi Chris,

Thank you for your advice! I would actually prefer to work with continuous light setup. Though I am not completely confident about the lack of vibrations at high magnifications with my rig. I will see if I can improve it in some way.

Truth be told, I've seen quite a few excellent scales shots with flash(es) at high magnification. A recent example are Adi's great Urania scales.

What problem(s) exactly did you find with scales and flashes? The lack of sharpness you mentioned does not make sense to me, honestly. It should be the other way around

Best,

- Macrero

[Macrero]

Butterfly and moth wing scales, in my experience, tend to be violently jolted by flash

Sorry, I had not understood that part, my poor english skills...

Does not the diffuser prevent the "jolting"?

[Macro_Cosmos]

Butterfly and moth wing scales, in my experience, tend to be violently jolted by flash

Sorry, I had not understood that part, my poor english skills...

Does not the diffuser prevent the "jolting"?

Simply put, the "impulse wave" from the flash will cause vibrations in the scales. If you take a flash, put it at full power and stick it on your skin, fire it, it will tickle a bit

The diffuser could shield this off entirely.
1) Flash at low power
2) Through diffuser

Another thing to note, flashes:
1) Variable output, you will have to equalise for exposure or let ZS handle it.
Check this out: https://www.youtube.com/watch?v=ittapvLIyIo
2) Recycle time, cheaper ones suffer quite a lot. Be liberal with the trigger intervals.

Someone I know use Godox AD200 strobes and get good results. Of course, making the continuous lighting setup more stable is preferable. Sometimes it's a matter of environment though, meaning it can't be done easily. I have to do my stacks after midnight since people walking around will shake everything up.

[Macrero]

That was what I thought. A good diffuser, proper flash power and distance between flashes and diffuser should prevent the photon jet (or whatever is causing the scales jetting) from hitting the scales.

But again, I have never used flashes for stacking at whichever magnification. I guess I will try to borrow a couple of flashes and try and see for myself.

Thank you for your advice!

Best,

- Macrero

[Chris S.]

Simply put, the "impulse wave" from the flash will cause vibrations in the scales. If you take a flash, put it at full power and stick it on your skin, fire it, it will tickle a bit

The diffuser could shield this off entirely.
1) Flash at low power
2) Through diffuser

Macro_Cosmos, this is utterly wrong, and has been debunked several times in this forum. Sadly, it is widely believed, as evidenced by past wrong answers when this question has come up.

Whatever "impulse wave" exists in someone's imagination, nothing of the sort is involved.

Further, putting a diffuser in front of the flash will not help at all. Neither will setting the flash at low power. So let's put this nonsense aside and consider the real answer.

. . . I've seen quite a few excellent scales shots with flash(es) at high magnification. A recent example are Adi's great Urania scales.

What problem(s) exactly did you find with scales and flashes? The lack of sharpness you mentioned does not make sense to me, honestly. It should be the other way around

(snip)

Does not the diffuser prevent the "jolting"?

Macrero, you asked good questions. As you say, there are excellent wing-scale shots taken with flash. Flash sometimes works well with wing scales; other times, flash kicks the scales so quickly and violently that they become hopelessly blurry in a photo. The difference is that reflective or transparent scales tend to work well with flash; dark scales that absorb visible light tend to work badly with flash.

When an object is hit with a bunch of visible-light photons, it may absorb them (if opaque), let them pass through (if transparent), or bounce them off (if reflective). If the object absorbs these photons, it heats up. This heating is incredibly rapid--I think of it as happening at the speed of light. With thin, low-mass objects such as dark wing scales, this heating can cause instantaneous, violent motion. This is probably due to two things: The heat may deform the shape of the wing scale, causing it to jump; and the heat may be instantaneously transferred to the air next to the scale, causing the air to expand and bump the scale.

The light-to-heat conversion, and heat-to-motion conversion, occur so rapidly that flash durations of even 1/50,000 of a second are not brief enough to freeze it out. And since the underlying cause is visible light photons, nothing that lets visible light through will prevent the problem. This is why diffusers don't help. Neither would putting the wing scales inside a sealed glass jar. Neither does setting the flash at a lower power setting, assuming that the photographer makes up for decreased light output by moving the flash closer to the subject. (If the photographer increases the sensor's ISO instead, the problem might be reduced, but would probably still occur to some degree, and at the cost of increased sensor noise.)

This has been amply demonstrated. A Crookes radiometer will spin when exposed to photographic flash. Since a Crookes radiometer is enclosed in a glass bulb, any imagined "impulse wave" should be blocked.

Somewhat painfully, I've explored this phenomenon in a number of ways, as it created problems for me back when I used flash for high-magnification macro work. One problem--frustrating at the time--is particularly illustrative.

I was photographing a glass-fiber filter that had been used to collect airborne soot (mainly black carbon), for an academic researcher studying particulate air pollution. At 100x, I framed an image of glass fibers that were fixed at one end, and loose at the other end. Some of these fibers were darkened with carbon, while other fibers were clean glass (which was either transparent or reflective of visible light, depending on the light's angle of incidence). I framed and focused under continuous light, then turned off the continuous lights and switched to flash to shoot the stack. As I recall, the stack was somewhere around 400 frames thick.

After I shot and assembled the stack in post, I was astonished to find the clean glass fibers well-imaged, but the soot-blackened fibers entirely missing. What on earth had gone wrong? Assuming human error (mine, of course), I turned on my continuous lights, set up the beginning and end points of the stack, and ran it again. And once again, only the clean fibers were visible. Egad!

After considerable frustration, I tried running the stack under continuous light. This time, all the glass fibers--both clean and soot-blackened--were clearly imaged. After pondering the difference, I realized that the culprit was flash, and the reason why. Under flash, the blackened fibers were jolted out of the plain of focus and were jittering wildly. Under continuous light, any heating effects operating on the blackened fibers were constant, so the blackened fibers assumed a steady position and remained there during the stack.

After this, I observed similar affects on other subjects. Since I dislike such variables ruining my stacks somewhat unpredictably, I eventually stopped using flash for high-magnification photography. (The other big benefit of continuous light is that it is much easier to predict how things will look. In this choice, I'm following in the footsteps of wise photographers who made it before I did.)

Other members of this forum have performed different tests that affirm the same cause of flash-induced subject movement. For those of us who have closely followed this subject, it is a settled issue. If anyone should present contrary evidence based on testing, it will deserve consideration and discussion. But authoritative statements without evidence lower the quality of our forum.

Good advice to beginning macro photographers is: "Use flash now, but be aware that it may cause problems down the road." For beginners, vibration of subject and macro rig is often their biggest problem, for which flash is practically a wonder-cure. But for advanced macro photographers who have eliminated vibration, flash can cause insurmountable problems with some subjects. At this point in the evolution of a photomacrographer, continuous illumination may deserve serious consideration.

--Chris S.

[Macrero]

Chris,

Thank you again for sharing your experience and for the helpful and detailed explanation.

I haven't worked "seriously" at high magnification, though the biggest issue I found while playing high-M is not vibrations, but subject movement.

Yeah, that's weird. I have a pretty solidly built setup, rig is placed over a brick table with a marble slab on top. There is another marble base between the equipment and the table, with anti-vibration pads. I use a solid industrial XYZ stage for my specimen holder.

Yet, when working at considerably high magnification, say 40X, subject is moving slowly. That is, I focus a point of the subject, within a few minutes, the focus is gone Sometimes when looking at the zoomed screen I can clearly see the focus displacement/subject movement.

That's not caused by the equipment (camera/bellows) manipulation, since often subject is still moving even after hours of the setup being quiet and untouched

I did not find explanation for that, except that maybe there is a ghost in my basement

I am planning to build a vertical setup for high magnification work, and see if that solves the weird issue...


Best,

- Macrero

Edit: We have posted at the same time. Just a clarification: I didn't make claims, I said I don't have any experience with flashes. If I had, I wouldn't be asking. I just wanted to hear the opinion of people who work (or have worked) with flashes at high magnification, before I spend money on flashes.

And to be honest, my (wrong) believing has not been influenced by Macro_Cosmos reply. I'm sorry if my post can be misleading for someone. Luckily, the matter has been clarified.

[Adalbert]

Hello Macrero,
If you want to avoid the negative effect of the vibrations you have to use the flash or camera with the shutter with min 1/32000 S.
The most important issue is the mechanical isolation of your rig from the environment.
The vibrations caused by the rig don’t play any role, because you can manage this problem.
But the vibrations coming from the outside are difficult to avoid and to manage.
I use Youngnuo YN660 because of the:
- 200mm zoom
- 1/128 power
- Integrated receiver
- High quality
- Nice price :-)
The biggest problem of this flash is the battery-cover. It can be used two times and is damaged.
This problem occurred in every one of my four YN660. But it is very easy to solve :-) Please take a look at the thread with the scales.
BR, ADi

[Macrero]

Hi Adi,

thank you for your reply.

Working at such high shutter speeds with continuous ilumination is obviously impossible. So, the only way to make sure there are no vibrations affecting, is to use a flash.

That's why I was considering to use flash. What I was ignoring is the scales jolting issue, pointed out by Chris.

I think I will end up building a vertical setup for high magnification work with scales. And will try to make it as steady as possible.

Best,

- Macrero

[Pau]

Yet, when working at considerably high magnification, say 40X, subject is moving slowly. That is, I focus a point of the subject, within a few minutes, the focus is gone Confused Sometimes when looking at the zoomed screen I can clearly see the focus displacement/subject movement.

That's not caused by the equipment (camera/bellows) manipulation, since often subject is still moving even after hours of the setup being quiet and untouched Shocked

I did not find explanation for that, except that maybe there is a ghost in my basement

Well, in your case the main concern must be hunting for the ghost. I couldn't even figure what can be the culprit but it sounds like some part sliding down or suffering plastic deformation, and the suspicious can be the subject holder or positioner. It could also be the subject itself when drying.

[Adalbert]

Hello Chris,

With thin, low-mass objects such as dark wing scales, this heating can cause instantaneous, violent motion.

I only have noticed that the grid-structure is better visible on the light, yellow scales (on the top):

https://live.staticflickr.com/65535/489 ... ccea_o.jpg
(Mitty 20x / 0.42)
BR, ADi

[Macrero]

Well, in your case the main concern must be hunting for the ghost. I couldn't even figure what can be the culprit but it sounds like some part sliding down or suffering plastic deformation, and the suspicious can be the subject holder or positioner. It could also be the subject itself when drying.

Yep, you are right. In my case the subject movement is the main problem. I tried using a different positioning stage, but the issue is still there. I will get another bellows to try. Not sure what else could I do, other than maybe build a vertical setup.

I discarded the subject's drying as a possible cause, since the issue is present, regardless of subject: Wings, dissected insects, laser printed paper, silicone wafer, etc...

I hope a vertical setup will solve the problem. I will start building one as soon as I have some free time.

Best,

- Macrero

[Adalbert]

Hello Macrero,

Working at such high shutter speeds with continuous ilumination is obviously impossible

yes, of course and therefore flash :-)
Do you expect a better performance from the vertical setup?
I’m asking about that because my rig can be used horizontally and vertically and I haven’t noticed any difference between the stacks made up to now.
BR, ADi

[Macrero]

Adi,

the only reason for the vertical setup is the weird subject movement issue I described above. If I can solve that, I would expect a huge improvement at high magnifications.

Vertical setup helps to avoid backlash, but other than that, assuming you have no Ghosts in your studio, as I have I would not expect significant difference/improvement.

Best,

- Macrero