Magnetic lighting stage for Bratcam

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g4lab
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Post by g4lab »

The one in the link is a micro sized one. The one my mechanic had was bigger but would have been just as useful.

This is probably the original and seems to be similar in size to the Mitutoyo

http://www.mtstn.com/products/185/3120/default.aspx

Here are some ones from Fred Fowler who are usually reasonbly priced.
Some of their stuff is Chinese now. They used to import precision gear from Germany and Poland and undercut Starrett and Brown and Sharpe.

http://www.fvfowler.com/pdf/2304/2304_179.pdf

http://www.nolansupply.com/bysubcategor ... specs=True

And the fust and champeen deal here!!!:
http://www.harborfreight.com/clamping-d ... 93051.html

And searching for the one immediately above turned up this:
http://www.harborfreight.com/75-watt-ma ... 90766.html

I like the idea of a Giant Shelob Macro Assimilator :lol:
It needs Artificial Intelligence and Mobility so it can operate unmanned.

rjlittlefield
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Post by rjlittlefield »

g4lab wrote:And the fust and champeen deal here!!!:
http://www.harborfreight.com/clamping-d ... 93051.html
I have an inexpensive segmented arm that looks just like this, except mine is from Enco, on a magnetic base. It would not work for holding strobes like Chris S. shows. The segmented arm doesn't lock up nearly tight enough. Completely unlike that Manfrotto 819-1 arm that I'm so happy with.

Perhaps apparently similar units from other manufacturers work better.

--Rik

Craig Gerard
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Post by Craig Gerard »

Bob^3 wrote:
g4lab wrote:I wish I had one of these:
http://www.lighttoolsupply.com/catalog/ ... oductID=17

Now that looks like a really useful arm. And the price is not bad either!
Here's a similar gizmo and some example applications.

http://www.visionarydigital.com/Accessories.html

The segmented arms are a bit fiddly, good for FO cables, holding reflectors, gobos, subjects, etc.


Craig
To use a classic quote from 'Antz' - "I almost know exactly what I'm doing!"

Chris S.
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Post by Chris S. »

AndrewC wrote:Mind you, I think collectively we are evolving a monster - I'm waiting for the first view of a stage made out of a 600lb granite slab, suspended from bungee cords, installed in a room carved out of living rock, overhung with an 8 legged multi-jointed lighting "Shelob", hooked to a 20 petaflop computer to enable real time instantaneous stacking, camera moving on a maglev table with laser positioning and all based on a $20 lens picked up on eBay .....
Andrew, thanks for the laugh, which brought a smile to my day, and for including another Tolkien reference--always a good thing. Humor aside, I’d point out that the inspiration here was to solve problems I really face, and not purely an obsessive-compulsive desire to create something absurdly over-engineered. Here is a real-life scenario for me: A good friend of mine is a retired botany professor, a legend in his field. Though his knowledge is encyclopedic, his specialty is cryptogamic botany—mosses, fungi, lichens, and other small stuff. Many of the diagnostic features of these organisms are visible only under magnification; some have never been documented, and others are recorded only in line drawings done in the early 1900’s. Sam, my kind and brilliant friend, will go out with me, and in a day we might collect, say, 30 species of moss, lichen, or fungus. If I want to document them, I typically start with a “portrait” of the entire “plant,” then take close-ups of features that Sam finds diagnostic. I’m not looking for art, here, but clear and explanatory images, which Sam will then annotate. For an individual specimen, I might need three to five individual images at a wide range of magnifications—and I need to vary the lighting to a large degree to illustrate various details. In this scenario, I’m not looking to create art, but to clearly document. But doing the math, this involves 90-150 separate images in a single session, many of which require focus stacking. So making the creation of each image systematic and efficient is a big deal for me. Hence, the ability to adjust the lighting very quickly and with minimal frustration is very important.

As an aside, Sam did his Ph.D. under the famous Alexander K. Smith, whose mushroom books were important and formative sources for me. I once asked Sam how Dr. Smith figured out where to place his lights for mushroom photography. Sam told me that Dr. Smith held a lamp in his hand, and moved it all over the place until he saw, through his ground glass, lighting that illustrated the features he found important. Then he mounted a light in this position, added a fill light near the lens to control the shadow contrast, and made the photograph. I wasn’t surprised to hear this—it’s a version of what I myself do. In the Bratcam lighting stage, I was looking to make this process as efficient as possible.
Joaquim F. wrote::shock: Is an really awesome illumination assembly, reminds me the robots in a factory car line!

. . . I also have 2 Nikon SB-26, the second I got recently and I am still trying to mount them in a convenient rig, you got a very clever setup with those articulated arms.
I have the flash connected by Nikon ttl cables to camera and mounted in mini-tripod with ballheads, in another "experiment" I try to mount in the extreme of a extra Nikon rail with a PG-1 stage at the end and a flat aluminium bar with mini ballheads attached. Do not think the extra triggers are required so the sb-26 have their own slave cell who can shoot with the built-in camera flash unless you use a shooting technique that includes a delay ...
I just can shot around 21X at maximun and using the shortest flash partial powers i don't detect vibration problems, may be at more magnification is best another shooting technique?
Joaquim, you are right—with SB-26 flashes, which include a built-in slave, you don’t absolutely need wireless triggers. However, I don’t like using on-camera flash, which can create difficult highlights, so I don’t have an easy way of triggering the optical slave function. And the eBay triggers are cheap enough that I simply purchased them and didn’t look back. Another factor is that I sometimes add other flash units, some of which don’t include optical slave functionality. The eBay triggers easily fire these units, at modest cost.

I use a technique elucidated a while back by Charlie Krebs: I shoot in a darkened room, lock the shutter up for a few seconds, take a long exposure (which allows any shutter-induced vibration to dissipate—but, since the room is dark, records no image—then fire the flash at the end of the exposure).

Like you, Joachim, I’ve tried Nikon TTL cables and mini-ballheads, but I much prefer this current rig. Getting rid of the TTL cables greatly increase freedom of movement for the lighting, and the Noga stands improve hugely vs. mini-ballheads that I have tried.

Mitch, thanks! Sorry to tell you that I didn’t actually photograph this moss—I just grabbed it from a nearby woods to illustrate the rig. Have to say that it was long past its prime—if it had been at its peak, I’d have photographed it with considerable care. But way to go, Mitch, for noticing. When the next summer season rolls around, beware—I’ll finally have the rig I need to capture mosses at their various peaks. I fully intend to document as many as I can—with the help of Sam.

Gene, thanks and thanks. I’m sure there are other good alternatives to the Noga stands—just as Kirk, Markins, etc. do not individually have a corner on quality ball heads. Your links make this a much more useful thread. For my own rig, I’ll stick with Noga and magnetic bases—not that other top makers aren’t competitive, but that I’d rather deal with common parameters for all my stands. But your links make this a much more useful lighting thread. Thanks!

Bob, huge thanks! A post like this takes far more time than it should, and hearing that it helps somebody—and particularly, somebody of high abilities—makes me smile and feel that it was worth the time to compose the post. Thanks again for your kind words.

I’ll say it again: We paint with light. Everything else is incidental. I do care about lenses, mountings, stepping, etc.—but light—light is what we paint with. It should take center stage.

I’m really pleased that this post attracted some attention. Thanks, everyone!

Cheers,

--Chris

AndrewC
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Post by AndrewC »

Question: why not "snoot" your flashes ? I used to shoot with open flashes but one rainy day made some slip on cardboard snoots and found the results more pleasing and easier to work with - with the snoot it is much easier to direct the incoming light. if you don't feel like briccolage (French term for DIY) Lumiquest make some nice slip on black plastic ones.
rgds, Andrew

"Is that an accurate dictionary ? Charlie Eppes

AndrewC
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Post by AndrewC »

Chris S. wrote:...
I use a technique elucidated a while back by Charlie Krebs: I shoot in a darkened room, lock the shutter up for a few seconds, take a long exposure (which allows any shutter-induced vibration to dissipate—but, since the room is dark, records no image—then fire the flash at the end of the exposure).

...
I used to do the same but after some tests decided it was overkill as the flash exposure is so short that it freezes any vibration motion and with my subjects I haven't been troubled by any "within subject vibration induced motion" (such as waving antennae). Now I just shoot with a 1/100th exposure and rear curtain-sync. There was another motivation - my family objected to me having the lights turned out :)

Try and run a comparative stack with both methods with a 10x objective and see if you can see the difference ...
rgds, Andrew

"Is that an accurate dictionary ? Charlie Eppes

Craig Gerard
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Post by Craig Gerard »

Another 'snoot' concept.

http://www.zootsnoot.com/

Craig
To use a classic quote from 'Antz' - "I almost know exactly what I'm doing!"

Chris S.
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Post by Chris S. »

Andrew, I do often snoot my flashes—mostly with black paper or poster board and tape. While I don’t find snooted flashes automatically better than unsnooted flashes, I’d agree that it’s an alteration that might well belong in everybody’s bag of tricks.

But you’ll recall that the SB-26 has a zoom feature, and that I’m often aiming these flashes at a diffuser, which itself becomes the effective light source. So the closer the flash is to the diffuser, the smaller is the beam of light that hits it, and therefore the smaller is the effective light source; the farther the flash is from the diffuser, the larger is the beam of light that hits it, and the larger the effective light source. One of my favorite approaches is one that I think Charlie Krebs may have been the first to describe on these fora long ago, with three flashes—one above, closer to the diffuser, and two to the sides, farther from the diffuser. The close one creates shadows, whose placement and edge-sharpness can be tuned. Then the two far ones create even fill, the contrast of which against the main light (effectively, the transparency of the shadows) can also be tuned. I usually don’t require snoots for this.

Craig, blast it—why did you have to go and show me those Zoot Snoots? I was happy enough with my “briccolage,” not knowing any better. The Zoot Snoots look great, and the devil on my shoulder is whispering in my ear that I need one for each of my flashes—maybe five or six Zoots. My wallet feels lighter already. Ignorance may not be bliss, but it can be economical. (Seriously, thanks for pointing them out.)

The lighting approaches I showed in this thread are of course very basic—I picked them because each has been demonstrated before in these fora. But I myself don’t usually use such approaches without adding gobos or other modifiers. I was trying to show a lighting rig that could quickly create just about any lighting approach—but didn’t intend it to be a treatise on macro lighting per se.

But Andrew, you’ve given me an opening (thanks, mate!) So I'll throw into the ring a few thoughts on macro lighting (in which I suspect you’ll largely concur).

I find most discussions of macro lighting too limited. They commonly involve achieving even subject illumination and control of distracting highlights and shadows. But at a higher order, macro lighting should also convey the shape and texture of the subject—which requires keeping some highlights and shadows, and carefully controlling their placement, size, shape, density, and falloff. The highlights and shadows contain information that the typical viewer should take in without a thought. Further, as creatures adapted to sunlight, we naturally expect the main light to come from somewhere above the subject; if the main light is somewhere else—such as below the subject, our brains trip up a little, unless the light source itself is in the image to rectify the counterintuitive light source. This is part of an image’s looking “natural” to the human brain. I mentally assign demerits to macro images that violate this principle. Some recent—and otherwise excellent—posted images had the light source below the subject. I think this greatly lessened the impact of those images.

I hope there will come a time when it is common knowledge how to get close enough, stack properly, avoid vibration and other unwanted movement, and we allocate more thought-space to considering how to use light to convey the essential qualities of a subject. When this community has a dedicated lighting forum, and that forum has active and enthusiastic postings, we will finally be talking about “painting” itself—rather than discussing brushes, canvasses, pallets, easels, frames, and other means to the ends. When we all become proficient in the technology, the art will lie in how we paint with light. (Lest anyone take me wrong, I very much appreciate—and hope I am a useful participant in—the equipment and technique fora; but I still look forward to the day when we talk about how to write like Shakespeare, rather than what quills and ink to use.)

Andrew—thanks for giving me a chance to get on my soapbox. In regards to your observation that the delay's buit into my approach may be overkill, you're probably right. The Bratcam is automated, and resides in a dark basement, so the absolute time required to take a stack is often moot, as I'm likely to be doing something else while the stacking takes place--so a delay of a few seconds between images often means little. But on a deadline--such as when Sam brings me a bunch of specimens, and I want to photograph them while still fresh--time savings might be quite useful. Overkill is nice because it allows forgetting about certain things and concentrating on others. But your suggestion that I test has merit. I'd point out that I shoot often at 20x, 40x, and 60x, so I should probably test at those magnifications, in addition to 10x.

I'm growing increasingly intersted in Bob^3's use of accelerometers. Such a tool would give me a quick way of determining where the overkill point kicks in.

Cheers, and very best regards,

--Chris
Last edited by Chris S. on Wed Dec 08, 2010 12:16 am, edited 2 times in total.

Bob^3
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Post by Bob^3 »

Chris, now you're speaking my language. That sir was very eloquently stated. And I could not agree more---light control on subject has to be top priority. That's why I have spent so much time on it. Your adaptable multiple flash arrangement to control and modulate light coming from all sides of the subject (as you say, not necessarily to produce even illumination), is similar to the concept I suggested awhile back about using a group of 10 or more LEDs positioned around the subject diffuser. Independently controlling each LED would allow fine control of highlights, shadows and contrast specific to each subject. I recently purchased a lot of 40 very small Xenon flash tubes with attached reflectors (from disposable cameras) to use in a similar fashion and allow shorter exposures.

Thanks for the sermon!
Bob in Orange County, CA

Chris S.
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Post by Chris S. »

Bob, it's ironic that just as you were posting a response I was editing my own post to include your contributions in another thread. I really did edit my post without knowing that you were responding simultaneously.

I'm quite interested in your use of LED elements. I do have concerns about the spectra created by LED's--especially the "green gap". But as discussed prior, there are applications in which LED light is used to induce broad-spectrum flourescence, and direct approaches are being devised that may produce a flatter sprectrum.

Thanks for your kind comments about my sermon on macro lighting. I've been itching to preach this, but wasn't sure it was appropriate. It's comforting that at least one very knowledgable contributor concurs.

Cheers, and very best regards,

--Chris

Bob^3
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Post by Bob^3 »

I do have concerns about the spectra created by LED's--especially the "green gap". But as discussed prior, there are applications in which LED light is used to induce broad-spectrum flourescence, and direct approaches are being devised that may produce a flatter sprectrum.
Not to beat a dead horse, but that was my point in starting the most recent thread on the new generation of high-CRI LEDs. All the older threads on the subject also left me with the distinct impression that due to the non-blackbody radiation curve of LEDs, especially the uncorrectable Metamerism caused by the steep blue spike in older LEDs, LEDs were largely unsuitable for macro lighting. I don't believe that was the intent of the older threads, just the impression I got in reading them.

I had meant to follow-up on the newer thread I started because I think some points may have been missed probably because I didn’t state them very clearly - but I ran out of time. At the risk of subjecting the dead horse (and forum members) to repeated beatings, I may resurrect that thread at some point. But before I do, I need a chance to collect some supporting data, as Rik very appropriately requested.

By the way, there is no "green gap" in the LED output in the sense that there is no light emitted at those wavelengths (like some CFLs). However, there is an area of decreased output in the green-cyan part of the curve. But this anomaly is also improved in the newer LEDs.
Bob in Orange County, CA

Bob S
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Post by Bob S »

Have you tried using one of the arms to hold the subject?

I wonder whether it would work or whether it would have problems with vibration or with inability to set a precise position.

Chris S.
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Post by Chris S. »

Bob S--No, I haven't. It would be easy to do a quick test for you, though. Is there a particular magnification would be of most interest?

Since my subject stage is micrometer-adjustable in all axes of movement except one (which is handled by the camera stage), I can quickly, easily, and precisely adjust the subject's position. There is no way the arms would come close to that, but they might be workable.

Bob^3--While I'd prefer not to get into too much discussion of LED spectra in this thread, I've recently had the opportunity to observe the efforts of researchers currently involved in improving the performance of LEDs in the green portion of the spectrum. While perhaps they should refer to it as the "green valley," they do still call it the "green gap." And while the latest LEDs have indeed improved, there is still work to be done--and indeed, I can attest that some very good people are working hard on it.

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Post by Bob S »

I had been thinking about 10X, if you are willing to try a test.

The thought was as follows. At some low magnification, an arm will certainly provide enough stability and can provide precise enough position, and is certainly cheaper, more suited to field use, and less expensive than a pile of ball bearing stages and goniometers.

At some high magnification it will prove to be too difficult to get precise position with the arm, and the arm might be prone to vibration just because it is such a long thin thing.

So where is the boundary? Certainly it is somewhat subjective, because different people will have different manual dexterity in position. Certainly it depends on specimen mass; high mass might provoke larger vibration at some frequency. But, just roughly, where does the arm lose the ability to handle the sample?

Chris S.
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Post by Chris S. »

Bob S, you pose a well articulated question. That is, of course notwithstanding your libelous depiction of my subject stage as a "pile." Had you described it as an "assemblage of epic proportions," an "engineering tour de force," or a "masterpiece of innovative brilliance," I'd consider forgiving you, despite such faint praise. (Note for the humor challenged--I jest.)

Tonight I tried using one of my smaller Noga stands as a subject holder. Even with the cheesy chip clip and rubber bands, it was solid as a rock--vibration at 10x was nil. Adjustability was pretty good--and certainly workable for field use. I did find it far less satisfying than my micrometer-driven subject stage; I'm used to "flying" around the subject with micrometers, while keeping my eye in the viewfinder to find the best viewpoint. Using the Noga stands to hold the subject required that I take my eye out of the viewfinder to perform adjustments, which is a substantial loss. But it was definitely workable.

I could see this approach being used in the field, but would probably add at least a rudimentary X-Y movement from a microscope stage, in order to permit subject movement while looking through the viewfinder.

As a litmus test, I did a stack of a fern sorus with a 10x N Plan with continuous lighting, and then again with flash lighting. Both appear to be nice and sharp. It's too late at night for me to stack and PP these images, but in the fullness of time I will do so and post them.

In the meantime, I'd suggest that at least the smaller Noga stand makes a very nice subject holder, if one wishes to avoid a pile, mound, or dungheap of precise adjustment devices.

Cheers, and very best regards,

--Chris
Last edited by Chris S. on Mon Dec 13, 2010 3:36 pm, edited 1 time in total.

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