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A field rig (a bit of the Bratcam)

 
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Chris S.
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Joined: 05 Apr 2009
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Location: Ohio, USA

PostPosted: Sun Mar 27, 2011 7:08 am    Post subject: A field rig (a bit of the Bratcam) Reply with quote

Ah spring, when a young man's fancy lightly turns to thoughts of field macro. Smile

Since recent threads have touched on field rigs, I thought it might be useful to share mine. Those following the Bratcam will recognize this focus block, here configured for field use. (Since the Bratcam went motorized, this manual focus block pretty much sees only field use, but in the beginning, I intended it to do double duty.) The spring assembly has been added since prior posting.

This approach delivers solid mounting, precision, long travel, and convenience. It didn't cost much to make. When someone asks which focus rail to buy, my thought is, "Make your own--you'll end up with a better unit for less money." The long Arca-Swiss type plate allows adjustment for framing--even if I weren't stacking, I'd want something like this.



Here with the parts labeled. Key is below:


A. Tripod
B. Ball head
C. Quick-release Arca-Swiss compatible clamp
D. Arca-Swiss compatible plate (made by Chris Hejnar)
E. Kirk Enterprises 4-inch Arca-Swiss compatible clamp, mounted upside-down
F. Custom adapter plate made by fabricator Don Wilson (contact details in my signature)
G. Focus block cut out of Nikon microscope
H. Spring assembly to keep gears of focus block consistently intermeshed (made by Don Wilson)
I. Another adapter plate made by Don Wilson
J. Another Kirk Enterprises 4-inch clamp, this time mounted right-side up
K. Arca-Swiss compatible plate (probably made by Chris Hejnar—pulled out of my box o’ assorted plates).
L. Camera and macro lens


Close-up of the spring mechanism. As others have noted, microscope focus blocks work best with a little bit of pressure on them, as gravity would have provided in their original use. It doesn't take much--a rubber band will suffice. But my rubber bands kept slipping off, so Don Wilson added this spring assembly for me.



--Chris
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rjlittlefield
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Joined: 01 Aug 2006
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Location: Richland, Washington State, USA

PostPosted: Sun Mar 27, 2011 10:12 am    Post subject: Reply with quote

Chris, this is awesome work -- great concept and documentation.

I do have one question.

I notice that the spring is pulling the focus block backward. But often for field work the rail and camera will be pointing downward. When that happens, it seems like the spring will be opposing the weight of the camera, so that at some point the system will be balanced out so there's no net anti-backlash force, either up or down.

Have you found this to be an issue in practice, or is the balance zone so narrow that it never really matters?

--Rik
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Chris S.
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PostPosted: Sun Mar 27, 2011 11:28 am    Post subject: Reply with quote

Thanks, Rik.

Good point. What I do is orient the focus block in whichever direction lets the spring and gravity work together. For these pictures, the camera was aimed slightly upward, so the spring faces to the rear. With the quick-release clamps, I can flip around the camera, the block, or both in a few seconds.
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Craig Gerard



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PostPosted: Tue Mar 29, 2011 1:28 am    Post subject: Reply with quote

Chris,

What are your thoughts with regard to lighting when using this arrangement?


Craig
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conkar



Joined: 18 Dec 2010
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Location: Sweden

PostPosted: Tue Mar 29, 2011 10:55 am    Post subject: Re: A field rig (a bit of the Bratcam) Reply with quote

Chris S. wrote:
Ah spring, when a young man's fancy lightly turns to thoughts of field macro. Smile
--Chris


Hi Chris!

What magnification to you like to addend with this setup?

.... and what is the distance from the the bottom of B and top of the L (eg the surface of the tripod to the top of the camera)?

Best regards,

Conny
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Chris S.
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PostPosted: Tue Mar 29, 2011 10:42 pm    Post subject: Reply with quote

Short answers first Wink .

conkar wrote:
What is the distance from the bottom of B and top of the L (eg the surface of the tripod to the top of the camera)?

Conny, this distance is 35 cm (13.75 inches).

By the way, a friend who looked at this rig objected: “But it’s so tall!” She thought the lens would be separated from ground level by the height of the rig, and therefore be difficult to use for low subjects. However, this is not the case—the rig can be mounted upside down, beneath the tripod, all the way down to ground level.

Let me demonstrate:



I do generally avoid using tripods with center posts, and the center post on the tripod shown wobbles a bit. So one of the things on my project list is to make two adjustable arms for bracing the center post against tripod legs for upside-down configurations. But before I do that, I’ll probably buy yet another Gitzo carbon-fiber tripod (I currently have three—does this ever end?) so that I’m customizing around something I really like. The aluminum Bogen/Manfrotto tripod I pulled out for this shot is not horrible, but my Gitzo units are much better.


conkar wrote:
What magnification to you like to addend (you mean "attempt," right?) with this setup?

With the lens originally shown—a Nikon 200mm micro lens without tubes or diopters—I’m optically limited to 1x. However, by adding extension tubes or replacing the macro lens with a bellows-mounted lens, I can of course go much higher. With this focusing block on this tripod, I’ve found 5x to be pretty easy. I suspect that higher magnifications will work OK, but won’t test this until I have to. For anything above 1x, I much prefer to bring the specimen into the studio, where there the wind is absent, the light-control complete, and the automated, super-stable Bratcam ready.

That said, the time will surely come when I can’t bring an important subject back to the studio—let’s suppose that a rare and crustose lichen is found growing on a gravestone. In that case, I’m of course not going to chisel it off and bring it home. I’m pretty sure that 10x will be doable with this rig, though more aggravating than it would be in the studio. And I suspect that 20x would be possible, though frustrating. For that, I’d probably bring sandbags and move to a heavier tripod than the Gitzo 1325 shown in the first photos in this thread. The limiting factor would not be the focus block, camera, or optics; it would be the tripod, wind, and potential subject movement (zero with the lichen-on-gravestone example, but distinctly non-zero with plenty of other subjects).


Craig Gerard wrote:
What are your thoughts with regard to lighting when using this arrangement?

Craig, I have tons of thoughts on lighting. . .as I’m sure, you do also. I'll list a few, here.

If I’m out on an overcast, windless day, I really like available light for subjects that permit it. In that case, I’m likely to bring reflectors, diffusers, gobos, and cookies (if the latter two terms are unfamiliar to anybody, think of them as shadow-producing, light-blocking items; where the light doesn't fall is every bit as important as where it does fall). If I’m shooting on a clear, windless morning or evening with low-angled sun, I’ll delightedly work with it using the same sorts of light modifiers.

For the other times, when one has imperfect light or wind and simply has to get the job done, here are several quickly-shot examples. Please bear with me, as there is very little yet to shoot in north-eastern Ohio, and so there are no worthy subjects in these examples. With the coming of spring, much will change in a few weeks.

Soft boxes: Here are Nikon Speedlights behind inexpensive Alzo soft boxes, on lightweight Impact stands, with Manfrotto umbrella holders to permit aiming the light. The Alzo boxes have just a single layer of diffusion material, and don’t soften the light enough for my tastes, so I have an extra piece of white rip-stop nylon clamped in front. With that modification, the light is nicely soft. One of these days, I’ll replace the binder clips with hook-and-loop fastener strips (many people would say "Velcro strips"--but Velcro is a registered trademark of Velcro Industries B.V., and similar generic materials are available). Also, I’d like to make some grids for them. The wireless flash triggers are inexpensive Yongnuo units, which so far work well.




For a more portable rig, I have Wimberley arms that clamp to the Arca-Swiss compatible Hejnar plate. Since the guts of the Wimberley arms are just RAM mounting parts, I might someday try making my own, as the Wimberley’s are in my opinion overpriced. This shot is for example purposes—in real life, I’d almost always add diffusion.



The eagle-eyed may notice three odd things in this group of images. One, I should have aimed the focus-block spring down, instead of up—oops! Two, note how much light spills into the lens hood. This was interesting to me, as I don’t normally get to see my own macro setups from this angle—though maybe I should. I think I’ll add flocking to the inside of this hood. Three, though the wireless flash triggers are shown, the transmitter is missing. Why? It’s on the camera I’m using to take these shots.


The A-S plate is a really good platform on which to clamp the Wimberley arms. On my to-do list is to add more arms for holding a background light and light modifiers such as diffusers, gobos, and cookies. If this requires more room, I’ll just use a longer A-S plate.




Since in this example setup, I’m showing the rig with a collarless 105mm macro lens, here is an illustration of how I mount the camera by its L-plate with an AS-compatible adapter. I find it a great convenience to have all of my tripods (and other support equipment), cameras, and footed-lenses set up for AS mounting—everything is compatible and quick to attach and detach. The particular AS adapter I show here, between camera L-bracket and Hejnar plate, comes from a company I prefer not to endorse for humanitarian reasons--I purchased the items I have from them prior to my awareness that they use their profits to hurt people they disapprove of. So I've removed their logos from my images. Similar products to this adapter are available from Chris Hejnar, Sunwayfoto, and Arca-Swiss. If you want details, PM me.




Last but not least, the “deli tub.” This one is shown from different angles; I have several cut in different configurations, but this one is my favorite. The tubs are of white, translucent plastic, and are easy to get from the delicatessen counter of a grocery store—the section where they sell potato salad, etc. This one has a hole cut in it for the camera, an area left uncovered for blasting with a flash, and reflective aluminum foil to bounce the flash’s light around. As you can see, I took a great deal of time and care in making this item. . . Wink Actually, I hacked it out in about two minutes when on assignment and faced with an urgent deadline and an unexpected need. But it’s since served me well for years. NB that the flash should not be placed flush against the tub, which results in little diffusion. All or much of the uncovered area of the tub should be hit with the flash. I keep meaning to make one of these with an attached arm for the flash, and a built-in focusing light—haven’t gotten around to it.

The deli tub:


There are a couple of other things on the project list for field macro lighting:

1) Adapt an approach similar to Graham46 and Tonygt19’s “Styrofoam cup diffuser” for field use. I’ve been using similar approaches—usually with additional gobos and cookies—very happily in the studio, and would like to have a field-portable approach, which doesn’t seem difficult at all. By the way, I must call it a “polystyrene cup diffuser,” having attended an interesting talk by a representative of the Dow Chemical Company, which owns the trademark “Styrofoam,” in which it was kindly but clearly noted that these cups are not made of the trademarked product.

2) Make a white, rip-stop-nylon light tent for field use. There are commercially-available ones, but none with all the features I want.

Cheers,

--Chris
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conkar



Joined: 18 Dec 2010
Posts: 200
Location: Sweden

PostPosted: Sun Apr 03, 2011 9:54 am    Post subject: Reply with quote

Chris S. wrote:
Short answers first Wink .

conkar wrote:
What is the distance from the bottom of B and top of the L (eg the surface of the tripod to the top of the camera)?

Conny, this distance is 35 cm (13.75 inches).
--Chris


Thanks Chris for the informations and sharing.........

It looks like a nice setup you build with the stands and lightning.

I think one of my own concerns when I building my setup it's the height, so by curiosity I measured the setup I use right now and it's near your numbers - I hit 33cm with some Novoflex equipment and a stackshot. So I'm glad to hear that your setup work out well.

In the laws of gravity I start the stacking a bit behind the center of the tripod. I have made a bracket with weights beneath the head of the tripod to balance the weight (B). I think that weight should be equal or more of the weight over head of the tripod (B) to get the setup as stable that it could be.

Regards,

Conny
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