Laser aiming and focus in photomacrography

A forum to ask questions, post setups, and generally discuss anything having to do with photomacrography and photomicroscopy.

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iconoclastica
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Re: Laser aiming and focus in photomacrography

Post by iconoclastica »

The 3V diode draws maximally 45mA, so the max power uptake is 135mW. Does this need a cooling body? The design could remain much simpler and more compact if the housing could be left out. Or perhaps replaced with a tightly fitting piece of aluminium tube.
--- felix filicis ---

Chris S.
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Re: Laser aiming and focus in photomacrography

Post by Chris S. »

Iconoclastica,
iconoclastica wrote:
Sat Sep 26, 2020 2:28 am
The 3V diode draws maximally 45mA, so the max power uptake is 135mW. Does this need a cooling body? The design could remain much simpler and more compact if the housing could be left out. Or perhaps replaced with a tightly fitting piece of aluminium tube.
Agreed that this small laser does not need a cooling body (though many larger ones do, of course). As I wrote in the original post, "The term “heatsink” is a misnomer here—we’re just using the item as a convenient mount—but “heatsink” is a useful search term."

I used the heatsink less for removing heat than as an inexpensive ($5.50 USD), convenient, premade part for adustably holding the laser. The heatsink also has a flat plate with pre-drilled holes, mounted parallel-to-the-laser's optical axis. This mounting plate made it trivial to mount it on my home-made eyepiece bracket.

If you have an approach that is simpler still, or even cheaper, I'd be delighted if you share it. More compact isn't a bad thing either, though I have had no problems with the size of my laser assembly.

Cheers, and I'd love to see your ideas,

--Chris S.

iconoclastica
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Re: Laser aiming and focus in photomacrography

Post by iconoclastica »

Chris S. wrote:
Sat Sep 26, 2020 11:28 pm
If you have an approach that is simpler still, or even cheaper, I'd be delighted if you share it. More compact isn't a bad thing either, though I have had no problems with the size of my laser assembly.
I have it in mind, but it still has to be demonstrated in real making. The diode is on its way from China, but our workshop is still closed due to covid. It may be some time, therefore..
--- felix filicis ---

physicsmajor
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Re: Laser aiming and focus in photomacrography

Post by physicsmajor »

I ordered a couple of these diodes and heatsinks/mounts. I'm going to experiment with 3D printing a mount for the heatsink, as well as just directly 3D printing a mount for the diode for Nikon.

If successful I'll post the STL files.

Pau
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Re: Laser aiming and focus in photomacrography

Post by Pau »

This is my version, much worse looking than the original by Chris but working well
Just a Chinese spare eyecup for my Canon DSLR, a 12mm diameter plastic tube wall fixation, some epoxy, a battery box and a switch.

IMG_0514br.jpg
IMG_0516br.jpg
IMG_0519br.jpg

I've observed that if I forget switching the laser off when measuring the light or taking the picture in automatic mode it absolutely fools the camera photometer, does it do the same with Nikon and other DSLRs?
Pau

Chris S.
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Re: Laser aiming and focus in photomacrography

Post by Chris S. »

Pau, what an elegant implementation! :D Thanks for posting it. Looks like a great approach for Canon bodies with similar eyepieces.

I'd not heard of "12mm diameter plastic tube wall fixation." Am glad to be aware of it now.

At present, I'm working on a version for another forum member. When finished, I think it would work on any brand or model of DSLR.
I've observed that if I forget switching the laser off when measuring the light or taking the picture in automatic mode it absolutely fools the camera photometer, does it do the same with Nikon and other DSLRs?
I, too, often forget to turn the laser off when shooting. However, since in the macro studio, I never use the light meter or shoot in automatic, this has never impacted exposure.

Higher-end Nikon camera bodies have a shutter to close the viewfinder. This is not necessary when one's eye is blocking light from the viewfinder, but is necessary for automatic-exposure shooting when one's head is away from the viewfinder, such as with some tripod work. Nikon is not alone in providing such a shutter, so I'd guess that the effect you're seeing is likely common to most brands.

--Chris S.

iconoclastica
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Re: Laser aiming and focus in photomacrography

Post by iconoclastica »

Here's the simplest design I could think of. The laser diode is forced into a tight fitting hole. Perhaps this is not up to long time usage and in that case I'll have to find a piece of aluminium tube that can be glued into the base.
laserpointer.jpg
The base is hooked to the viewfinder (Canon 7D) by two layers of acrylic sheet, 1 and 2 mm thick. Since this is dremel-art rather than laser cutter precission, I show the design here:
eyecap.png
--- felix filicis ---

JKT
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Re: Laser aiming and focus in photomacrography

Post by JKT »

How could this be made to work with mirrorless?

If the lens was directly supported (as opposed to being supported via camera) then it should be possible to create a system that attaches to the lens bayonet. So you'd first use the laser at the top (vertical) of the lens and when that seems OK you'd swap that to camera. This seem cumbersome, but I don't really see another way (except with a microscope setup with beam splitter). Should it work? If it should, how sensitive would it be to Z-axis placement off the laser?

Pau
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Re: Laser aiming and focus in photomacrography

Post by Pau »

JKT wrote:
Sun Oct 25, 2020 12:43 am
How could this be made to work with mirrorless?
In the DSLR setup the laser is focused at the mirror screen (optically at the same plane of the sensor) by the viewfinder optics.
I guess that if you shine the laser on a screen placed at that position it will work, maybe also without screen but still focusing the laser to the position where the sensor would be placed. I've just made a too crude handheld test with tracing paper as screen and it seems to work.

Of course this doesn't seem very practical.
Pau

Chris S.
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Re: Laser aiming and focus in photomacrography

Post by Chris S. »

JKT wrote:
Sun Oct 25, 2020 12:43 am
How could this be made to work with mirrorless?
I've given this considerable thought. My sense is that the laser should be placed in the infinity space between camera and tube lens. An implementation that appeals to me is a 45 degree mirror on a flip-out arm (flip out for laser aiming/focus, flip in out of the way for photography). I have an example of such a device (though for a different purpose), among some formerly expensive optical junk from Olympus, where it seems to work well mechanically. Pretty sure I could pull one of these assemblies out and integrate it into my Bratcam rig.

On the other hand, if wishes to add the availability of through-the lens axial illumination, then there is an argument to add a half-silvered mirror at a 45 degree angle, again in the infinity space, with the ability to switch between sighting laser and illuminating light. This approach and the one above are not mutually exclusive.

So conceptually, the idea seems simple enough. But in implementation, should I pursue an inexpensive approach that includes rare parts I've scavenged from junked equipment, plus some machining (likely easiest and cheapest for me)? Or a system built with off-the-shelf-parts from the likes of Thorlabs and Edmund optics (likely more expensive, but accessible to anyone who can afford to buy and assemble the parts, and not needing special tools and techniques)? Or design a tube-lens holder with integrated laser sight, with through-the-lens axial lighting as anavailable add-on, that could be manufactured and sold with plug-and-play ease at lower cost than the Thorlabs or Edmund assemblies? I'll admit that the first approach most matches my personal needs--or more precisely, the needs I would have if I used a mirrorless camera. (I don't have one at present.) But each of these three approaches has merit.

Comments?

--Chris S.

Chris S.
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Re: Laser aiming and focus in photomacrography

Post by Chris S. »

iconoclastica wrote:
Sat Oct 24, 2020 12:53 pm
Here's the simplest design I could think of. The laser diode is forced into a tight fitting hole. Perhaps this is not up to long time usage and in that case I'll have to find a piece of aluminium tube that can be glued into the base.
Iconoclastica,

Thanks much for posting your solution (pictured in detail several posts above). I think it a really valuable contribution to this thread. :D

--Chris S.

JKT
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Re: Laser aiming and focus in photomacrography

Post by JKT »

Pau wrote:
Sun Oct 25, 2020 1:09 am
Of course this doesn't seem very practical.
Can't argue with that. :)

Chris S.
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Re: Laser aiming and focus in photomacrography

Post by Chris S. »

JKT wrote:
Sun Oct 25, 2020 1:21 am
Pau wrote:
Sun Oct 25, 2020 1:09 am
Of course this doesn't seem very practical.
Can't argue with that. :)
Oddly, it seems eminently practical to me. Another solution would be to replace the lens tube (in an infinite system) with a cage system (such as available from Edmund Optics and Thorlabs) with a hole on top. Then just drop the laser into the tube (within infinity space, naturally) when needed. For shooting, pull the laser out and cover the hole.

The only thing that has kept me from building one of these implementations is that I lack a mirrorless camera.

--Chris S.

iconoclastica
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Re: Laser aiming and focus in photomacrography

Post by iconoclastica »

The beauty of the DSLR-laser combination is that it works with any objective. I am switching between finite, infinite and of the shelf lenses all the time. When using either finite or infinite objectives, a 90-degree side input can be easily made from a salvaged epi-illuminator. Even the very incomplete ones often offered on eBay would suffice. Axial ligthing comes with that solution for free, if one would want such a thing.
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JKT
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Re: Laser aiming and focus in photomacrography

Post by JKT »

Chris S. wrote:
Sun Oct 25, 2020 1:30 am
Oddly, it seems eminently practical to me.
Well, it is independent of used objective and practical in that way. On the other hand in vertical system like mine the removed camera body is a problem ... especially if I don't want to unplug shutter, USB and power cables. Horizontal system should be easier here.

If the required light is actually point source at the focal plane, a strong LED there might do as well. A small light cone would be preferable in order to get better intensity. Could be just enough ... or not. Alternatively a frame sized field of small LEDs would give you rough framing as well.

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