Flash setup for Zeiss Standard microscope (now Mk II)

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Pau
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Post by Pau »

soldevilla wrote:Have you considered a flip mirror instead a beam splitter? You will achieve twice light with the same flash.
Yes, you're right, I know your clever mirror based setup, but the goal is to have simultaneous view through the eyepieces (or computer screen) while shooting, this is important to capture moving critters like protozoa, not so much with static subjects like prepared slides or minerals, but its also useful during manually driven stacking. I have enough light to fire the flash at 1/4 or less power.
Pau

Pau
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Post by Pau »

JohnyM wrote:Do you have any idea how to synchronize it with camera? I was thinking of doing so, but have no clue how to sync it. Or if you think of manual thing, it's unpractical.
Very easy: I use a (pictured) dedicated TTL flash cord that connects the camera and flashgun shoes, with all the electric contacts. With Canon Utilities I can control the flash power and other functions from the computer.
In fact I can also control the unit wirelessly as slave with the camera built in flash, but the cord is more practical. If you use a generic manual or not dedicated flash unit, you can also use a standard X sync flash cord.
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zzffnn
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Post by zzffnn »

Thank you for this thread, Pau.

I stole your idea and made something similar, using the Surplus Shed 40mm prism cube that you referred to me. The main difference between my rig and yours is that I switched around the LED and flash, and I have no cage /mount for the prism cube. I simply aligned everything.

Basically, I lay my heavier LED flat, stand my flash on mini tripod or books, then point the diffused flash tube down as close as possible to the prism cube. The silver surface of the flash tube has surface area of around 20mm * 40mm.

I am guessing that is about good enough for my Nikon Optiphot's field lens/aperture (which opens at around 40 mm max). If I put two flashes there, both would be off center by a lot, as the flash tubes only reside at the very center of flash head surface. I cannot get two flash tubes any closer, unless I take them out off the flashes.

My flash has no collimator lens, just a diffusion sheet. I would use it at widest angle (around 28-35mm, if I remember correctly) and put it as close as possible to the prism cube.

My DIY LED has its own diffusion and collimator lens of the right strength. By itself without the prism cube, it works for my Optiphot perfectly.

There is no (collimator or diffusion) lens after my Optiphot's field diaphragm, other than that of LED's.

I just want to report here and thank Pau. I won't be able to test the set-up soon, as I will be traveling. But the prism cube worked perfectly fine directly under condenser, on top of field lens, for high NA darkfield. I suspect by placing it after field diaphragm, I will get more even illumination and lose slightly more lumens. A good trade off.
Selling my Canon FD 200mm F/2.8 lens

Pau
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Post by Pau »

Hi zzffnn,
Thanks for your kind words. It would be nice to see your results and setup here or (better) at a new thread when you have time to post them.
Pau

Pau
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Post by Pau »

Now the Mark II version that allows true Köhler

The idea and components are mostly the same but the LED is much more adequate and both the LED and flash tube are closer to the prism. It's also more compact and strong.

The components labeled
Image

The flashgun plastic lenses have been removed because in some cases they produce bands and because now the prism beamsplitter cube can protrude inside to be almost in contact with the tube reflector housing
Image

The components mounted. Inside the control box there is a 250V AC to 12V DC transformer and a Luxdrive 2100mA constant current driver dimmed with a 20K logarithmic pot to feed the Cree XM-L2 4500-5000K LED
Image

Mounted on the focusable collimator lens at the Zeiss WL microscope
Image

Frontal view of the flash tube firing through the prism, despite being very powerful the LED light is clearly surpassed by the flash light pulse fired at 1/128 power
Image

The rear focal plane imaged at Köhler with a Bertrand lens in the light path.
Both the LED surface and the flash tube are almost perfectly focused and fulfill the rear focal plane. A prism beamsplitter a bit smaller would allow to perfect focus but this works well with evenly illuminated field with both light sources.
Image
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zzffnn
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Post by zzffnn »

Beautiful work, Pau! Thank you for sharing.
Selling my Canon FD 200mm F/2.8 lens

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