MicrobeHunter.com Microscopy Forum

I connect a flash and a lamp at the base of the microscope using a beam splitter. When using the lamp everything seems fine but whenever I use the flash the images come out blurred in one direction. I tried swapping the beam splitter ports, using live view vs regular shooting but the problem persists to a different extent. Any clue as to whats causing it and how to fix the situation?

Maybe because your flash is a relatively large, asymmetric, source

... whereas the lamp appears to have centring and focusing adjustments.

As a first try, I would put a mask [and probably a diffuser] over the flash; to convert it into a smaller diameter, circular source.

MichaelG.
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P.S This link [which I have posted previously, but could not locate that post] is worth a look:
http://www.micrographia.com/articlz/art ... pc0300.htm

Edit: managed to locate that post, once I searched for 'micrographia' instead of 'flash' !!
viewtopic.php?f=24&t=5930&hilit=micrographia&start=30

I wonder if the position of the flash filament is the problem.

In Charles Krebs' setup he made sure that the flash filament was on the same plane as the bulb's filament in order to be able to achieve Köhler.

http://www.krebsmicro.com/microsetup2/index.html

You also may need to add an additional field stop to the flash unit (see link below)

https://www.nikon.com/products/microsco ... /index.htm (click on Koehler illumination)


An additional thought: Could it be flashing twice?

Is the shutter synced or open, just flashing for exposure.

The faint bands above all the edges might be caused by movement during exposure. Other than that, try putting a diffuser into the flash light-path. Another thing to try is substituting a hand-held led flashlight for the flash unit, and move it around laterally at the flash's normal position, to see (through the eyepieces) if you can duplicate the shadow or striation effect you are getting.

Thanks eveyrone for the suggestion and advice. I took a shoot with the flash turned on but it was under the table and 100% of the light was provided by the centered lamp. The result was blurred. Same shot but with the flash turned off and no more blur. Also given the sound of the shutter when using flash and the direction of blur generally following the movement of the shutter mechanism I am now convinced its not an optical thing but rather vibration induced by the shutter mechanism.

Interesting result, Wes
... But how do you take the 'lamp' exposures ?
... Do you not use the camera shutter for those ?

MichaelG.

Wes wrote: Also given the sound of the shutter when using flash and the direction of blur generally following the movement of the shutter mechanism I am now convinced its not an optical thing but rather vibration induced by the shutter mechanism.

Can you provide a photo of your setup?

How are shutter vibrations transmitted to the flash ? The camera is fairly remote from the illuminator.
Perhaps the synchro signal to the flash interferes (electronically) with the camera exposure mechanism ?

Hi Wes,
both fotos, lamp and flash seem to have a gradient. Was it oblique illumination? DIC.
Try to setup camera to 1/200s and not shorter. Also try the manual settings at Camera not ETTL. Anyway sharing the camera & flash setting would also help to clarify.

Exactly; if the flash is off-center and the lighting is thus not optimal, than the camera auto-exposure may be using too long of an exposure, picking up vibration.

Can you put a light block; a simple black card, piece of foam or some other stop behind the beamsplitter and see if the problem persists? I wonder if the flash is reflecting around and travelling backwards through the beamsplitter, then reflecting off the illuminator reflector and forward again.

ImperatorRex wrote:Hi Wes,
both fotos, lamp and flash seem to have a gradient. Was it oblique illumination? DIC.
Try to setup camera to 1/200s and not shorter. Also try the manual settings at Camera not ETTL. Anyway sharing the camera & flash setting would also help to clarify.

Well this is my first time experimenting with an external flash in photomicrography and I used the standard settings i.e ETTL and first curtain sync with 1/100s. I followed your suggestion and it seems to get better, manual settings in live view mode seems best so far.



MichaelG. wrote:Interesting result, Wes
... But how do you take the 'lamp' exposures ?
... Do you not use the camera shutter for those ?

MichaelG.

In this case I had the shutter open in live mode with the camera controlled from the computer. I carefully focus and the take the shot with the mouse which I lift off the table and wait for a few seconds for all vibrations to disappear. I don't know why but when the flash was ON even though it was under the table the camera made a much louder noise and the subject was blurred which is why I thought its not a light issue but rather something to do with the mechanism.

75RR wrote:Can you provide a photo of your setup?

Here it is.

Wes wrote:... In this case I had the shutter open in live mode with the camera controlled from the computer. I carefully focus and the take the shot with the mouse which I lift off the table and wait for a few seconds for all vibrations to disappear. I don't know why but when the flash was ON even though it was under the table the camera made a much louder noise and the subject was blurred which is why I thought its not a light issue but rather something to do with the mechanism.

I am not familiar with your camera. but that seems a very logical deduction.
Apologies if I have missed the vital bit of information; but what model of camera are you using ?

MichaelG.

The camera is Canon 50D and the flash is Speedlite 430EX II.

Hi Wes,
I would slowly start investigation of the issues. Since both fotos shows a kind of oblique illumination effect first try to figure out where this effect comes from.
a) directly attach the lamp to the microscope without any Adapter. Then make fotos with Canon utilities with Life-view. Check the fotos if there is any issue.
b) try to eliminate the isse with the oblique illumination effect with the lamp attached to the adapter. Bye the way is it the Zeiss Winkel Beam Splitter? Remove the flash when doing the anlayse, so leave the port open. Are you happy with background illumination in the sample? Is it without grandients?

Until you have confirmed that you are sure that the light path and illumination with the lamp and Zeiss-adaptor is working well I would not even start to analyze the flash optimization. Again your first foto with the lamp and the adopter does not look right for me, so this would be the first step to look at.

Wes: Having said not to look a flash-fixing, just few questions did you switch of the pilot light when doing the foto with the flash? 1/100 is still long enought to let the pilot light to pass through? I usually set 1/200s and reduce the pilot light. The flash power is set manually and should be a fraction of the max. power, e.g. 1/16, 1/32...to keep the flash duration short. Its a quick try and error to find a reasonable value.

Ah sorry ImperatorRex I forgot to include it in my previous post. The gradient effect is from DIC where I use unmatched components (63x/1.4 slider with a 40/0.95 CZJ apochromat). And this is the Carl Zeiss beamsplitter.

Wes wrote:The camera is Canon 50D and the flash is Speedlite 430EX II.

Thanks, Wes ... Have donned my thinking cap !

MichaelG.

Hi Wes,
OK. Does the flash allows you control/set the flash power manually? I had a Speedlite 380 in the past and it does not allow, so it was one of the reason not to use anymore. ETTL mode is difficult to controle and start with.
Maybe a quick check without the beam splitter, manually holding the flash directly to the stativ flange. This check shall help to conclude if issue is related in using the beam splitter or not.

Yes I can control the flash output manually. I will try your suggestion to omit the splitter and just manually align the flash to the light port. With regards to the manual flash setting, if I understand correctly, the lower the flash output the faster the image capture would be meaning less chance for vibrations sneaking in. If that is correct I would swap the positions of the flash and lamp on the beam splitter (assuming the issue is not with the splitter) so now the flash can use the 70% port instead of 30% as I had it so far.

Yes, the less power, the lesser flash duration. Switching the flash lamp position will better support that. The exposer time at the camera itself is not that critical, but if you leave the "pilot light/lamp" on you should probabely setup to 1/200s, so the dimed pilot light is not captured in the image.

Wes,

Have a look at this page:
https://photographylife.com/what-is-ele ... in-shutter
... particularly the comments by Shane Castle.

MichaelG.

MichaelG. wrote:Wes,

Have a look at this page:
https://photographylife.com/what-is-ele ... in-shutter
... particularly the comments by Shane Castle.

MichaelG.

That is interesting !! sounds very relevant for the present issue, but important even if it is irrelevant.

Yes thank you MichaelG. This is great especially the videos as I can now clearly picture what the mechanical cycles are like.

I think I figured out why I was getting the blur initially (the first photos I posted). As I had the flash set to E-TTL the mirror cycle would have to be completed for the camera to get the pre-flash exposure reading. So the momentum of the mechanical cycle would generate the blur which is parallel to the direction of cycling.

I think this article explains why I'm having issues http://www.krebsmicro.com/Canon_EFSC/

I think its time to roll out the 100W lamp.

Perhaps a temporary separate stand for the camera (if only to rule out vibration) would clarify things.

My camera kicks like a mule so I have it on a tripod - it looks more cluttered than it actually is.