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Reflex camera Vs compact camera!
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Charles Krebs



Joined: 01 Aug 2006
Posts: 5805
Location: Issaquah, WA USA

PostPosted: Tue May 17, 2011 11:30 am    Post subject: Reply with quote

Arturo,
Quote:
Than, if i understand, freezing the movement of microorganisms depend not much of exposure to the flash but by duration of it.

Exactly. And if you have checked to be sure that the microscopes continuous light is at a level that does not also record an image, then the image is created only by the light from the electronic flash. And in that situation, the motion/vibration "stopping" ability is only determined by the flash duration. The lower the power level, the shorter the flash duration (with many of this type of unit the duration range will be something like 1/700 second to as short as approx 1/40000 sec). On some flash units it is possible to manually set a specific power level. With the 220EX flash you are using, you can't set the power level manually, but the duration does change in the same way with "auto" flash exposure.

I'm not saying that there will be no use for "High Speed Sync" with a microscope set-up. But since you have control over the microscope continuous light source you will generally be better off not using it. The power level (amount of light the flash emits) is much less in "High Speed Sync" mode.

Here are two clips from the 220EX manual. In the first clip you can see that the full power guide number (a measure of the total light output) is 22m/72.2 ft (ISO 100). The High-Speed Sync guide number, when the shutter speed is set to 1/2000 second is only 3.8m/12.5 ft (ISO 100). This means that the total possible light output is 5 stops (32X) less!




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arturoag75



Joined: 05 Feb 2010
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PostPosted: Wed May 18, 2011 12:55 am    Post subject: Reply with quote

Hi Charleie,
I understud what you mean .... I do not know because I was convinced that the shutter was the main element.... will try later and lat you know it!...
many thanks again
arturo
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arturoag75



Joined: 05 Feb 2010
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PostPosted: Tue Nov 08, 2011 9:01 am    Post subject: Reply with quote

hi,
I open again this post to update you on developments ......
few days ago i got the original microscope adapters for my scope and an old Canon EZ 540 flash and i'm doing tests with it applied in place to the big lampehouse of Zeiss Photomicroscope.. this way is observed of Kohler illumination (at least partially).
This unit allows to reduce power up to 1 / 128 with a flash of very short duration but strong enough for normal observations in DIC and phase contrast ... also has a zoom function that allows you to move the bulb.
I placed a spotlight as a pilot light , a semireflecting mirror in front of the flash bulb and a diffuser filter..
I attach some test images obtained with this unit ....
if you have quastions i answer as soon as possible!
best
arturo

Flash unit in place of lampehous

frontal view

very fast moving of nematode frozen

euplotes

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Pau
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Joined: 20 Jan 2010
Posts: 4913
Location: Valencia, Spain

PostPosted: Tue Nov 08, 2011 4:26 pm    Post subject: Reply with quote

Arturo, thanks for postiing your setup.
I'm very interested in it because I'm going to make a flash setup for my Zeiss Standard for DIC, so I have some questions:
- Do you use the optics in the Zeiss 100w lamphouse or just the ones inside the microscope?
- Does the Ikea LED lamp provide enough light to visually use the scope with DIC and high magnification like in your posted last picture?
- May you provide a clearer picture of the attachement of the flash and mirror to the scope?
- Is the flash unit complete or did you remove the plastic difuser to focus the tube in Köhler?
- Does the camera allow any automatic function of this Canon flash or it's just like to use an old manual flash? (and what camera, powershot or EOS?)
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arturoag75



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PostPosted: Wed Nov 09, 2011 12:54 am    Post subject: Reply with quote

Hi Pau,
here the answers:
1 My zeiss PM is equipped whit two illuminator, one rear the base (100w) and a big lampehouse on top ( for halogen, HBO XBO etc.); i use just this by removing the big cover you have the Kolher lens group fitted on scope and you can fix the flash unit just there..this way kolher illumination is ok.

2 Yes the led is ok and you have enough light also in DIC and PH whit 100x objectives but in this case a darkened room is recommended.

3 This is an attempt to test it and base must be improved .. but here is how it should be



4 no i removed flash diffuser.

5 Camera canon 600d allow only manual mode and you have to set manually power of the flash..

hope this help you!
is you have quastions i'll answer as soon as!
best
arturo
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Pau
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Joined: 20 Jan 2010
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PostPosted: Wed Nov 09, 2011 9:52 am    Post subject: Reply with quote

Arturo, many thanks for your clear and detailed aswers.
Now, another question:
Did you tested your Canon 220EX with this setup?. I may be interested in this little unit (or 270EX) because it can be fully controled both in automatic and manual modes from the camera (and computer if tethered).
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arturoag75



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PostPosted: Wed Nov 09, 2011 12:24 pm    Post subject: Reply with quote

Hi,
yes i tried 270 ex but this is very low power unit to make good job whit high magnification DIC and Phase applications....the 540 ez is very low expensive now(i bought it for 45 Euro) and a very powerfull unit..in same cases you can shot whit it at 1/128 of full power (only 1/64 on the 270 ex)whit a good amount of light .
i had a 220 ex but, if i remember good, it don't allow manual power set .
hope this help
best
arturo
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Pau
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PostPosted: Wed Nov 09, 2011 2:26 pm    Post subject: Reply with quote

Thanks again Arturo, it's very helpful.
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