Search found 28 matches

by st_m
Wed Aug 02, 2006 10:45 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Post Processing
Replies: 1
Views: 14182

Hello! Although I know, many people prefer the flexibility of RAW foramts, I nearly always use JPEG. Wity my (now old) D100, it was absolutely necessary to set it to its highest quality JPEG. There are three settings, "fine", "norm", "basic". This is independent from pixel number, which could be set...
by st_m
Thu Jul 20, 2006 1:23 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Ruthenium Red
Replies: 1
Views: 13801

Ruthenium Red

Does anyone have experience with the dye ruthenium red? In which concentration should it be used? And dissolved in water? Diluted ammonia?
Thanks, Steffen
by st_m
Thu Jun 29, 2006 5:39 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Canon EOS Rebel XT...First impressions.
Replies: 3
Views: 15802

Well, that's with all this electronics stuff. The cheaper, the worse (but not the other way round, the more expensive, the better). There is so much competition (in price) today, that they all use the cheapest ever available components for all and everything. Eventhough their engineers know it bette...
by st_m
Wed Jun 21, 2006 1:47 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Aperture shape
Replies: 3
Views: 16182

Aperture shape

I have a thechnical question again: Does anyone know, how the shape of the aperture diaphragm affects the image? Well, of course, if it's close to a circle, it shouldn't have too much influence, and just changes the "bookeh" of a photograph a bit. But I wanted to know, what happens physically to the...
by st_m
Wed Jun 21, 2006 1:36 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Photo multiplier
Replies: 2
Views: 14532

Now my circuit is running... Actually, I have first tried the 3-transformer-50Hz-solution. But the frequency was too low to get a smooth output with an acceptable capacitor value. So I finally built a SMPS with an inductive step-up-converter. Yes, it works! 1200V with no load and no post-regulation,...
by st_m
Wed Apr 19, 2006 1:09 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Photo multiplier
Replies: 2
Views: 14532

Photo multiplier

I have a question again: Is there an expert about photo multiplier tubes and the corresponding high voltage electronics? Two days ago, I have tried to build a 300 - 1000 V power supply for such a tube. Has anyone done that before? My problem is, I cannot decide, which design I should use. I tried to...
by st_m
Wed Apr 19, 2006 12:54 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Aperture
Replies: 11
Views: 32149

I have done the experiment again. With a much larger photodiode (BPW20R), and an op amp circuit with high gain. http://www.photomacrography1.net/images/BPW20R.jpg I used the same objective lens (4*, NA = 0.2). The ratio I have measured now is about 1:722 (average of 5 measurements, all carefully don...
by st_m
Fri Apr 14, 2006 3:01 pm
Forum: Photography Through the Microscope Gallery
Topic: pollen
Replies: 1
Views: 3707

pollen

A pollen particle of a narcissus.

Image
400x, brightfield

I post that image, because I would like to know, what are the yellow spots? They can be found in / on most of them.

Any idea? Thanks!

Steffen
by st_m
Sat Apr 08, 2006 2:31 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Aperture
Replies: 11
Views: 32149

For a first try, I used this tiny cute photodiode (BPW32): http://www.photomacrography1.net/images/BPW32.jpg Its active area is 0.97mm^2. I reverse-biased it with 6.00V, and measured the current through it. In a dark room, it showed 0 (on a digital instrument with 100nA resolution). Put at the top o...
by st_m
Sat Apr 08, 2006 1:44 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Aperture
Replies: 11
Views: 32149

Yes, I have already prepared a photodiode which has a photo current proportional to the incident light intensity over many orders of magnitude. Will try soon.

Steffen
by st_m
Sat Apr 08, 2006 12:43 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Aperture
Replies: 11
Views: 32149

Thanks a lot! I was just wondering, could it be, that the image brightness is so much less than the brightness of the specimen? Well, 1/10000 is a bit pessimistic, as I have never seen a 10* objective with a NA of 0.1. A value of 0.3 would be more realistic, but still... But probably it is true, and...
by st_m
Fri Apr 07, 2006 12:25 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Aperture
Replies: 11
Views: 32149

Thanks for your answer. I have now read the article above. Well, that gives some insight. Actually, the reason why I asked this question is, I wanted to know how the typical photographic f-stops relate to the NA of a microscope objective lens. And still about the absolute image brightness. Even if t...
by st_m
Fri Apr 07, 2006 8:20 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Aperture
Replies: 11
Views: 32149

Aperture

I have a question regarding the aperture value of a photographic lens: Does anyone know, what the numerical value (e.g. f/2.8) means? What is its physical meaning? Is it true, that the projected image (in the film / CCD sensor plane) has a brightness of 1/2.8 of the surface brightness of the subject...
by st_m
Thu Mar 23, 2006 9:54 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Camera settings readout through flash cord
Replies: 1
Views: 12618

Camera settings readout through flash cord

I have a question: When I set my SB800 flash on any camera, I can read the settings (ISO, focal length of the lens according to which it automatically zooms its own reflector, aperture and (calculated) maximum subject distance) in the display of the flash. These data have to be transferred from the ...
by st_m
Tue Mar 21, 2006 10:31 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: New Plan Fluor lens
Replies: 3
Views: 16039

Well, but it's not especially designed for DIC. The "M" means "medium aperture (0.5 - 1.0; because of slider)", and "N" Nomarski. What's the "2" for, I don't know. But I don't use it for DIC (although I would like, but have a look how much brand new Nikon DIC equipment is). There are no other flouri...