Search found 69 matches

by Asha
Mon Dec 19, 2016 9:47 pm
Forum: Equipment Discussions
Topic: Mitakon 20mm f/2 4.5X Super Macro Lens
Replies: 50
Views: 14887

I just saw the announcement, and am highly intrigued because I have a full-frame DSLR! Looks like B&H carries the brand, but there is no listing yet.
by Asha
Sat Nov 26, 2016 1:03 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Best Photoshop spot removal options for stacking?
Replies: 19
Views: 5199

. . . a new-ish program for Mac OS (not sure if that is what you use). It is called Affinity Photo. Thanks, Asha. Affinity Photo sounds like excellent software, and I devoutly wish it wide acceptance. Adobe’s coercing users into eternal-payment bondage opened up a hole that I hope competitors will ...
by Asha
Wed Feb 03, 2016 9:18 am
Forum: Equipment Discussions
Topic: 3d printed linear stage
Replies: 20
Views: 6544

ChrisR wrote:Is there a translucent colourless material one could use?

... transmitted light... :P
And a hole big enough to put a fiber optic light! ;)

I'm very impressed with the design and detail--great work!
by Asha
Mon Feb 01, 2016 6:57 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Beating the diffraction limit
Replies: 9
Views: 1810

mawyatt, I looked at the article again--it shows the measured profile in Figure 1, with the rings at <1um FWHM. They probably can get away with a less stringent setup than what we've been discussing (the same figure also shows a "High NA objective") ;)
by Asha
Mon Feb 01, 2016 5:29 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Beating the diffraction limit
Replies: 9
Views: 1810

Rik, a couple more thoughts about the diffraction limit...at my work, we routinely use infrared wavelengths. Since diffraction physics is wavelength dependent, these systems reach the diffraction limit quite easily, even with optical mirrors that have visible machining marks which would destroy imag...
by Asha
Mon Feb 01, 2016 5:14 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Beating the diffraction limit
Replies: 9
Views: 1810

mawyatt, when I posted, I couldn't remember the name, but it is a micro-lithography lens. It is basically like a giant microscope objective used in reverse, and for very small features, they tend to use the blue to UV spectrum. I'm not even sure if the materials used for high UV transmission would p...
by Asha
Mon Feb 01, 2016 12:32 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Beating the diffraction limit
Replies: 9
Views: 1810

Yes, they don't claim to exceed the diffraction limit that I could see. They did address the issue of dispersion--they used a broadband laser to etch the features in the lens, and also did some testing to see if the flexible mounting material could be controlled to improve focus. Interesting tidbit ...
by Asha
Mon Feb 01, 2016 12:02 pm
Forum: Equipment Discussions
Topic: LED choice for video using microscope
Replies: 23
Views: 2692

Does the brightness (power) difference between the two emitters mean that the spectral response of the 6000K LED is shifted upwards compared to the lower power 3000K emitter? If so, would this mean that the CRI difference would effectively not be as great? By brightness (power) do you mean luminous...
by Asha
Mon Feb 01, 2016 11:37 am
Forum: Equipment Discussions
Topic: LED choice for video using microscope
Replies: 23
Views: 2692

I am wondering if the article should be read with caution--the camera he used has a Bayer filter (2 green, 1 red, 1 blue in a block pattern). Cameras with different kinds of sensor designs (eg a stacked sensor such as Foveon) may not behave the same way. This article should not be taken as universa...
by Asha
Mon Feb 01, 2016 11:31 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Beating the diffraction limit
Replies: 9
Views: 1810

Maybe for monochromatic light. As a diffractive optical element, it would probably have a grating effect, causing chromatic dispersion in broad-band light. That would have to be compensated, somehow, if it were to be put to general use.
by Asha
Mon Feb 01, 2016 9:13 am
Forum: Equipment Discussions
Topic: LED choice for video using microscope
Replies: 23
Views: 2692

Andy--my opinion is that you should still go for the higher CRI bulb with the 2600-3700K balance. the reason is that the spectral curve has much better output across the spectrum. As Bushman.K said--look for better reds and not so bad greens :)
by Asha
Mon Feb 01, 2016 9:06 am
Forum: Equipment Discussions
Topic: LED choice for video using microscope
Replies: 23
Views: 2692

And here is an article on the same topic, but written from a bit different point of view - regular photography with daylight (high CRI and high color temperature light source). It gives certain illustrations of histograms without suppressed green and with it. In case of LEDs, we don't need to suppr...
by Asha
Sun Jan 31, 2016 8:26 pm
Forum: Equipment Discussions
Topic: LED choice for video using microscope
Replies: 23
Views: 2692

Thanks for your response, Bushman.K! Between yours and Rik's posts, plus my own experience, it seems to me that the shift in light temperature would be easily compensated for, without too much loss in the perceived color "truth". In addition, just thinking about the Planck curve for varying Kelvin, ...
by Asha
Sun Jan 31, 2016 6:23 pm
Forum: Equipment Discussions
Topic: LED choice for video using microscope
Replies: 23
Views: 2692

Bushman.K--doesn't the camera internal software compensate for the spectral response of the sensor? The sensor rarely has the same spectral sensitivity as human eyes, and because it is Silicon, is heavily weighted toward the red and near infrared (Our eyes are optimized to green).
by Asha
Sat Jan 30, 2016 2:26 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Masking help
Replies: 7
Views: 1487

Here is a tutorial for masking hair in CS6, but this would work in other PS versions as well. The trick is to use the highest contrast channel, put the content into a spare channel, and boost contrast of the new channel with levels or curves. http://www.dummies.com/how-to/content/how-to-mask-hair-fu...