Search found 18508 matches

by rjlittlefield
Sun Oct 17, 2021 10:11 pm
Forum: Equipment Discussions
Topic: How good are alternatives (clones) to Mitutoyo lenses
Replies: 57
Views: 1272

Re: How good are alternatives (clones) to Mitutoyo lenses

Well, I certainly put my foot in it. I'm sorry, I didn't know; I meant no offense. :( Well, I for one am smiling. No offense taken, no apologies necessary. :D Here is a recent response that I gave to an interviewer regarding the question that you're asking: Periodically people ask me why they shoul...
by rjlittlefield
Sun Oct 17, 2021 8:10 pm
Forum: Equipment Discussions
Topic: How good are alternatives (clones) to Mitutoyo lenses
Replies: 57
Views: 1272

Re: How good are alternatives (clones) to Mitutoyo lenses

Were those mostly issues with chromatic aberration? I'd love to know what issues would be of most significance to look out for when inspecting the performance of an objective. The usual complaints that I see reported for used objectives are not CA, but lack of sharpness and related aberrations, oft...
by rjlittlefield
Sun Oct 17, 2021 8:03 pm
Forum: Equipment Discussions
Topic: Mitutoyo MPlan 5x vs Mitutoyo QV 2.5x Comparision
Replies: 29
Views: 356

Re: Mitutoyo MPlan 5x vs Mitutoyo QV 2.5x Comparision

I am a bit puzzled, usually if a sensor is spec'ed as 1/2 inch, it normally refers to diagonal dimension, then this (1/2 inch - 12.7mm) is a bit different from 8mm. From https://en.wikipedia.org/wiki/Image_sensor_format#Table_of_sensor_formats_and_sizes : Sensor sizes are expressed in inches notati...
by rjlittlefield
Sun Oct 17, 2021 4:19 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Hexamethyldisilazane (HMDS) -- a drying aid
Replies: 3
Views: 198

Re: Hexamethyldisilazane (HMDS) -- a drying aid

René, thanks for the comments and links. In searching the forum, I had noticed that you were the only person mentioning HMDS, so I had hoped you would add to this thread. The t-butanol technique is completely new to me. Quick search found what seems to be a good overview article at http://www.bio.um...
by rjlittlefield
Sun Oct 17, 2021 1:37 pm
Forum: Technical and Studio Photography -- Macro and Close-up
Topic: What is this fly with legs like a flea?
Replies: 17
Views: 574

Re: What is this fly with legs like a flea?

Megaselia scalaris Can it be the same specimen as this little fly that I captured in my house in Malaga (Spain) that was on an open melon? It was extremely small, as you can see on my hand I would bet pretty heavily that yours and mine are not the same species. For starters, yours has an obvious "c...
by rjlittlefield
Sun Oct 17, 2021 9:01 am
Forum: Equipment Discussions
Topic: Mitutoyo MPlan 5x vs Mitutoyo QV 2.5x Comparision
Replies: 29
Views: 356

Re: Mitutoyo MPlan 5x vs Mitutoyo QV 2.5x Comparision

RobertOToole wrote:
Sat Oct 16, 2021 9:40 pm
I did post the same images here on the forum but searching on the site and using google I cant bring up the post for some reason.
viewtopic.php?t=42949 ?

--Rik
by rjlittlefield
Sat Oct 16, 2021 6:58 pm
Forum: Technical and Studio Photography -- Macro and Close-up
Topic: What is this fly with legs like a flea?
Replies: 17
Views: 574

Re: What is this fly with legs like a flea?

I have a book on order: https://www.amazon.com/gp/product/041256520X "Scuttle Flies: The Phoridae" by H. Disney, 1994. Current list price $299 but out of stock. Amazon found me a copy in the UK for less than $30 including shipping. (No, they aren't offering any more for that price.) I'll report bac...
by rjlittlefield
Sat Oct 16, 2021 2:32 pm
Forum: Photography Through the Microscope
Topic: Linagilptin
Replies: 2
Views: 65

Re: Linagilptin

Linagilptin Nice crystals! I'm wondering, is the chemical perhaps "Linagliptin" ? (It's a slight spelling difference, and easily made. I was amused when searching to find that https://pubmed.ncbi.nlm.nih.gov/31811859/ says "linagilptin" in the title but not in the abstract, while the abstract has t...
by rjlittlefield
Sat Oct 16, 2021 10:46 am
Forum: Equipment Discussions
Topic: Mitutoyo MPlan 5x vs Mitutoyo QV 2.5x Comparision
Replies: 29
Views: 356

Re: Mitutoyo MPlan 5x vs Mitutoyo QV 2.5x Comparision

It feels like it shouldn't matter how much physical space there is in the infinity space but apparently it does in at least one system When thinking about telecentricity, calling that space "infinity" is a misleading over-simplification. It's important to realize that the space behind the objective...
by rjlittlefield
Fri Oct 15, 2021 10:52 pm
Forum: Equipment Discussions
Topic: Mitutoyo MPlan 5x vs Mitutoyo QV 2.5x Comparision
Replies: 29
Views: 356

Re: Mitutoyo MPlan 5x vs Mitutoyo QV 2.5x Comparision

Then again, relative comparison between two objectives, a deep stack can make it easier to tell which one is less telecentric (my dis-prove clarification) between the two. Sure, if you want to assume that both stacks are affected equally by possibly serious errors caused by too much OOF. Personally...
by rjlittlefield
Fri Oct 15, 2021 8:39 pm
Forum: Equipment Discussions
Topic: Mitutoyo MPlan 5x vs Mitutoyo QV 2.5x Comparision
Replies: 29
Views: 356

Re: Mitutoyo MPlan 5x vs Mitutoyo QV 2.5x Comparision

Telecentricity is determined by the location of the limiting aperture, as seen from the front of the lens. In most of the systems we work with, the limiting aperture will be within the objective, and in that case telecentricity depends only on the objective, not at all on the tube lens. In the case ...
by rjlittlefield
Tue Oct 12, 2021 10:20 pm
Forum: Photography Through the Microscope
Topic: Birefringence (Fluoresence!) of Anthraquinone Inclusions in Lobster Mushroom
Replies: 4
Views: 133

Re: Birefringence of Anthraquinone Inclusions in Lobster Mushroom

Hi Rik. Yes, you are almost certainly right. Duh. Alizarin excitation is green, emission red. I'll check it tomorrow to be sure. You know, cryptocrystalline birefringence was sounding good to me too, until I tripped over that bit about the "monochrome green". I'm glad you made that observation! --Rik
by rjlittlefield
Tue Oct 12, 2021 7:51 pm
Forum: Photography Through the Microscope
Topic: Birefringence (Fluoresence!) of Anthraquinone Inclusions in Lobster Mushroom
Replies: 4
Views: 133

Re: Birefringence of Anthraquinone Inclusions in Lobster Mushroom

The red color of the inclusions is essentially the same whether viewed using white light or monochromatic green. Do I understand correctly that you illuminate with green, but then observe red? If so, then I suspect that you're seeing fluorescence, red emission from a green excitation. Any non-absor...
by rjlittlefield
Tue Oct 12, 2021 1:50 pm
Forum: Nature Photography -- Macro and Close-up
Topic: Predacious Diving Beetle And Wasp
Replies: 2
Views: 111

Re: Predacious Diving Beetle And Wasp

I'm impressed you could get anything at all! I would have been more like "What just happened?"

--Rik
by rjlittlefield
Sun Oct 10, 2021 9:48 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Hexamethyldisilazane (HMDS) -- a drying aid
Replies: 3
Views: 198

Re: Hexamethyldisilazane (HMDS) -- a drying aid

Adding some sources, before I lose the URL's... https://en.wikipedia.org/wiki/Surface-tension_values https://lnf-wiki.eecs.umich.edu/wiki/Critical_point_drying https://lnf-wiki.eecs.umich.edu/wiki/Tousimis_915B_Critical_Point_Dryer https://en.wikipedia.org/wiki/Supercritical_drying https://en.wikipe...