Telemicroscopes

Have questions about the equipment used for macro- or micro- photography? Post those questions in this forum.

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MaxRockbin
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Telemicroscopes

Post by MaxRockbin »

I'm sure this is old hat to many, but I had never seen such a thing before:

http://www.company7.com/questar/microscope/qm100.html

This is a lens capable of 34x at the image plane at 15cm with 1.1 micron resolution N.A. 0.142

Sensor size? The PDF brochure linked to at the bottom of the page shows field of view for a 2/3" CCD. But the picture on the page I linked to shows the lens on a DSLR (of course, it might just be sharp in the center 2/3" of the sensor).

One note in the PDF is "helical baffling" in the central tube. Maybe it's just easier to manufacture than parallel baffles at the same interval as the helix "threads." Or maybe there's some advantage to the baffle not being perpendicular to the front of the lens.

I don't know how practical this lens is for typical photomacrography. For studio use, the extra w.d. is a luxury not generally worth the expense and lower optical quality vs a normal objective. For field use? It might be ideal if you're trying to photograph, say, a mineral inside a dark crevice (it has a coaxial illumination option). But otherwise, I'm not sure where it would be needed. Questar suggests it's handy when you need to shoot through a transparent window - like inside a furnace or a test tube.

Anyway, fun to read about!

If you want to buy one, the closest thing to pricing I found is this similar device (which looks like it's probably a whole self contained microscope/camera setup) on ebay for $14,500. Plus shipping.

http://www.ebay.com/itm/like/2619799842 ... ps&lpid=82
If your pictures aren't good enough, you're not close enough. - Robert Capa

soldevilla
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Post by soldevilla »

Questar is a old, well know mak telescopes maker. And high priced.

I have tested (for fun) playing with my very high quality russian Maks. Only is needed unscreew a screw for to wide the focusing range. Because all are mirrors, no CA are show. But for me too much workimg distance :D

Some time ago I found mirror objective for microscope. I feel that they have very high quality, but I suspect that it is very far of my VISA :(

http://www.newport.com/Reflective-Micro ... /info.aspx

rjlittlefield
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Post by rjlittlefield »

soldevilla wrote:Some time ago I found mirror objective for microscope. I feel that they have very high quality, but I suspect that it is very far of my VISA :(

http://www.newport.com/Reflective-Micro ... /info.aspx
I tried using a reflective objective like that one, a long time ago, and found that it would be very difficult to use in my application. The diagram looks great, but it only shows the light rays that you want to use. With diffuse episcopic illumination, the objective also lets through a bunch of light rays that you do not want to use. Those cause a huge problem with veiling glare, sort of like failing to block the ring of a BD objective. I'm sure they would be fine with properly structured illumination, or for laser focusing which seems to be one of their main applications.

I assume the Questar comes properly masked so that problem is solved by the designer, not the user.

--Rik

g4lab
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Post by g4lab »

The mirror objectives have been around forever and often appear on fleabay. They are widely used in FTIR and Raman spectroscopy to minify the probe spot. They are supposed to be pretty free of chromatic aberration because they are mirrors. But you do see the central obstruction very clearly in the out of focus images.

I have never tried a Questar LDM though a lab I worked in had one once. The professor that owned it would bite your head off if you even thought about looking at it so I left it alone.

I do have a 3.5 inch Questar telescope. It is really wonderful because it sits on an elevator tripod originally intended for a view camera and whenever there is something I want to see I just pick it up and carry it outside to my front walk and turn off the porch light. Although I love the quality of it they used to have a slogan that "the telescope you use is the best one" and Questars are very usable.

I think they can be converted to LDMs with a parts substitution but it might be the corrector plate which would be expensive and probably a big deal. The closest I have tried to focus it is across the street which it does amazingly well.

MaxRockbin
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Post by MaxRockbin »

This Questar does seem to be a somewhat different animal than the Newport reflector objectives. For example, 6" working distance (!) vs 10mm at 30 odd x magnification on sensor.

Also, it is catadioptric - so some part of the system is using refraction.

Rik, regarding your comment about stray light and glare, at least someone has put a lot of thought into the subject regarding this category of lens. I ran across the term "telemicroscope" (which lead me to the Questar) when I saw a patent for annular baffles for telemicroscopes:
https://www.google.com/patents/US5121251

There also seems to be quite a lot on the subject of baffle design for reflector telescopes of various designs (NASA has a blurb about exotic baffles in the Hubble, but other than a simplistic sketch, I haven't found any details). One interesting baffled design proposal for telescopes suggested the idea of using curved surfaces (ellipses and hyperbolas) instead of flat baffles inorder to reflect stray light hitting them back more or less the way it came.
If your pictures aren't good enough, you're not close enough. - Robert Capa

rjlittlefield
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Post by rjlittlefield »

MaxRockbin wrote:a patent for annular baffles for telemicroscopes:
https://www.google.com/patents/US5121251
This patent has the flavor that makes my teeth grind. What the fellow has actually invented is probably very original and clever. But what the patent office has allowed to slip through is a Claim 1 that appears dangerously close to being violated by any microscope that has an LWD objective and a baffle anywhere in the barrel. The only saving grace would be that in an ordinary microscope the "front lens" does not fit "within the circumference of the barrel". Sigh...

--Rik

MaxRockbin
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Post by MaxRockbin »

Here's a patent I think you'll find more interesting (and less frustrating):
http://www.google.com.py/patents/US4542963

It's a "specular" baffle design by a NASA scientist. It doesn't work quite the way I thought. The diagrams make it clear. Light bounces back and forth between an elliptical vane and a flat vane (the front of the next vane down the tube) and ultimately back where it came from. Pretty neat.

Apparently, there are several of these reflective baffle designs:
http://proceedings.spiedigitallibrary.o ... eid=997633
Benefits and drawbacks of specular baffles, which are being investigated as an alternative to the standard diffuse black baffle, are summarized. An overview of four specular baffles designs, the elliptical baffles, Linlor baffle, bielliptical baffle, and Lockheed-Stavroudis baffle, is given.
(I'd post the whole abstract, but they have a copyright notice warning not to do that. So this is an excerpt for review purposes. If that's inappropriate - please delete).

NOTE: This design was intended for an infrared telescope, so maybe not optimal where heat isn't an issue. The patent notes that optical blacks don't necessarily absorb infrared well and in any case heat from absorption can be a problem. I ordered the proceedings book, so maybe the whole article will explain when these baffles make sense...

(EDIT: Added Note)
If your pictures aren't good enough, you're not close enough. - Robert Capa

rjlittlefield
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Post by rjlittlefield »

MaxRockbin wrote:Here's a patent I think you'll find more interesting (and less frustrating):
http://www.google.com.py/patents/US4542963
Good call on both counts. That's a very nice piece of work!

From the patent:
This invention relates to an optical system incorporating a plurality of reflective baffles which return incoming off axis rays from the optical system. More particularly, it relates to such an optical system incorporating reflective baffles which prevents off axis rays in infrared wavelength regions from reaching a focal plane of the optical system, without absorbing such infrared rays to a significant extent. More particularly, it relates to such an optical system especially adapted to receive infrared images and which is cooled with liquid helium or other suitable cooling means.
The requirement to block without absorbing is not one that I would expect in an ordinary optical system.

For a general discussion of baffles, with some useful links, I am reminded of the old posting HERE.

--Rik

soldevilla
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Post by soldevilla »

g4lab wrote:I think they can be converted to LDMs with a parts substitution but it might be the corrector plate which would be expensive and probably a big deal. The closest I have tried to focus it is across the street which it does amazingly well.
As is well know for all owners of SCT telescopes, the way to modify the point of focus is to vary the distance between the front element (meniscus or Schmidt lame and secondary mirror) and the main mirror. In my MTO russian telelens there is a screw as limit of helical focuser. Take this screw off and the focus can be extended to receive an eyepiece and convert the telelens in a great telescope. The telescope was designed to focus to infinite, but... later I will take my 500/8 MTO and test it as micro photo lens. Only for fun, again.

dolmadis
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Post by dolmadis »

I am sure that we will all wish to hear more about your test...........

Regards


John

zzffnn
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Post by zzffnn »

One may want to note that the Questar QM 100 is $50k new and $10k used. My first reaction after reading a bit about this thing was, cool, how much is this toy (I would consider buying it)? Then, I went, OK...hmmm........maybe later.

There are a few other professional options at >$3000 used, if you have that much toy fund.

A more affordable hobbyist (not professional) option is a close focusing binocular - Pentax Papilio 8.5x21 or 6.5x21 for around $130. Much less resolution and magnification, but very portable and convenient for chasing live insects/ants. Close focus is 300 mm. Many forum members have version I or II of this binocular macroscope.

One can put diopter in front of normal binoculars, but focusing is difficult that way. Not very practical if one is chasing an insect.

I have an Orion 10-25x 42 monocular that close focus to around 300 mm too. But its focusing mechanism is too stiff and view is too dim at over 20x. So much so that I rarely use it.

Alternatively, one can of course buy a dissecting microscope with long working distance (100 mm -150 mm typical) and articulating arms. Cost is typically >$250. Most of those would be heavy (>= 9 lbs) and not portable.
Selling my Canon FD 200mm F/2.8 lens

soldevilla
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Post by soldevilla »

Just a quick tests.

I have extended until the end of the thread my MTO 500/8, and working at aprox. 60cm I have a macro x1 (+/-). My test bench is only some blocks of wood and the image is not focused, but as espected, no CA. for people that take photos of insects in the nature, can be interesting... for mineral samples, not too much :D

Image

Later I have unmounted the two optical parts and tested how grow the magnification. However, the two parts are not aligned (remember my test bench :P ) With 10 cm aprox of work distance, 4mm. fill all the image. The image I obtained is very bad, a lot of scattered light, But I´m sure that machining a part for to have the primary mirror and the secondary mirror aligned. the MTO can offer nice images. But too much work for a test that I no use for mineral samples.

soldevilla
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Post by soldevilla »

And is not really necessary a Questar for to have a great maksutov lens. The russian MTO 100/10 is a very high quality Mak. I have used it for my images of the Sun and Moon, and visually as a great, small planetary portable telescope until 250x.

Image

g4lab
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Post by g4lab »

I love using the Questar to look at sunspots. I need to make an umbrella with a hole in it. Watching the transit of venus a while back was a hoot.
"Just like on tv!" :lol:

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