Search found 986 matches

by hans
Thu Mar 28, 2024 7:30 am
Forum: Microscopes and optics
Topic: Do I need another objective?
Replies: 36
Views: 1136

Re: Do I need another objective?

I’ve wondered about the formula that suggests that when condenser NA is lower than Objective NA the result is an average of the two. Intuition suggests that NA should revert to the lower of the two. Does anyone know if there is a mathematical basis for the averaged formula? I wondered the same thin...
by hans
Thu Mar 28, 2024 2:31 am
Forum: Microscopes and optics
Topic: Field number vs. field stop diameter in "negative" eyepieces
Replies: 0
Views: 23

Field number vs. field stop diameter in "negative" eyepieces

Quick follow up question/clarification regarding: ... The FN is the field diaphragm of the eyepiece. ... (I never understood where the positive/negative terminology for this classification of eyepieces comes from, but anyways...) In a Huygens eyepiece, for example, where the field lens before the fi...
by hans
Wed Mar 27, 2024 5:02 pm
Forum: Microscopes and optics
Topic: Leica Reichert Jung Polyvar (models)
Replies: 86
Views: 34497

Re: Leica Reichert Jung Polyvar (models)

No , we aren't talking apples and apples. ... I will rephrase that because either I jumbled the words or you misunderstood them. A 15X/20 eyepiece produces an image circle that is the same size that a 10X/30 eyepiece would produce. I don't think it can ever be apples to apples unless you specify mo...
by hans
Wed Mar 27, 2024 4:30 pm
Forum: Microscopes and optics
Topic: Leica Reichert Jung Polyvar (models)
Replies: 86
Views: 34497

Re: Leica Reichert Jung Polyvar (models)

Only if the camera was in my eye. The image circle at the enrance to the eye is 20mm. If you hold a quarter out at arms length it will obscure the moon but if you bring it right close to your eye it will obscure a third of the sky. I thought this 20 mm was some physical measurement you personally h...
by hans
Wed Mar 27, 2024 6:27 am
Forum: Microscopes and optics
Topic: Leica Reichert Jung Polyvar (models)
Replies: 86
Views: 34497

Re: Leica Reichert Jung Polyvar (models)

Of course. You are viewing the exit pupil from what, 10 inches away with a camera lens. I don't know where uou have your screen. My point was that the apparent field your eye sees right st the cornea is 20mm. Put the scale at your eye. The strip of lens paper being projected onto is at the exit pup...
by hans
Tue Mar 26, 2024 8:32 pm
Forum: Microscopes and optics
Topic: Leica Reichert Jung Polyvar (models)
Replies: 86
Views: 34497

Re: Leica Reichert Jung Polyvar (models)

Ok, so to clarify: The entire theory revolves around the 10X eyepiece. The descriptions of how the F.N. system works are carried out using a hypothetical 1X objective and 10X eyepiece. Measure the exit pupil of a 10X/20 eyepiece and see what you get. Only with the 10X eyepiece can you easily and qui...
by hans
Tue Mar 26, 2024 5:31 am
Forum: Microscopes and optics
Topic: Leica Reichert Jung Polyvar (models)
Replies: 86
Views: 34497

Re: Leica Reichert Jung Polyvar (models)

First question: ...and the 4/5/7 reflect the height index 4 in the first position supports a 25mm FN eyepiece, the 5 is 22mm FN the 7 supports a 20mm FN. All intermediate image components, those that mount between the objective ba and the tube lens. had a corresponding height index number and and su...
by hans
Sun Mar 24, 2024 9:45 pm
Forum: Microscopes and optics
Topic: Leica Reichert Jung Polyvar (models)
Replies: 86
Views: 34497

Re: Leica Reichert Jung Polyvar (models)

I think the confusion is here: If you measure a 20 F.N.field viewed through a 10X eyepiece at your eye : the actual diameter of the viewed field, with a transparent scale or ruler right as the image enters your eye, it will measure 20mm. ... A 20mm F.N. with a 15X eyepiece will measure 30mm and a 20...
by hans
Sat Mar 23, 2024 11:33 pm
Forum: Microscopes and optics
Topic: Leica Reichert Jung Polyvar (models)
Replies: 86
Views: 34497

Re: Leica Reichert Jung Polyvar (models)

Since the FN discussion started with what is considered "supported" I would point out that in this example: It is a system that is base 10, so it doesn't represent the real field vs. apparent field circmstance for a 15X or a 5X eyepiece intuitively. An easier way to visualize it is if the 15X eyepie...
by hans
Mon Mar 11, 2024 1:38 am
Forum: Microscopes and optics
Topic: What are these square-lobed 4- and 6-sided screw heads used in the Reichert 410 Microstar IV?
Replies: 9
Views: 2480

Re: What are these square-lobed 4- and 6-sided screw heads used in the Reichert 410 Microstar IV?

The tiny set screws that fix tube length on the nonadjustable eye tube on are the same 4-flute 0.048" McMaster 7048A12. The four screws holding the shroud covering the IPD adjustment are 6-flute 0.060" McMaster 7048A65. I don't remember if there are any others on the series 10 heads. I also have a 6...
by hans
Wed Jan 10, 2024 9:23 am
Forum: Microscopes and optics
Topic: Correction Collar : Leitz [surprise]
Replies: 11
Views: 12630

Re: Correction Collar : Leitz [surprise]

I would guess "image sharpness" is referring to focus not spherical aberration and this is pointing out an advantage of their implementation compared to older or less sophisticated implementations where the correction adjustment changes focus at the same time? It would be an "ideal method of focusin...
by hans
Mon May 08, 2023 8:06 pm
Forum: Beginner's corner
Topic: - Scope Over Time -
Replies: 2
Views: 1438

Re: - Scope Over Time -

The acquiring, cleaning, learning, and repairing journey is half the fun to me. Same here, my general advice would be: The "Frankenstein" microscope idea doesn't really work as well as one might hope, and as imkap said, forget about buying a bunch of individual parts. Sometimes there are deals but ...
by hans
Mon Mar 13, 2023 11:35 pm
Forum: Microscopes and optics
Topic: Olympus E A40 0.65 160 Objective Haze
Replies: 26
Views: 3988

Re: Olympus E A40 0.65 160 Objective Haze

With a drop of Cargille Immersion Oil Type B directly on slide and coverslip on top. Looks sharper, at least. Still not great contrast but I'm not sure what is expected for that objective. The different colors of the chromatic aberration on the left and right sides of the image (more red and cyan o...
by hans
Sun Mar 12, 2023 7:58 pm
Forum: Microscopes and optics
Topic: Olympus E A40 0.65 160 Objective Haze
Replies: 26
Views: 3988

Re: Olympus E A40 0.65 160 Objective Haze

40X 0.65 should give a pretty bad (but maybe not that bad) image if used with no cover glass. Might be worth sticking a 0.17 mm cover glass on top of the micrometer slide with a small drop of immersion oil to get an idea how much of the haze is from the objective itself vs. lack of cover glass.
by hans
Thu Jan 05, 2023 5:26 am
Forum: Microscopes and optics
Topic: Did I jusr stumble on a simple solution ?
Replies: 16
Views: 3058

Re: Did I jusr stumble on a simple solution ?

Interesting observation, I suppose the effect should be somewhat analogous to using a phase telescope or Bertrand lens for alignment, except of course it can't actually be used for phase alignment since it comes before the objective. What sort of water filter did the beads come from?
by hans
Tue Nov 01, 2022 5:03 am
Forum: Microscopes and optics
Topic: the scale on the condenser's aperture
Replies: 27
Views: 4888

Re: the scale on the condenser's aperture

I don't think I can understand that statement. The NA is the product of the RI and the sine. Mathematically it is easy to prove that NA <= RI * sin(theta) is always true, so the NA can never be greater than the RI Yes, maybe I misunderstood the question, if the the NA set by the condenser aperture ...
by hans
Sun Oct 30, 2022 4:15 pm
Forum: Microscopes and optics
Topic: the scale on the condenser's aperture
Replies: 27
Views: 4888

Re: the scale on the condenser's aperture

the NA is defined as a sinusoidal function of the top angle of the light cone The sinus is maximal (1.0) when that angle equals 90°, when the NA equals RI. How can the condenser 'know' which media are applied? NA is not affected by the media applied to the condenser if the the selected NA is less t...
by hans
Fri Jul 22, 2022 5:55 am
Forum: Microscopes and optics
Topic: Looking for information on this Bausch & Lomb Microscope
Replies: 5
Views: 1704

Re: Looking for information on this Bausch & Lomb Microscope

Looks close to these Cambridge Instruments and Leica branded "StrataLab" models on eBay:
https://www.ebay.com/itm/312568716638
https://www.ebay.com/itm/224445518547
by hans
Tue Apr 19, 2022 2:51 am
Forum: Camera systems and imaging
Topic: B&L Stereozoom Photography ?
Replies: 85
Views: 32857

Re: B&L Stereozoom Photography ?

If the adapter is somehow blocking off a significant portion of the aperture (leaving only an offset sliver near the periphery) maybe that could explain both the dimmer view and the lack of radial symmetry in the CA that Scarodactyl mentioned?
by hans
Tue Apr 19, 2022 1:30 am
Forum: Camera systems and imaging
Topic: B&L Stereozoom Photography ?
Replies: 85
Views: 32857

Re: B&L Stereozoom Photography ?

Bram, were those all taken with the same exposure settings? Oddly the full image through the camera port looks noisier to me but I don't notice much noise difference in the 100% crops.
by hans
Sun Feb 13, 2022 8:32 pm
Forum: Pictures and Videos
Topic: Endoplasmic reticulum visible with phase contrast?
Replies: 12
Views: 4578

Re: Endoplasmic reticulum visible with phase contrast?

Yeah, I think Lomonaut and I were seeing microplicae as described in the papers linked in post #5. The photos in the 1960 paper linked in the first post are the only examples I found claiming to show the endoplasmic reticulum with phase contrast. I couldn't access the 1958 paper by Fawcett and Ito t...
by hans
Fri Feb 11, 2022 10:43 pm
Forum: Collecting microscopes and slides
Topic: Bad slides
Replies: 15
Views: 7330

Re: Bad slides

Yeah I have a set I bought used on eBay (don't know the original source but the slide labels and wood case look identical to the ones sold by AmScope and others) that has the granules real bad:
viewtopic.php?f=10&t=10885
by hans
Fri Feb 11, 2022 10:04 pm
Forum: Pictures and Videos
Topic: Endoplasmic reticulum visible with phase contrast?
Replies: 12
Views: 4578

Re: Endoplasmic reticulum visible with phase contrast?

Yeah, they are not always visible, or maybe not all cells have them over large areas? I looked through quite a few cells to find the examples above where the fingerprint-like pattern is visible and in focus simultaneously over a relatively large area. I measured roughly 500 nm spacing between the ri...
by hans
Fri Feb 11, 2022 8:54 pm
Forum: Microscopes and optics
Topic: Intermitent lamp issue.
Replies: 5
Views: 2227

Re: Intermitent lamp issue.

Oh, one other consideration: are the microscope, camera power supply, computer, monitor, and anything else connected to them via cables all plugged into the same power strip? Worth trying that too if they are not already.

Beautiful microscope and video quality, by the way, even with the flicker.
by hans
Fri Feb 11, 2022 7:05 pm
Forum: Microscopes and optics
Topic: Intermitent lamp issue.
Replies: 5
Views: 2227

Re: Intermitent lamp issue.

Unfortunately the flicker occurs periodically and at settings that otherwise function perfectly. When the problem occurs it's visible at all combinations of FPS, Exp, ISO and at lamp brightness levels. This seems like pretty good evidence against the flicker coming from the illumination. Maybe elec...
by hans
Tue Feb 08, 2022 7:21 pm
Forum: Pictures and Videos
Topic: patterns on cheek cell membrane
Replies: 6
Views: 2584

Re: patterns on cheek cell membrane

I also wondered about these patterns while setting up some phase contrast stuff I bought a while back. My first guess of endoplasmic reticulum was almost certainly incorrect then after some more searching I was thinking maybe microplicae: https://www.microbehunter.com/microscopy-forum/viewtopic.php?...
by hans
Fri Aug 06, 2021 4:36 am
Forum: Microscopes and optics
Topic: Condenser corrections aplanatic, achromatic, etc. -- which planes are they referring to?
Replies: 71
Views: 28391

Re: Condenser corrections aplanatic, achromatic, etc. -- which planes are they referring to?

Shined a flashlight through some more condensers. Various AO/Reichert "Abbe aspheric" and achromatic/aplanatic condensers from several generations in brightfield mounts all projected the iris sharply near infinity. The 1205 turret with 1201 achromatic/aplanatic condenser was interesting, lots of var...
by hans
Thu Aug 05, 2021 9:01 pm
Forum: Microscopes and optics
Topic: Condenser corrections aplanatic, achromatic, etc. -- which planes are they referring to?
Replies: 71
Views: 28391

Re: Condenser corrections aplanatic, achromatic, etc. -- which planes are they referring to?

A camera with lens focused at infinity looks at the slide; the slide has a row of small pinholes, spaced ~1.2mm to each other. The condenser illuminates the slide from below, with iris closed to minimum. if the illumination is not parallel/telecentric, we'll see many "bokeh balls", for each pinhole...
by hans
Thu Aug 05, 2021 5:23 pm
Forum: Microscopes and optics
Topic: Bausch & Lomb 4mm 1.00 water immersion objective
Replies: 11
Views: 6289

Re: Bausch & Lomb 4mm 1.00 water immersion objective

Yeah after looking at some more stuff, definitely corrected for dipping I think. Changing illumination to get closer to filling the objective aperture and using a test subject that is darker overall with some bright spots (black permanent marker on the frosted end of a slide) makes the spherical abe...