Search found 715 matches

by hans
Thu Mar 04, 2021 6:54 pm
Forum: Microscopes and optics
Topic: AO 20x comparison
Replies: 11
Views: 244

Re: AO 20x comparison

I opened the images in tabs to compare while flipping back and forth but they are the same ones as in the first post -- files got mixed up?
by hans
Thu Mar 04, 2021 6:47 pm
Forum: My microscope
Topic: My very first compound microscope!
Replies: 21
Views: 275

Re: My very first compound microscope!

I trialled a Chinese made 60X .80 planachro and the image quality isn't good enough. The contrast is poor and it wasn't well corrected to the periphery. It also suffered from terrible centering, a common plague of the internet hawked Chinese microscopes and their objectives. Same with a 20X I tried...
by hans
Wed Mar 03, 2021 6:18 am
Forum: Microscopes and optics
Topic: Olympus U-DICT versus U-DICTS
Replies: 16
Views: 172

Re: Olympus U-DICT versus U-DICTS

From the linked earlier discussion: John, do you have any idea how large the angle theta can be before it starts to seriously degrades image quality? In theory I could move the default position of the objevtive prism even higher up than it is now, which could help me get DIC with my 4x objectives as...
by hans
Wed Mar 03, 2021 4:59 am
Forum: Microscopes and optics
Topic: AO 20x comparison
Replies: 11
Views: 244

Re: AO 20x comparison

The 1077 and 2556 were nearly equal, I could rotate the turret between the two and the focus was nearly identical... This is establishing that the parfocal distance (nominally 34 mm) is the same. Could try measuring working distance directly using the scale on the fine focus knob while carefully lo...
by hans
Wed Mar 03, 2021 3:29 am
Forum: Microscopes and optics
Topic: AO 20x comparison
Replies: 11
Views: 244

Re: AO 20x comparison

Regarding working distance, for the objectives that specify 0.17 mm cover glass, it would the clearance between the objective and the surface of the cover glass. Not sure if you were taking that into account already, or if it would be enough to explain the discrepancy you are seeing, though.
by hans
Wed Mar 03, 2021 3:04 am
Forum: Pictures and Videos
Topic: Triceratium antediluvianum
Replies: 4
Views: 126

Re: Triceratium antediluvianum

Nice video. I did a google image search to try to get a better idea of the 3D shape and your video is already the 11th result. Are these fairly rare?
by hans
Wed Mar 03, 2021 2:51 am
Forum: Microscopes and optics
Topic: AO 20x comparison
Replies: 11
Views: 244

Re: AO 20x comparison

Might be worth trying with cover glass to see how much difference it makes for the 1022 and 1077. There is very little difference at 10X 0.25 but the difference is obvious at 40X 0.66. Not sure about 20X 0.5. Do you have any immersion oil? I usually stick a piece of cover glass to the calibration sl...
by hans
Wed Mar 03, 2021 2:15 am
Forum: Beginner's corner
Topic: Compound Microscope for Gross Anatomy Observation?
Replies: 32
Views: 489

Re: Compound Microscope for Gross Anatomy Observation?

Good to hear it is working out, looked pretty clean in the photos in the listing. You could get the 4X and 100X for starters to fill out the nosepiece, those came standard on most configurations, I think, and should not be too difficult to find or expensive. The 4X is nice for finding stuff in water...
by hans
Wed Mar 03, 2021 1:45 am
Forum: Microscopes and optics
Topic: Zeiss Neofluar 40x0.75 objectives: phase vs non-phase performance in BF, Oblique, DF
Replies: 5
Views: 124

Re: Zeiss Neofluar 40x0.75 objectives: phase vs non-phase performance in BF, Oblique, DF

Interesting comparisons. It looks like there is contrast inversion of some features comparing between the plain/PH2 and BF/OL images of PetrHum. Any thoughts whether that would just be due to variation in focus point you mentioned, or could be related to phase ring in the PH2 objective? Are the imag...
by hans
Mon Mar 01, 2021 8:14 pm
Forum: Beginner's corner
Topic: Compound Microscope for Gross Anatomy Observation?
Replies: 32
Views: 489

Re: Compound Microscope for Gross Anatomy Observation?

Humor me, what are the obvious things? Just all the mechanical stuff, that everything operates smoothly throughout the full range with minimal backlash. In particular, there should be almost no perceptible backlash in the fine focus -- it should reverse direction as soon as you start turning the kn...
by hans
Mon Mar 01, 2021 7:06 pm
Forum: Microscopes and optics
Topic: I don't really understand these objectives
Replies: 3
Views: 141

Re: I don't really understand these objectives

Is it possible you are seeing two different reasons for not being able to focus the objectives below and above 20X -- running out of mechanical travel in the focus mechanism at lower magnifications, higher magnifications could theoretically be focused but the image still appears hazy/indistinct due ...
by hans
Mon Mar 01, 2021 6:47 pm
Forum: Beginner's corner
Topic: Compound Microscope for Gross Anatomy Observation?
Replies: 32
Views: 489

Re: Compound Microscope for Gross Anatomy Observation?

Nice, that one has the hard-to-find 20X plan achro. Note that since it is listed as used it is guaranteed "fully functional" and the seller has to pay return shipping within 30 days (or negotiate a partial refund) if there is anything wrong, so check it out carefully as soon as you get it to take ad...
by hans
Fri Feb 26, 2021 10:51 pm
Forum: Home-made microscope adaptations
Topic: AO Cycloptic Illuminator
Replies: 3
Views: 116

Re: AO Cycloptic Illuminator

Looks nice and bright. I have an old fiber optic ring light I use but the fan in the light source is annoying, LED would be nice.
by hans
Fri Feb 26, 2021 10:42 pm
Forum: Microscopes and optics
Topic: AO Industrial Series
Replies: 6
Views: 130

Re: AO Industrial Series

dtsh wrote:
Thu Feb 25, 2021 1:55 pm
...I had missed that blurb.
Easy to miss the many blurbs scattered around the site. I remembered seeing it when I was considering buying an EpiStar a few months ago. If you decide you don't want the no-cover objectives let me know, I have some interest in looking at electronic stuff.
by hans
Fri Feb 26, 2021 10:39 pm
Forum: Beginner's corner
Topic: Help to decode my objectives specifications Thanks
Replies: 6
Views: 152

Re: Help to decode my objectives specifications Thanks

It looks like that model Celestron 44341 does not have a condenser so it may not be easy to get the full performance of a better-corrected, higher-NA objective.
by hans
Fri Feb 26, 2021 10:36 pm
Forum: Microscopes and optics
Topic: Anyone know how to fix this?
Replies: 5
Views: 169

Re: Anyone know how to fix this?

If the bearing surface in the tube extends deep enough maybe another option would be to drill it out oversize to some depth, to get clearance to put a sleeve over the break without having to precisely turn down the shaft?
by hans
Fri Feb 26, 2021 10:33 pm
Forum: Microscopes and optics
Topic: DIC Prisms
Replies: 3
Views: 111

Re: DIC Prisms

Cool, what package? I messed around with pyoptools some but haven't done anything interesting with it yet.
by hans
Fri Feb 26, 2021 10:28 pm
Forum: Microscopes and optics
Topic: Back Focal Plan of Olympus BX Objectives
Replies: 7
Views: 98

Re: Back Focal Plan of Olympus BX Objectives

Looks like at least some of the ones you are interested in are given on Olympus's web site, UPLFLN20X for example specifies BFP position -19.1 mm:
https://www.olympus-lifescience.com/en/ ... 06530.html
by hans
Thu Feb 25, 2021 5:18 am
Forum: Microscopes and optics
Topic: A small tip for users of Bausch & Lomb.
Replies: 7
Views: 149

Re: A small tip for users of Bausch & Lomb.

apochronaut wrote:
Tue Feb 23, 2021 12:49 pm
Off and on the repair entailed cleaning off caked on mascara from the eyepieces.
So they put in these fine ridges to scrape off and collect the mascara before it makes it to the lens...?
by hans
Thu Feb 25, 2021 2:07 am
Forum: Microscopes and optics
Topic: AO Industrial Series
Replies: 6
Views: 130

Re: AO Industrial Series

There is this attributed to Gregg Kleinberg on the "AO History" page of P.S. Neeley's site: The AO 3000, which was a modular "industrial body" with reflected light, was based on the Series 10 architecture. The only main difference was that the higher power objectives were not cover slip corrected. T...
by hans
Tue Feb 23, 2021 5:01 am
Forum: Camera systems and imaging
Topic: Are photo eyepieces needed?
Replies: 23
Views: 2129

Re: Are photo eyepieces needed?

If the eye ball is placed at the point of focus just above the eyepiece why does this not work for a naked camera sensor? Because the eye has a further lens arrangement that expands the image onto the retina? Yeah, that's correct. In effect the tube can only illuminate 49% of the sensor making it a...
by hans
Tue Feb 23, 2021 4:54 am
Forum: Microscopes and optics
Topic: A small tip for users of Bausch & Lomb.
Replies: 7
Views: 149

Re: A small tip for users of Bausch & Lomb.

Yeah, thanks, this is good to know. I carefully removed the lower shrouds (one was already loose when I got the microscope) when cleaning but didn't go any further. Now the 10X Huygens eyepieces... how long does it take to get used to these? The short eye relief is actually not nearly as uncomfortab...
by hans
Tue Feb 23, 2021 4:45 am
Forum: Home-made microscope adaptations
Topic: Micro-cam or Web-croscope
Replies: 15
Views: 351

Re: Micro-cam or Web-croscope

...check that the webcam is not a black and white. Whenn I put the lens the right way on the cam I get some colour meaning that the driver I use is ok. Strange, ImageMagick indicates the image is greyscale: hans@uganik ~/Downloads identify -verbose comptage_levures_webcam.jpg Image: Filename: compt...
by hans
Sat Feb 20, 2021 6:16 am
Forum: Illumination Techniques
Topic: Anyone try one of these LED setups?
Replies: 3
Views: 1226

Re: Anyone try one of these LED setups?

I bought a few things from that seller (the WF10X/22 eyepieces Scarodactyl reviewed, calibration slide, some reticles) and the quality seemed fine.
by hans
Sat Feb 20, 2021 6:07 am
Forum: Microscopes and optics
Topic: AO2/AO4 Mystery Lens
Replies: 15
Views: 325

Re: AO2/AO4 Mystery Lens

apochronaut wrote:
Fri Feb 19, 2021 8:42 pm
You had commented earlier on about a change in working dustance, Hans. There is a small change with the compensating optic installed.
Interesting, is this change relative to a 2/4 with without the compensating lens or relative to an older 160 mm tube length stand?
by hans
Fri Feb 19, 2021 8:38 pm
Forum: Microscopes and optics
Topic: AO2/AO4 Mystery Lens
Replies: 15
Views: 325

Re: AO2/AO4 Mystery Lens

Don't have a 2/4, just curious, but still confused -- was the lens optional, or is it just missing from one of quantum's stand? If optional, what configurations originally included it? Maybe this explains the two different measured tube lengths?
by hans
Thu Feb 18, 2021 7:56 pm
Forum: Microscopes and optics
Topic: AO2/AO4 Mystery Lens
Replies: 15
Views: 325

Re: AO2/AO4 Mystery Lens

...the actual tube length of the microscope is somewhat more than 160mm. I measured it once and it came out around 200mm. The compensating lens has some function in adapting the 160mm objectives to the longer tube. If the purpose of the lens was to increase the tube length without modifying the wor...
by hans
Thu Feb 18, 2021 7:54 pm
Forum: Microscopes and optics
Topic: Comparison of AmScope's Plan & Non-Plan Objectives
Replies: 30
Views: 2846

Re: Comparison of AmScope's Plan & Non-Plan Objectives

After reading more about aberrations and looking at various patents I understand now that in technical contexts there is not just a single field curvature discussed. Sagittal and meridional rays are considered separately and the difference in curvature between those two cases corresponds to astigmat...
by hans
Thu Feb 18, 2021 3:31 am
Forum: Illumination Techniques
Topic: Darkfield stop sizing
Replies: 60
Views: 1415

Re: Darkfield stop sizing

To get back to the first point, it seems the calculations of stop diameters to match different NA objectives might need an adjustment for the field-of-view. For 40x 0.65NA objective the field-of-view is small relative to the calculated stop diameter, but it becomes significant for lower power, lowe...