Search found 402 matches

by patta
Sun Sep 10, 2023 6:42 pm
Forum: Digital processing
Topic: measuring psf without fluorescence
Replies: 12
Views: 2641

Re: measuring psf without fluorescence

A rougher version of previous post
Just a black pencil ("Sharpie" ot others) on slide, leaves some tiny holes often suitable for star test.
The metallic mirrors are better though.
by patta
Sat Jun 10, 2023 9:06 am
Forum: Beginner's corner
Topic: Image separation behavior in through-focus range of a microscope objective lens
Replies: 5
Views: 1230

Re: Image separation behavior in through-focus range of a microscope objective lens

I'd vote as well astigmatism (and/or coma)
it happens on the center of the field, so there may be miscollimation or misalignment of some lens.

You can raytrace with zemax and other, shift or tilt one of the lenses off-axis
by patta
Tue May 30, 2023 6:51 am
Forum: Microscopy accessories
Topic: Objective caps
Replies: 5
Views: 2034

Re: Objective caps

Can 3D print those models
(or order them from Craftcloud)
https://www.thingiverse.com/thing:4568767
They work; won't be as good/cool as the Olympus!
by patta
Wed May 24, 2023 8:30 am
Forum: Illumination Techniques
Topic: Types of Phase Contrast and when to use which type
Replies: 12
Views: 2519

Re: Types of Phase Contrast and when to use which type

I fear that all this beautiful variety of phase contrast methods has disappeared, and today ony standard "bright" setups are normally available - with no indication wether is High, Medium or Low like in the table linked above. The trouble with pond life, is that there is a bit of everything; I have ...
by patta
Mon May 22, 2023 10:46 pm
Forum: Beginner's corner
Topic: Subjects and method for dry mount, no cover slip?
Replies: 8
Views: 1554

Re: Subjects and method for dry mount, no cover slip?

While trying to mount diatoms, I've tried this: Filter pond/seawater with coffee filter squeeze the the result on the glass let it dry If the sample was nice there will be full of algae and microrganisms, stuck to the glass. Usable; with coverslip then gets better and more robust. Did you try Uni-Po...
by patta
Mon May 22, 2023 6:34 pm
Forum: Illumination Techniques
Topic: Is Dark Field Possible at 100x with Immersion Oil?
Replies: 25
Views: 14707

Re: Is Dark Field Possible at 100x with Immersion Oil?

It is also relatively easy to do "opposite df" with the condenser outputting small NA (like 0.5) and a central stop patch placed inside the objective, so the direct illumination is stopped. With this method, objective NA can be as high as will; darkfield is dark; but there are horrible diffraction a...
by patta
Mon May 22, 2023 11:35 am
Forum: Illumination Techniques
Topic: Is Dark Field Possible at 100x with Immersion Oil?
Replies: 25
Views: 14707

Re: Is Dark Field Possible at 100x with Immersion Oil?

In case of interest- and lacking budget for the above mentioned Nikon 1.43-1.20
my "ball" oil df condensers are still on sale...
Max objective NA revised down to 1.25.

I should warn that DF at such high NA works only for very thin and clean specimens - things thicker than like 2 micron make a mess.
by patta
Thu Apr 20, 2023 5:30 am
Forum: Microscopes and optics
Topic: Schmidt objective
Replies: 4
Views: 1026

Re: Schmidt objective

Oh remembered, I've made a similar setup time ago: observing a small spherical mirror with 4x objective. No confocal, immersion nor two-photons. Immersion could be done with a chamber, but not easy to put the microscope horizontal (oh wait, the old horseshoe stand tilts) How to make the spherical mi...
by patta
Thu Apr 20, 2023 5:06 am
Forum: Microscopes and optics
Topic: Schmidt objective
Replies: 4
Views: 1026

Re: Schmidt objective

That is very nice, I like the idea of using the immersed mirror as main magnification element - so it doesn't care about the refractive index of the immersion medium. Their application is looking inside larvas of fish - pretty thick and irregular specimen, so they want to match the index of the refr...
by patta
Thu Feb 02, 2023 3:00 pm
Forum: Illumination Techniques
Topic: Testing high NA darkfield condenser
Replies: 58
Views: 17490

Re: Testing high NA darkfield condenser

Too late, the 3D print bug hit again: Plastic dummy slide, coverslip holder 2.0 They're plastic, not so stiff, and they soak up water and oil. But sit flat and the slide can be put flush over the condenser or the objective. Two model, the one on the photo need a dab of glue to fasten the coverslip. ...
by patta
Mon Jan 30, 2023 9:09 am
Forum: Illumination Techniques
Topic: Testing high NA darkfield condenser
Replies: 58
Views: 17490

Re: Testing high NA darkfield condenser

Voila, here too, making those Cobb slide from a beer can, sorry for disregarding the previous suggestion by chas, and thanks MichaelG for the video link! the aluminium is a bit too thin, like 0.1mm, while the one used in the video linked above looks much thicker (0.5mm?) It is difficult/impossible t...
by patta
Sun Jan 29, 2023 5:55 pm
Forum: Microscopes and optics
Topic: Ancient Leitz Wetzlar darkfield condenser
Replies: 18
Views: 3336

Re: Ancient Leitz Wetzlar darkfield condenser

Oh my gosh so cool things those ancient setups!!
by patta
Sun Jan 29, 2023 12:10 pm
Forum: Microscopy accessories
Topic: Olympus objectives
Replies: 2
Views: 2221

Re: Olympus objectives

(unserious post, rainy Sunday) I don't have either, but sure bet that the more expensive ones are better. A discussion with the wife or a check on the bank account may help to take the right decision. Me, at the prices they are going I'd rather buy a boat and get some rare samples from deep and offs...
by patta
Sat Jan 28, 2023 10:39 am
Forum: Illumination Techniques
Topic: Testing high NA darkfield condenser
Replies: 58
Views: 17490

Re: Testing high NA darkfield condenser

About funnels, I take the bait to advertise one of my earlier DYI - 3D print creations https://www.microbehunter.com/microscopy-forum/viewtopic.php?f=28&t=14262 Sure brass would be better than plastic, but now I have funnels for almost all objectives. The centre stop/inverted darkfield/dispersion st...
by patta
Thu Jan 26, 2023 12:34 pm
Forum: Microscopes and optics
Topic: InFocus™ Dynamic Optical Focusing Systems (tubelens on steroids)
Replies: 14
Views: 5067

Re: InFocus™ Dynamic Optical Focusing Systems (tubelens on steroids)

The patents are not bad - there is both some good substance and some nonsense mixed in, but overall show competence in the field and are quite explanatory (while often patents are purposefully incomprehensible). However I couldn't grasp what is being patented exactly. I stop here because of time con...
by patta
Thu Jan 26, 2023 11:20 am
Forum: Illumination Techniques
Topic: Testing high NA darkfield condenser
Replies: 58
Views: 17490

Re: Testing high NA darkfield condenser

My condenser ain't anything special, and don't think it is better than a normal cardioid. It is what I could make quick by myself with the materials at hand (half-ball lenses) instead of getting gouged on ebay for some antique Ultracondenser. Perk is that it can be made with very high NA, the last p...
by patta
Thu Jan 26, 2023 8:00 am
Forum: Illumination Techniques
Topic: Testing high NA darkfield condenser
Replies: 58
Views: 17490

Re: Testing high NA darkfield condenser

Two questions I still have about this condenser is regarding it's focus and chromatism? In every other DF condenser I have come across, great lengths were taken to pass the light through using finely polished mirrors and glass components, whether lenses or blocks. In this condenser the reflecting s...
by patta
Wed Jan 25, 2023 11:36 pm
Forum: Microscopes and optics
Topic: InFocus™ Dynamic Optical Focusing Systems (tubelens on steroids)
Replies: 14
Views: 5067

Re: InFocus™ Dynamic Optical Focusing Systems (tubelens on steroids)

About the mad idea of apochronaut of "stretching" an high NA objective to longer working distance I've played a lot with refocusing the tube lens, that does this stretching. Results usually poor in my case. Yes, I guess too that increasing the working distance reduces NA. How much? Let's take as exa...
by patta
Wed Jan 25, 2023 10:52 pm
Forum: Microscopes and optics
Topic: InFocus™ Dynamic Optical Focusing Systems (tubelens on steroids)
Replies: 14
Views: 5067

Re: InFocus™ Dynamic Optical Focusing Systems (tubelens on steroids)

Ok so I've (partially) read some from the site and some from the patents this infocus is a focusing lens. Like moving the tube lens. Many here have done more or less the same with the "poor man infinity", using as tube lens a (focusable) camera lens. Also similar effect can be achieved in afocal pho...
by patta
Wed Jan 25, 2023 8:30 pm
Forum: Microscopes and optics
Topic: InFocus™ Dynamic Optical Focusing Systems (tubelens on steroids)
Replies: 14
Views: 5067

Re: InFocus™ Dynamic Optical Focusing Systems (tubelens on steroids)

sorry I've read only now the previous linked thread.
don't know now. I think Hans was right. Posts #2 and #3 start seeming reasonable.
by patta
Wed Jan 25, 2023 4:23 pm
Forum: Microscopes and optics
Topic: InFocus™ Dynamic Optical Focusing Systems (tubelens on steroids)
Replies: 14
Views: 5067

Re: InFocus™ Dynamic Optical Focusing Systems (tubelens on steroids)

By the way, variable spherical aberration correction is also common in camera macro lenses, that have a further "floating" lens that moves when focusing: such that when the lens is focused near, the spherical aberration (and maybe others) are corrected for that focal distance. Similar to the "correc...
by patta
Wed Jan 25, 2023 9:20 am
Forum: Microscopes and optics
Topic: InFocus™ Dynamic Optical Focusing Systems (tubelens on steroids)
Replies: 14
Views: 5067

Re: InFocus™ Dynamic Optical Focusing Systems (tubelens on steroids)

The marketing material of Margolis are sure a bit over-the-top rants, but I really like the guy and its designs. That are quite simple at the end, but as written above, it is in business, so there are costumers willing to pay for a ready made working system. I'm a big fan of black enamel, while desp...
by patta
Wed Jan 25, 2023 8:49 am
Forum: Illumination Techniques
Topic: Narrow wavelength blue filter
Replies: 3
Views: 1762

Re: Narrow wavelength blue filter

A bit late on retail, there are filters for Astrophotograpy; not cheap too https://www.baader-planetarium.com/en/filters.html Otherwise you can use a blue LED - more energy efficient! And they have pretty well defined wavelength and narrow band. I use the screen of my phone (OLED), displaying a pure...
by patta
Wed Jan 25, 2023 8:24 am
Forum: Illumination Techniques
Topic: Phase Contrast condensers.
Replies: 10
Views: 2759

Re: Phase Contrast condensers.

So summary: - Condenser oiling has no direct effect on phase contrast - In the 1950's the first Phase systems used oiled condensers just because that was the norm - Later, high NA dry condenser came along, and today (I think) all commercial phase condensers are dry - High NA oil objectives can be us...
by patta
Wed Jan 25, 2023 8:01 am
Forum: For forum members who want to buy and sell equipment
Topic: Leitz Phaco condenser centering keys - trade /swap
Replies: 4
Views: 1406

Leitz Phaco condenser centering keys - trade /swap

To vintage Leitz owners I have two extra keys for centering the Phaco condenser (Leitz 402a turret) Those are not the original unobtanium Leitz tools, but watch keys #5; they fit perfectly and do the job. Only defect is that they're so small, easy to be lost. I will send them as letter; plz provide ...
by patta
Wed Jan 25, 2023 7:38 am
Forum: Illumination Techniques
Topic: Testing high NA darkfield condenser
Replies: 58
Views: 17490

Re: Testing high NA darkfield condenser

AO dovetail coming... I've taken back this project, and, dismal discovery, wasn't really NA 1.4 :oops: One of the testing objectives - CARL ZEISS JENA 60x 1.40 - upon closer observation turned out to have NA 1.3-ish, not the stated 1.40. I'm in good company about NA cheating... If somebody has a cal...
by patta
Wed Jan 18, 2023 4:30 pm
Forum: Illumination Techniques
Topic: Phase Contrast condensers.
Replies: 10
Views: 2759

Re: Phase Contrast condensers.

So weird, I thought of oiling the condenser as something exotic and innovative... instead it was the old standard!
by patta
Wed Jan 18, 2023 1:09 pm
Forum: Illumination Techniques
Topic: Phase Contrast condensers.
Replies: 10
Views: 2759

Re: Phase Contrast condensers.

My take on why Oiled phase condensers are not common (never thought about before today): The illumination, the phase annulus has NA much smaller than the objective : for an oil objective with NA 1.25, the annulus (the hollow cone illumination) is like 0.7-0.8, so there is no need to oil the condense...
by patta
Fri Jan 13, 2023 2:04 pm
Forum: Beginner's corner
Topic: Polychromatic polarization
Replies: 28
Views: 9616

Re: Polychromatic polarization

I've just discussed with others this "polychromatic stacking", as post #17, and in order to convince them that it's legit I had to make some more decent images: small chunks of Mica fibers of polyester both at 4x NA 0.10 It also turned out that this method has been presented already in the 90's. Any...
by patta
Wed Jan 11, 2023 11:28 am
Forum: Resources (online, books etc.)
Topic: Citizen Microscopy
Replies: 15
Views: 4762

Re: Citizen Microscopy

Big battle:
Linear aperture (telescope diameter)
vs
Angular aperture (microscope NA)

Both lead to a crave for flat field, fluorite apochromat objectives.