MicrobeHunter.com Microscopy Forum

I use what is likely an ancestor to the 40X 0.75 Fluotar fairly regularly. If it isn't , Leica would have used it as a prototype, if they didn't think they could make something even better otherwise, so the HCX 40X 0.75 Fluotar is probably at least as good as what I am using and notable due to W.D. ...

So then, might that not be pre-war Zeiss or possibly ROW? Weddig was in what became East Germany too.

The way I have typically branded condensers is stylistically. Comparing lettering, knurling and lathing and if available the design of the iris handle. None of that checks any boxes for me plus there were a considerable number of German makers. I have to assume it is German. Interesting stacked desi...

I would say not chromium and probably a nickel alloy. Some version of what was at the time called German Silver. Copper, nickel and zinc in varying percentages ,, depending on who made it and what it was made for. It was widely alloyed in Germany after about 1870 or so., used frequently where a brig...

Chromium plating for commercial use was exclusive to the U.S. until after 1925. Although some small parts were plated in the early 20's, they didn't start using chrome for things like automobile bumpers until around 1927. I have a brand new # 7 objective of that same form as your 6, identical to the...

Finally, regarding the defocused Abbe condenser, I don't normally use an Abbe condenser either but remember reading somewhere how the large spherical aberration prevents filling the entire NA range of high-magnification objectives at any single focus setting. Perhaps the specific defocus setting yo...

Is the 6 not just a partial? Leitz shorter focal length objectives could be separated, so that a funnel stop section or iris diaphragm section could be threaded into the lens section. Likely 1920's based on the knurling and brass. Chrome plating wasn't used prior to the early 20's. Lacquered brass w...

Sometimes the objectives are very short, only about 1 cm. long. These were usually used when a vertical illuminator was placed between the objective and microscope body tube. Since the vertical illuminator increased the tube length, the upper part of the objective barrel which in the pre-plan era wa...

On chemical microscopes met. microscopes and polarizing microscopes there were seldom revolving noepieces in the early days, up into the 1950s or even 60s. In order to speed up the changing of objectives a quick change mount was employed, each of which included centering screws so each objective cou...

Thanks! The scales were very evident, almost reptilian.

I can see where they are trying to go business wise. Every company, especially one that recently underwent changing of the guard , sits down and sets a course at critical junctures. Some very formerly well placed and innovative corporations did not do that effectively : Polaroid, Kodak. Had they see...

Zeiss coated optics cleaner spray. For when you assume the coating is damaged after isopropyl meths soapy didn't work. Meade and Takahashi apparently don't trust it on their coatings. There are reports of it damaging the coating on astronomical instruments. It's target market may be eyeglasses whic...

Thanks. I probably haven't seen a Lacrymaria then. I see these swan necked ciliates occasionally in habitats that I would suspect to be fairly nutrified. I didn't know to speciate them by the mouth and it is hard to by proboscis length, since they can stretch them. I tried to catch the mouth in focu...

There two scenarios. One is the fungus is growing on a film or fine airborne debris deposited on the glass or two is on the coating. Since almost all optics have been coated for many years now, I assume it is on the coating. If the microscope is older you might be lucky and it is on glass only. Some...

I agree. Plus, acetone can dissolve some substances you don't want dissolved if it gets into the wrong place.

This is the other big fish in the little pond. #'s 1 and 2 I first thought a rotifer but is likely an Icthydium at full steam ahead. I was unable to capture a good image of it's lateral feelers, or what appeared to be feelers or bristle sensors extending out from it's head. Visually it looked to hav...

These were found in a fairly fertile sluggish creek crossing a farm. It is being fed a bit from cattle manure. Although the temperature is still quite cold, there is a thick cap of algae and much activity This is a Lacrymaria about 200 microns long. The first is 2 are 40X .66 Plan Achro Dark Phase. ...

My post really wasn't about Abbe and I don't doubt whether he understood basic physics or not. I don't think Zeiss would have kept him around if he was lax in that department. He undoubtedly guided Zeiss towards incorporating condensers into their better microscopes and of course had the most ubiqui...

Resolution is affected by multiple elements. An N.A. .90 cone of white light is modified differently when passing through a .90 N.A. objective than when passing through a 1.40 N.A. objective. It also splits at the front lens and does not behave like a monochrome ray does in a simple illustration as ...

Could you point me to Harry's point about DF, I missed that too.

Phase objectives tend to sacrifice resolution for contrast enhancement, so they aren't the best choice for assessing condenser performance.

I am all for practical tests and practical solutions. So, missing from the discussion are some of those variables that don't get included in the math, such as how well corrected the condenser is, the diameter of the lenses, image circle described etc. In order to lessen the effects of those variable...

One of the problems with the F.N. calculation is that it is simple and easy to determine only as long as a 10X eyepiece is being used. As was amply illustrated in the other thread that probably stimulated this one, once you have field stops that are rationalized based on maximizing optical possibili...

1) The math is only well established for the variables of the system that are included in the math.If one thinks that they are fully cognizant of all the variables and that they have a formula to explain them all, then they are either out to lunch or they aren't spending enough time looking in a mic...

Using math as the final arbiter to describe complex systems is only as good as the number of variables that can be included in the calculations. Those must be envisioned in their totality in order to make sense of the math but in a complex system such as is being assessed here , how can that be done...

So then, why not use angle as an indicator of f.o.v. ? Would it not be a better indicator of the field width?

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...

It is apochronaut, not apochromat. That is a type of lens. It is not always easy to rely on one's perception of things around you when you are bound in a system and can't get out. I used the term image circle to describe what is being seen because you were relying entirely on theory out of a book, w...

All you need is an iris equipped objective, a .90 corrected condenser and a corrected condenser that allows the objective to work at or above the calculated combined N.A. to determine that.....and probably a good diatom slide, maybe something like p.angulatum.

Your example of a 15x/20 eyepiece returning a30mm isn’t possible. No , we aren't talking apples and apples. You seem entiely stuck on the actuality of the true measurements you have provided and that is all true mathematically but you had to get out a calculator to determine at least some of them d...