MicrobeHunter.com Microscopy Forum

It isn't related to the illumination, rather to the wave retardation of the phase ring. Bright phase retards the waves passing through the annular ring , which has the effect of causing particles with a higher refractive index than the surrounding medium to appear bright. Dark phase retards the wave...

I like this comparison, although I am surprised that the phase , suppressed the oblique contrast a little . Perhaps a reverse phase( bright, anoptral or whatever the mfg. calls it) might have worked better with this sample. Oblique illumination was much used in the past. Most of the older research m...

I echo all of the above...... You mentioned your microscope having a 3X eyepiece. These are very uncommon , although Spencer did have a small bore projection eyepiece used for polarization work, marked 3X. If there is a 3 marked on it, and no X, it likely indicates that it is a #3 eyepiece, which wa...

Between the time AO entered into it's infinity era and shifted over to D.I.N. objectives for the 400 series, they had a certain amount of design alteration take place with respect to their phase contrast objective range. Prospective buyers , might want to consider this when shopping for objectives. ...

Thanks for looking, anyway. My search turned up one supplier, who appear to be defunct ,now. I thought someone would have encountered them, somewhere.

I guess Leica sold off some older designs they weren't going to be using to the Chinese, or let a factory they are involved with , use them. The 40X objective is actually a 40X .66, not a .65 as mentioned in the original post. Does it have a 24mm correcting lens in the bottom of the head and a 50mm ...

I've never seen a de-lamination that looked like that. Usually de-lamination has either a flowing or curved wispy form. which looks almost like condensation on the lens, distinct small air bubbles or an amoeba like form , where air has crept in along one seam and the lenses have separated. Always th...

Dennis. You should be able to knock the broken drill bit piece out with a small drift punch. A good cheap alternative is a finishing nail well clamped in a pair of vice grips. That way you can see what you are doing. Clean the hole up with the same size drill and then tap it for the U.N.F. thread th...

I'm curious what the N.A.'s of the 4X and 20X are? I can see the 10 ,40 and 100 N.A.'s

On the front surface of the bottom lens?

These were conceived during that period when the long slide into eventual extinction began I wonder if the "high council" at AO had a ceremony proclaiming the microscope the inaugural instrument of their eminent demise ? I think AO did an excellent job of weathering the storm, though. They continue...

Low resolution picture of the AO Spencer 15 I have. Scope was in very bad shape to start with, had aluminum oxidation all over it among other problems. Rodney Rodney; I'm curious how those cat.# 146 eyepieces work on that microscope? They were an odd eyepiece for their time, that required a compens...

That hazy or fogged quality to the image is almost always a sign of delamination, if a film on the back or front element has been ruled out. OIl impregnation usually causes a skewed image, no image, or a change in the focal point. I have had moderate success fixing them. If it is an older lens and t...

These are occasionally referenced as materials used in research projects where certain contrast enhancing techniques have been employed, such as D.I.C., phase. I have been unable to find , a supplier or who makes them. Does anyone know?

AO made a 100X .90 Cat. # 1867, dry planachro objective for use uncovered. It works well for quick smears that are being quickly assessed but with a cover it has a very blurry image which is about as good as their coverslip corrected 100x when used without oil. It's spherical aberration that is the ...

75RR: No, I don't think you can use an oil-immersion objective dry and expect to get acceptable images (assuming that you can get the object in focus). I thought the test was to show that one could. Wasn't it in response to the question below? Does that mean that using a 100x/1,25 objective dry wou...

To clarify your testing, the objective is oiled to the slide in all your shots and it was just the condenser which was not oiled or oiled? Yes; only the oil or no oil between the condenser and slide was altered. Focus of the camera had to be corrected with each shot because I was using the eyepiece...

The one parameter I couldn't control was focus, so there may have to be some interpretation around that. The fine lines in the diatoms were very hard to define and there is obviously some drift from image to image to image but the bigger picture is still apparent. The abbe aspheric is a surprise. Ve...

Here are the same 4 condensers , all other parameters kept equal , except this time they are immersed. The results of this simple test are pretty much what one would expect. The 1.25 abbe condenser induced the worst chromatic abberration, whether dry or immersed, however there wasn't as much of a di...

As a general rule you can knock off about .50 when no oil is used. Does that mean that using a 100x/1,25 objective dry would give the equivalent of a 100/0,75 and if so is that a feasible/practical use of the objective?[/quote] Somehow the response I had intended didn't get into the post. All objec...

These were made by Carton Optical in Japan, and stencilled for whoever wanted to import and market them. I've seen black and pale green ones branded Tasco , grey ones branded Lumex and Monolux. There were Selsi and Lafayette ones in the U.S. too but probably a dozen other names. Intras is a new one ...

I think the important word in Murphy's text, is optimal. In theorizing about microscope optics, it is easy to forget about the resolution capability of the eye. This is where the lower limit of magnification comes into play. With an objective such as a 25X neofluar,with a potential N.A. of .60, drop...

The theory was whether it was possible to build a wide angle, high N.A. achromatic condenser from the materials I had at hand. I certainly didn't approach it mathematically. My parameters were. 1) achromatism 2) as wide an aperture as possible 3) as broad a field coverage as possible. What I had to ...

Last picture of the 1.4 achromat being viewed from below with the led flashlight about 7cm. below the collector lens.

Here are some further pictures with illumination added in.

Abbe condensers are like bald tires. They can do a basic job and get you where you want to go but if there are any changes in the conditions , you need to make a change to take advantage of them. Almost all of the AO/Reichert Microstar 400 series microscopes were fitted with a very good 1.25 N.A. ab...

I'll just make this one comment , though. AO launched a clever plan. and it did sustain them until about 2000 or so when the last Microstar 400 series were made. It seems as though they knew way back in the early 60's that the Japanese juggernaut was going to be a difficult one to evade, so they wen...

These were conceived during that period when the long slide into eventual extinction began, for AO. Up until the 50's, the competition for almost all N.A. made products was house league or additionally from countries that had fairly similar labour costs. In the 50's, unfortunately for many companies...

Lomo to be fair, are fairly good and available at the right price. They are an excellent way of getting into water immersion, if you have a 160mm microscope. They also can be used on some infinity scopes with short barrels( AO 10/20,110/120, 60,160), for dipping and seem to be older Zeiss 160mm desi...

In former times, the term oil immersion was much less used. The term homogeneous immersion was more often seen, this being an acknowledgement that the system worked best with a complete immersion, from the condenser through to the objective front, that maintained as close to homogeneity of the refra...