Uncategorized – Microscopistas

The right bulb in the Zeiss Axioskop 20 microscope.

When a microscope is delivered it is very important to provide a replacement lamp, in addition to the one installed in the equipment, so that the user can continue working in case it runs out. But it is of great importance to make sure that the lamp is the right one. In this case it is a Zeiss Axioskop 20 with a 6v 20w lamp whose Zeiss reference is 380079-9690-000.

On many lamp sales sites the OSRAM 64250 HLX is said to be an equivalent bulb, but this is not true. I have been told in a German microscope accessories store that the OSRAM replaces the Zeiss that is no longer manufactured and that it is the same. Let’s see why they are not equivalent bulbs.

Zeiss and OSRAM bulbs — We see with the naked eye the differences between the lamps

In this image of the two bulbs we see two fundamental differences. On the one hand, what is most striking is the different shape of the filaments. The Zeiss lamp, on the left, has a flat filament, to fill the field of view, as we will see later. Another fundamental difference refers to the height that the filament reaches with respect to the pins. The difference in height between one and another filament is about 3 mm.

To fully understand the effects of these differences in construction, we must test the microscope with both lamps and focus the filament, in the style of the classical Köhler configuration. To do this, in this Zeiss Axioskop 20 model we must remove a diffuser that is located at the base, between the lamp and the collecting lens, as we see in the photograph.

The Axioskop 20’s simple lighting system from below

We must remove that frosted glass to be able to focus the filament.

Detailed view without the frosted glass.

We place the OSRAM bulb in the microscope’s lamp holder, inserting it in its entirety. We try to focus the filament by regulating the height of the condenser and this is what we see.

It is impossible to see the filament centered.

In order to see the filament centered in the visual field, we will have to extract the bulb between two and three millimeters. But it is a complicated maneuver because you have to be continuously looking, turning off, cooling, extracting, checking … to obtain a result like this:

The bulb must be removed in order to center the filament.

To achieve this, you have to turn the microscope over, remove the ground glass filter, and center the filament. This is not something that everyone can do easily.

Now we are going to see how the filament of the Zeiss bulb looks. Placed in the lamp holder normally, as we see in the image below.

The Zeiss bulb positioned all the way into the socket.

Zeiss bulb filament occupying the entire visual field.

Appearance of the flat filament of the Zeiss bulb in the center of the system.

Los efectos en una muestra son significativos. Con la bombilla OSRAM sin centrar, es decir, simplemente puesta como la pondría un usuario habitual, el filamento descentrado como hemos visto, y el regulador de iluminación al nivel 2, tendremos esta imagen. The effects in a sample are significant. With the OSRAM bulb not centered, that is, simply placed as a regular user would put it, the filament off-center as we have seen, and the lighting regulator at level 2, we will have this image.

Poor lighting because the OSRAM filament is off-center.

To get more lighting we have to raise the regulation to the maximum level. The microscope gets hot and the image is not good either, because the filament is off-center and the light is coming from the right side. We see the sample.

Illumination at maximum and poor due to the off-center filament.

However, with the Zeiss lamp, at lighting level 2, it is uniform, with minimal heating, as seen below:

More uniform lighting with the Zeiss lamp.

Serve this small text to convince us that it is very necessary to use the right lamps for each microscope. In the case of the Zeiss Axioskop 20 the dedicated Zeiss bulb 380079-9690-000 cannot be substituted for the OSRAM 64250 HLX, as many stores say. The results are not good because the bulbs are obviously different as seen in the first photograph. Illumination is essential for obtaining good images in microscopy, and halogen illumination begins at the filament of the bulb. If this fails, the entire system will suffer and the quality obtained will be poor, in addition there will be overheating. Suitable flat filament bulbs for the Zeiss Axioskop 20 microscope can be purchased at the Zeiss Shop.

In future posts we will deal with other basic aspects of the regulation of microscopes.

See you soon microscopists.

Zeiss Axioskop microscope analysis.

Among the professional microscopes of the big brands that have been sold the most over the last 30 years is the Axioskop range from Zeiss. Specifically, we are going to talk here about the Zeiss Axioskop 50. It is a very good microscope that does everything you can ask for from a quality instrument. It is robust, with considerable weight, but does not take up much space on the table. It is mechanically accurate. Its focus system is simple and effective. It has good lighting. It comes standard with a 50w lamp, although it is prepared to reach 100w. It is very expandable, because Zeiss manufactured all the necessary accessories. Optically it has a great quality, wide field of view and all kinds of lens and technical settings. So the ZEISS Axioskop 50 is a great microscope. We are going to analyze it briefly in this post.

The Stand

The first thing that strikes you about the Zeiss Axioskop 50 is the slenderness of its stand. Generally microscopes in its category are wider. The base of the Axioskop is T-shaped. Its four supports on the table are designed to provide great stability. It has two in the back, further apart, and two in the front, almost together. Actually, most microscopes have this arrangement, also the Olympus BX series and Leica DMs. But the Axioskop is narrower. Its narrowness, which would seem to be a stability drawback, is not, thanks to its good construction. The rubber “feet” are elastic and firm enough to make the Axioskop a very stable instrument. At the same time, being narrower leaves us a lot of free space on the table, and access to the back is easier

Microscope Zeiss axioskop 50 — Front view of the Zeiss Axioskop 50

The front of the base is quite narrow. No more room is needed to accommodate the mirror and field diaphragm system. This way we have a lot of space on the table. Let’s look at a later image.

Here the considerable size “house of the lamp” stands out. It can accommodate up to a 100w lamp, although for that we must have an external power supply. With the source incorporated into the microscope, as seen in the image, the maximum allowed is a 50w lamp, sufficient for most techniques. In this model we can also see the train for overhead lighting, in which the same illuminator can be installed for incident light in brightfield or an illuminator for fluorescence. We also see the green power button and the knob for adjusting the brightness.

Accesories and other elements

Incident illumination

The microscope supports a wide variety of configurations and comes in many different ways. A basic system would be a binocular, without optovar and exclusively diascopic or transmitted lighting. In the model in the image above, we see that it is available for episcopic top lighting. This is a great advantage because it allows us to access all the techniques that require this type of light source. For this type of lighting we have a centrable field diaphragm, as well as a filter holder in the form of a slider. Below we can see the breakdown of the elements that compose it.

As we have said before, the same illuminator that is used for the transmitted light technique can be placed for the incident light.

The head.

The head can be basically binocular or trinocular. Within the trinocular heads we have several different types. In this case, in the first photo we see that the head admits the image output towards the eyepieces, towards the phototube or in a 30/70% ratio between eyepieces and phototube respectively. There is another more basic model that only allows you to select between eyepieces or phototube.

Different Axioskop heads — 100/100/70-30

The external difference between the two models is a control with a black ball at its end located on the left side of the head and a diagram with the different configurations in the more configurable upper model, while the head that only allows choosing between eyepieces or phototube it’s all white.

The insertion diameter of the eyepieces is 30mm and the tube has a slit in its upper part where some eyepiece models fit so that it does not rotate. Not all eyepieces have these characteristics, which are manifested by the presence of a small screw on the side of the eyepiece that fits into the slit. Personally I find it very useful because sometimes I use an eyepiece adapter for photography with my mobile phone. By not rotating the eyepiece due to the weight of the phone, the image appears centered and in position.

Optovar or Fluorescence filter holder.

Zeiss invented a very successful system for its Standard series microscopes: the Optovar. In the Axioskop, the system was preserved although with fewer features. Basically it is an optical system that allows to increase the optical capacity of the microscope by 1.25x and 1.6x on the selected objectives. Thus, with a 100x objective and a 10x eyepiece we reach 1000x magnification. but with the Optovar system we get up to 1250x even 1600x. Obviously, the resolution capacity is not going to improve because, as is known, it depends directly on the numerical aperture of the objective, but in many cases the Optovar is a great resource. Let’s see some images of the system.

This Optovar in the photograph has a superior grip and therefore is installed without the characteristic fins that some Axioskops have, such as the one in the second photograph above, which mainly serve to protect from dust. In those cases the Optovar slides using a lower grip.

In the place of the Optovar and with the same dimensions, the Zeiss fluorescence filter holder can be inserted, which in the Axioskop 50 does not yet work with the cube system, but with independent filters and mirrors. Up to four positions present the portafilters that can be configured at will.

Elements of transmitted lighting.

After the illuminator that we have already talked about, there is a filter and a collecting lens that directs the light towards a completely closed mirror that is part of the field diaphragm. It is very compact and easy to replace.

Collector zeiss axioskop — Collecting lens.

Among these elements there is a rubbed or frosted glass whose purpose is not well known. It’s on the right side of the base, next to the focus knob. It can be removed or placed in the path of the light with the help of a 3mm allen key and is used for the correct lighting configuration. To see the filament of the lamp.

Nosepiece.

It usually has a capacity for six objectives. It is very wide and robust and makes the difference with more modern or lower-end microscopes. Quite heavy, it is very easy to assemble and disassemble with its eight upper screws, which fix it to its support and to the stand. Its operation is very smooth thanks to its very wide ball bearing track, with very marked “clicks” in the positions of the objectives.

The knob seen in the third photograph, to the left of the nosepiece (in its normal position it would be in front of the microscopist) has to do with the Optovar or the fluorescence filter holder. To extract these elements you have to pull towards us to release the accessories that we mentioned.

Stages and condensers

There is quite a variety of plates with different sizes, with controls on the left and right. As a curiosity, to say that most stages of the Standard series microscopes fit the Axioskop, at least the most modern of the gray models, which are fastened with four screws. The only thing is that they have the XY coaxial control slightly shorter than the original ones for the Axioskop. In previous images we can see the typical 0.9 NA Zeiss condensers with a flip-up lens, and here below a condenser for phase contrast and dry dark field.

In later posts we will comment on the optical elements and their characteristics, as well as the adjustments that must be made to the microscope for optimal operation and thus get all their capabilities.

In short, the Zeiss Axioskop is a very robust and versatile microscope. With simple and very effective mechanics. It is not a delicate microscope that is easily misaligned. It is very strong and robust and easy to disassemble and adjust. It has many accessories at a very good price. It is of optics corrected to infinity and with an unbeatable image quality.

A very good choice.

How to get a cheap professional microscope

When buying a microscope for professional use, we have many doubts, especially if we are not very familiar with the handling of these devices. In reality, there are very few people who know first-hand the behavior of a wide variety of equipment from different brands. And although there are experienced professional microscopists, who spend many hours in front of their instruments, they are generally always working with the same equipment. I’m talking about hospitals and analysis centers mainly.

This post is dedicated to all those who are looking for a professional quality microscope and do not know where to start. When I speak of professional quality I mean exactly that, which is not a mere word that is used to sell more. It is common to see the expression “professional microscope” applied to 400-euro equipment in many advertisements. Be clear that such a thing is impossible.

The goal of microscopistas.com is precisely to provide professional-grade microscopes at reasonable prices. This can only be achieved in the used microscope segment. Quality used microscopes, mainly from the four big brands recognized by all specialists and users around the world. These four brands are: Leica (Leitz), Zeiss, Olympus and Nikon.

I do not mean that outside of these brands there are no competent manufacturers and acceptable equipment. It is simply that analysis laboratories, hospitals, universities and research centers definitely do not work with brands other than these.

These equipments are very expensive, very much. We are talking about their prices starting from two thousand euros in their simplest ranges. They are intended for education in schools and secondary schools. I’m talking about the Zeiss PrimoStar, the Leica DM 500, the Nikon Eclipse E100 or the Olympus CX. These lower ranges of the big brands are made in China. Good quality is expected from them, but their configurations are very limited and scaling up is almost impossible. They have pre-centered condensers, and sufficient illumination for their purpose but little for future extensions that become impossible. Of course, its handling is simple and correct, although the quality of its materials leaves a lot to be desired

On the other hand, there is the option of other brands made in China that have achieved a certain reputation. Their prices are much cheaper and in the price range of two thousand euros we have very complete and expandable equipment. I’m talking about brands like Motic, Optika and the like. I have tested some of these microscopes and they are quite well built. They are an option to consider and much cheaper than the big four brands of premium microscopes.

But, nothing is comparable to a good microscope of prestigious brand. You can tell that only when you see the instrument. Second-rate home designs are generally years behind. But it is not only the design, but the quality of its components makes a tremendous difference. The greater weight and volume of these devices tells us about the quality of their construction before even entering to assess their technical characteristics that mark distance. And the touch they have is soft but firm and precise at the same time.

Microscopistas.com was born, as I have said before, from the desire to provide top-level equipment at affordable prices. Especially oriented towards both the medical or veterinary professional who performs their own analysis and tests and the hobbyist looking for a microscope with practically unlimited possibilities. Because this is one of the characteristics of the equipment that you will find in our store. These are instruments that come from hospitals, analysis laboratories, veterinary centers and similar institutions. They are equipment that has been renewed because institutions always tend to seek greater efficiency and that is why they acquire more modern, more automated devices, etc. Therefore they are equipment that has been checked and maintained throughout their lives, and now they have a second chance.

The microscopes that we offer at microscopistas.com are of premium quality, as we say, and have these characteristics:

Its constructive quality is excellent. The fits, the quality of the parts, the smooth operation … you won’t find it in cheaper brands.
These opticcs are the top. Wide fields, lens coating, flatness, infinity corrections, and everything you can hope for and want.
Ergonomics have been highly studied in these instruments, because they are professional tools for intensive work, designed to be used during long working hours.
They can be extended to practically all contrast techniques. Mainly because they have a good source of lighting and the accessories for it are available at affordable prices. So we can scale from bright field to phase contrast, dark field, polarization, fluorescence and even Differential Interference Contrast (DIC).
They have a multitude of accessories for all the needs that may arise, as these brands have always had a competition for innovation and development and have covered all the needs of customers of all kinds.

Thus, from microscopistas.com we believe that the best decision when purchasing a microscope for professional use when the budget is limited, is to buy a used microscope from one of the four premium brands: Leica, Olympus, Nikon and Zeiss.

These microscopes will not let you down, they will never fall short, you will have no trouble finding accessories. It is true that some are no longer manufactured, but their use has been so widespread throughout the world for so many years that it is not difficult to find replacement parts, or accessories for an extension. At microscopistas.com we also offer the service of supplying parts and accessories for the most important microscopes, as well as consulting without obligation.

The microscopes used for professional use that we recommend can be found among these examples:

Leica DMLB, DM2000, Leitz Aristoplan, Orthoplan, etc.
Zeiss Series Axioskop, Axiovert, AxioScope…
Nikon Eclipse 400, 600, 50i,55i, etc.
Olympus series BX, older BH-2, etc

There are quite a few microscopes with these characteristics, but any of the above will suit your needs perfectly if you are a professional user. And let’s not say if it is for amateur use, since many of these microscopes that have worked for years in the professional world, end their days at the table of a hobbyist of microscopy, mycology, mineralogy, etc. For many of these hobbyists, these kits have been the object of desire for years, and now they have the opportunity to enjoy one of these used professional microscopes at affordable prices.

To finish, just say that these devices when they were new cost many thousands of euros and were only accessible to government institutions or medical research or analysis centers that handle large budgets. Some of this equipment can be yours today for a very small part of its original price. And remember that a well-maintained microscope has an unlimited lifespan.

You can get more information by writing to this contact form.