Reichert zetopan questions

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Lukas
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Reichert zetopan questions

#1 Post by Lukas » Sat Jan 15, 2022 5:53 pm

Hello everyone,

Recently I could not resist purchasing this overdesigned mechanical miracle for cheap. It needed cleaning, new halogen lamp, power supply, and oiling in there and there. Condenser adjustments ​took quite a while to figure out.
Also I was able to construct adapter for my Panasonic GH4 camera. Nice thing about it - m4/3 sensor size is just about right for this purpose without reduction optics. Pictures are not bad, I would say. Polarization was also easy to do.
However, I am struck with setting up dark field for it. I think patch stop can not be inserted because the condenser is monolithic with it's Koehler illuminator - correct ?
Is it so that patch stop must be at the same level as field diaphragm ?
Any ideas to DIY it, or any solution ?

Regards,
​Lukas
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Re: Reichert zetopan questions

#2 Post by zzffnn » Sat Jan 15, 2022 8:33 pm

Welcome to the forum.

Please remove your condenser and take many photos of different configurations. The more the better.

Not many people have Zetopan condensers; plus there are quite a few different condensers for Zetopan to start with.

It is unlikely that a condenser would not allow you to insert filters near condenser iris diaphragm.

Worst case scenario, you can use molding putty and stick a glass slide with patch stop under condenser frame. Or put patch stop over field diaphragm over light source.

Lukas
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Re: Reichert zetopan questions

#3 Post by Lukas » Sun Jan 16, 2022 11:37 am

Hi,

The scope comes with a two diaphragm condenser, with a top lens having N/A 1.3. It seems to work well with objectives 25x and higher.
With lower magnification I need to swing top lens out, so, in principle, it's useable.
Bottom diaphragm seems to work well to limit stray light in the photo tube, so I find it quite useful.
However, trying to place a patch stop below bottom lens does not seem to work. ​I guess the lens assembly is responsible to making even illumination.
Also I have seen some condensers with rotating turret on sale. Quite expensive unfortunately. Anyone has experience with those ?

Regards,
Lukas.
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Re: Reichert zetopan questions

#4 Post by BramHuntingNematodes » Sun Jan 16, 2022 2:47 pm

Dang that thing is fancy
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

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Re: Reichert zetopan questions

#5 Post by zzffnn » Sun Jan 16, 2022 3:21 pm

Lukas,

Your condenser's bottom iris acts as field diaphragm, so placing a patch stop there won't be too effective.

Try:

1, placing patch stop under top "swing out" lens, above first (upper) iris:

2, inserting a thin plastic sheet with black circular patch stop hand-drawn on it, near that bent lever.

This is related:

http://www.microscopy-uk.org.uk/mag/ind ... topan.html

I have been wanting a Polyphos condenser from Zetopan. That one should work well for variable dakrfield.

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Re: Reichert zetopan questions

#6 Post by apochronaut » Sun Jan 16, 2022 4:44 pm

This might be of use to you. Looks to me like it might be a paraboloid which would allow you possibly to go down to a 25X objective. Some of these had a toric lens in the bottom which allows for DF down to the 10X. I can't tell from the photos if this one does.
It does not look to be cardioid. There is a cat.# on the bottom which probably can be traced to find out the specs.
https://www.ebay.com/itm/REICHERT-Micro ... ect=mobile

Lukas
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Re: Reichert zetopan questions

#7 Post by Lukas » Sun Jan 16, 2022 8:16 pm

Hi,

After some time of thinking I decided to give it a try and place patch stop between bottom lens and field diaphragm.
Made it from plastic sheet with a drop of black paint.
Then it seemed to not work at all. However I proceeded to test every lighting configuration of microscope I could think of.
Surprisingly, it appeared dark field works only with 63x objective with it's iris closed.
Resolution was similar to bright field, illumination low.
What is so special about this iris diaphragm inside the objective ? Is it so that with this microscope it's necessary for DF ?

Regards,
Lukas.
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Re: Reichert zetopan questions

#8 Post by apochronaut » Sun Jan 16, 2022 9:57 pm

The objective must be working at an N.A. that is at least .20 less than the condenser. By closing the iris you are lowering the N.A. of the objective. You didn't say what the N.A. of your 40X is.

For DF with a high magnification higher N.A. objective, you will get better results if the condenser is set up as much as possible to mimic a DF condenser. This means, the top lens should be flipped into operating posiition, the iris diaphragm needs to be wide open and the condenser should be oiled to the slide. This allows you to maximize the N.A. of the objective and achieve superior results.

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Re: Reichert zetopan questions

#9 Post by Lukas » Mon Jan 17, 2022 11:40 am

Hi,

Thanks for explanations. The objective that worked was 63x/80 Ph. I guess I should try with different patch stops in the future.
After reading your reply, I found more detailed explanation. Maybe of interest to others :

https://www.chem.uci.edu/~dmitryf/manua ... oscopy.pdf

Also I checked DF condenser you have posted in the link. Unfortunately, it does not look the same as in zetopan catalogue.
Wondering if part found on e-bay is from other model ?

Regards,
Lukas.
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apochronaut
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Re: Reichert zetopan questions

#10 Post by apochronaut » Mon Jan 17, 2022 2:15 pm

I figured for 69.00 + shipping you could get it up and running. The sleeve size will be correct for Reichert but you might just check with the seller and measure it. You can drop your condenser out of the Akehurst slide and measure it. I can't remember what the Reichert sleeve diameter is.

The Zetopan used an Akehurst Slide type of condenser mounting system but the condenser itself has a sleeve mount, which fits into the Akehurst Slide. No doubt other Reichert models used a plain sleeve fitting and it would be unusual for Reichert to use different sleeves, since DF condensers are optically universal.

The ebay condenser has the capacity to work on your microscope but you would either have to remove your BF condenser from it's alide and put the DF one in or find a spare Akehurst slide for a Reichert somewhere.

Since you posted a catalogue image from Reichert. The two condensers pictured in the cat. image are the same in function but 9 99 00 18 has in addition a toric lens in the bottom which broadens the field projected by the condenser. It would work for 10X objectives and up. The model 9 99 00 03 would cover the field of objectives only 25X and up likely but maybe only 40X and up. I haven't used that one but I have used a 9 99 00 18 .
The field coverage of a DF condenser( any condenser) is dependant on the f.o.v. of the eyepieces as well. I have used a DF condenser similar to 9 99 00 03, which was good from 25X objectives to 100X with a 20mm f.o.v. but if the f.o.v. was closed down to 18mm, it's function could be brought down as far as a 20X objective.

The reason your 63X ph objective worked for DF is that you closed the iris to beyond the N.A. location of the phase annuli. You can get DF by closing the iris yes but he farther you close the iris, the lower your N.A. drops. Since DF can only be initiated if the objective N.A. is at least .20 lower than the condenser and a 40X ( .65???) objective would not get DF and you had to close off the 63X iris a great deal to get it : that indicates that your patch stop is too small, working at too low an N.A.

When using iris diaphragms to get DF you don't want to close the diaphragm any more than about 1/3 of the diameter. For instance with a 1.25 N.A. objective the diaphragm would be closed to between .80 and .90.

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Re: Reichert zetopan questions

#11 Post by Lukas » Tue Jan 18, 2022 11:17 am

Hi,

Thanks for advice. I would like to search first for a DF condenser complete with slider, and suitable down to 10x. If I can not find it then would consider part from ebay you have recommended.I guess in the worst case the holder could be 3D printed or machined from something.
By the way, yesterday I have experimented with different patch sizes out of curiosity.Surprisingly, it either worked with 63x/iris closed only or not at all. Any other objective did not work.So, it's time to relax a bit and search for parts, and use bright field for now.

Regards,
Lukas.

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Re: Reichert zetopan questions

#12 Post by apochronaut » Tue Jan 18, 2022 2:02 pm

So, in that case, your phase annulus is working as a DF restricter for that objective with that DF occluder.

I see the Reichert toric DF condenser occasionally on ebay. It isn't normally noted in the listings because few would know that. You have to get a picture of the underside of the condenser to see the toroid lens mounted in there. It is shaped like a doughnut; a convex ring around a concave center.

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Re: Reichert zetopan questions

#13 Post by wabutter » Fri Jan 21, 2022 10:21 pm

I haven’t seen a two diaphragm condenser for the Zetopan since the 70, As Phil pointed out, the bottom iris functions as a field diaphragm, while the upper iris is the aperture diaphragm. The dark field stop would need to be at that conjugate plane. I don’t think there is a practical way to accomplish this using the condenser you have. Please do not deconstruct that condenser. It is unique and quite a nice piece of engineering, The DF consdenser listed in the related post would be the best option for working in DF. Of course if you can find the phase turret condenser for the. Zetopan, the phase annular ring can be used as well. That is a nice look system. The Zetopan was truly a unique and versatile platform for its day.

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Re: Reichert zetopan questions

#14 Post by photomicro » Sat Jan 22, 2022 11:37 am

wabutter wrote:
Fri Jan 21, 2022 10:21 pm
I haven’t seen a two diaphragm condenser for the Zetopan since the 70, As Phil pointed out, the bottom iris functions as a field diaphragm, while the upper iris is the aperture diaphragm. The dark field stop would need to be at that conjugate plane. I don’t think there is a practical way to accomplish this using the condenser you have. Please do not deconstruct that condenser. It is unique and quite a nice piece of engineering, The DF consdenser listed in the related post would be the best option for working in DF. Of course if you can find the phase turret condenser for the. Zetopan, the phase annular ring can be used as well. That is a nice look system. The Zetopan was truly a unique and versatile platform for its day.
yes, this is quite a condenser, equivalent to the Leitz one that is similar, and the design after Max Berek I believe. The upper diaphragm controls the aperture, the lower one the field illumination. If you swing aside the top lens (assuming this one does) then the lower diaphragm acts as the aperture diaphragm.

In his seminal text, Needham suggested that using one would confuse microscopists used to dealing with the more 'normal' diaphragms in Kohler !

I had one when I had a Zetopan, and they weigh a ton, testament to the fantastic engineering.

Have you discovered that the condenser fits via a slider? This is via an attached ring, and this can be removed, allowing other condensers to be fitted. For dark-field stops, you need a simpler condenser type, that is all.

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Re: Reichert zetopan questions

#15 Post by Lukas » Sat Jan 22, 2022 12:12 pm

Hi,

I understand it's value of course. The level of precision is rare these days, I think. Also the scope has some nice features I particularly like - it's big, has 6 piece turret; focusing is very precise, also accessories are possible to obtain at reasonable pricing. Servicing is easy. Halogen bulb is powerful and nice for colors. The biggest drawback for me it the stage X-Y controls that are somewhat slow to use while chasing live specimens. But not such a big of a deal.
You've suggested a phase turret condenser. Have to admit already ordered it. It was close to 500 euros for a complete kit. That's more than twice I've paid for entire Zetopan : ).Not sure yet if empty holes will be large enough to fit a DF stop, but we will see.
Now, about DF condensers. They come with two numbers 1.18/1.42/D. Why two numbers and not one? Also, I think that those condensers must be used with oil. Or it could also be used dry with some limitations ?
Also I am searching for a solution to easily lower light intensity without altering color temperature. I've read that neutral density filters should be used for this. I've seen some ND filters for cameras which should fit. But required size is vintage and not so easy to find. Any simpler solution ?

Attached a picture of one idea to attach SLR camera to the base. I do not know if it's a right way to use it without intermediate optics whatsoever. But the picture quality seems to be all right. After some experiments it became apparent that it's quite important to limit stray light inside the tube. So, adjustments of field diaphragm are quite important for photography.
Does a DF condenser also allow for limiting stray light ?

Regards,
Lukas.
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wabutter
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Re: Reichert zetopan questions

#16 Post by wabutter » Sun Jan 23, 2022 8:12 pm

Generally when you encounter a short coming such as the stage x-y control there is often a corresponding plus. In this case, the stage level coaxial stage control offer a bilateral access so you can use either the left or right hand to operate the stage movement. It might not be a plus for you, but probably is for someone. As far as the DF condensers offered in two forms. 9 990003 version of the condenser is for use with the Microspectrophotometer while the 9 990018 is for the general use. Yes, these condenser are immersion type. they will not work dry. These condensers do not have an aperture diaphragm so you can't attenuate intensity via that manner.
You might want to explore the multisystem condensers that had magnetic inserts for DF as well as single phase annular rings. Below is a picture of the catalog of for these condensers
Image.jpeg
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Hopefully you can open this file.

As you pointed out accurately, the best way to attenuate intensity with out changing color temperature is via ND filters. These can be found in most camera stores and be simply placed over the light well of the illuminator. ND filters ten to be additive, so if you have a 50% transmission and a 25% transmission filter, you can achieve 75% attenuation by stacking. If I remember correctly there was a filter slider that had two slots between the illuminator and the stand that could handle more than three filters per slider.

Interfacing SLR or DSLR cameras was not a common practice for this vintage microscope, but it appears you have developed a nice adaptation. If it works all the better, Using intermediate optics may be helpful in improving FOV.

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Re: Reichert zetopan questions

#17 Post by Hobbyst46 » Sun Jan 23, 2022 8:28 pm

wabutter wrote:
Sun Jan 23, 2022 8:12 pm
ND filters ten to be additive, so if you have a 50% transmission and a 25% transmission filter, you can achieve 75% attenuation by stacking.
Actually, not additive though serial. You achieve 87.5% attenuation : with such stacking, light intensity falls 8-fold - first halved (by the 50% filter) then quartered (by the 25%).

There are two types of ND filters - reflective and absorptive. Reflective filters are in fact partial mirrors. They are better because their transmission does not depend on the wavelength. Absorptive filters look like dark colored glass. Their transmission slightly depends on the wavelength. In turn, they are probably cheaper and definitely have a longer lifetime, because they are not coated.
ND filters are available in many sizes and can be square or circular. When thin (say, 1-2mm) they can be cut to size like ordinary glass.

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Re: Reichert zetopan questions

#18 Post by wabutter » Sun Jan 23, 2022 9:16 pm

Absolutely correct. I was oversimplifying, Thanks for clarifying.

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Re: Reichert zetopan questions

#19 Post by Lukas » Mon Jan 24, 2022 8:33 am

Hi,

Thanks for pointing out condensers with magnetic sleeves. I haven't thought about that. In catalogue I see several pats are shown with might be of use for me. 9990017 on of them. Seems have sort of low N/A of 0.65. Is it so that if such a condenser would be used for DF, only objectives up to ~0.4 could be used ?
After some experiments I was amazed how much image quality can depend on just as simple thing as a light bulb. 50/60/100w halogen were tested made by osram for general purpose. Type GY6.35. Fits perfect. 50 watt was usable but color temperature a bit too low. 60w looking different a bit and for some reason not good at all. 100w was whiter, but also the image looked more detailed and clear, so a rheostat is out of question.
Yesterday another solution for reducing light popped into my head. I took some polarizing filters and crossed at a specific angle. Seems to work : ). Filters I'm experimenting with are used for mobile phone screens. It has one adhesive side and is supposed to be glued on top.
Now, response to previous post about cameras and FOW. Yes there is quite a crop by using m 4/3 sensor directly. The diameter of disc projected seems to be about 23 +/- 1 mm at the level of the sensor. Sensor size is 17.3 x 13 mm. However I find that near the edges chromatic aberrations become more and more of a problem. Also not all objectives I use are plan. So this could be viewed as an advantage, considering a lower magnification objective can always be used for larger FOW.

Regards

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Re: Reichert zetopan questions

#20 Post by JWW » Tue Jan 25, 2022 8:07 pm

I'm not trying to butt in this thread, but I have a question about the Zetopan. I have two Zetopans. I haven't figured out how to use either, and I have quite a few accessories. Condenser wise I have the flip-out lens (A=0,95), the UV Nr. 19 806, an IK Nr. 54 229, and this one (see attached image). Any idea what this particular condenser is?
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Re: Reichert zetopan questions

#21 Post by apochronaut » Tue Jan 25, 2022 8:36 pm

That's the Toric DF condenser. El Primo. The same basic condenser in a modified mount was used for the AO series 10/20 as well and some later Reichert microscopes.
See the posts above.

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Re: Reichert zetopan questions

#22 Post by JWW » Tue Jan 25, 2022 9:18 pm

... thanks apochronaut, at least I know what I have.

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Re: Reichert zetopan questions

#23 Post by Lukas » Sat Jan 29, 2022 11:52 am

Hi,

A few days ago phase contrast kit has arrived. It seems to be so called ""anoptral" system, which is a sort of darkened optics(?). Condenser has UV marking at it. Took a little while to setup and align everything. A dark field patch stop was made from black paper and inserted into one of condenser slots with a filter. It seems to work with 10x and also 25x objectives. Not sure about the quality, though, as I have no experience how it should look like with a dedicated condensor. The phase contrast also works and is very nice to look at. Still there in an interesting issue which plagues when 25x is used with phase contrast; in photograph its visible on the left side. I've readjusted everything multiple times from koehler illumination to centering light source and of course aligned phase rings. In no way I can get even illumination of the field. In all other modes and settings it's more or less good. Anyone has experience with this ?
Also I find it that Ph images on internet are quite scarce. Attached pictures of some test images.

Regards,
Lukas.
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Re: Reichert zetopan questions

#24 Post by photomicro » Sat Jan 29, 2022 1:41 pm

Lukas wrote:
Sat Jan 29, 2022 11:52 am
Hi,

A few days ago phase contrast kit has arrived. It seems to be so called ""anoptral" system, which is a sort of darkened optics(?). Condenser has UV marking at it. Took a little while to setup and align everything. A dark field patch stop was made from black paper and inserted into one of condenser slots with a filter. It seems to work with 10x and also 25x objectives. Not sure about the quality, though, as I have no experience how it should look like with a dedicated condensor. The phase contrast also works and is very nice to look at. Still there in an interesting issue which plagues when 25x is used with phase contrast; in photograph its visible on the left side. I've readjusted everything multiple times from koehler illumination to centering light source and of course aligned phase rings. In no way I can get even illumination of the field. In all other modes and settings it's more or less good. Anyone has experience with this ?
Also I find it that Ph images on internet are quite scarce. Attached pictures of some test images.

Regards,
Lukas.
Anoptral contrast was proposed by Wilska, and is effectively a form of negative phase contrast. More refractive features in the object are shown as bright against a relatively dark, almost brownish background.

The condensers are the same, it is the objective that has a different phase annulus. This is the 'A' designation on your x25, ie. Ph A. If you have non-A type objectives, these will give 'normal' (or positive !) phase contrast. Each type are suited to different subject characteristics. American Optical had three variants I think, and some 1980s Nikon gear did.

When using your x25 for phase...how are you adjusting the illuminating diaphragm immediately under the condenser? A lot of such condensers leave the diaphragm out when using phase, but the Zetopan ones I think are still 'active' It can make quite a lot of difference.

Mike

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Re: Reichert zetopan questions

#25 Post by Lukas » Sun Jan 30, 2022 6:41 pm

Hi,

Thanks for advice. Indeed, the bottom diaphragm can improve things a little bit while using phase contrast. Was not expecting that.
By the way, is it normal that different objectives are slightly off center to each other while looking where center of field diaphragm is ?
Also, perhaps anyone knows if Ph objectives from any other manufacturers are compatible with zetopan, as 40x is missing ?

Regards,
Lukas.

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Re: Reichert zetopan questions

#26 Post by apochronaut » Mon Jan 31, 2022 3:45 pm

Lukas wrote:
Sun Jan 30, 2022 6:41 pm
By the way, is it normal that different objectives are slightly off center to each other while looking where center of field diaphragm is ?
Also, perhaps anyone knows if Ph objectives from any other manufacturers are compatible with zetopan, as 40x is missing ?

Regards,
Lukas.
Due to the splay of the objectives in the nosepiece and the precision required in numerous mating surfaces, parcentering of objectives in a microscope is not a guarantee. Some companies in the past, Reichert being one of them, tested microscopes prior to leaving the factory to ensure parcentering within a guaranteed specification but moving objectives around the nosepiece and or changing to other objectives could easily put the nosepiece out of spec. Spencer/AO had a novel way of assisting users to not move objectives around the nosepiece. They put a rivetted on little c.o.b. tag at each location of the nosepiece, designating the magnification that should be there, so they should stay in their centered locations.
In a second hand microscope it is best to rotate the objectives around the nosepiece one place at a time, either clockwise or counterclockwise to find the best parcentering. If one has to be a little off, it is best to have the lowest one, since due to the narrow field of the high magnification objectives it is sometimes possible for the second highest magnification center to be outside of the f.o.v. of the highest magnification center. The best centering should always be between the two highest magnification objectives.

Unfortunately, the width and diameter of the several phase diaphragms, is a highly variable specification between manufacturers. The magnification of the condenser and objective duo is also variable at the rear of each objective's focal plane, compounded by the width and diameter of each phase annulus. This is further compounded by the parfocal length of the objective. So, there are 7 essential specifications that will affect each of the required overlaps between the diaphragm and phase plate annulus.
It isn't unheard of for an objective from another manufacturer to work or partially work but it is either trial and error or one needs to find someone who has done the legwork. A good start would be to remove one variable and aim for objectives with the same parfocal length. In your case 37mm or close. Old black based objectives from Olympus were just under 37mm and there may be a few of those around. Wild was also 37mm but the most common in the long run would be Reichert. Any with a yellow ring at the top and or an A would be Anoptral phase.

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Re: Reichert zetopan questions

#27 Post by Lukas » Mon Jan 31, 2022 10:47 pm

Hi,

Thanks for explanation. Now I know that nothing is wrong with the objectives. By the way, I figured out a way to use objectives that are a somewhat shorter than necessary. The trick is to wrap a little bit of cheapest and thinnest teflon tape on the back of the thread. So the objective can be left screwed out a little and does not wobble. Attached a picture with chinese 35 mm parfocal one. Seems to work : )
Also I observed that while using DF, it's extremely sensitive to tiniest amount of dust or dirt on cover glass(and perhaps below slide). It's visible as large unfocused circles, and more pronounced at 25x magnification than other. I went so far as to clean slide and cover glass by using cleaning kit I use for a camera sensor. Is it normal, or something is off with DF patch stop adjustments ?

Regards,
Lukas.
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Re: Reichert zetopan questions

#28 Post by BramHuntingNematodes » Tue Feb 01, 2022 12:56 am

If you seeing every dust particle and it's driving you to obsessively clean everything you're doing it right
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

apochronaut
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Re: Reichert zetopan questions

#29 Post by apochronaut » Wed Feb 02, 2022 3:34 pm

Lukas wrote:
Mon Jan 31, 2022 10:47 pm
By the way, I figured out a way to use objectives that are a somewhat shorter than necessary. The trick is to wrap a little bit of cheapest and thinnest teflon tape on the back of the thread. So the objective can be left screwed out a little and does not wobble. Attached a picture with chinese 35 mm parfocal one. Seems to work : )


Regards,
Lukas.
There are parfocalizing shims available, in incremental thicknesses. They come in a group of standard thicknesses, which you then add together to get in between thicknesses. An option if your plumbing tape method gives out eventually. With lower magnification objectives, altering the tube length is not without an effect on the optical quality. A little is probably not much of a problem but with low magnification objectives, a couple of mm can throw the objective's corrections off.
It has to do with where the intermediate image is formed by the objective. Reichert finite tube transmitted light objectives form their intermediate image 147mm up the tube from the objective shoulder, which means that Reichert eyepieces collect that image 13mm down from the optical tube lip.

The DIN standard 58887 has become a more or less standard of the industry and it dictates that the intermediate image should be 10mm down from the lip of the optical tube, or 150mm from the objective shoulder in a finite system. Whether your Chinese objective adheres to that or not, I don't know but if it does, moving it out a little(3mm) from the nosepiece would bring it into line with the required location of the intermediate image for the Reichert eyepieces, while possibly altering the corrections of the objective some.

Historical note.
Some old school monocular microscopes right up until the late 40's had a graduated adjustable draw tube so one could use objectives that required a specific tube length and intermediate image location, and then the user could set the optical tube at that length. That is one of the reasons that monocular microscopes persisted so long after binocular versions had become very common. It wasn't uncommon for microscopists to have an array of specialized objectives of various parfocal measures, made by various makers. An adjustable drawtube and sometimes a different eyepiece allowed for the use of any of them. Spencer went so far as to custom manufacture objectives of various parfocal lengths. While their standard was 34mm parfocal, they also made quite a few objectives to the 36 2/3mm Bausch & Lomb standard and I have even come across a 4mm 44X .85 fluorite that is 32mm parfocal, obviously intended to be used in the same nosepiece with Zeiss objectives or in a Zeiss microscope. Presumably, the intermediate image distance was the 13mm of Zeiss rather than the 11mm of Spencer.

Lukas
Posts: 20
Joined: Wed Jan 12, 2022 12:45 pm

Re: Reichert zetopan questions

#30 Post by Lukas » Fri Feb 04, 2022 11:51 am

Hi,

It could be that objective's corrections are off, but I don't see any problems obvious. I think that 10x chinese objective is quite sharp actually, so I'm not yet advanced enough to need an expensive plan apo. So far the biggest factors were sample preparation and lighting, which for my zetopan seems to be geared towards >>40x objective and higher. I fugured out that seemingly uneven lightint at 25x(most pronounced at Ph setting) is also because of this, as illumination ring just barely covers the field of view. Apparently the phase condenser should have had an additional lens at bottom for low magnifications, but it does not. And I don't even know how should it look like and what to search for. However there are workarounds there and there while taking pictures : from cropping it, switching "in/ex" lighting on microscope, using larger magnifications and so on.
Also I have tested chinese adapter with intermediate lenses. I found it introduced additional color distortions and sometimes flares, so conclusion is just use direct exposure to camera sensor.

Regards,
Lukas.

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