43x very dim

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Timemaster1212
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43x very dim

#1 Post by Timemaster1212 » Sat Feb 24, 2018 8:15 pm

So I was told that the 43x objective needed a "special" way of illumination. Now I ask, what is this technique? I did make sure that it was clean, and it is indeed so, however is still seems remarkably dim. Thank you all for your input.

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Re: 43x very dim

#2 Post by Timemaster1212 » Sat Feb 24, 2018 8:22 pm

I forgot to say that this occurs when the diaphragm is partially closed, if wide open, it is much brighter but I loose quite a bit of contrast

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Re: 43x very dim

#3 Post by wporter » Sun Feb 25, 2018 12:06 am

Which diaphragm is that, exactly? The field diaphragm (the lever behind the lightwell) should be basically open (well, technically just wider than the field of view, but I've never seen a Riechert scope where it made any difference that it was wide open; Apo can probably correct me if the AO scopes were more fussy), and the condenser diaphragm should only be closed about 1/3 of its travel, stop moving it closed if you get any sort of diffraction lines on the outer edges of your specimen.
Does your objective have an iris? If so, it should be wide open at all times unless you are doing darkfield work.

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Re: 43x very dim

#4 Post by apochronaut » Sun Feb 25, 2018 3:14 pm

There was no 43X with an iris, that I know of. There was a very rare 45X .85, but it could be phase. This is what should be on the barrel of your objective.
Firstly, at the bottom there should be 7 yellow rings. Above that, there should be 3 sections with embossed lettering. In one section it has the AO crest and under that the word SPENCER. Rotating the objective clockwise you will come to 43X and under that N.A. .66. Rotating the barrel clockwise you will come to MADE IN U.S.A. and under that a serial #. Is there anything else written on the barrel?

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Re: 43x very dim

#5 Post by MicroBob » Sun Feb 25, 2018 4:12 pm

The 43x needs a proper illumination with the condenser. This should be racked up until close below the slide. The condensor aperture should be open or just a little closed. If there is a swing in lens below the condensor it should be out of the way normally (Apochronaut - ist this true for this stand?). Can you post an image that shows your condensor and it's position?

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Re: 43x very dim

#6 Post by apochronaut » Sun Feb 25, 2018 10:57 pm

Defects in getting the light where it belongs; illumination centering, condenser centering and even a lack of parcentering of the objectives are all possible, as well as making sure all the lens surfaces in the illumination pathway are clean.

The series 4 has a pretty low output bulb. When everything is properly aligned and all of the lens and prism surfaces are clean, the illumination is perfectly adequate for anything the microscope is designed for, with the exception of 970X oil immersion DF, for which a self illuminated DF condenser was available.

If you are getting a decent image with the 10X and a dim image with adequate contrast with the 43X, and when bright enough, a bleached out image with the 43X, I would look towards a combination of dirt and mis-alignment being the culprit. Two lens surfaces you might not have considered cleaning are the upper and lower surfaces of the compensating tube lens , situated just above the nosepiece under the head. Dirt there would cause less of an apparent problem with the 10X , than with the 43X. You also have no base line, with which to judge the performance of the 10x. perhaps it too is smudgy but sufficiently less so, than the 43X , so that in comparison, it seems o.k. That compensating lens pack threads out by the way. Also the rear lens , down in the 43X objective barrel , if dirty, will have a big effect on contrast and if the objective turns out to be a phase and therefore require a "special" way of illumination, that also would contribute to lower contrast.

Low power objectives have higher illumination and higher apparent contrast than higher power objectives, so whatever problems are affecting the 43X , might not be as evident with the 10X.

The microscope is 60 years old and possibly has a lot of dust and or films caused by microscopic airborne particles have made their way in. I once cleaned a w.w.II pair of British Navy binoculars that had so much nicotine residue on the prisms that the image was, barely discernible and yellow. Someone liked cigars. Maybe they were Winston Churchill's.

All older microscopes , should be thoroughly cleaned, a.s.a.p. after receiving them, unless you have been assured that they have received adequate maintenance throughout their life.

MicroBob , I suspect he does not have a swing out auxillary condenser. That normally shouldn't affect the 43X too much but swinging it out and getting Köhler established would be helpful nonetheless.

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Re: 43x very dim

#7 Post by Timemaster1212 » Mon Feb 26, 2018 4:16 am

OK, sorry for the late reply. When not on my microscope trying to learn (made a cool DIY phone adapter, should talk about it), i was hanging out with my family.
1. My 43x objective has no other writing on it apo
2. The swing out condenser is swung in, if not it gets really dull
3. I noticed how dim the scope was as a whole
4. I will post a pic of the condenser tomorrow, but it seems to be alligned. And i followed a youtube video on Kohler illumination, but I either notice no difference, or I am doing it incorrectly.

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Re: 43x very dim

#8 Post by Timemaster1212 » Mon Feb 26, 2018 4:17 am

Any cleaning tips would be helpful. Also, how does one fix stiff coarse adjustment, along with any other stiff controls.

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Re: 43x very dim

#9 Post by apochronaut » Mon Feb 26, 2018 1:26 pm

the aux. swing out condenser should be out of place for the 43X objective.
For cleaning , the easiest and best way to start and get the instrument quickly usable is with isopropyl alcohol. you will get it 90% or more clean quite quickly ; enough so that you can evaluate it's performance and make further adjustments and lubrication. you can go back and do a perfect clean later. that takes a lot more time and requires better cleaning tools and observation techniques.

use tightly wound cotton swabs. cheap ones are loose and leave a lot more fibers behind, so q-tips or equivalent are the base line but there are better laboratory quality ones available too.

for each lens surface, begin by putting a drop of isopropyl on a swab. moisten the lens surface with the swab and while rotating the swab slowly and gently, pick up as much dust and dirt as possible with one rotation. repeat with the other end and again if necessary. another moistened swab can be used to remove any remaining light or adhering film. one or two need to be used to do a sort of polishing of the surface.

do the following surfaces on the series 4. the rest can be looked into later. 1) collecting lens front surface, just ahead of the bulb. 2) collimating lens rear surface just behind the mirror. 3) mirror 4) illumination window bottom and top. 5) bottom and top surfaces of the aux. condenser lens 6) condenser bottom lens( make sure the iris is wide open and you don't leave cotton fibers on the iris leaves 7) condenser top lens 8) front lens surface of all objectives 9) back lens surface of all objectives 10) bottom and top surface of the compensating lens 11) window in bottom of the head 12) windows under each eyepiece 13) field lens entry surface of each eyepiece 14) eyelens exit surface of each eyepiece. Also clean the glass envelope of the tungsten bulb.

All other surfaces, require a degree of dis-assembly to expose them. They are likely less dirty than the other surfaces but in old microscopes they can have a significant amount of dust and film but getting the exposed surfaces cleaned up should brighten up the image, significantly.

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Re: 43x very dim

#10 Post by MicroBob » Mon Feb 26, 2018 6:10 pm

There is one further possibility for the dim light: It is an old scope and the bulb may have been changed to a a lower power model that just happend to be at hand. Have a look what is written on the bulb. It might also be a mismatch of bulb and transformer.

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Re: 43x very dim

#11 Post by Timemaster1212 » Mon Feb 26, 2018 10:57 pm

I was thinking actually, it would be really easy to 3D print a LED illumination attachment that would easily fit in the current bulb slot with no modifications to the microscope at all, just screw in the new light source using existing space and screws, but giving me much more light. Or even using a different bulb that's much brighter. Idk what do you guys think for a long term project?

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Re: 43x very dim

#12 Post by apochronaut » Tue Feb 27, 2018 2:06 pm

it is not as easy as it sounds to retrofit a microscope to led. the collimating lens and field iris system is carefully designed to make use of a light source that originates from a filament, whereas led light usually originates from a broader cross sectional area. there usually ends up being a considerable amount of wasted light in led retrofits. sometimes it is best to by-pass the illumination system altogether, and place your led illuminator, right under the stage. i have made a number of retrofits and the most successful have been in remote illuminators for stereo microscopes, where the light can be beamed directly onto the stage. i have found , however that led light , similarly to fluorescent ( but not as bad), provides poor shadowing and therefore poorer 3 dimensionality in a stereo microscope.

led light is much more monochromatic than either tungsten or halogen. there are many microscope samples that require a broader spectrum light source in order to see the most details.

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Re: 43x very dim

#13 Post by Hobbyst46 » Tue Feb 27, 2018 3:59 pm

While I fully agree with Apochronaut on every aspect and potential issue with LEDs, for my scope a LED source was the only option when the ancient tungsten lamp became problematic.
So in the case that you nevertheless want a LED here is my experience.

A DIY LED illumination may involve some electrical and mechanical challenges, especially the mechanical fitting into the microscope, sufficient cooling for the LED etc. I preferred to buy mine ready. From retroDiode.com. They make them for many brands including AO. A 10w LED provides super strong illumination. Great for darkfield, phase, etc...
There are two potential issues though.
1. Dark bands in the photos, like with commercial household LEDs. These can be eliminated (mostly but not entirely) by ordering the lamp with a 21khz PWM dimmer instead of the standard, cheaper, PWM dimmer. A constant current power supply might be better but retroDiode do not supply it as far as I know.
2. The LED Color temperature. Mine is 6500k and I filter it to remove some of the blue. But there are other options.
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Re: 43x very dim

#14 Post by Crater Eddie » Tue Feb 27, 2018 4:20 pm

For what its worth, I spent a lot of time on DIY LED conversions for a couple of my LOMO scopes, documented here in the forum. Ultimately I went back to the original halogen illumination for both. I tried cool white, warm white, and neutral white LEDs with very pleasing results (neutral white was the best), but eventually the eyestrain and headaches forced me to abandon them.
Your results might be different of course.
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Re: 43x very dim

#15 Post by apochronaut » Tue Feb 27, 2018 5:14 pm

Hobbyst46 wrote: I preferred to buy mine ready. From retroDiode.com. They make them for many brands including AO. A 10w LED provides super strong il

I'm guessing you have never tried this 10 watt option from retroDiode? A 10 watt led is absolutely wimpy, in comparison to 100 watt halogen and completely useless for high resolution DF, despite what their adds say. I challenged them on their claims and they admitted that their retrofits were not a suitable conversion for 1000x DF.

Despite the many claims of led having such and such an equivalence to halogen or tungsten illumination and the fact that Amscope or Omax microscopes are sold with 3 and 5 watt led illuminators along with claims for DF and 100x w./iris objectives as accessories, who uses one of those for 1000X DF? It's all B.S., like 50% of Amscope and Omax's marketing. Just carrots to lure the naive.

Anybody I know, who has successfully used led illumination for higher magnification, higher resolution microscopy is using a minimum of 20 watts and some as high as 40 watts.

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Re: 43x very dim

#16 Post by Hobbyst46 » Tue Feb 27, 2018 6:03 pm

apochronaut wrote: I'm guessing you have never tried this 10 watt option from retroDiode? A 10 watt led is absolutely wimpy, in comparison to 100 watt halogen and completely useless for high resolution DF, despite what their adds say. I challenged them on their claims and they admitted that their retrofits were not a suitable conversion for 1000x DF.

Anybody I know, who has successfully used led illumination for higher magnification, higher resolution microscopy is using a minimum of 20 watts and some as high as 40 watts.
I am using this 10 watt option all the time on my scope. The intensity is blinding, so I have to add ND filters. This may be peculiar to my microscope only. I can only speak from personal experience. And just to remove any doubt, I do not gain anything from retroDiode.com.

About DF: I get very good DF with 6-16x objectives and bad to none at all with 25x-100x objectives. Should I blame it on the LED?
My original microscope manuals say that DF can be obtained even with 40x objectives and higher - it just requires manipulation of the condenser. And the original illumination of the old Zeiss standards is a 6V 15W tungsten, which even when new, did not come close to the intensity of halogen lamps.
So I suspect that the fact that I fail to get high-mag DF on my scope is incorrect alignment of the condenser. It is a turret condenser.
Is there a commercial inexpensive 20-40W LED illumination for these old microscopes?
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Re: 43x very dim

#17 Post by apochronaut » Tue Feb 27, 2018 6:22 pm

I am unsure of how Zeiss originally configured the Standard for high resolution DF. I think, maybe, a rear mounted high output illuminator housing? It would not have taken place using a stop , abbe condenser, and 15 watts though. 10 watts led, works out to be about the same as 40 watts of halogen, depending on the location of the bulb relative to the condenser and the precision of the led system.
60X or 100X DF, usually requires an oiled, dedicated, DF condenser, and also requires very high illumination. Other companies had alternative illumination for high res. DF, a 50-100 watt external illuminator housing or a a self illuminated DF condenser.



Going back to the illumination system on the 4. It is a rear entry illuminator, so it is in perfect condition for a retrofit to a high output led or a high output halogen but the collector lens is fairly small. I could try an led in there. I have some direct conversions for that ba15d socket but the bulb is only supposed to be about 180 lumens. I could see, how much of the light gets collected.

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Re: 43x very dim

#18 Post by Timemaster1212 » Tue Feb 27, 2018 6:59 pm

Hm, so would an LED be the best option for a retrofit? It would be relatively easy i thought originally, but now I am wondering if i still should...

Well as long as it is not permanent i will be willing to try. I started this thread because the microscope was shockingly dim, my Nikon G is decently bright at 40x, and that is without a condenser (waiting to save money to go get it serviced and repaired, then my AO will follow, for now it is ok). So i thought "Why not build a housing to hold a similar bulb to the nikon, or even use something more modern like LED's.

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Re: 43x very dim

#19 Post by MicroBob » Tue Feb 27, 2018 8:16 pm

From my experience I have nothing to complain about a working LED conversion. With a 10W LED and a cardioid darkfield condenser I get a very good illumination with the oil immersion objectives. Of cause LEDs are not perfect and there are some disadvantages, but for me the advantages are more important. Some of these disadvantages can be adressed, some not. But from my view point they are not that important for a newbie with a dim light.

For the newbie these points are the most important to know:

- LEDs have a good efficience, but not that good
==> You need a good heat transmission away from the LED, aluminium, copper are good materials, forget plastics
- LEDs need a current limitation, they burn out otherwise
==> You need to inform yourself about electronics
- stronger LEDs offer bright light
==> You need a dimmer, most of the time the LED will run in tick-over mode
- Most high power LEDs have a lens on them that can disable the orignal light path
==> grinding the lens flat helps

So LED lighting is a nice improvement for most microscope from my point of view, but it is not as easy as it sometimes seems.

To put things in perspective: 1W LED lighting is all you need for brightfield up to 100x oil immersion. The cooling ist not that problematic at this power level. Mounting an LED that is already bounded on a star-board with heat transmission paste to a strip of aluminium sheet metal will suffice. As a power source you can use a cheap laboratory power supply with current regulation. You will need to spend some time and money on experimentation.

On the other hand side: A well working halogen illumination is fine as well...

Bob

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Re: 43x very dim

#20 Post by apochronaut » Tue Feb 27, 2018 8:55 pm

Great. could you post some pictures with your 100x oil immersion DF/led illuminated system?

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Re: 43x very dim

#21 Post by Hobbyst46 » Tue Feb 27, 2018 9:13 pm

AS mentioned above, I cannot do 100x DF as yet.
I can try phase contrast in addition to BF. Within a couple of days.
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Re: 43x very dim

#22 Post by Timemaster1212 » Tue Feb 27, 2018 9:16 pm

Which one would be the easiest and the cheapest, I am a freshmen in highschool so I don't have too big of a budget :roll:

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Re: 43x very dim

#23 Post by wporter » Tue Feb 27, 2018 10:04 pm

Before you start making time-consuming/expensive mods to your microscope illumination system, you might want to try this: get one of those $5-10 chinese high-lumen pocket flashlights off ebay, such as (and I am not recommending this exact model in particular):

https://www.ebay.com/itm/Tactical-Polic ... nqoh-VBDOQ

Zoom it down to a tight beam, remove your existing lamp holder, etc.; prop the flashlight up behind, or insert it into, the light port at the rear of your scope, turn it on, and see what this does for you light-wise.

Some cheap experimentation like this is worth more than endless advice from us people who are not on-site.

As a further word of caution, avoid the strobe setting (lol).

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Re: 43x very dim

#24 Post by Timemaster1212 » Tue Feb 27, 2018 11:43 pm

Hehe, thanks man. In fact I can do that now. Also, can someone explain the swing out lens for the condenser (I am willing to post a pic if needed)

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Re: 43x very dim

#25 Post by MichaelG. » Tue Feb 27, 2018 11:56 pm

Timemaster1212 wrote:... And i followed a youtube video on Kohler illumination, but I either notice no difference, or I am doing it incorrectly.
If you have an iOS device ... This is a very helpful interactive tutor

Koehler Tutor by Andrew Barlow
https://itunes.apple.com/gb/app/koehler ... 28178?mt=8

Highly recommended !!

MichaelG.
Too many 'projects'

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Re: 43x very dim

#26 Post by apochronaut » Wed Feb 28, 2018 1:03 am

Timemaster1212 wrote:Which one would be the easiest and the cheapest, I am a freshmen in highschool so I don't have too big of a budget :roll:
There is a lot of info. on the internet about how to diy some interesting contrast enhancement techniques.
There is a slot in the bottom of the condenser. You can put a DIY darkfield stop in there, made out of cardboard, or other types of filters and stops.. That will allow you to do DF up to and including the 43X objective, if it is precisely made. You will need to get your illumination bright enough, possibly with wporters advice about the flashlight.

Here is some information on how to do a DF stop and some other techniques.
http://www.microscopy-uk.org.uk/mag/ind ... trast.html


Phase contrast requires a special condenser and special objectives to do. The cost would likely be at least 250.00 and probably more to get a set for phase for that microscope and they are becoming a bit rare, due to their age.

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Re: 43x very dim

#27 Post by Timemaster1212 » Wed Feb 28, 2018 3:01 am

Well i will have a project to keep me up tonight :D I will definitely try the darkfield spots. And i was looking at the phase contrast, maybe it will be an interesting summer gift from my sponsors 8-) if i am lucky enough to find a set :lol: I will be posting pictures comparing the old lighting system vs. the led flashlight probably this weekend. Have an excellent night all of you!

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Re: 43x very dim

#28 Post by MicroBob » Wed Feb 28, 2018 3:18 pm

The question after the needed LED power for high power dark field came up. I did a test with my Zeiss Jena NF with 10W LED and a 90:1 n.a 1,25-0,8 Zeiss Jena achromat (old design, 33mm length) and two different dark field condensors.

First test with a Zeiss Jena cardioid darkfield condenser, unknown n.a., originally meant for the older LG. Here I needed 6W for a good visible image, 100% light to the two eyepieces. I had to close the aperture of the objective to ca. 1,0 to get a good dark field. I assume that the max. n.a. of the condenser is 1,2.

Second test with a Zeiss Jena pancratic condensor with the cardioid dark field head, set to n.a 1,4. I was able to open up the objectives aperture to the full n.a. of 1,25. Obviously the pancratic condesor produces a different light cone from the other cardioid condenser. Here I used the full 10W and would have preferred 20W. I looked for the reason of this difference an found it. The pancratic condensor is used with a lens on the light outlet that only has about half the diameter of the light outlet itself. So here we have a loss of about 75%! :shock: I will have to investigate this further. There has been a separate high power lamp to put under the NF but this makes the instrument really unwieldy. For me it is difficult to believe that Zeiss Jenas flagship condenser would make acheiving darkfield so difficult.
I will clean my two so far no used pancratic condensers and will do some more testing with them. Apart from the power consumption the image was nice.

Hobbsyt46: Do you use the darkfield stop from your phase condenser or do you have a separate darkfield condenser?
On german ebay they seem to be much rarer than the Zeiss Jena darkfield condensers. I have no idea why.

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Re: 43x very dim

#29 Post by Hobbyst46 » Wed Feb 28, 2018 4:19 pm

MicroBob
I am very glad that you are pursueing this subject.
I only have two condensers. One is the simple brightfield condenser with a swing out lens, NA 1.3. I do not use it,
The other one is thd Achromat aplanat 1.4 condenser, model 7z if I recall correctly. It has BF, DF, PH2, PH3 and three empty positions (for DIC I believe). I inherited it by luck, otherwise would be rare and very expensive.
For DF I use the PH3 with the 6,3x, 10x & 16x objectives. The DF ("D" position) yields DF only with the 25x and it is quite poor. I already worked on this condenser several times, tried to place opaque stops in the empty openings, add DIY Rheinberg filters, but never got anything useful with the 25x-100x objectives- I guess that they were either wrong size or uncentered.

The objectives I use are 40x0.75 Ph2 Neofluar, 63x1.4 Ph3 Planapo, 100x1.3 Ph3 Planapo.
,
I also tried high- mag DF by placing stops in the filter holder beneath the auxiliary lens below the condenser - failed.
Condenser change on the GFL scope is inconvenient because it is small and the condenser downward movement is limited. In addition, I am somehow believe that Zeiss intended that the Achromat Aplanat will cover all possibilities - but maybe thisis not thd case...
Last edited by Hobbyst46 on Wed Feb 28, 2018 5:00 pm, edited 2 times in total.
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Re: 43x very dim

#30 Post by Hobbyst46 » Wed Feb 28, 2018 4:21 pm

Is German eBay a separate site from "English/American" eBay?
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