Hi all this is my first post. I am very new to microscopy, but have been a keen astronomer for 35 years, and have some knowledge of optics.
I have just purchased a 1982 Olympus CH microscope (ebay) and am enjoying inspecting the miniature life from my bird bath.
I have magnifications of 40x, 100x and 400x. Just like astronomy, one tends to use the lower maginfications more. Indeed I find 400x too much and would like to try 200x, but the 20x objective seems a rare Olympus item.
Should I look for a 20x objective or add a 20x eyepiece to my current 10x one??
thanks John
Olympus 20x objective??
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Charles Krebs
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John,
Welcome! I think you'll really enjoy watching "inner space" with your microscope.
For some reason I missed your message earlier this week. 20X objectives are less common, but Olympus made several in the objective line used on that microscope. I think you would be much happier with a 20X rather than going to higher power eyepieces. The 20X eyepieces would make subjects appear twice as large compared to the 10X eyepieces, but you would not be getting any more detail. The detail obtainable is determined by the objective's numerical aperture. Some people find that moderately enlarging the detail with 12.5X or perhaps 15X eyepieces works for them. But every time I have tried 20X eyepieces I could not wait to get back to the 10X ones. The 20X eyepieces were much more "critical" of eye position, and the image never looked anywhere near as crisp... probably "empty magnification" as a result of over-magnifying the resolution afforded by the objective. (And I'm not even sure Olympus made 20X eyepieces for the objectives used with that scope).
I think the Olympus CH microscope used the same "LB series" objectives as the Olympus BH . If you don't already have some idea of what objectives were made in that series, they are listed toward the back of a BHS catalog (5.6mb pdf) you can get here:
http://www.krebsmicro.com/BHS-BHT_Microscopes.pdf
If these were the ones used on the CH, they were DIN, 45mm parfocal distance. Olympus corrective ("K") eyepieces should be used for the best results. But there are some other 16X-25X non-Olympus objectives that can provide a very nice view.
And it would probably be even less expensive (or at least close to the same cost) to track down a good 20X objective rather than getting a good quality pair of 20X eyepieces.
Welcome! I think you'll really enjoy watching "inner space" with your microscope.
For some reason I missed your message earlier this week. 20X objectives are less common, but Olympus made several in the objective line used on that microscope. I think you would be much happier with a 20X rather than going to higher power eyepieces. The 20X eyepieces would make subjects appear twice as large compared to the 10X eyepieces, but you would not be getting any more detail. The detail obtainable is determined by the objective's numerical aperture. Some people find that moderately enlarging the detail with 12.5X or perhaps 15X eyepieces works for them. But every time I have tried 20X eyepieces I could not wait to get back to the 10X ones. The 20X eyepieces were much more "critical" of eye position, and the image never looked anywhere near as crisp... probably "empty magnification" as a result of over-magnifying the resolution afforded by the objective. (And I'm not even sure Olympus made 20X eyepieces for the objectives used with that scope).
I think the Olympus CH microscope used the same "LB series" objectives as the Olympus BH . If you don't already have some idea of what objectives were made in that series, they are listed toward the back of a BHS catalog (5.6mb pdf) you can get here:
http://www.krebsmicro.com/BHS-BHT_Microscopes.pdf
If these were the ones used on the CH, they were DIN, 45mm parfocal distance. Olympus corrective ("K") eyepieces should be used for the best results. But there are some other 16X-25X non-Olympus objectives that can provide a very nice view.
And it would probably be even less expensive (or at least close to the same cost) to track down a good 20X objective rather than getting a good quality pair of 20X eyepieces.
Charles,
Thank you for your help.
I understand that of course it is the objective that gives the resolution and ability to magnify. The same holds true in astronomy of course, but astronomers are not able to instantly change the objective of the telescope, so think always in terms of what is the best eyepiece for each viewing object. I must get out of this habit.
I shall look for a 20x objective - I have seen one an S Plan but the dealer wanted $390 for it which is almost twice what I paid for my microscope!
In the meantime, I have been playing cut outs making dark field masks out of black card. I am amazed at the results from such simple materials!
Thanks again
John
Thank you for your help.
I understand that of course it is the objective that gives the resolution and ability to magnify. The same holds true in astronomy of course, but astronomers are not able to instantly change the objective of the telescope, so think always in terms of what is the best eyepiece for each viewing object. I must get out of this habit.
I shall look for a 20x objective - I have seen one an S Plan but the dealer wanted $390 for it which is almost twice what I paid for my microscope!
In the meantime, I have been playing cut outs making dark field masks out of black card. I am amazed at the results from such simple materials!
Thanks again
John
Hi John,
I first used a 20x objective about twenty years ago. It was love at first sight and has remained my favourite lens when looking at smaller plankton. I usually scan the sample with the 10x and then study the specimen with the 20x and often do not bother going up to 40x.
BTW, for over 30 years, the olympus CH was the microscope that I used on a day to day basis for work. It is a fantastic, well built microscope which can take an incredible amount of abuse ( eg dropped onto a concrete floor from 1 metre !). I think that it is an excellent choice for a first microscope and one I would risk buying sight unseen off the internet. The commonest problem seems to be failure of the rheostat controlling the intensity of the built in light source.
- I foresee many happy years of microscopical adventures ahead.
Keep looking down...
BrianO
I first used a 20x objective about twenty years ago. It was love at first sight and has remained my favourite lens when looking at smaller plankton. I usually scan the sample with the 10x and then study the specimen with the 20x and often do not bother going up to 40x.
BTW, for over 30 years, the olympus CH was the microscope that I used on a day to day basis for work. It is a fantastic, well built microscope which can take an incredible amount of abuse ( eg dropped onto a concrete floor from 1 metre !). I think that it is an excellent choice for a first microscope and one I would risk buying sight unseen off the internet. The commonest problem seems to be failure of the rheostat controlling the intensity of the built in light source.
- I foresee many happy years of microscopical adventures ahead.
Keep looking down...
BrianO