Amscope 20x eyepieces....decent??

Everything relating to microscopy hardware: Objectives, eyepieces, lamps and more.
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Terry Mc
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Amscope 20x eyepieces....decent??

#1 Post by Terry Mc » Sun Jul 12, 2020 5:25 pm

I know that you get what you pay for!
However, I don't have the $$$ for top-end 20x E.P.'s for my BH-2, and I'd like to expand my range of magnifications via a 20x EP set. I have a mix of SPlan and Zeiss objectives.

These are cheap EP's...will the views be anywhere close to those in my stock Olympus EP's?

apochronaut
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Re: Amscope 20x eyepieces....decent??

#2 Post by apochronaut » Sun Jul 12, 2020 6:02 pm

On most microscopes , 20X eyepieces can only be used with objectives of 20X and under. With the other objectives, if you ignore the decimal in front of the N.A. # , it must be equal to twice the magnification. In other words you would need a 40X .80,. 60X 1.20 etc.

Increasing the mag. with eyepieces is not ideal, since the eye relief suffers and there is often a loss of contrast, even when the objective is within spec.

Eyepiece quality or design would only marginally affect the above.

Terry Mc
Posts: 22
Joined: Mon Jun 15, 2020 11:16 pm

Re: Amscope 20x eyepieces....decent??

#3 Post by Terry Mc » Sun Jul 12, 2020 8:02 pm

apochronaut wrote:
Sun Jul 12, 2020 6:02 pm
On most microscopes , 20X eyepieces can only be used with objectives of 20X and under. With the other objectives, if you ignore the decimal in front of the N.A. # , it must be equal to twice the magnification. In other words you would need a 40X .80,. 60X 1.20 etc.

Increasing the mag. with eyepieces is not ideal, since the eye relief suffers and there is often a loss of contrast, even when the objective is within spec.

Eyepiece quality or design would only marginally affect the above.
Thank you sir!

Terry Mc
Posts: 22
Joined: Mon Jun 15, 2020 11:16 pm

Re: Amscope 20x eyepieces....decent??

#4 Post by Terry Mc » Sun Jul 12, 2020 8:37 pm

apochronaut wrote:
Sun Jul 12, 2020 6:02 pm
On most microscopes , 20X eyepieces can only be used with objectives of 20X and under. With the other objectives, if you ignore the decimal in front of the N.A. # , it must be equal to twice the magnification. In other words you would need a 40X .80,. 60X 1.20 etc.

Increasing the mag. with eyepieces is not ideal, since the eye relief suffers and there is often a loss of contrast, even when the objective is within spec.

Eyepiece quality or design would only marginally affect the above.
In my case however, eye relief is not an issue; I regularly observe with telescope eyepieces featuring all sorts of eye relief. This being one of my regrets concerning microscope eyepieces, that advanced designs such as we see in telescope eyepieces aren't appropriate for microscopes.

apochronaut
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Re: Amscope 20x eyepieces....decent??

#5 Post by apochronaut » Mon Jul 13, 2020 1:40 am

That isn't exactly true. This a common misconception that comes with being introduced to a telescope before a microscope. To turn it around. What if I said it is regrettable that telescopes only come with one objective lens and even more regrettable that you can't turn a 100mm refractor into a 100mm apochromat refractor in 5 seconds, something you can do the equivalent of in a microscope.

Eyepieces can do many wonderful things for a microscope just as in a telescope but just as in a telescope it costs. Generally speaking ordinary eyepieces such as Huygens or Kellner or even modest W.F. types are used for basic microscopes but as the microscope increases in sophistication : has better colour correction, resolution and wider fields, eyepieces become a more refined part of that performance. One pair of U.W.F. eyepieces for a high resolution microscope can easily cost the equivalent of an acceptable grade lab microscope. Microscope eyepieces tend to be more proprietary, whereas eyepieces for telescopes more universal. I can only think of a few instances where a company offered just microscope eyepieces for sale.

However, to go back to your original question, pushing the magnification into empty magnification zones and the optical problems that causes, cannot be overcome by any improved eyepiece designs. Physics is physics.

carlh6902
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Re: Amscope 20x eyepieces....decent??

#6 Post by carlh6902 » Mon Jul 13, 2020 3:30 am

Amscope eyepieces of any magnification are a poor choice for your BH2. The Olymous LB objectives on the BH2 provide an unfinished intermediate image, and rely on matching Olympus WK, WHK, or SWHK eyepieces to provide a fully corrected image for viewing.

Now, as for 20x eyepieces, you're now getting into to the special case where you will generally get poor results with any manufacturer's eyepieces. My advice is don't waste your money on 20x eyepieces. Instead, get a good set of Olympus WHK15x eyepieces, and use these where appropriate (always avoiding empty magnification - be like Ted).

https://drive.google.com/file/d/19GrLTD ... p=drivesdk

Carl
--- If you're in the Kansas City area and you need help with an Olympus BH-2 scope, PM me. I love to work on these things ---

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75RR
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Re: Amscope 20x eyepieces....decent??

#7 Post by 75RR » Mon Jul 13, 2020 5:22 am

carlh6902 wrote:
Mon Jul 13, 2020 3:30 am
(always avoiding empty magnification - be like Ted).
your be like Ted reference sent me on a wild internet search ... thought it was a Ted Nugent reference until I clicked on the link at the end of your post. :)

47 pages ... impressive

this is from page 6:
"In fact, some of the best microscopes available from the Big Four manufacturers (Leica, Nikon, Olympus, and Zeiss) are now manufactured in China."
Thought it was just lower end microscopes that had been outsourced to China - such as the Primo Star for example.
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)

Terry Mc
Posts: 22
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Re: Amscope 20x eyepieces....decent??

#8 Post by Terry Mc » Mon Jul 13, 2020 5:44 am

75RR wrote:
Mon Jul 13, 2020 5:22 am
carlh6902 wrote:
Mon Jul 13, 2020 3:30 am
(always avoiding empty magnification - be like Ted).
your be like Ted reference sent me on a wild internet search ... thought it was a Ted Nugent reference until I clicked on the link at the end of your post. :)

47 pages ... impressive

this is from page 6:
"In fact, some of the best microscopes available from the Big Four manufacturers (Leica, Nikon, Olympus, and Zeiss) are now manufactured in China."
Thought it was just lower end microscopes that had been outsourced to China - such as the Primo Star for example.
Good stuff and we can all be grateful that it wasn't a Ted Nugent reference. A Jeff Beck reference always welcome though :)

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75RR
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Re: Amscope 20x eyepieces....decent??

#9 Post by 75RR » Mon Jul 13, 2020 6:34 am

Terry Mc wrote:
Sun Jul 12, 2020 5:25 pm

I'd like to expand my range of magnifications via a 20x EP set.
Copy pasted this from a previous post of mine - seemed simpler, this is the link if anyone is interested viewtopic.php?f=5&t=7096&p#p62773

Useful magnification:

There is a formula (well a rule of thumb really) to calculate this: Range of Useful Magnification (500-1000 x NA of Objective)

In which the 500 x NA (Numerical Aperture) is the minimum necessary for the detail present in an image to be resolved,
and anything over 1000 x NA gives empty magnification.

as an example:
For a Plan 40/0,65NA Objective
the range would be between
500 x 0,65 = 325 and
1000 x 0,65 = 650 so
below 325x total magnification, detail will not be resolved
above 650x total magnification, no additional detail will be resolved

best Useful Magnification Range for this objective is between 325x and 650x

A quick test is to multiply the NA of an objective by 1000,
then multiply the magnification of the objective by the magnification of the eyepiece,
if the second figure is higher then using that objective with that eyepiece will result in empty magnification.


Another useful test is to divide the max magnification by the objective's magnification, this gives you the max eyepiece magnification for that objective.
In this case 650/40 = 16. Therefore a 16x eyepiece would be ok (just) but a 20x eyepiece would give empty (too much) magnification with this objective.
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)

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