20x eyepiece

Everything relating to microscopy hardware: Objectives, eyepieces, lamps and more.
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neal Shields
Posts: 58
Joined: Sat Jun 04, 2022 8:02 pm

20x eyepiece

#1 Post by neal Shields » Tue Mar 07, 2023 7:44 pm

About a year ago I got a new Olympus microscope with DIC capability.

I love it but...

My old microscope a Zeiss Ultraphot had an Optivar which I quickly realized had spoiled me.

An Optivar is another set of lenses between the objective and the eyepiece.

In my case I had 12.5 power eyepieces and 10, 40, 100x objectives. The optical had settings of 1.25x, 1.6x and 2x

That meant with a 40 power objective I could get very close to 1000x without oiling things up. (12.5 x2 x40) Granted I was probably getting empty magnification at the 2x setting.

With my new Olympus the jump was 10 to 40 to 100.

Often I wanted more than 40 but didn't want it bad enough to oil things up.

Recently I purchased a 40x 1.15NA water objective. As a result I also purchased two 20x eyepieces.

This gives me 800X capability without oil and with no empty magnification!

I thought I would only use the 20x eyepieces occasionally but I put them on about 2 months ago and haven't gone back.

Anyone else have experiences with 20x eyepieces?

The 20x also just happens to be closer to my camera field of view with a 5x projection eyepiece.

Neal

Scarodactyl
Posts: 2775
Joined: Sat Mar 03, 2018 9:09 pm

Re: 20x eyepiece

#2 Post by Scarodactyl » Tue Mar 07, 2023 8:27 pm

Olympus has a similar mag changer as an optional add-on. I like them.
I wouldn't want to use 20x eyepieces as my daily driver, or a 5x projection lens for that matter. A lot of what you pay for in an objective is field coverage and not having access to the wider field feels wasteful. But sometimes they hit the spot.

apochronaut
Posts: 6272
Joined: Fri May 15, 2015 12:15 am

Re: 20x eyepiece

#3 Post by apochronaut » Tue Mar 07, 2023 9:48 pm

As long as the N.A. is there to keep you out of empty magnification, there is no reason why not. Typically, once you get above a 15X (16X with certain brands), the benefits associated with the extra magnification are cancelled out by a tighter eye relief and narrower field, though. 15X in U.W.F. or even just W.F. at present seems to be the ultimate combination of real field of view, apparent field of view, w.d. increase and increased resolution and magnification.
A 40X objective used with a 10X/20 W.F. eyepiece will cover 500 microns at 400X. A 60X objective used with a 10X/20 W.F. eyepiece will cover 334 microns at 600X.
If your 40X has a high enough N.A. and most do, replacing the 10X/20 eyepiece with a 15X/20 U.W.F. will give you the working distance of the 40X objective and cover 500 microns at 600X, with a stunning apparent field. Even a standard or modest 15X/16 W.F. with the 40X will cover a greater field than the 10X/20 with a 60X. About 20% greater or 400 microns.
I don't think there are too many 20X eyepieces there yet, at least I haven't seen any. Eye relief would be difficult and very expensive to achieve.

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