Barlow 2.0x vs higher power eyepieces, implications?

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KRinAZ
Posts: 3
Joined: Fri Dec 25, 2020 7:51 pm

Barlow 2.0x vs higher power eyepieces, implications?

#1 Post by KRinAZ » Fri Dec 25, 2020 8:31 pm

I have an Amscope SM-3T stereo microscope enroute, with the supplied lens/eyepiece it is 7x - 45x, using the 10x eyepieces & no barlow lens.

At times I will want to go to a higher power, but don’t understand the implications of replacing the 10x eyepieces with 20x eyepieces to take the power to 14x - 90x, or by using a 2.0 barlow lens with the stock 10x eyepieces to also achieve the same 14x -90x.

I’m guessing there are field of view, clarity, focus flatness, working distance, etc., changes - I would like to understand the pro’s and con’s of each approach to doubling magnification - before making purchases.

I have 2 primary uses for this microscope:
1) Examining crushed hard rock ore for microscopic precious metals - which I will sometimes want the higher power for.

2) SMD electronics work - the microscope’s stock 7x - 45x will be fine for this work.

I plan to keep a 1.0 barlow /lens protector on to keep soldering gunk off the objective and to protect in general.

I wonder if just replacing the 1.0 barlow with a 2.0 barlow - for times when I need the higher magnification - would be the way to go?

Scarodactyl
Posts: 1223
Joined: Sat Mar 03, 2018 9:09 pm

Re: Barlow 2.0x vs higher power eyepieces, implications?

#2 Post by Scarodactyl » Fri Dec 25, 2020 9:28 pm

The big difference is that eyepieces magnify the image you already have, while the auxiliary lens is grabbing an inherently higher mag, higher resolution image. Practically speaking, a barlow lens is going to halve your working distance and double your resolution, while 20x eyepieces double mag but at the same resolution (like zooming in on a digital image). The barlow may also add to curviture of field and other distortions.
Between the two I'd take the aux lens every time.

einman
Posts: 1317
Joined: Tue Feb 24, 2015 1:03 am

Re: Barlow 2.0x vs higher power eyepieces, implications?

#3 Post by einman » Sat Dec 26, 2020 5:18 am

I agree- Take the Barlow objective. As mentioned the objective gives twice the resolution while increasing magnification. The eyepiece only increases magnification. Most manufacturers if providing maximum na numbers generally do so with the 2x objective mounted.

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