Stereoscope comparison (AmScope vs Vision Scientific)

[fociwm]

Hi,

Just FYI,

I recently had a chance to compare an AmScope stereoscope and a Vision Scientific stereoscope. AmScope products do not seem to be parfocal in general. There is one stereoscope head in the ZM line that is parfocal (sold alone without stands etc), but other than that, it was not easy to find parfocal scope heads. On the other hand, Vision Scientific seems to have only one stereoscope head across the entire product line, and this head is parfocal. I found Vision Scientific's parfocal stereoscope head much easier to use.

I've been using expensive dissection scopes in the lab and did not know that low-cost models were often not parfocal. I was looking for a scope that I could use at home. I've not had a chance to test other brands, but the Vision Scientific product was very convenient to use because of the parfocality.

Cheers,

[PeteM]

Not sure if this is intended to be helpful first post . . . or just spam? My experience is that both brands tend to be cheaply made; but also that AmScope models can be found that are more or less parfocal when the magnification is switched or zoomed.

[Dubious]

The Amscope stereo zoom I had was parfocal--if you followed the correct procedure to adjust parfocality.

[Scarodactyl]

Looks like the same models ordered from the same suppliers.

[fociwm]

Sorry it looked like a spam or ad. Yes it was my first post. But I bought the scope because I became very interested in doing something at home with my daughters. I just found Oliver’s site and loved it. I subscribed yesterday for his newsletter.

To be more clear, I tested the ZM line of amscope. It had a 0.3x barlow lens, which had, when attached, a 27cm focal length at max zoom. Then, if you turned the focusing knob to the minimum zoom, the focal length became like maybe 10cm?? or something. This difference was longer than the travel distance of the focusing knob. That is, I had to adjust the boom stand height, which was basically unusable. This is beyond acceptable range. (This was an over $1200 scope I purchased for the lab and it was returned. I have a Leica stereoscope in the lab and was trying to purchase another or two stereoscopes but cheaper ones. I was surprised that low cost scopes were not parfocal. I think my expectations were too high.)

You know that Oliver has a AmScope stereoscope and he constantly adjust the focus whenever he changes the zoom. I didn’t realize how bad it was until I actually had my hands on it. Without the barlow lens, it may still be workable for hobby. But not for a professional setting.

I also bought a Vision Scientific scope, a $300 single arm boomstand version for myself and daughters, not for the lab. I couldn’t afford AmScope for home use. Lab budget and home science budget are in different categories. So I couldn’t buy any AmScope stereoscope, which seemed to be more expensive than others. I was looking for a cheaper brand. This Vision Scientific scope was parfocal and I am very happy. I put an order of another one for the lab this time with double arm (single arm is inconvenient for the lab use because it always tilt) with gooseneck light (I am not very optimistic with this gooseneck but it is only $70, which is cheap for the lab) that will give me some more space for dissection under the scope than usual ring light. We’ll see how it goes. As I said in the main post, Vision Scientific scope is not perfect either. The lens is not bright. But hopefully it works fine with the gooseneck lighting. Otherwise, I may need to return them too and go for big 4 brands (price is over $10k for Leica, which is very expensive even for the lab budget.)

[fociwm]

The Amscope stereo zoom I had was parfocal--if you followed the correct procedure to adjust parfocality.

I didn’t know that it was possible to adjust the behavior of the zoom lens complex of the AmScope stereoscope. Can you share the method? I couldn’t find it on the internet. Also I appreciate it if you share the product number so that I can check it out for my next purchase for the lab.

[viktor j nilsson]

The Amscope stereo zoom I had was parfocal--if you followed the correct procedure to adjust parfocality.

I didn’t know that it was possible to adjust the behavior of the zoom lens complex of the AmScope stereoscope. Can you share the method? I couldn’t find it on the internet. Also I appreciate it if you share the product number so that I can check it out for my next purchase for the lab.

You need to be able to adjust the diopter setting on both eyepieces. Here's how you do it:
https://www.specialtyoptical.com/blog/- ... icroscope/

[fociwm]

Looks like the same models ordered from the same suppliers.

It may very likely be true. But when I communicated with the customer service representative of AmScope, he said that parfocal stereo heads should have such description in the product info page. And he pointed me to the only ZM line zoom stereo head described as having a parfocal zoom. On the other hand, all Vision Scientific stereo zoom heads are basically the same head and it is parfocal. This one was different from the AmScope’s parfocal ZM head.

Maybe I need to search more but I couldn’t find more parfocal stereo zoom head in AmScope homepage by myself.

BTW, I’m interested in the Chinese supplier. Can you share the info of the company?

[fociwm]

The Amscope stereo zoom I had was parfocal--if you followed the correct procedure to adjust parfocality.

I didn’t know that it was possible to adjust the behavior of the zoom lens complex of the AmScope stereoscope. Can you share the method? I couldn’t find it on the internet. Also I appreciate it if you share the product number so that I can check it out for my next purchase for the lab.

You need to be able to adjust the diopter setting on both eyepieces. Here's how you do it:
https://www.specialtyoptical.com/blog/- ... icroscope/

Ah. I think you misunderstood my post. What I meant was the parfocality across different zoom levels. If it is parfocal, the focus shouldn’t change when you turn the zoom knob. The specimen should be in focus across the entire zoom range. This is different from diopter adjustment for two eyes.

[PeteM]

Viktor's point was that getting a stereo zoom microscope parfocal involves focusing at high magnification and then (without changing the focus) zooming to low magnification. At that point you use the diopter adjustments to get things in focus. Might have to tweak it, but that's the basic approach. Thus, a key to getting either a multi-magnification or a zoom stereo microscope parfocal is to have either a body or objectives with diopter adjustments.

Personally, I'm not a fan of any of the $300-$500 or so Chinese-made stereo zoom microscopes. A zoom is a complex mechanism and cheap ones often come with compromises to begin, then wear and go further out of adjustment, and sometimes fairly quickly break things like the plastic zoom adjustment gear. I wouldn't buy one for a lab and likely not for a school where they'd see some rough use. Still - they can be OK for a hobbyist with careful use and recognizing their limitations in terms of optical clarity, field of view, working distance, and slight zoom defects.

[viktor j nilsson]

Yes, my link was exactly what you are looking for. Read it again.

[fociwm]

Yes, my link was exactly what you are looking for. Read it again.

Sorry for my misunderstanding. Yes, your link is correct. And I remember this procedure. I guess I had to test the scope with this method.

But I very much doubt that it would correct over 15cm focusing knob rotation. That is just too much. This diopter method may correct a bit of misalignment of parfocality, which is for may be a half rotation of the focusing knob, but not for such a big change. This is for parfocal zoom scopes and the service rep said the head was not parfocal.

Yes this procedure may ‘reduce’ the non-parfocality a bit, but it won’t be enough to solve it entirely.

[fociwm]

Viktor's point was that getting a stereo zoom microscope parfocal involves focusing at high magnification and then (without changing the focus) zooming to low magnification. At that point you use the diopter adjustments to get things in focus. Might have to tweak it, but that's the basic approach. Thus, a key to getting either a multi-magnification or a zoom stereo microscope parfocal is to have either a body or objectives with diopter adjustments.

Personally, I'm not a fan of any of the $300-$500 or so Chinese-made stereo zoom microscopes. A zoom is a complex mechanism and cheap ones often come with compromises to begin, then wear and go further out of adjustment, and sometimes fairly quickly break things like the plastic zoom adjustment gear. I wouldn't buy one for a lab and likely not for a school where they'd see some rough use. Still - they can be OK for a hobbyist with careful use and recognizing their limitations in terms of optical clarity, field of view, working distance, and slight zoom defects.

Thanks for your advice. Yeah, we’ll see. $500 is I think worth risk for a while. I can easily afford it in the lab. If this turns out to be too flimsy or not reliable as you said, I will just purchase one from big 4 next time. I will let you know in about a year.

Having said that, my experience with the VS stereo zoom scope for the last couple of weeks at home was quite good. So, for hobby, I recommend it.

[fociwm]

Yes, my link was exactly what you are looking for. Read it again.

Sorry for my misunderstanding. Yes, your link is correct. And I remember this procedure. I guess I had to test the scope with this method.

But I very much doubt that it would correct over 15cm focusing knob rotation. That is just too much. This diopter method may correct a bit of misalignment of parfocality, which is for may be a half rotation of the focusing knob, but not for such a big change. This is for parfocal zoom scopes and the service rep said the head was not parfocal.

Yes this procedure may ‘reduce’ the non-parfocality a bit, but it won’t be enough to solve it entirely.

Just for the sake of the completeness of this thread, the parfocal ZM line stereo zoom head is ZMDG6745T, which is sold separately. All other heads in the ZM line AmScope stereoscopes are not parfocal, as of last week.

[viktor j nilsson]

Yes, my link was exactly what you are looking for. Read it again.

Sorry for my misunderstanding. Yes, your link is correct. And I remember this procedure. I guess I had to test the scope with this method.

But I very much doubt that it would correct over 15cm focusing knob rotation. That is just too much.

15cm! That can't be right. Is that how it's supposed to work? I had no idea if could be that bad.

[Dubious]

The one I had was the Amscope SMDG-2T-6WB stereo microscope, bought through Amazon. It was nicely parfocal through the zoom range once I followed the procedure described above. I was surprised that simple procedure worked, but it did, and before following the procedure I had to do a lot of constant focus adjustment The scope also had sharp optics, I thought. In the end, I returned it because I found it difficult to keep both pupils within the exit cones of light--one or the other was always blinking out. This is the usual situation with all binocular heads to some degree, but I have never found it as twitchy as with this one. I think there was some subtle misalignment, but it is also possible it was just my eyes.

[Scarodactyl]

Just for the sake of the completeness of this thread, the parfocal ZM line stereo zoom head is ZMDG6745T, which is sold separately. All other heads in the ZM line AmScope stereoscopes are not parfocal, as of last week.

This is definitely incorrect, though it would not be surprising at all for an amscope rep to not know what parfocal meant or what features their products have.
The very first zoom stereo ever released (B&L stereozoom) was parfocal. This isn't a new or exotic feature. I don't think there's ever been a stereo microscope designed to be refocused 15cm between magnification steps, that would have to be set up very wrong or defective. I have owned one of Amscope's cheaper meiji-lookalike stereos and it was parfocal as I recall. The amscope-branded SF2-tra nikon-645-alike (apparently made by Novel Optics) I had more recently was perectly parfocal, though something about it bugged my eyes.

BTW, I’m interested in the Chinese supplier. Can you share the info of the company?

Hard to know what middle men Amscope deals with or if they're closer to the factories, many smaller suppliers apparently work with View Solutions (whose direct outlet is Bolioptics).

[fociwm]

Just for the sake of the completeness of this thread, the parfocal ZM line stereo zoom head is ZMDG6745T, which is sold separately. All other heads in the ZM line AmScope stereoscopes are not parfocal, as of last week.

This is definitely incorrect, though it would not be surprising at all for an amscope rep to not know what parfocal meant or what features their products have.
The very first zoom stereo ever released (B&L stereozoom) was parfocal. This isn't a new or exotic feature. I don't think there's ever been a stereo microscope designed to be refocused 15cm between magnification steps, that would have to be set up very wrong or defective. I have owned one of Amscope's cheaper meiji-lookalike stereos and it was parfocal as I recall. The amscope-branded SF2-tra nikon-645-alike (apparently made by Novel Optics) I had more recently was perectly parfocal, though something about it bugged my eyes.

Hm... That's very strange then. Well, then I guess the ZM line of AmScope is something everyone needs to avoid?? The service rep originally said it was parfocal, then got back to me a day later and said, apologizing, it was not parfocal. Clearly, he did some research. Then he said that ZMDG6745T was parfocal. If you check out its product page, it boasts about parfocality, which indirectly suggests that others are not. And I couldn't find any other product pages boasting about parfocality even in manuals of some, other than ZMDG6745T.

I don't remember the specific model number of Oliver's AmScope stereoscope, but in many of Oliver's videos, he had to adjust the focus when he turned the zoom knob. And he apologized/complained about it. Assuming that he knew how to use/calibrate his scope, I guessed his scope was not parfocal. So, I thought it was normal for many (if not most) low-cost stereoscopes.

The ZM one I received from AmScope might have been probably(?) OK to use for hobby (too expensive for a hobby though) without the barlow lens. But after I attached the 0.3x barlow lens (which amplifies non-parfocality like 3.3 times), it was ridiculously wild to use. One example was that the focal plane at max zoom was below the table and I had to flip the focus boom beam to the top position. Then the difference of focus distances between min and max zoom was longer than the entire travel of the focus knob!!! I don't think this is fixable with the diopter calibration procedure (it can't fix non-parfocal optics). It was genuinely not parfocal.

Anyway, I totally agree with you that all stereoscopes must be designed parfocal and it is not an exotic feature. I guess the AmScope is to blame as my experience with the ZM line and Oliver's videos (though I don't remember his model) attest. Their stereoscopes have design flaws.

[Dubious]

The simple procedure I followed made a lot more difference to parfocal zooming than I would have thought possible. It may be that the scope you tried was a lemon. I remember the scene you mention from Oliver's video, and is possible he did not know how to adjust for parfocal zoom as his expertise seems mainly with compound microscopes (non-zoom)--someone should ask. Amscope buys from manufacturers that are, I understand, copying a few successful designs that have been in use for many years, and it makes sense those designs would incorporate parfocal zoom.

Glad the VS scope is working out for you--in the end, that's what matters, and better quality or simply better quality control is worth paying for. BTW, I do still have an Amscope non-zoom stereo microscope (turret with two objectives). It and its stand are a lot smaller physically (not always a bad thing) and about half the price, but has worked out well for me and some young friends. Even has internal batteries that power its upper and lower LED lighting for extended periods of remote use. Probably not suitable for lab or industrial use, but would work quite well for many home uses. This is the model I have--also comes in other variants:
https://www.amazon.com/gp/product/B005B ... UTF8&psc=1

[fociwm]

The simple procedure I followed made a lot more difference to parfocal zooming than I would have thought possible. It may be the scope you tried was a lemon. I remember the scene you mention from Oliver's video, and is possible he did not know how to adjust for parfocal zoom as his expertise seems mainly with compound microscopes (non-zoom)--someone should ask. Amscope buys from manufacturers that are, I understand, copying a few successful designs that have been in use for many years, and it makes sense those designs would allow parfocal zoom.

Thanks for the info. Yeah, I might have received a lemon. I'll try the calibration procedure for the next scope.