Bausch & Lomb SZ4 to SZ7 differences?

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dazz
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Bausch & Lomb SZ4 to SZ7 differences?

#1 Post by dazz » Wed May 19, 2021 7:17 am

Hi
What are the differences between the B&L SZ models (4,5,6 and 7)?
Are there any differences that make a real difference?
Does the model number define the year of manufacture?

Dazz

apochronaut
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Re: Bausch & Lomb SZ4 to SZ7 differences?

#2 Post by apochronaut » Wed May 19, 2021 12:11 pm

There are quite a few differences. First and the most obvious is the zoom ratio. 3:1 for the SZ4 and 7:1 for the SZ7.
Additionally, the SZ7 can be fitted with a trinocular attachment for a camera mount. The same location on the body can alternately receive a coaxial illuminator. The literature on that , indicates that it needs to be factory installed.

If one chooses to bump the magnification with 15X eyepieces , the two microscopes use different designs. The SZ3 uses cat.# 31-05-62 15X eyepieces. The SZ7 uses 31-05-68 15X eyepieces. I suspect that the only difference between them is the f.o.v. The schematics show a slight difference in the lens curvature and air gap between the upper and lower lens groups but I 'm pretty sure that results in the latter having a wider field.

The SZ4 has a limited range of supplemental or aux. objectives : .5X and 2X. In addition to those, the SZ7 also can receive .25X and 1.5X. The SZ4 aux. lenses thread on. The SZ7 lens fit with a kind of bayonet. I am unsure of why exactly this is but likely the SZ7 supplemental lenses have corrections that are unique to the SZ7 optical system.

Later , around the Leica years of mfg. , .3X, .75X and 1.5X supplemental lenses were released for the SZ1,2,3,4 and 5.
There were also subsequent releases of specialized eyepieces. 12.5X, 15X U.W.F. and 30X. Those aren't designated for any particular model of stand.


The SZ7 has a particularly long optical section to accomodate the longer lens travel in the zoom section. It needs to sit a little higher in order to provide working distance, particularly with the low magnification supplemental lenses. Therefore it needs usually an R stand or boom mount.

Scarodactyl
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Re: Bausch & Lomb SZ4 to SZ7 differences?

#3 Post by Scarodactyl » Wed May 19, 2021 12:38 pm

To add to that, the sz6 is yet another thing. It was probably the last model b&l put out before being absorbed into cambridge instruments and it is pretty different. It has much lighter weight construction and a zoom system similar to the sz 1-5 but using side knobs specially set up to give the whole zoom range within less than one turn of the knob. They also use yet another set of auxiliary lenses. You're more likely to find it branded Leica or Cambridge than Baush and Lomb. They're honestly not as well built and I wouldn't consider it as good as other models in the sz family, but they're very light and the zoom is nice, and there is a trinocular option.

PeteM
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Re: Bausch & Lomb SZ4 to SZ7 differences?

#4 Post by PeteM » Wed May 19, 2021 12:54 pm

Some additional points.

The SZ4 was commonly used in industry - so many of them appear on the used market and sometimes without a stand. They might formerly have been incorporated in some special rig. It's a fairly robust scope, though some have been abused in their former life. Since there are more heads than stands - it's best to buy one with a stand than imagining a cheap one will show up later. I've had more than a dozen pass through. In good condition, it's a good general purpose stereo microscope. The earlier and even lower zoom range versions can also be good. Depending upon the task, even a single fixed focus may do the job.

The SZ5 is much less commonly seen.

The SZ6 has been panned by a one optical outfit (their "stereo microscopes to buy and avoid" gaining wide circulation) as having been built to a lower standard from that time in B&L history. However, the one example I've had was OK in my opinion. On edit - I see Scarodactyl has said much the same thing.

The SZ7 has a mixed reputation. Many love it for its high resolution and exceptional (for the time and still today) zoom range. It was also available on a very solidly built "R" stand with fine focus, a transmitted base, and often an x-y table. Others hate it because the complex zoom arrangement can get out of whack and the couple dozen optical surfaces inside may have been coated with something like industrial fumes or dust over the years, resulting in a grayed-out image with very low contrast. I've had around half a dozen of these - ranging from excellent condition to unusable.

So in all cases -- and particularly with the SZ7 -- you want to be able to carefully examine one in advance of a purchase or buy from a seller where it will easily be returned if their are issues.

There are other used stereo zoom microscopes out there (covered in past posts) with wider fields of view, ample working distance, and somewhat better chances of having one arrive in good condition or be more easily repaired if slightly out of alignment.

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Re: Bausch & Lomb SZ4 to SZ7 differences?

#5 Post by BramHuntingNematodes » Wed May 19, 2021 1:10 pm

I seem to remember seeing some copy for the sz5+ which accepted 30mm eyepieces. The regular sz5 also had a slightly larger zoom range.

The coaxial illuminator fitted to many SZ7 is very good, but will almost certainly take significant repair and work to get functional. Often the scope will perform much better with this device removed before these repairs have been made
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

PeteM
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Re: Bausch & Lomb SZ4 to SZ7 differences?

#6 Post by PeteM » Wed May 19, 2021 5:22 pm

The number after the "SZ" is indicative of the zoom range. Four times for the SZ4 and so on up to seven times with the SZ7. The earlier SZ2 and SZ3 were also useful, if more limited, ranges.

apochronaut
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Re: Bausch & Lomb SZ4 to SZ7 differences?

#7 Post by apochronaut » Wed May 19, 2021 6:31 pm

That isn't accurate. SZ1 and 2 aren't zoom at all
. SZ1 has a fixed 1X objective. SZ2 has a fixed 2X objective. SZ3 has a 1 to 2.5X zoomrange, SZ4 a .7 to 3X zoomrange SZ5 a .8 to 4X zoom range and SZ7 a 1 to 7X.

Scarodactyl
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Re: Bausch & Lomb SZ4 to SZ7 differences?

#8 Post by Scarodactyl » Wed May 19, 2021 7:44 pm

BramHuntingNematodes wrote:
Wed May 19, 2021 1:10 pm
I seem to remember seeing some copy for the sz5+ which accepted 30mm eyepieces.
You're probabky thinking of the sz6+. The trinocular version also takes 30mm eyepieces.

To add to the pile there is also the stereoZOOM4 or however it's branded, which is like the normal sz4 but built to the pattern of the sz6 with side knobs.
I will say the weird quick zooming on the sz6 is very nice to use. I've only had two copies though, one I had to return since it was moldy, another came with a scope and was also moldy but only on two lenses. That second one was actually the GIA branded variant, and as far as I can tell the only difference is some idiot used loctite on the eye tubes. Once I got those off with a strap wrench getting in and cleaning it was easy and left no residual damage, but either removing the eyepieces was too rough or it was already damaged because it is misaligned (didnt check before cleaning since it was very foggy), and there doesn't seem to be an easy way to realign it, so it's probably toast.

I have run into a lot of sz7s with permanent damage, mostly because I bought a large lot cheap early in my microscope days which were already bad and were then shipped all in one box with no padding, adding a new suite of incredible mechanical faults. Cleaning in and of itself isn't too bad with iso and some q tips, but opening the pod is a bit of a pain since you need an ultra tiny imperial allen wrench to loosen the set screw in the zoom knob and you have to deal with the black rubber dust gaskets around thr oculars which may be hard and brittle now (newer Leica ones are white and stay supple). They also have a couple set screws that adjust alignment easily, though I have had mixed success with that. Honestly I love them when they're good but I also kind of never want to see one again, I've just had too much grief from bad copies. My advice is don't try to scrape for a deal if you want one, just pay for one listed in good condition and return it if something is wrong with it, do that a few times and you'll get a good copy.

Soon after the sz6/4 Leica moved to the GZ4 and 6, which are almost the same as the stereoZOOM 4 and 6 but with much uglier aesthetics, and the gz4 has a nonstandard 88mmish round mount diameter while the gz6 is a standard 76mm. They might have done some mechanical improvements too but their reputation is still breaky. They also did the gz7 which is just the sz7 with an esd safe plastic shell, that one is good if you ever find one. And from there on out it's all the S series which are still very expensive on the used market.

Someone in China still makes copies of the original sz4, or at least used to. You can still buy new compatible auxiliary lenses anyway. I have no idea if the chinese pods arw actually mechanically or optically similar, or just shaped the same.

PeteM
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Re: Bausch & Lomb SZ4 to SZ7 differences?

#9 Post by PeteM » Wed May 19, 2021 8:32 pm

apochronaut wrote:
Wed May 19, 2021 6:31 pm
. . . SZ2 has a fixed 2X objective. SZ3 has a 1 to 2.5X zoomrange, SZ4 a .7 to 3X zoomrange SZ5 a .8 to 4X zoom range and SZ7 a 1 to 7X.
Phil, what name does the B&L StereoZoom with a 1-2x range go by? I've had those (2x zoom range), plus the 3 with a 2.5x range, the 4 with a 4x range, the 5 with a 5x range, the 6 with a 6x range, and the 7 with a 7x range. Also curious why they would call their fixed magnification stereo microscopes SZ (StereoZooms)?

dazz
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Re: Bausch & Lomb SZ4 to SZ7 differences?

#10 Post by dazz » Thu May 20, 2021 7:47 am

Hi
It seems to me that the SZ4 version is the most plentiful on e-bay, but many are on sale from e-bay shop traders. The prices are high. Probably justified if they have a return warranty. In my case, the cost of shipping exceeded the price of the SZ4 I just purchased on e-bay. A warranty is no use to me. I have no opportunity for a pre-purchase inspection. Buying from e-bay is high risk for me.

The number of SZ's auctioned by individuals seen is relatively few. The market led prices (highest bidder) are much more sensible, especially if they include at least part of a boom stand and the eye pieces.

Knowing that the difference versions of B&L are not all compatible with stands and accessories is really useful if I buy one. The SZ4 I have purchased is sufficient for my needs (PCB repair) if it is serviceable. I don't need a lab grade instrument. The extended zoom range of a SZ7 is just not needed. That is useful information for me.

Dazz

apochronaut
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Re: Bausch & Lomb SZ4 to SZ7 differences?

#11 Post by apochronaut » Thu May 20, 2021 10:12 am

PeteM wrote:
Wed May 19, 2021 8:32 pm
apochronaut wrote:
Wed May 19, 2021 6:31 pm
. . . SZ2 has a fixed 2X objective. SZ3 has a 1 to 2.5X zoomrange, SZ4 a .7 to 3X zoomrange SZ5 a .8 to 4X zoom range and SZ7 a 1 to 7X.
Phil, what name does the B&L StereoZoom with a 1-2x range go by? I've had those (2x zoom range), plus the 3 with a 2.5x range, the 4 with a 4x range, the 5 with a 5x range, the 6 with a 6x range, and the 7 with a 7x range. Also curious why they would call their fixed magnification stereo microscopes SZ (StereoZooms)?
Well, then. Can you point me in the direction of a Stereozoom 2? I used the terms iconoclastically. They exist in B&L catalogues with headings such as Stereozoom Series Microscopes. They are actually known and highlighted in the same catalogues as Stereo 1 and Stereo 2, Fixed Power Pod.
Most of this forum is valuable as a reference tool for people asking questions. It is probably therefore a good idea to provide accurate answers. You wouldn't want someone to spend too much of their valuable time searching for a Stereozoom 2 now, would you?

apochronaut
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Re: Bausch & Lomb SZ4 to SZ7 differences?

#12 Post by apochronaut » Thu May 20, 2021 10:52 am

dazz wrote:
Thu May 20, 2021 7:47 am
Hi
It seems to me that the SZ4 version is the most plentiful on e-bay, but many are on sale from e-bay shop traders. The prices are high. Probably justified if they have a return warranty. In my case, the cost of shipping exceeded the price of the SZ4 I just purchased on e-bay. A warranty is no use to me. I have no opportunity for a pre-purchase inspection. Buying from e-bay is high risk for me.

The number of SZ's auctioned by individuals seen is relatively few. The market led prices (highest bidder) are much more sensible, especially if they include at least part of a boom stand and the eye pieces.

Knowing that the difference versions of B&L are not all compatible with stands and accessories is really useful if I buy one. The SZ4 I have purchased is sufficient for my needs (PCB repair) if it is serviceable. I don't need a lab grade instrument. The extended zoom range of a SZ7 is just not needed. That is useful information for me.

Dazz
The SZ4 is a very good and useful instrument. One thing about the 1.2.3.4 and 5 is that the supplemental lenses, if you ever need one are available off and on. Supplemental lenses for the 7 are very uncommon.
There were various stands available for the pods. A, was a plain rack and pinion focus arm fitted on a stand with a removable glass or opaque( black or white) insert in a clip stage. B, was the same with an accessory base allowing for transmitted illumination. K was the same standard vertical arm and focus on a flat platten. KT had a short cutaway base with no stage. S, was a simple boom base and arm on a flat platten and SK had a heavy cast base with a counterbalanced boom arm.
There was also an R stand , larger and more robust with fine focus and the same 20 watt transmitted illumination base as the Balplan lab microscope had. In fact, the R stand is basically a Balplan stand carrying a Stereo/Stereozoom arm.
When fitting the low power supplemental lenses, .3X and .5X to a pod mounted in either the A or B stands there is an extension required on the vertical column, the part # 31-07-03 elevator, to create extra working distance for those L.W.D. lenses. On the other stands, there is enough room.
There was a mechanical stage available too but it is mostly seen on the R stand.
There is a an ebay merchant, zephyr, I believe it is. He is a dealer: mostly a very good service technician , who sells used equipment from time to time. He often has B & L Stereos and AO too, as they get surplussed during upgrades. Sometimes he has whole units, sometimes pods, sometimes parts. Everything is checked over and where there is any problem, it is clearly noted but I have not known him to sell anything with major problems. Just little things that don't really affect functionality. Most of his stuff is good and clean. His prices are very good.

PeteM
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Re: Bausch & Lomb SZ4 to SZ7 differences?

#13 Post by PeteM » Thu May 20, 2021 5:49 pm

apochronaut wrote:
Thu May 20, 2021 10:12 am
PeteM wrote:
Wed May 19, 2021 8:32 pm
apochronaut wrote:
Wed May 19, 2021 6:31 pm
. . . SZ2 has a fixed 2X objective. SZ3 has a 1 to 2.5X zoomrange, SZ4 a .7 to 3X zoomrange SZ5 a .8 to 4X zoom range and SZ7 a 1 to 7X.
Phil, what name does the B&L StereoZoom with a 1-2x range go by? I've had those (2x zoom range), plus the 3 with a 2.5x range, the 4 with a 4x range, the 5 with a 5x range, the 6 with a 6x range, and the 7 with a 7x range. Also curious why they would call their fixed magnification stereo microscopes SZ (StereoZooms)?
Well, then. Can you point me in the direction of a Stereozoom 2? I used the terms iconoclastically. They exist in B&L catalogues with headings such as Stereozoom Series Microscopes. They are actually known and highlighted in the same catalogues as Stereo 1 and Stereo 2, Fixed Power Pod.
Most of this forum is valuable as a reference tool for people asking questions. It is probably therefore a good idea to provide accurate answers. You wouldn't want someone to spend too much of their valuable time searching for a Stereozoom 2 now, would you?
Yes, as said before, I can point you in the direction of a StereoZoom with 2x zoom. We've had three of them with the 1-2x zoom range. Picture shows one of them. They are are plentiful out here in the Bay Area - many of them still in good shape and not a bad option if 20x is all that's needed at the top end.

You can also find the 1-2x Zoom listed on page 19 of the Bausch & Lomb catalog (1962?) subtitled "Fixed Power Models and StereoZoom Variable Power Models."
StereoZoom 1-2x
StereoZoom 1-2x
Screen Shot 2021-05-20 at 10.29.55 AM.png (102.65 KiB) Viewed 411 times
B&L Fixed Power and StereoZoom Variable Power Scopes
B&L Fixed Power and StereoZoom Variable Power Scopes
Screen Shot 2021-05-20 at 10.47.12 AM.png (241.49 KiB) Viewed 411 times

Scarodactyl
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Re: Bausch & Lomb SZ4 to SZ7 differences?

#14 Post by Scarodactyl » Fri May 21, 2021 6:13 pm

Not to mention the various poorly documented variations used in stereoscopes.

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