Is it really all about the objectives?

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Joe Henry
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Is it really all about the objectives?

#1 Post by Joe Henry » Mon Jan 24, 2022 2:46 am

It seems to this novice that the quality of the objectives is the biggest factor for image quality, yes? I mean for example, one can put high quality modern objective on an old scope from the 30-60's to improve image, correct? Thanks.

Scarodactyl
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Re: Is it really all about the objectives?

#2 Post by Scarodactyl » Mon Jan 24, 2022 3:35 am

Not exactly. On some systems it's almost just the objective, but on others it is the vital combination of the objectives and the eyepieces and/or tube lens.

Greg Howald
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Re: Is it really all about the objectives?

#3 Post by Greg Howald » Mon Jan 24, 2022 4:08 am

Scarodactyl wrote:
Mon Jan 24, 2022 3:35 am
Not exactly. On some systems it's almost just the objective, but on others it is the vital combination of the objectives and the eyepieces and/or tube lens.
Well said. I think a better answer could be given with some specificity. What scope are you referring to. With that info better answers could be provided for you.

BramHuntingNematodes
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Re: Is it really all about the objectives?

#4 Post by BramHuntingNematodes » Mon Jan 24, 2022 4:17 am

Lighting is pretty important.
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

Alexander
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Re: Is it really all about the objectives?

#5 Post by Alexander » Mon Jan 24, 2022 4:26 am

Joe Henry wrote:
Mon Jan 24, 2022 2:46 am
It seems to this novice that the quality of the objectives is the biggest factor for image quality, yes? I mean for example, one can put high quality modern objective on an old scope from the 30-60's to improve image, correct? Thanks.
Yes and no. There are basically two optical systems. Older microscopes and low end contemporary ones feature finite optics designed for tube length like 160 or 170 mm. Finite objectives depend on correcting eye-pieces for best picture quality. Modern midrange and high-end microscopes feature infinite optics. Those depend on specific tube lenses. It is impossible to work with an infinite objective on a finite microscope.

On the other hand may a 1937 Leitz Ortholux be upgraded using high-end optics from 40 or 50 years later. The Ortholux was 170 mm and Leitz still produced finite objectives half a century after the first Ortholux. It would not work with a contemporary Leica high-end objective. Those are infinite and feature a larger thread as well. Even a low end Leitz microscope from the 1930th could be upgraded this way.

The objective may be the most important part but it is not the only one relevant. Condensers, eye-pieces, tube lenses and lightning play a big part as well. You can use more modern eye-pieces, high-end condensers and lightning on a 1930th microscope, off course.

Comparing picture quality of a contemporary microscope with a 80 years old one you might be surprised how little the difference is, if any. A modern binocular tube produces less contrast than a 1930th straight tube for example. The lenses and prisms in the binocular have a negative impact on picture quality. This loss is a trade-off for improved operator comfort.

Joe Henry
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Re: Is it really all about the objectives?

#6 Post by Joe Henry » Mon Jan 24, 2022 5:10 am

Thanks for the replies. I bought an old 1936 Bausch & Lomb scope. What are the limitation on this scope as far as objectives? Thanks again.

apochronaut
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Re: Is it really all about the objectives?

#7 Post by apochronaut » Mon Jan 24, 2022 2:37 pm

I can offer some insight into this because of some direct comparisons I have made over the years. Spencer apochromats vs. Bausch & Lomb apochromats vs. Leitz apochromats from the 1940's for instance. At the end of this text is a link to a visual comparison of every 60-63X objective in my possession at the time, going back to the 1870's.

Microscope optics did not change much between W.W. I and W.W. II. Each of the major manufacturers produced a full series of achromats, a few fluorites and a full series of apochromats. There was some development of flatter field optics but basically, each company produced optics of comparable quality to another within any given category. Differences were subtle by way of slight differences in contrast or ca control etc. Unless one is comparing directly, most differences will be unnoticed. During and after W.W. II there were a huge number of technical advances and microscope optics took a big leap forward from the mid-50's on but only in some ways.
The principal advances were the possibility of wider more well corrected fields, better contrast and flatter fields. Resolution advanced some but microscope companies have been able to make high resolution optics for over a century. Later in the 1970's the use of computer ray tracing began and that was another generational leap allowing for better refinements in advances already envisioned. Ray tracing has been very effective in advancing optics. Sometimes two objectives made a few years apart that look identical, upon disassembly can be found to have a difference internally : lens cell construction or barrel coating or a baffle indicating that something was computed to require a change, usually to increase contrast.

There is no doubt that objectives and their compatible lens systems have gotten better but Alexander is correct, sometimes older objectives are surprising in how high a quality their output is.
Bausch & Lomb was a very high quality maker from their inception right up until they merged with 7 other companies and the brand slowly disappeared. The older optics, were as good as anyone's. You can see it in the comparison below, taking particular note of image # 3,9 and 12. Image # 9 suffers from a lack of depth of field while having high resolution and freedom from ca. In more modern apos, similar conditions still apply but depth of field and especially contrast have improved.

viewtopic.php?f=5&t=4963

Joe Henry
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Re: Is it really all about the objectives?

#8 Post by Joe Henry » Mon Jan 24, 2022 5:53 pm

Thanks to everyone for posting to my questions....much appreciated, Joe.

BramHuntingNematodes
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Re: Is it really all about the objectives?

#9 Post by BramHuntingNematodes » Mon Jan 24, 2022 6:25 pm

A good first step for updating this scope might be a B&L big silver-barreled 15x WF eyepiece. The FOV and relief advantages are pretty noticeable.
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

EYE C U
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Re: Is it really all about the objectives?

#10 Post by EYE C U » Mon Jan 24, 2022 7:14 pm

glass quality and grinding

Joe Henry
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Re: Is it really all about the objectives?

#11 Post by Joe Henry » Wed Jan 26, 2022 11:07 pm

Thank you for the replies

AntoniScott
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Re: Is it really all about the objectives?

#12 Post by AntoniScott » Wed Feb 23, 2022 10:01 pm

I'm going to state that YES is IS really all about the objectives. Granted there are those that will disagree. Yes. other factors are important, too. But to throw a wrench into the works, just as an experiment to satisfy my endless curiosity and basically answer your above question, I took a good Olympus objective and viewed the image with a very inexpensive eyepiece ( actually the 15x eyepiece from a Lafayette Radio and Electronics microscope from the late 1950's) and the image quality was excellent. Granted the field of view was small as would be expected but the image quaity was excellent, answering my questions about the objective being the most important part of the microscope.

apochronaut
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Re: Is it really all about the objectives?

#13 Post by apochronaut » Wed Feb 23, 2022 11:09 pm

A microscope such as your Lafayette would have used a Huygens type eyepiece. Huygens eyepieces were used on all microscope brands as default eyepieces for about a century because their design just happened to provide an adequate degree of correction for microscope objectives that required further off axis correction, all of which have very similar designs within several categories. Huygens eyepieces are also inexpensive to make so a basic microscope with good imaging could be put on the market at a competetive price using them. While your test does show that the Olympus objective is a good objective and no doubt better than the chromatic Lafayette objective of the same magnification, you could also use a much more expensive eyepiece with it : any number of compens eyepieces for instance or a proprietary w.f. design from a number of other brands and get a poor image from it using that combination. It wouldn't be the objective or the eyepiece that would be at fault, it would be the combination of objective and eyepiece.
No objective used with other optics in the system that are incompatible, is as good as another objective used with compatible optics. Generally objective quality is an issue of type and compatability not brand.
Generally objectives exist as chromatic, achromatic, plan achromatic or flat field achromatic, fluorite, planfluorite or flat field fluorite, apochromatic and plan apochromatic or flat field apochromatic, with a few other types thrown in by some companies, usually in the higher levels of correction. In each category, once you factor in specs. such as N.A. equivalence , coated vs. not and rule out a possibility of mismanufacture, microscope objectives are all quite similar in performance.
It is the specification of the objective that determines it's performance not who made it.
The biggest problem with average objectives from mass marketers is that the specs. on the barrel are a best case scenario, not necessarily an actual scenario. The production standards and q.c. are not present to guarantee those specs.

AntoniScott
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Re: Is it really all about the objectives?

#14 Post by AntoniScott » Thu Feb 24, 2022 11:18 am

Thankyou Apochronaut for an indepth analysis of eyepiece/objective compatability. I'm not aware of any of the specifications that are required for matching eyepieces to
objectives. I was just using my visual acceptance of one image over the other.

My unscientific study of using old Lafayette Radio and Electronics eyepieces (two 5x, 10x and 15x eyepieces from their low level miroscopes from 1959) were to see differences in field of view and possibly image degradation due to the obviously poorer optics of the low level Lafayette eyepieces. I compared these eyepieces to new AmScope eyepieces of similar magnification and could see no difference whatsoever other than the reduced field of view of the Lafayette eyepieces. It was a surprising revelation to me, but it did draw attention to my observation that the image quality was determned more by the objectives than the eyepieces.

Regarding objective specifications translating into image quality. My experience is that there is no way of determinng the peformnce of any Chinese made objective just by the numbers stamped on the barrel or an overly-hyped description. Although a totally unscientific approach, I would guess that the higher the price of the Chinese made objective, the better the quality of the optics. I have seen a 60x objective from China that had the same specifications on the barrel that was significantly dimmer that an Olympus equivalent.

Scarodactyl
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Re: Is it really all about the objectives?

#15 Post by Scarodactyl » Thu Feb 24, 2022 4:30 pm

Just a thread or so ago you also said
AntoniScott wrote:
Tue Feb 22, 2022 1:24 pm
I did an exhaustive side by side comparison between the E series and other more epensive Olympus objectives and was hard pressed to see any difference.
There probably is a significant a difference between Olympus's cheapest student grade objectives and their higher end ones. The eye can be pretty forgiving on the general impression it gives, especially if you're not actively looking for particular types of aberrations. It's when you start taking photos that everything becomes harder to filter out.

apochronaut
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Re: Is it really all about the objectives?

#16 Post by apochronaut » Thu Feb 24, 2022 5:37 pm

and outside of a modest f.o.v. It is much more economical to manufacture a plan objective to an 18mm spec., than one to a 22mm spec. For instance, lots of Chinese objectives are speced to 18mm or 20mm still. Put even a 22mm optical tube on many of them and the Demons of Peripheral Energy Scatter (D.O.P.E.S.) run amok.

AntoniScott
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Re: Is it really all about the objectives?

#17 Post by AntoniScott » Thu Feb 24, 2022 10:06 pm

I can't argue that there is not a difference between E series and expensive objectives.I would expect that. I just stated that I was hard pressed to detect a difference, especially since every thing I own is used, not new.

I had access to dozens of objectives so had the luxury to pick and choose the best out of the bunch. After comparing similar type objectives via A-B comparisons ( i.e. SPlan, DPlan, A series, E series, EA series) I was able to select what one gave me the best image quality. The ones that were rejected but were still quite useable were probably degraded through age, cloudy interior lens surfaces, misuse, etc. Every objective I own (with the exception to the E series) is used so it is realistic to say that old objectives would have some problems worse than others. Every now and then you find one that is problem free.
Taking the best objectives in my collection and comparing E series objectives to SPlan, DPlan, A series, EA series, did not reveal too much differences in optical quality other than a marginal improvement in color, contrast and resolution. Some had a flatter field of view. The best objective I own that has the best optical quality, color, contrast and resolution is a DPlan 50x oil immersion.

There is no point to taking camera images to document my points of view because no camera I own can resolve these differences.

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