Flourite Objectives on Amscope

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einman
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Flourite Objectives on Amscope

#1 Post by einman » Sun Jan 15, 2017 4:43 pm

I noticed Amscope is now offering infinity planfluorite objectives on their website..just an FYI.

billbillt
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Re: Flourite Objectives on Amscope

#2 Post by billbillt » Sun Jan 15, 2017 5:11 pm

Thanks for the heads up.. May turn out to be very good quality..

apochronaut
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Re: Flourite Objectives on Amscope

#3 Post by apochronaut » Mon Jan 16, 2017 1:58 pm

Oddly, they don't seem to offer the 4x and 10x, separately; just in sets of 4. I would try a 4x, just to see but given the optical performance of the Chinese made achromats and planachromats, I have tried, I wouldn't hold my breath. The 40x and 100x are around 300.00 and 600.00 respectively, so given that one can get other infinity planfluorites, with known, stellar, performance , on the used market for a lot less, they would be a bit of an expensive long shot, too. Another odd thing about them is the length of the 10x objective , which like their achromat 10's, is really short. Hard to believe that it would be L.W.D. at .30, so it must not be parfocal, which would be ridiculously bad, in this day and age, if it turns out to be true.
One of the ways, legitimate microscope companies create higher N.A. objectives is to incorporate fluorite elements into the design. This results in a 40x objective, for instance that has an N.A. of .85 instead of .65 and some benefit in better colour correction too. They typically, don't go around calling these fluorites though, unless the design is a dedicated fluorite design, which tends to vault the lens into the stratosphere, in terms of price and quality too.

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billben74
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Re: Flourite Objectives on Amscope

#4 Post by billben74 » Mon Jan 16, 2017 2:09 pm

I have bought the x4 na 0.13 infinity fluorite.
It is possible to buy them individually, although the website is a bit confusing.
Its my first fluorite so can't compare it too any others but it is better than my previous x4 na 0.1 plan achromat.

See my "colourful screw" for an example of it in action.

I am minded to get the x10 na 0.3 at some point based on my experience with the x4.

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Re: Flourite Objectives on Amscope

#5 Post by apochronaut » Mon Jan 16, 2017 4:06 pm

I hadn't noticed those pictures to be with a fluorite. Nice pictures but to evaluate the objective, I would like to see some comparisons, with some sort of dark on white test subject, right across the field and without any further post processing : a large diatom or grating of some type. If they were to turn out to be based on the Olympus pattern, and I suspect that to be the case because the planachros that are marked and physically designed similarly are, it should work on infinity corrected microscopes made by Olympus, AO/ Reichert series 400 ( + 10% mag.), some of the microscopes of Chinese mfg.including the Zeiss Primostar infinity but not likely other Zeiss infinity, Leica Delta and HC optics based instruments( + 10% mag.) but not HCX and Nikon infinity too( + 10% mag.). Hopefully, the price is right.

einman
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Re: Flourite Objectives on Amscope

#6 Post by einman » Mon Jan 16, 2017 7:46 pm

I have found the variation in Chinese planachromats vary but those on the Bestscope I have purchased are better than to equal to those on nearly every scope I have. They are based on the Olympus design and as mentioned in earlier posts are equivalent to those provided on the Olympus BX series microscopes as viewed by several individuals. Their FN is also greater than most if not all of the older planachros (>22) available for the Big 5 scopes. In terms of posting photos everyone knows that photos represent the photographers ability and equipment as much as if not more than the performance of the objective. Even the manufacturers such as Zeiss and Olympus rarely post images as a means of comparing performance internally or externally.

I have seen at least 4 designs of Chinese planachromats. One design looks very very similar if not identical to the Olympus. Another is slightly different while the other 2 are completely different.

These fluorites do not have the 0.85 NA found on older objectives (although nether did Leitz) and as such avoid the need for a collar.

I for one would not rely on a photo to assess performance..unless the photographer had a reputation.

billbillt
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Re: Flourite Objectives on Amscope

#7 Post by billbillt » Mon Jan 16, 2017 8:52 pm

I am sure these Amscope objectives would be more than sufficient in quality and performance for the home hobbyist where cutting edge technology and expense is not required.....

BillT

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Re: Flourite Objectives on Amscope

#8 Post by einman » Mon Jan 16, 2017 10:40 pm

billbillt wrote:I am sure these Amscope objectives would be more than sufficient in quality and performance for the home hobbyist where cutting edge technology and expense is not required.....

BillT
I would tend to agree. I look forward to an assessment when someone on the forum purchases one.

apochronaut
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Re: Flourite Objectives on Amscope

#9 Post by apochronaut » Mon Jan 16, 2017 10:41 pm

Not a good idea to lump them all together. There are many instances in the past, where a series of objectives has existed, presumably engineered and made to the same standards, yet certain models in actual use, fall short of the mark. New releases and or substitute model numbers, all of a sudden appearing, often point to this.
I think the 4X, at 60.00 U.S.$ ( surprise, surprise; the price has already been slashed!) , plus shipping and entry fees looks to be a valuable option for those seeking an alternative to the fairly simple achromat designs around and even the planachros. Contrast is an issue with many Chinese objectives and this PlanF , is likely a way around that, hopefully, anyway and at a pretty good price. I don't know of another substitute for it, that sells in sufficient quantities and at a low enough price on the second hand market, to be a better option. It would be a hard sell though, because when it comes to the image quality coming through the infinity corrected planachro 4X objectives, made by the recognizable makers; they aren't too shabby. It is one of the magnifications at which the designs are as close to perfection as they could be and some individual achromats, even by the 1980's were so close to apochromats, as to be almost indistinguishable.
At the level of the 10X, things get a bit more complicated. 10X planachros can be excellent too and all of a sudden, as well, there are second hand options for planfluorite , or even planapo objectives, sometimes at very good prices( under 100.00) and this one with it's short body , looks suspiciously like it might be a difficult lens to work into a truly parfocal system. It's performance level is a mystery, yet and it is 150.00,,close to 200.00 by the time it lands at a foreign door. For that kind of money I can buy other and certainly better planfluorite and even planapo objectives, dovetailed to the instrument and know it will be good and parfocal.
The 40x and 100x, at 250.00 + and 550.00 +, are off the table. They are way more than what I could buy planfluorites and planapos for, second hand , of known performance and dovetailed to their purpose and there is still no evidence that these PlanF would be any better than a really good planachro, which are not all created equal.
Add to this, the extreme reputation of Amscope's acumen and service orientation and the value of these could well be measured as the inverse of their magnification.
Time will tell but outside of the 4X, they don't look to be much of an option at all.

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Re: Flourite Objectives on Amscope

#10 Post by billbillt » Mon Jan 16, 2017 11:51 pm

apochronaut wrote:Not a good idea to lump them all together.
Time will tell but outside of the 4X, they don't look to be much of an option at all.
I feel that most hobbyists here pay very little attention to the hair-splitting technicalities and minuscule improvements from one to the other.. At the end of the day, it is still just a hobby and super specifications of an objective actually has small importance.. It is the fun achieved using what you have and enjoying it that really matters ..

The Best,
BillT

apochronaut
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Re: Flourite Objectives on Amscope

#11 Post by apochronaut » Tue Jan 17, 2017 12:57 am

Exactly my point. That's why I elucidated the relative potential value of these objectives, and indicated much more economical and likely better alternatives.

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Re: Flourite Objectives on Amscope

#12 Post by apochronaut » Tue Jan 17, 2017 9:57 am

The 4x, is now out of stock, at Amscope.

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Re: Flourite Objectives on Amscope

#13 Post by billben74 » Tue Jan 17, 2017 10:51 am

I'm not surprised the x4 is out of stock, as you say Apo -> this is good value and (although I haven't has time to be very rigerous in my comparison) it definately seems to me to better than my achro x4, na 0.1 that it has now replaced.

I may stick my neck out an go for the x10. The x4 is 45mm parfocal, and whilst not precisely parfocal with my other 45mm parfocal objectives its so close it really doesn't bother (switching to x4 is a faff anyway as the field iris has to be adjusted so a few microns of adjustment are not really a problem).

The x10 is for me still a good option, although this will obviously only be true if its significantly better than my x10 planachro.
My guess is that it will be. But it will have to wait a little while for the microscope fund to fill up again...

When I do I will report in my experience.

I doubt I will go for the others unless the price drops a lot.

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Re: Flourite Objectives on Amscope

#14 Post by apochronaut » Mon Feb 12, 2018 4:35 pm

I decided to buy a couple of these, since the price was still pretty low. Eventually, with the exchange to $CDN., Amscopes asinine shipping costs outside the U.S. and the Canadian government's asinine rakeoff at the border, the pair ended up costing me about 300.00 $CDN. That isn't too terrible for a pair of new planfluorite infinity corrected objectives, if they were to perform well and I am also interested to know, how the Chinese makers are forging ahead. This is a good test.

The first thing that I noticed is the weight of the Chinese objectives, and the diameter. They are fairly heavy, so lots of glass in there, and the coating looks impressive. The barrels and finish are only adequate but then all objectives over the past 25 years or so have declined in finish, with paint replacing etching etc.


The two objectives are marked 4X .13 PlanF and 10X .30 PlanF. I am comparing them to a 4X .12 Planachro from AO/Reichert circa 1985, a 10X .25 Planachro from the same series AO/Reichert and a 10X .30 Planfluor AO/Reichert of the same vintage. I could buy the two AO/Reichert Planachros used for around 75.00 ea., if I look around but the 10X .30 Planfluor might cost about the same as the Amscope or around 150.00. I have seen them go much cheaper in the past, though. All of the objectives are 45mm parfocal D.I.N.


The Amscope 4X is quite short and fat, 28mm long , weighing 81 gm., the AO/Reichert 4X is much longer at 38mm, weighing 102 gm. The Amscope 10X is also shorter(32mm) than the two AO/Reichert(40.5mm)and the respective weights are 88 gm., 106 gm. and 98 gm. Based on this length difference, I would expect the two Chinese objectives to have longer working distances.
They were tested in a Reichert Diastar, with a 20mm f.o.v.

The Amscope objectives appear to be corrected for a 200mm infinity tube, with the magnification equaling that of the objectives I am comparing them against. They both parcenter well, with the 4x Being a little off.
They also appear to have a field limitation. Many of the Chinese microscopes are sent out with 18mm f.o.v. eyepieces and that seems to be the limit that these objectives have plan performance up to. With a 20mm f.o.v., there is some falloff over the perimeter 2mm of field, with some flare and lateral chromatic aberration occurring. It isn't too much of a problem but the characteristic begins slightly before an 18mm diameter, so they are not fully plan. This is is definitely disappointing and it is easy to see that the performance of these is cut very close to the bone, obviously as part of the cost cutting structure of their offering.

The 4X .13PlanF vs. the 4X .12 Planachro. The first thing noticeable is that the Amscope is brighter than the AO/Reichert objective. Colour is more intense , although the background has a blueish cast and the contrast is a little higher. Using the aux. condenser lens on the AO/Reichert abbe aspheric condenser, the field is just barely filled with the Amscope objective , due to it's longer w.d., which is equal pretty much to the 10mm difference in the their length, since the two are almost perfectly parfocal. The Amscope has noticeably better resolution in the center of the field but that advantage begins to fall off at about the 16mm f.o.v. point as the AO/Reichert's superior planarity and edge correction dominates. AO/Reichert's achromat objectives of this period were close to fluorite performance, when it came to colour correction, so with low refraction specimens the two objectives perform about equally in that regard but with specimens of a higher refaction, such as diatoms, the AO/Reichert planachro has a slight edge in the center of the field with a decided edge towards the periphery.
Overall, as a low power scanning objective the AO/Reichert presents a more pleasant wide field experience but for critical examination of details in the center of the field, the Amscope objective has an edge in resolution and contrast

The 10X .30 PlanF vs. the 10X .25 planachro and the 10X .30 planfluor. Again, the planarity falloff of the Amscope objective is noticeable but not as evident as it is with the 4X. Brightness and contrast of the three is almost identical, with the AO/Reichert Planfluor having a slight edge.. At the center of the field, the Amscope PlanF and AO Planachro are pretty much identical in resolution, with the AO/Reichert Planfluor being noticeably superior in bringing out the fine details of very finely structured diatoms, for instance. Both of the AO/Reichert objectives are superior outside of about the 75% of the field center. With specimens of higher refraction, the Amscope objective elicits a decided irridescent internal c.a in many structures, across the field while the AO planachro and planfluor elicit almost none. In this regard the AO/Reichert planfluor is only slightly better than the planachro. The three objectives are parfocal, so the Amscope example has about a 9mm advantage in w.d.
Overall, there is virtually no advantage of the Amscope 10X .30 objective over a higher grade planachro, with the objective really just performing about at the level of such a specification. Pretty disappointing really, given that AO/Reichert 10X .25 infinity corrected planachros are almost a dime a dozen.

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Re: Flourite Objectives on Amscope

#15 Post by MicroBob » Mon Feb 12, 2018 8:15 pm

Hi Apochronaut,
thank you for your thorough testing! I think that many people don't really feel competent enough to buy second hand and for them it is especially interesting to read what is on offer beyond the simple achromats. Your review shows nicely that decades ago very nice optics have been made that don't fear comparison to modern equivalents. A field of view of 18mm is fine for me but there are systems that offer quite a bit more. Above a certain price point one becomes quite picky and the expectations rise. Probably the amateurs comparison between used quality brand equipment and new import equipment is a bit unfair, but it also shows that even the Chinese can't whittle an objective from a coke bottle and some metal scrap.
I don't have an infinity microscope but from what I have read the use a tube lens that is designed for the objectives in use. I asume here that you have tested on a nice old americal or austrian infinity stand. Is there a chance that the chinese planfluorites would have scored better on a stand of their own origin?

Bob

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Re: Flourite Objectives on Amscope

#16 Post by apochronaut » Mon Feb 12, 2018 10:50 pm

I did test them with Japanese eyepieces with an 18mm f.o.v. and the the poor peripheral planarity was less objectionable but they were still not perfectly plan. I have noticed that with Chinese planachros too. They are more what I would call semi-plan. The 10X is better and almost completely plan but then, it's failings are that it does not provide any resolution gain, or colour correction gain over a 10x .25 planachro, even at center field. It is simply, not as good an optical design as the other two objectives.

I did consider that there might be a correction mismatch in my Diastar stand, for these objectives but several clues have ruled this out in my mind. 1) The planarity, lateral ca and peripheral flare are inconsistent between the two Chinese objectives. The 4X is worse.This indicates a degree of design variance, which indicates that they arose out of a low cost development program, using limited types of glass. These types of peripheral correction variance are a traditional problem in microscope optics across the board but were largely solved after the 1970's in most factories of quality, due to a larger # of glass choices. The same degree of peripheral variance between the two Chinese objectives would exist if those objectives were mounted on any microscope.

My experience with tube lens mis-corrections, have all shown evidence of mis-match in the central portion of the field as well as at the periphery and in the case of these objectives, their performance in the center of the field is excellent for the 4X and mediocre for the 10X.

It should be noted as well, that fluorite glass is used in many objectives, as a tool with which to control dispersion and increase the N.A. Not all objectives , that have fluorite glass in them are called fluorites. It is possible that the marketers of these objectives are over stepping the bounds of what many would consider to be adequate fluorite characteristics.

I can see myself using the 4X , mainly due to it's excellent center of the field performance . It would be good for large specimens, insects etc. but the 10X , just is not good enough to meet what I consider fluorite quality.

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Re: Flourite Objectives on Amscope

#17 Post by einman » Sun Feb 18, 2018 12:44 am

Excellent observations! I believe there are variations in terms of quality within the realm of infinity Chinese objectives. I have purchased a few 20X objectives and found variations in terms of being parfocal and in terms of contrast and resolution. Although I am not as adept at assessing CA etc as Phil is.

I believe that there are degrees of quality within the offerings from China. Meaning an infinity objective made in China for one of Nikon's higher end stands or Olympus' higher end stands are most likely superior. Within both the Nikon and Olympus line of objectives there are significant cost differentials with little to no explanation as to why when reading the brochures.

It would be interesting to continue this thread with observations as detailed as Phil's with other infinity objectives produced in China for say Nikon, Zeiss or Olympus.

I would like to compare the planachros as well. The Bestscope I own listing for $1600 or so on Amazon performed very well against my favorite scopes. I would love to see how the planachros on that stand would fare under similar scrutiny given these planF objectives. That is the problem facing hobbyists. I have seen several variations, in terms of cosmetic appearance, on E-bay for Chinese infinity objectives. Does that indicate potential differences in internal quality and construction? Who knows. Are there generic Chinese objectives, heavily discounted, equivalent to the higher end Name brand objectives ie Olympus. Discounted, not because they are inferior, but simply because they are not "branded"? I sincerely believe so. Finding those objectives is a crap shoot however. This is why so many of us prefer to fall back on the older quality stands from the Big brands.

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