60x Plan Infinity Objective. Danger gets a little heavy

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Roldorf
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60x Plan Infinity Objective. Danger gets a little heavy

#1 Post by Roldorf » Fri Jun 28, 2019 1:33 pm

Just arrived today. I have not had time to play with it yet but it is mounted on the scope and I have retired the 100x oil. It does work and gives a nice clean and focused wall to wall image. Will take some photos when I get round to it.
Last edited by Roldorf on Wed Jul 03, 2019 6:20 am, edited 1 time in total.
Alan
Bresser Science Infinity 4x 10x 40x 60x 100x oil. Canon EOS 4000d
Optika SFX 90

farnsy
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Re: 60x Plan Infinity Objective.

#2 Post by farnsy » Mon Jul 01, 2019 6:36 pm

Not enough information. What's the make and model?

Looking forward to getting your perspective on it after you have played with it a bit more. I'm actually surprised 100X oil is so clearly the standard when it seems like lots of people would prefer to use 60X dry, especially for hobby-level scopes.

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75RR
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Re: 60x Plan Infinity Objective.

#3 Post by 75RR » Mon Jul 01, 2019 6:50 pm

I'm actually surprised 100X oil is so clearly the standard when it seems like lots of people would prefer to use 60X dry, especially for hobby-level scopes.
Most manufacturers include a 100x in order to be able to claim a higher max magnification. It is supposed to help sell the microscope, though most hobbyists find they have little use for it.

100x objective x 10x eyepieces = 1000x magnification. That is pretty much as high as one can reasonably go.

The dodgier the seller the higher the claimed magnification, with some claiming 1600x and even 2000x.

In practice a 4x, 10x, 20x and 40x cover most of our viewing needs. If one has a 5 objective nose piece then a 60x is nice but it is a bit more demanding than a 40x, so it can take a little practice.
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Re: 60x Plan Infinity Objective.

#4 Post by Roldorf » Mon Jul 01, 2019 6:55 pm

Hi farnsy

Well I just got fed up of cleaning the oil off the 100x i'ts a pain and for how often I use it (because of the cleaning and the subjects we look at, mainly mushroom spores). It was taking up space in the head soooo out it came. I still have it and when I need the extra magnification it can always go back in.

It basically is a no-name objective from Bresser microscopes here in Germany as is the scope, however I am very pleased with it. See here.

https://drive.google.com/open?id=1NigXv ... msgZP7DT2S

and here viewtopic.php?f=6&t=7655&p=67589#p67589
Alan
Bresser Science Infinity 4x 10x 40x 60x 100x oil. Canon EOS 4000d
Optika SFX 90

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Re: 60x Plan Infinity Objective.

#5 Post by Wes » Mon Jul 01, 2019 7:04 pm

What is the numerical aperture? I tend to pay more attention to the NA rather than magnification. If I had to choose between two objectives with the same NA I would probably choose the one with lower magnification because it would produce a better looking image. That being said my favorite is the 40/0.95 objective.

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Re: 60x Plan Infinity Objective.

#6 Post by apochronaut » Mon Jul 01, 2019 7:30 pm

Usually a 40X of sufficient N.A. that one can tweak 600X out of it is sufficient but I use a high magnification, high N.A. objective quite a bit too. The extra detail is absolutely necessary for certain small subjects and once one jumps to fluorite or apochromat objectives, the combination of high N.A. and better colour correction makes the small oil cleanup job, a routine 1 minute task.

If a 60 or 63X has been designed with an N.A. of .90 or .95, one can still get enough out of it to provide better detail but I find the common .85 60X objectives a bit limiting. Most better colour corrected 40X .70 and higher with 15X W.F. eyepieces give better imaging than an average 60-63X .80 or .85 achromat.

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Re: 60x Plan Infinity Objective.

#7 Post by Wes » Mon Jul 01, 2019 7:43 pm

apochronaut wrote:the combination of high N.A. and better colour correction makes the small oil cleanup job, a routine 1 minute task.
Don't forget the condenser top lens, without oiling it you are restricted to 0.95

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Re: 60x Plan Infinity Objective.

#8 Post by Hobbyst46 » Mon Jul 01, 2019 7:43 pm

Cleaning immersion oil is a nuisance, but a must sometimes. One should know that the two ubiquitous types of oil have different viscosities, namely 150 and ~1300 cP, respectively. The former is fairly convenient (for both the condenser and objective) and is relatively easier to clean off.
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Re: 60x Plan Infinity Objective.

#9 Post by apochronaut » Tue Jul 02, 2019 2:46 pm

Wes wrote:
apochronaut wrote:the combination of high N.A. and better colour correction makes the small oil cleanup job, a routine 1 minute task.
Don't forget the condenser top lens, without oiling it you are restricted to 0.95
Usually, I oil the condenser, mainly because I have found that the type I mostly use, isn't much better than a dry achromat, if it isn't oiled and for some of the subjects I view, maximum N.A. is useful. I do use a dry achromat sometimes.

The issue as to whether a .90 dry achromat for instance, limits the N.A. of an oil immersion objective to the N.A.of the condenser is an interesting one. On the surface it looks like that is a cut and dried limiter, with the condenser sort of clipping off the N.A., thereby making it unavailable to the starving objective. My observations over the years don't support that. The effective N.A. of the objective would appear to be reduced by a fraction of the difference between the N.A. of the condenser and the N.A. of the objective. So, an oiled 1.32 N.A. objective used with a .90 condenser would have a working N.A. of around 1.15.

The constant, 1.22 in the numerator of the Rayleigh criterion formula helps determine the fraction.

The Rayleigh criterion is R=1.22lambda/N.A.objective+N.A.condenser where R is resolution in nm and lambda is the wavelength of the light .

Using the Rayleigh criterion and light of 500 nm, an objective of 1.30 and a condenser of 1.30, the theoretical limit of resolution will be 234.62 nm.
Using the Rayleigh criterion and light of 500nm, an objective of 1.30 and a condenser of .90, the theoretical limit of resolution will be 277.27 nm.
Now if, the N.A. of the objective were to be reduced by the condenser to an effective N.A. equal to that of the condenser, then the theoretical limit of resolution with 500 nm light, a .90 condenser and a .90 objective would be 338.9 nm.

So, based on the Rayleigh criterion an objective being used with a condenser of .90 has considerably better resolution than it would have if it's N.A. is being reduced to that of the condenser.

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Re: 60x Plan Infinity Objective.

#10 Post by Wes » Tue Jul 02, 2019 8:04 pm

Interesting, you are right. Do you think that the condenser NA itself, ignoring the objective, would be limited to 0.95 without oiling it (if for example it has 1,4 indicated on the condenser top lens)?

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Re: 60x Plan Infinity Objective.

#11 Post by apochronaut » Wed Jul 03, 2019 1:38 am

The condenser is always below an N.A. of 1, if not immersed. I did a little hobby condenser designing, and some rudimentary testing of off the shelf dry and oil abbe, dry and oil abbe aspheric, dry and oil achromat aplanat and dry and oil diy condensers. One of the diy condensers was an apochromat. Based on that and whatever literature and physical examples I could find around, it seems that the highest you can get a dry condenser to perform at is about .95. An oil condenser can go to around 1.52 but there were only a few of those ever made.
What I did find out though, is that superior broad field colour correction in a dry condenser achieves better results over the totallity of a plan image, than a higher N.A. immersed condenser if the immersed condenser is not well corrected.

It is easy to see why the better mfg. opted for dry achromat condensers beginning in the 1980's. Despite the restriction of N.A. to below 1, the ultimate image quality over a wide field is improved when compared to an oiled abbe condenser with a higher N.A..Ultimately an oil immersion achromat is the best option.

It is a bit of a tragedy that abbe condensers are used in the marketing of stencil microscopes as a sort of gold standard, when in fact they were invented due to a crisis at Zeiss. At the time , Zeiss didn't believe in condensers. People were fitting Zeiss microscopes with condensers made by other companies, many of them already achromats. They hired Abbe to come up with a solution and his simple design became a standard for all basic microscopes, mainly because it works and is cheap. A lousy condenser is better than no condenser, right? For any upgraded sytem beyond an achromat system though, they are very sketchy and anything but a gold standard. The only time I use an abbe condenser is as an example of what a condenser should not be like.

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Re: 60x Plan Infinity Objective.

#12 Post by Roldorf » Wed Jul 03, 2019 6:15 am

apochronaut

Posts always seem to develop into extremes when you get on your high horse. I can understand why some some members seem to get annoyed when you get into 'Lecture Mode' as your last post on a fairly simple subject (my acquisition of a 60x Plan Infinity Objective) seems to have become.
Most of the members here, especially me, don't have the money, resources, patience or knowledge to delve into the design of optics, we want to look at the images under the objectives as that's what excites us and gets our blood flowing.

If it's a little 'blurry' by your standards some of us don't worry so much and in any case are not able to do anything about it even if we did.

May I make a 'suggestion'? Concentrate your reply's to the subject matter of the post and ignore the posts of those who you consider to have 'inferior knowledge' and 'need a bit of teaching'.

You make the rest of us feel as though we shouldn't be here talking about our cheap microscopes and equipment.

So give us all a break and tone it down a bit.
Thanks in anticipation.
Alan
Alan
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Re: 60x Plan Infinity Objective. Danger gets a little heavy

#13 Post by apochronaut » Wed Jul 03, 2019 11:27 am

You will eventually appreciate it, once you get your feet wet regarding microscopy. Right now, you have amply indicated that you have a lot to learn. Your appreciation of your instrument would be furthered by reading and learning, rather than criticising those taking their time to put their long years of experience at your disposal. As for the criticism, it pretty much goes in one ear and out the other. It doesn't matter.

I was responding to a question by another member who apparently understood and appreciated the explanation. Microscopes are supposed to resolve detail. I supplied some information about ways to achieve that and why some people are being duped by manufacturers into believing they are getting more than they are. If you have a problem with that , then you just have a problem , period.

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Re: 60x Plan Infinity Objective. Danger gets a little heavy

#14 Post by Wes » Wed Jul 03, 2019 11:40 am

I personally thoroughly enjoy apochronaut's posts, the more detailed the better. I can only improve my own understanding by hearing what he has to say.

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Re: 60x Plan Infinity Objective. Danger gets a little heavy

#15 Post by geo_man » Wed Jul 03, 2019 11:47 am

If you don’t like certain people’s Posts, I suggest that you ignore them. Others may find value.

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Re: 60x Plan Infinity Objective. Danger gets a little heavy

#16 Post by Roldorf » Wed Jul 03, 2019 11:48 am

apochronaut

Well I would suggest that if you are replying to another members question then you should address that member at the top of your post. (See example here).
Then I can just skip over your comments instead of having to read through lots of boring technical detail to see if you have anything interesting to say.
Alan
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Optika SFX 90

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Re: 60x Plan Infinity Objective. Danger gets a little heavy

#17 Post by 75RR » Wed Jul 03, 2019 11:54 am

It is quite common for threads to deviate from an OP’s question, as subsequent posters reply to comments left by previous posters.

As long as the OP’s question has been answered there is not much harm in it, though ideally such sidetracking should be kept to a minimum

and moved to their own new thread when they go substantially off the original topic.
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
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Re: 60x Plan Infinity Objective. Danger gets a little heavy

#18 Post by Roldorf » Wed Jul 03, 2019 11:54 am

geo_man
If you don’t like certain people’s Posts, I suggest that you ignore them. Others may find value.
Hi, I usually do however this is a post that I started and of course I am interested in what people have to say but not when it is 'off topic' and a little bit insulting so I suggest that you ignore my comments to 'apochronaut' and it will save you some typing.
Alan
Bresser Science Infinity 4x 10x 40x 60x 100x oil. Canon EOS 4000d
Optika SFX 90

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Re: 60x Plan Infinity Objective. Danger gets a little heavy

#19 Post by Roldorf » Wed Jul 03, 2019 11:56 am

75RR

I heartily agree and that is exactly what I am suggesting in this instance.
Alan
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Re: 60x Plan Infinity Objective. Danger gets a little heavy

#20 Post by apochronaut » Wed Jul 03, 2019 11:58 am

Roldorf wrote:apochronaut

Well I would suggest that if you are replying to another members question then you should address that member at the top of your post.
I believe the abrassive post you are referring to began with a quote that was headed " Wes wrote". Isn't that enough for you?

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Re: 60x Plan Infinity Objective. Danger gets a little heavy

#21 Post by Roldorf » Wed Jul 03, 2019 12:01 pm

apochronaut

The short answer is 'NO'
Alan
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Re: 60x Plan Infinity Objective.

#22 Post by farnsy » Wed Jul 03, 2019 7:17 pm

apochronaut wrote:It is a bit of a tragedy that abbe condensers are used in the marketing of stencil microscopes as a sort of gold standard, when in fact they were invented due to a crisis at Zeiss. At the time , Zeiss didn't believe in condensers. People were fitting Zeiss microscopes with condensers made by other companies, many of them already achromats. They hired Abbe to come up with a solution and his simple design became a standard for all basic microscopes, mainly because it works and is cheap. A lousy condenser is better than no condenser, right? For any upgraded sytem beyond an achromat system though, they are very sketchy and anything but a gold standard. The only time I use an abbe condenser is as an example of what a condenser should not be like.
apochronaut, when you refer to "abbe" condensers, I take it that you mean abbe condensers that are not aplanic or achromatic. Is that right?

I had previously thought that "abbe" refers to the whole class of modern, iris-bearing condensers, including those with the corrections I mentioned. It sounds like I may be wrong. Given your knowledge on the subject and the degree of interchangeability between systems that condensers have, this seems like a really interesting topic to me. If Roldorf does not want this discussion in his thread, I would be interested in a full scale apo-discussion on the subject in a new thread, including your view of appropriate condensers for use with 60X dry objectives.

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