Resolution

[lorez]

nor have a discerning enough eye to *really* know anyway.

I lifted this quote from Kurt in an earlier thread and thought it worthy of its own discussion.

I believe we all have a discerning eye, but what we may not have is a reliable scale for making the determination. Such a scale may be a diatom test slide or a well prepared slide of some bacteria. The other thing is a means by which to become very familiar with the available test slide and therein may be the limiting factor; a microscope with which to establish a base from which later comparisons can be made.

The second part of the equation is the microscope in question. I would guess that almost everyone in this crowd is a "multiple microscope" owner and will have no problem in making the comparison.

It probably goes without saying, but it is important to establish the best possible illumination on the microscopes. Also, be sure to look at the same feature on the slide with each microscope. It's easy enough if you are using a diatom test slide, but on a bacteria or other slide it is a good idea to mark the feature with a marking pen like a cell mark or sharpie.

In a perfect evaluation we would be testing only the objective, but since many are not easily interchangeable it may be just as meaningful to evaluate the system in which it is used.

For the stereo microscopes I use a resolution target, but the epiphany for me was a specimen dish of very small copper balls (about 0.3mm) that I was looking at with a no-name stereo microscope. Then I had the bright idea that I should also look at them with the B&L StereoZoom 4. The expression "Holy Moly" comes to mind.

lorez

[gekko]

Good food for thought, lorez. After reading it, I thought I would compare, using the same microscope and optics, the effect of illumination on "resolution". I will compare Koehler and "simple" (not Koehler, not critical) illumination (by putting a diffuser over the field lens). I'll use a diatom slide for the comparison, as you suggested.

[lorez]

Good morning, gekko.

I'm interested to see/hear about your conclusions. In a round-about way I do what you are suggesting every time I encounter a microscope in need of some extra attention.

lorez

[gekko]

Good morning, gekko.

I'm interested to see/hear about your conclusions. In a round-about way I do what you are suggesting every time I encounter a microscope in need of some extra attention.

lorez

I'll try to do the test this week and will post the results.

[KurtM]

For this exciting episode of True Confessions: I still don't know exactly what Numerical Aperture (aka N.A. aka NA) is, or what it should mean to me. I'm plenty familiar with the term, have had it explained many times, and have read about it in many different places, but still my fuzzy old brain refuses to compute it. I almost despair of ever getting it, but you never know when somebody is going to say something that will click and turn the light on, and so, with that, if any of you cares to have a go at Numerical Aperture For Dummies, I'm all ears (eyes)! Thank you.

[lorez]

I may join gekko in preaching heresy, but I don't think it's important to know the physics of the NA. It is printed on the objective barrel and the higher the NA the greater the resolution, all other factors being equal. I will say, however that all equivalent NA objectives do not preset equivalent resolution. All the glass in the objective also makes a big difference, not to mention the microscope itself and the users ability to properly set it up. You have microscopes of sufficient quality to show you what good resolution looks like and you can make your own comparisons with your other microscopes.

lorez

PS If you search Numerical Aperture you will find dozens of explanations that may/will confuse the heck out of you.

[Dale]

Where does one find .3mm copper balls? I would like to create a slide for resolution comparisons.
Dale

[gekko]

KurtM, I think you may be thinking too deeply. I am not sure I can do better than lorez. I apologize if the following is too "patronizing". You can think of NA as just the mathematical definition of "aperture". As you know, other things being equal, a telescope with a larger diameter objective has better resolution, same with microscope objectives. If, as a rough analogy, you think of the objective as a filter (such as an audio filter), the objective's aperture would define the cut-off frequency of a low pass (spacial) filter. The higher the cut-off frequency (more bandwidth corresponding to a larger aperture or NA) the more details (higher spacial frequencies) you see and the truer (more "faithful") the image would be (hence higher resolution). A more direct and much simpler way of thinking about it is in terms of resolving a diffraction grating, which would also explain clearly why it is that a larger aperture gives better resolution, but that is more difficult to explain without drawing pictures.

[lorez]

Where does one find .3mm copper balls? I would like to create a slide for resolution comparisons.

Dale, I think a diatom slide would be a good place to start. Once you are familiar with what you are able to see under your optimal conditions you will have a bench mark for comparison. Your AO 10 microscope is a good place to start as it has very good objectives that produce sharp images.

There is not much that one can do to change resolution within the actual components, but the settings of the microscope will certainly make a difference.

As for the balls, they are long gone. I was given the little tray of balls by a person who was using them commercially as we were trying to improve his microscope situation.

If I were to speak metaphorically, I would use a basketball as an example. Viewed from a distance the ball appears to be an orange sphere. Getting closer it is possible to see the texture of the surface and realize that the ball is not as smooth as it originally appeared. The same happened with the balls, except that I changed the lens system. What a surprise. With one microscope the balls appeared to be smooth, but when viewed with the second I could really see the nature of the surface. That was a lesson I'll never forget.

In spite of equivalent magnifications and presumably equivalent NAs the lens systems were nowhere near equal.

So, what's the conclusion here ? For me it is having a reliable reference slide with which to make objective comparisons. When I was using the first microscope I did not know what I was missing.

lorez

[Rodney]

The question for me is, how do I make this camera pick up on what I observe through the microscopes eyepiece.
So if I can`t define the fine lines of these particles at 200x, I would be out of the contest for diatoms.

Looking through the microscope without camera the particles are a lot sharper, sharp enough to be well defined lines.

Rodney

[lorez]

The question for me is, how do I make this camera pick up on what I observe through the microscopes eyepiece.
So if I can`t define the fine lines of these particles at 200x, I would be out of the contest for diatoms.

There are several variables here. The camera quality is one, the connection to the microscope is the second, and the third, which you will never overcome is that the eye always sees the image more sharply than the camera and subsequent viewing device (computer, TV, projection screen, etc.). Since I don't know about any of your equipment I can't comment more specifically.

You are certainly not out of the contest for a diatom. Your B&L DynaZoom, with original objectives (in good condition), will give an excellent image. If you have not had the opportunity to look at a prepared diatom slide I think you will be pleasantly surprised when you do, When you are evaluating the comparative resolution of your various scopes you should use only the microscope (IMO) so you are seeing the product of the microscope optics before the image is strained through all the electronics of the system.

lorez

[Dale]

I found some really nice ones, but it seems some agency called the USAF has them with real high prices.
Strained! I like that!
Dale.

[lorez]

I found some really nice ones, but it seems some agency called the USAF has them with real high prices.

If you are meaning the USAF 1951 resolution target they are available from several sources at around $125, but for a hobbyist they are not really necessary.

If you are meaning "little copper balls" I'm sure the USAF has the most expensive ones on the planet.

lorez

[Rodney]

I tried all my bausch and lomb objectives Lorez and thanks, they all perform very close to the same. Camera mount and light is good, this camera will not pick up on fine detail.

I tried all the limited camera settings for this camera, I may be able to tweek in an half a.. decent photo at times depending, until I may purchase another camera.

Rodney

[Dale]

Did I miss what they were, or came from?

[gekko]

I tried all the limited camera settings for this camera, I may be able to tweek in an half a.. decent photo at times depending, until I may purchase another camera.

My 2 cents' worth: I think your camera is a very good one, but I would study the manual to see what manual setting (as opposed to automatic ones) it has, then I would try to experiment with them. One great advantage of digital over film cameras is that it costs nothing to experiment to optimize the images.

[Rodney]

Thanks Gecko, I have tried every manual setting this camera has in program mode. If I have missed one i`m not sure where its at.

What Canon technical support said was, what I have is a entry level camera and I would need to upgrade to obtain better photo`s, and they would help me find the right one when I get ready.

Rodney

[billbillt]

Hi Rodney,

Your camera worked real well in this configuration... Wonder why not now?....

[billbillt]

Here is the above photo before cropping..... Looks much better than your "particles" photo for some reason....

[Rodney]

I don`t know, but I do know the camera will pick up on certain slide samples a lot better, like the camera is confused with certain ones.

I went through every camera setting with a test run of the same slide. The best one out of 10 was this one. I`m going to change the slide to something else.

Rodney

[Rodney]

Take a look at the front lens of this camera, 4 times the size of a widefield eyepiece. Has absolutely no way to control the aperture of the lens other than zoom function.

And the quality of the zoom is questionable since you never know where you are at with it or where you were at.

Rodney

[lorez]

I think the discussion about resolution has been derailed. We need a new topic for the cameras.

lorez

[gekko]

You may have tried what I'm going to suggest (in which case please ignore this). Have you tried setting to manual focus (set it to infinity, or closer up to 12 inches say). This way you can focus the microscope and not worry about the camera's whim as to where it will focus. Also, I would try various zoom settings and choose the one that gives you the largest field of view. Again, if you've already tried all this, please ignore my suggestions.

[Edit:] lorez, you are absolutely right-- sorry I was writing this when you posted your message above (you always seem to beat me by a few milliseconds ]
Rodney, please start a new thread for camera discussion as suggested by lorez.

[Rodney]

Not a problem, I can pick back on the camera elsewhere if needed. Yes I have tried all the infinity and macro settings.
So I will just use what I can get out of the camera and not start another topic.
Thanks,

Rodney