Diatom Brightfield/Darkfield/PC/DIC

Starting out in microscopy? Post images and ask questions relating to the microscope and get answers from our more advanced users on the subject.

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NicoVB
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Post by NicoVB »

I have both of them Alan, the NFK and the FK 2.5.
On first sight there is not much difference
I'll compare them in a same setup.
Last edited by NicoVB on Fri Oct 14, 2016 4:59 pm, edited 1 time in total.
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Pau
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Post by Pau »

Alan Wood wrote:... Sadly, there does not seem to be any way to overcome the narrow field of view that results from the small sensor without affecting image quality.
In fact, there is, as I explained before it can be done with the afocal method, of course not with the original Olympus design used as originally intended.

The 24x36mm film format was sometimes called "miniature"...no really surprising that makers didn't provide photo adaptations for smaller "sensors"
Pau

Charles Krebs
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Post by Charles Krebs »

You have gotten good answers. I'll reiterate some of the key points, and maybe add a few more.

As Pau said 1.25X from the DIC component together with the FK2.5X means to have a magnification into camera of 3.125X. This is quite high for a MFT camera. As you can see, this records a significantly cropped image in comparison to what you see through the viewing eyepieces. (If you are using 10X eyepieces...BTW... what are the markings on your viewing eyepieces?)

It is also not a good idea to use bellows to alter the "designed for" distances of these optics, especially with high NA plan apo objectives.

With the objectives you have (excellent, by the way!) you really must use a corrective eyepiece of some type before the camera. If you want to try to make a change and try to record a better representation (size-wise) of what is seem through the eyepieces setting up an "afocal" arrangement would be your best bet.

You mentioned that you tried this with a 50mm lens but it did not work well. That focal length is too long for a MFT sensor. Ideally you would want to use a 30mm lens, or if that is not possible, a 35mm lens (with a 10X eyepiece). Use a single focal length lens (not a zoom), and try to find a lens that is compact. A "high eyepoint" eyepiece is also very helpful at making this work well.

You don't mention your camera model... which one is it? Some earlier Olympus MFT models had some vibration "issues", while more recent models have addressed this issue.

Pau
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Post by Pau »

NeQo wrote:I really want to stick to the 2.5 photo-eyepiece.
So the only thing...
In that case the only really good option is to go for a FF camera, Canon and some Sony A7 models will work well and will be easy to adapt (but you already know it, I think).
Pau

NicoVB
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Post by NicoVB »

Yes, thank you for your great tips.
From a photographer's pov i'm indeed not happy with the results atm.
I could go with the current setup, but i'll never be pleased with the result.
Raising my bar higher than that.

Because i wanted to stick with the FK 2.5x, i just keep running into more problems and unpleasing results. high CA is a big issue for me, so i need to change directions now.
Indeed buying a FF crossed my mind, but my budget does not allow me to do that (read: my wife says i'm crazy :) )
Ah, you all intended it already to go for afocal setup, but i need to run into a wall for myself before changing tactics.

I own several Olympus camera's, a E500, E3 and my latest model a OM-D E M-1. (not the new mark II)
I like the EM-1 most because it's shutter free, so it has it's anti-vibration advantages in microscopy.
This macro 35mm f3.5 4/3's seems excellent, that is a budget lens and i intended to buy one before, because of it's 1:1 macro features and excellent reviews.
I opted for the Pro 50mm f2 1:2 some time ago and use an EX-25 extension tube to get 1:1 magnifications.
Seemed like the best buy then. And i think it still is, the 50mm is razor sharp.
No need to buy m4/3 lenses yet, they all work perfectly with the MMF3 4/3 to m4/3 adapter, and i can still use them on my older body's off course.

In a fact it's a bit sad that Olympus does not provide an adapter of some kind to use the E-system 4/3 or m4/3 system on scopes to make them backwards compatible.
But on the other hand they made so many different models of scopes and objectives, it would be impossible to make one general adapter with 1.65x magnification.
I would buy it instantly if it existed...

EDIT:
Although there is a reference (Mar 2006) of an official connector with 1.2x magnification on DPreview, the link page does not exist anymore.
From the Olympus website, http://www.olympus.co.uk/medical/31_E-1.htm ,
it seems the E-1 uses an E1-PB/SPT1.2x adapter to connect to a microscope.

The E1-PB [Upper mount : Four Thirds mount, Lower mount : PE mount, Fixed prism (50/50%),
View Finder with reticle FN 18 ( with E1-STP1.2X)} and the
E1-SPT1.2X [Upper mount : PE mount, Lower mount : dovetail, Magnification: 1.2x].

As the first part is a four-thirds mount it should work with ant E series body.
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Charles Krebs
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Post by Charles Krebs »

A few random thoughts...
Because i wanted to stick with the FK 2.5x, i just keep running into more problems and unpleasing results. high CA is a big issue for me,
Does this mean you are experiencing high CA right now, or is it something you want to avoid because you are particularly sensitive to it? I would be a little surprised if you are experiencing "high CA" with Plan Apo objectives and the FK2.5X designed to be used with them. This is as long as the FK2.5X is being used properly at the designed distances. If you deviate from the proper usage all bets are off. This would be especially puzzling since (if used properly) you are "over-magnifying" and thus recording only the central part of the image. Typically CA is very low there.

Another thing that I wonder about... is this your first foray into microscope imaging? If so, it can be initially discouraging to realize how big a "hit" the image quality can take because of diffraction. There are extremely few situations where you can get a microscope image that gives the same impression of "sharpness" or "resolution" that you can get with say, a traditional landscape image. Using too strong an additional magnification into the camera can hugely increase this problem.

Here's an example....
You have a 20/0.65 Plan Apo. If you use the DIC component and also the 2.5X FK you are providing a 3.125X magnification into the camera. The "on sensor" magnification will be 62.5X. If you look at that in "normal photography" terms it means your "effective aperture" would be f48! (relationship is m/2NA). You would also record only a strong central crop of what you see through 10X viewing eyepieces).

If you were set up to provide a 1.2X magnification into the camera, your "on sensor" magnification would be 24X. This would make your "effective aperture" about f18.5. (You would also be recording most of the view seen through 10X eyepieces.

f48 compared to f18.5. Both are far smaller than one would really like, but between the two, f18 will show much better image quality (much less image deterioration from diffraction.)

(The microscope objective forms an image inside the microscope-- the "intermediate image". This contains all the information that it can resolve. The higher the NA the greater the potential resolving capability. When you add viewing eyepieces or photoeyepieces you can alter the size of this image, but there is no additional information that can be produced. If you want additional magnification of a subject it is always advisable to go to a higher power, higher NA objective rather than increasing the secondary magnification... such as going to 15X or 20X eyepieces).

NicoVB
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Post by NicoVB »

I personally don't like CA, because i want to see my images rolling out of my camera as "clean" as possible.
So i want to avoid it, and that means that my current setup does not match my "personal" expectations.

Yups, complete microscopy newbie here :D
I always liked macro, but micro is just a whole new world, great to explore that.

Not discouraging, but very challenging to combine old and new techniques together.
Absolutely love that quest.
Trying out setups in all different kind of possibilities, great great.
But i see my own limitations, because i lack a lot of technical information and/or background.
It will come, step by step.
When you make the most fantastic discovery, a lot of people want a piece of it...

NicoVB
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Post by NicoVB »

The 35 mm macro 4/3 arrived today and there is a significant difference in the Angle of View between the 2 objectives.
35mm: 34°
50mm: 47°
I handheld the camera above the objective, and nearly the whole field of view was visible, so great beginning.

Image
When you make the most fantastic discovery, a lot of people want a piece of it...

Pau
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Post by Pau »

Congrats for your new lens, it will work better for afocal
I handheld the camera above the objective...
I guess you're referring to the eyepiece

Your coverage image seems a bit too optimistic, if you use 10X FN18 or FN20 eyepieces the coverage will be smaller than your green line although much better matched than with the 50mm
35x10/250 = 1.4X, and with the intermediate piece it will be 35x10x1.25/250 =1.75X. Even with 1.2X the image rectangle will not arrive to the round field eyepiece border
Pau

NicoVB
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Post by NicoVB »

yeah, I was a bit too optimistic indeed, but the difference is huge. :smt038

And i'm satisfied with a first result like that:
Image

Next problem:
1. vignetting and brightness burn on the inside of the picture. (Corrected above)
2. When i set my intensity of the light higher, the lens closes it's shutter, although it set all on manual, maybe something to do with metering.
Need some more tests on "ESP", "centered weighted" or "spot mode".
When you make the most fantastic discovery, a lot of people want a piece of it...

Pau
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Post by Pau »

1. vignetting and brightness burn on the inside of the picture. (Corrected above)
Posting samples of uncorrected pictures of some more "normal" subjects could help to understand the issue, but it sounds to illumination not enough even, again Köhler is the way
2. When i set my intensity of the light higher, the lens closes it's shutter, although it set all on manual, maybe something to do with metering.
Darn! those stupid automatisms...I hate the machines designed to be more clever than humans...and the engineers who design them.
Be sure that the ISO setting is manual and low. Also maybe this auto diaphragm function could be deactivated, look at the camera manual
Pau

NicoVB
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Post by NicoVB »

Vignetting was caused due to some light reflecting between the camera and ocular.
An empty toilet roll around as a temporary measure. Fixed! :D
When you make the most fantastic discovery, a lot of people want a piece of it...

NicoVB
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Post by NicoVB »

on point 2.

Sometimes a solution is sooooo easy. Just forget to think about it.
Locking the Auto Exposure (AEL) in my camera did the job.
:oops:
When you make the most fantastic discovery, a lot of people want a piece of it...

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