High résolution tests

Jean-marc · Post by **Jean-marc** » Sat Mar 26, 2011 3:10 pm

Hello,

Today was good challenge: solve 3 difficult diatoms in the shortest time.
Somebody will say that it is not an interesting topic, but for testing objective, and your scope, it is essential if you do not have the famous Richardson test slide !
A very good friend of mine spent 2 slides including one of Mr Kemp. This one has 2 tough Frustulia rhomboids and the famous A pellucida. Well, actually I had already succeed on NBS slides ,but I wanted to try again to see if the Mr Kemp slides were as good.
On the other slide, Pinnularia, I think is nobilis.

Shooting:
Lighting 100W
Coolpix 995 installation 1/8e
Condo FN 1.44 under polarized light
PL APO 63,1,4 pH 4 (for the same goals that phase contrast can be used in a light background in HR without loss of detail)
All test resolved within 20 min

Easiest: Frustulia rhomboides dots approximately 0.30 µ

Amphipleura pellucida: dots separated by about 0.2 to .24 microns
less detailed than the NBS slides.

Finally one of the hardest, so called because she asked me fewer problems than A pellucida
Pinnularia nobilis: .17 to .18 microns beads separated (validation SEM)

AP NBS slide that I took a few days ago

A+ for any others tests

JM

Pau · Post by **Pau** » Sat Mar 26, 2011 3:38 pm

Jean Marc, a good classic resolution test.
I'm intrigued about the concentric light rings in both four pictures. I don't think it can me caused by the objective phase ring, perhaps the microscope illuminator or condenser?

Charles Krebs · Post by **Charles Krebs** » Sat Mar 26, 2011 6:12 pm

Jean_marc,
It is always nice to feel that you r equipment is "tuned" properly.

Pau,
The concentric rings are "artifacts" introduced by the lens in the Coolpix.

arturoag75 · Post by **arturoag75** » Mon Mar 28, 2011 2:55 am

Wonderful test Jean Marc,
i'm very intersted in hig resol..
probably if you try whit dark blue light you can get finest structures.
well done
arturo

rjlittlefield · Post by **rjlittlefield** » Mon Mar 28, 2011 7:41 am

Charles Krebs wrote:The concentric rings are "artifacts" introduced by the lens in the Coolpix.

This effect is widely discussed in some communities, such as the Yahoo Microscope group, but I have never seen a convincing technical explanation for it. Has anyone else?

--Rik

Tom Jones · Post by **Tom Jones** » Mon Mar 28, 2011 10:09 am

Several years ago, I bought a Scoptronix MaxView Plus adapter for my Canon G3 to use as my first digital microscope camera. It too showed the concentric rings. I was appalled at the thought that all of my photographs would have that artifact. When I called Scopetronix to complain, they said they had never seen it before and couldn't explain it. They sent me another one that worked correctly. So, maybe only some of the Coolpix adapters have the problem.

Tom

ChrisLilley · Post by **ChrisLilley** » Mon Mar 28, 2011 10:40 am

rjlittlefield wrote:
Charles Krebs wrote:The concentric rings are "artifacts" introduced by the lens in the Coolpix.
This effect is widely discussed in some communities, such as the Yahoo Microscope group, but I have never seen a convincing technical explanation for it. Has anyone else?

--Rik

I have seen similar rings produced by aspheric elements. Mostly though this only shows up as 'onion ring' structure in unfocussed highlights.

Old, ultra-expensive lenses uses aspheric elements that were individually hand ground. Modern, vastly cheaper lenses use simple or composite moulded plastic aspheric elements. The mould is CNC machined and thus has concentric ridges.

Both production methods arise from the fact that automatic polishing in an aspheric surface is, apparently, hard to do.

I don't know if the specific coolpix uses such an aspheric lens element.

SONYNUT · Post by **SONYNUT** » Mon Mar 28, 2011 10:51 am

it must be an older lens. you can count the rings

rjlittlefield · Post by **rjlittlefield** » Mon Mar 28, 2011 11:16 am

ChrisLilley wrote:The mould is CNC machined and thus has concentric ridges.

The key conundrum is this: The camera lens does not produce concentric rings when it's used by itself. If it did, not many cameras would get sold! Neither does the microscope, same reason. The rings only appear when the two are used together.

So the challenge is to explain how it is that the combination makes rings appear.

What exactly is the interaction between the microscope optics and camera optics, that causes rings in the final image?

--Rik

Charles Krebs · Post by **Charles Krebs** » Mon Mar 28, 2011 11:43 am

What exactly is the interaction between the microscope optics and camera optics, that causes rings in the final image?

Might have something to do with the "point light source" characteristics of microscope imaging. For example, extremely tiny dust specks and very slight cleaning streaks (on the filters over the sensor) that are no problem at all in "normal " photography are a real plague with microscope images. And the higher the magnification (and Jean-marc is pushing the limits here) the worse it seems to be!

Jean-marc · Post by **Jean-marc** » Mon Mar 28, 2011 1:46 pm

Hello all,

Thank you Arturo.

I am waiting some UV LED tro try a better resolution. For the moment I used a CB12 filter with the 100W halogen and polarizers.

Charles is right, more you push the magnification more you see the rings. (Sonysut My camera is 5 years old

)
Accordly to many articles, the rings come from the bad grinding of some lenses of the coolpix.
Anyway, the goal was not to make esthetic photos but to push the performance of the scope under theorical résolution.
I would like to try some others camera, perhaps soon ?

A+

JM

peter-h · Post by **peter-h** » Tue Mar 29, 2011 2:37 am

Hello Jean-marc,

you can see, what is possible with a UV-LED from Nichia @ 365nm.
http://www.mikroskopie-ph.de/Amphi-UV-03.jpg

Regards
Peter

Jean-marc · Post by **Jean-marc** » Wed Mar 30, 2011 12:37 am

Hi Peter,

Yes I know very well since a lot this beautiful photo. I will be happy to get full details like you .

Thank you

Regards

JM

Jean-marc · Post by **Jean-marc** » Wed Apr 13, 2011 3:17 pm

Hi,

Just a new try with my new objective, an Olympus Splanapo 100/0,8-1,40
It is a very good objective, perhaps the better 100/1,40 I ever tried.

Lighting 100W
Coolpix 995 1/16e
Dark field 1.44 condenser under polarized light
Magnification x2

A+

JM

René · Post by **René** » Thu Apr 14, 2011 1:30 am

Hi Jean Marc,

How's the view with the Olympus lens coming out without polarised light, compared with that Leitz(?) 63x?? I have less contrast with the Oly Splanapo then with e.g. a zeiss neofluar 100/1.3. I have used it with an Olympus 1.2-1.4 cardioid condenser. Polarised light is only of limited use, check for example the Frustulia with it, that gives very strange images.

Best wishes, Rene