Diatom photo test (was: Finally my old_new Olympus BH2 is refurbished)

[deBult]

Ha Anne,

This info helps: So I may have the flat side downwards ....

As I'm new to this Diatom world: I'm under the impression Rolf and myself are pucturng SIMILAR but not the same Diatom species?

My slide says the Origin is Russia (not Japan).

Maarten

[deBult]

Rolf,

To really compare, we should have exactly the same specimen. I can sent you the slide, but don't break it If you agree, sent me your adress via personal message.

I'll take you up on your offer: much obliged. You have PM.
Shall I send you my slide in return to picture on the Leitz?

I can reduce the differences in setup as I also have the Original Olympus e-pl camera and a NFK 5*

Best Maarten

[rhamvossen]

Hallo Maarten,

I can reduce the differences in setup as I also have the Original Olympus e-pl camera and a NFK 5*

I don't think that's a good idea, as far as the projective is concerned. You have a better setup with the NFK2.5x and the OM photo-adapter and you want to have the best results from that. Mine was just a sub-optimal improvised and loose camera adaptation because of the too big enlargement of the NFK5x. Best,

Rolf

[anne]

Ja Maarten,
Du hast recht, die Species von Rolf ist vermutlich A. ornatus aus Japan.
Deine Species könnte A. ehrenbergii sein.
Hier von Anatoly fotografiert:
https://www.mikroskopie-forum.de/index.php?topic=23160.0
lg
anne

[deBult]

A. ornatus (Rolf send me his slide)

* Olympus BH2-BHT stand, NFK 2.5 projective, Adapter L, Aplanatic condenser
* Olympus PL6 M4/3 camera, JPEG all auto settings, approx. 1/400 second
* White balance, Light sharpen & vibrance, exposure correction +1 stop, converted to BW (All in Adobe Lightroom 6)

* SPlan Apo 20* na 0.70
* Splan       20* na 0.46

[deBult]

A. ornatus again this time in phase contracts (Rolf send me his slide)

* Olympus BH2-BHT stand, NFK 2.5 projective, Adapter L, Abbe type phase condenser
* Olympus PL6 M4/3 camera, JPEG all auto settings, approx. 1/4 second
* White balance, Light sharpen & vibrance, exposure correction +1 stop, (All in Adobe Lightroom 6)

* Positive Low Low phase DAchromat PLL 20 na 0,40
* Negative High phase DAchromat NH 20 na 0,40

[rhamvossen]

Hallo Maarten,

Thanks for the images. How do the brightfield images look before the black&white conversion? The depht of field looks OK, especially with the Splan20. Could you also try a long exposure time, like 2 seconds, to rule out any unsharpness due to vibrations? Best,

Rolf

[Peter Reil]

Hallo Maarten,

die Hellfeldbilder sind super!

Freundliche Grüße
Peter

[deBult]

Thank you Peter R.

After I completed the refurbishment of the BH2_BTU scope I'm now testing it and work on improving my photo skills.
With the scope there came a series of objectives and not all of them are in 100 % good shape. In particular the SPlan Apo 20* shows a minor "chip" in the corner of the front lens impacting  -amongst others - contrast,
The SPlan Apo 40 has a minor scratch (subject for next tests).

I'm currently working on 2 diatom slides mounted by Anne G. A. ornatus Ehrenberg from Japan and and A ehrenbergi from Russia
Rolf Hamvossen is guiding me on depth of field and sharpness. We both are exchanging the same slide via the postal service and comparing our results.

Next 2 pictures with The SPlan Apo 20* na 0.70: the first one is with a shutter speed of 1/60the of a second the second one 2 seconds: aim is to check the impact of vibration.
I'm using a CH2 trino: this allows me to disconnect the camera from the scope (My Olympus E-PL6 camera is known for shutter vibrations).

As I do not have a ND neutral density filter I used a POL filter plus set the voltage for the bulb to the lowest setting to achieve the 2 second exposure as recommended by Rolf.
Al post processing settings are identical except for the white balance this was set per picture as the 2 second versions were orange/yellow before WB correction.
No conversion to BW this time: so colour fringes caused by lens faults should be visible this time.

Observations:
* The Plan Apo has slightly reduced contrast compared to the SPlan
* the 2 second shutter speed does not improve the sharpness impression much compared to 1/60 (or 1/400): so the mounting of the camera is OK now.
* parfocality between the viewing and photo eyepiece-projection on the sensor is an issue: I have to do minor corrections: the E-PL6  camera display is way to small to do this properly
* The A. ornatus diatom has  less depth/height compared to the A ehrenbergi: so no stacking required. (Stacking may help an additional bit with the outer ring of the diatom: no stacking used this time)

[deBult]

The Normal SPlan 20* na 0.46

[deBult]

The DPlan 20* na 0.40

[rhamvossen]

Hallo Maarten,

The first image with the Splan 20/0.46 is excellent, you are good to go . Indeed, no stacking is needed with this diatom. The image has also minimal chromatic aberrations, so no need to convert to black&white, which in my opinion makes an image a little 'lifeless'. So, your setup is OK and the vibrations due to short exposure times are minimal. Next week I will try to make some pictures with your slide. Best,

Rolf

[rhamvossen]

Hallo Maarten,

I took some pictures of the Arachnoidiscus ehrenbergi from your slide. I used the Splan20 in normal brightfield and I focused more towards the edge in stead of the center, which you can clearly see, the center is a bit blurry. Results are comparable to your images. Only white balance correction and some contrast enhancement, no sharpening.

Left: NFK5x-L.
Right: a WHK10x eyepiece in the phototube and a Sigma 30 mm camera objective as relais optics.

I find the picture were I used the Sigma 30 mm objective a little bit better, like I have seen also in the previous test. Maybe it's because the projective is not at a optimal distance from the sensor.

Best,

Rolf

[rhamvossen]

And 2 pictures with oblique illumination, single images.

Left: Splan20, oblique illumination by decentering brightfield position of phase contrast condenser on BH2
Right: Zeiss-Winkel 25/0.45, oblique illumination by decentering auxiliary lens on Zeiss-Winkel Standard GF

I have put the BH2 back in the closet, and my trusty Zeiss-Winkel GF took it's place again. I prefer the oblique illumination from the much older Zeiss-Winkel objective.

I will return the slide to you.

[Bob]

Hi Rolf,
I think you have decentered your illumination in different directions for these two images, giving a different relief impression. Here I turned your image 180° and to my eyes the relief effect is reversed. The Zeiss image is on the left now after turning it around. It shows a lot less chromatic error, clearly nicer than the Olympus image. Which eyepiece or projective did you use? AFAIK Zeiss and Olympus used different chromatic corrections, so this might explain the colour fringes in the Olaypus image it you had used a Zeiss eyepiece.

Bob