Diatom Slide

[75RR]

Thinking of purchasing a Diatom Slide at some point.
Apart from their intrinsic beauty, I thought it would be useful in focus and illumination fine-tuning and therefore as a photographic model and a lens comparison tool.
Any tips in terms of new or old slides, arrangement, source, type of Diatoms or mounting medium preferences?

[75RR]

Came across this site in my internet searches: http://www.diatoms.co.uk/
Was recommended in an old thread in photomacrography.
http://www.photomacrography.net/forum/v ... aef66bc473

Would still like some feedback on this if anyone has some personal experience. Thanks

[microgreen]

Hello 75RR

The mounter is Klaus Kemp,a very well established master of the art(and skill) of mounting diatoms.
I have one of his 8 form test mounts and I am very well pleased with it.
The slide was very clean( no air bubbles)
The slide was well packaged in a plastic slide mailer for posting.

Unless you are in the position of being able to see an old diatom slide for sale I would steer clear of it.
Good luck

Have a Happy New Year
Tony
East Riding of Yorkshire(UK)

[75RR]

Thanks Tony
and a Happy New Year to you

[gekko]

I have the 8-form diatom slide from Klaus Kemp. I agree that his work is excellent, and also he is very nice to deal with. If you wish, I can easily take a picture of the one I have and post it here if you wish me to, although he has a picture of the slide (as well as other arrangements) on his website. I guess this would be the one for comparing or testing objectives, as the diatoms are carefully placed right under the cover glass. I have a couple of other slides of "strewn" diatoms, where the diatoms lie at different random depths and orientations and are not suitable for what you want them for.

[75RR]

... I can easily take a picture of the one I have and post it here if you wish me to ...

That would be nice if it is not too much trouble. Did not see an image of the 8 Form Test Plate on the site.
Will be contacting Klaus Kemp in the New Year (January) to order one. Just have to decide where to ask him to post it.

[gekko]

... I can easily take a picture of the one I have and post it here if you wish me to ...

That would be nice if it is not too much trouble. Did not see an image of the 8 Form Test Plate on the site.
Will be contacting Klaus Kemp in the New Year (January) to order one. Just have to decide where to ask him to post it.

Below is a link to the images I took of the slide. Both are from the same photo but downsized by different amounts (the first that shows the whole slide lost too much resolution when reduced to 900 pixels, so I cut up the original size in two and combined them and then downsized to a width of 900 pixels). In either case, the photos do not do justice to what I saw through the microscope, but I thought would give you an idea. Please let me know if you like me to take higher resolution images of each diatom separately using higher power. Those were taken with the 10x objective and I used a green filter to avoid chromatic aberration.

[75RR]

Thanks gekko.
Great to see what the "8" look like.
Useful selection. I can see why they were chosen.
No need for more resolution, will be looking at my own soon. :)

[75RR]

Update:
My 8 Form Test Plate from Klaus Kemp has arrived!

Among my first tests I want to make a comparison between the Optovar magnifications: 1x - 1.25x - 1.6x - 2x and also see how they compare with the actual objective they are potentially replacing.
e.g. I have two 25x objectives: a Pol Neofluar 25/0.60 and a PH2 Neofluar 25/0.60 which multiplied by 1.6x = 40x
I have three 40x objectives: a F 40/0.65 a PH2 40/0.65 and a Plan 40/0.65

Not a true test as all things are not equal, but it should be interesting none the less.


This might take a little time as I am still fine tuning both the Zeiss RA and the illumination system.

[gekko]

Great! About the Optovar, I think it is equivalent to having eyepieces of different power, but much more convenient. It should not affect the resolution, since, as you well know, that is determined by the microsope's "working" NA (as a rough rule of thumb, the average of the objective's NA and the NA to which the condenser aperture is set). But it certainly would be an interesting comparison-- I hope you will post the results.

[75RR]

I think it is equivalent to having eyepieces of different power...

I agree; it is not a substitute for quality objectives, if one has them!
If however, one does not have them, it does provide a useful and practical substitute.
e.g.
40 x 1.25 = 50
40 x 1.6 = 64
One could, I suppose, argue that cameras with zoom functions and those with higher resolution have made the Optovar redundant.
I think this would only be true of cameras with quality optics and only if viewing and photographing the subject through a monitor.