MicrobeHunter.com Microscopy Forum

I bought a Zeiss Jena 10x .30 phase objective recently and was very disappointed with it's phase performance. I couldn't get it to 'phase' well at all. The objective looks fine, the phase ring, while faint, was there, it just didn't do what I was hoping. I wasn't sure if it was supposed to look that way or not as a 10x. I only have experience with one other phase objective and that looks how I expected.

I bought the 10 ph to replace a 9x .20 lomo. As I now had a 'spare' objective I decided to experiment. I got out my fine Copic marker and clamped the objective in the lathe and drew a ring on the back lens element. Fitted it to my 'scope and made a quick phase ring.. lo and behold... a much better phase objective than the Zeiss Jena. The view went the color I was expecting, the halos were there and I could see immediately it was how a phase objective should look. Obviously my diy phase could do with some work, this was frustration coming out and quick and dirty was all I was in the mood for. Still, not bad I guess.

Very clever, Gary!

Did you match the marker ring size to an existing phase annulus, or make up a phase ring as well?

No, I made the ring to suit the objective. I don't own a phase condenser so I make all my own anyway. I do have a thing I made that I'll be doing a write-up on. It works for phase, COL, oblique, darkfield and brightfield, kind of an all-in-one lighting device I concocted to make life easier.

After the success of the 9x I also modified the 10x and a 20x with even better results. I wish I'd tried this before, but of course, who'd have guessed it would even work with a marker pen

Amazing nice job!
Do you get phase contrast with more transparent objects?
Please show more of your device for the variety of illumination modes.

The phase isn't as pronounced with fully transparent subjects, I think my phase rings are a bit too small and too 'made of ink' to be ideal. It still works better than the Jena objective though. I need to do more experimenting. The lighting contraption I'll be writing about soon. I still need to do some work on it.

Hi Gary,
Did you ever show any more of the " lighting contraption"
I have a similar project sitting in random parts in my head at present.
I'd be interested to see how you put your ideas together.
Cheers

Companies that market more than the standard " phase contrast" system, as an array of different versions of phase; negative, positive, high , medium, low contrast, anoptral, dark, light, B-minus etc., use different densities , location and size of phase rings to attain each particular contrast technique. American Optical got heavily into this in the mid. 40's and by 1948 were marketing 26 different phase objectives in 7 different series. Later they made the Polanret continuously variable phase system, where the size, frequency, and amplitude can be altered to gain an effect.

It seems you have hit on one of these positions. The transparency of your marker ring resembles a little, the bright phase rings of the 50's AO objectives. Those also moved around in the lens pack, with some of the rings deeper towards the front element and some very close to or on the rear element, depending on the described contrast and phase shift.

We get accustomed to seeing phase contrast as having a fixed type of performance, with a specifically grey background and a certain degree of luminosity, halo and contrast when in fact it is a continuum. Systems labelled phase contrast are a still photo taken from what in fact is a moving picture.

And here it is:

https://www.ebay.com/itm/Rare-Complete- ... SwdYlZpEue

Hi folks,
This has become a bit of a thread hijack, but an interesting one.
Up to an hour or so ago I had never heard of the AO Polanret, what an interesting machine.
I've been scratching around the net looking for info on it.
Here are 3 interesting links from a blog by David J Jackson that shed a bit more light on it.
There's quite a lot of other interesting info hidden in the blog well worth a scratch around.
https://bettermicroscopy.blogspot.com/2 ... art-i.html
https://bettermicroscopy.blogspot.com/2 ... inues.html
https://bettermicroscopy.blogspot.com/2 ... ot-ao.html
Thanks apochronaut and wporter for pointing this contraption out, I'd love to have a long play with one.

Awesome work. Hope the write-up come soon. I am very interested in the DIY type stuff.

Hi Gary,
nice work - I'm looking forward to see you contrast system!

PZO and Zeiss Jena also made variable phase contrast systems. I own a PZO scope with it and the phase effect is changed continously by turning a polarizer below the condenser. With the Zeiss Jena pancratic condenser the size of the ring is changed to suit one of two rings in the objective.

I have built a foldable microscope stand and made two phase stops for the old, short Zeiss Jena objectives I use on it. For a first test laser printed phase stops on overhead sheets work well.

Bob