VAC2 - first attempt

[IanW]

These are my first efforts using a homemade VAC2 design. This was a crude effort since my tools and skills are minimal. I only needed the one filter since I am using it with my Zeiss Jena NF equipped with a zoom condenser. The design comes from Arthur Strange and consists of one polarising disc with a full quadrant removed and a smaller full disc pasted on top dead centre at the point of full extinction. Another polariser is inserted beneath.

I can see a little effect but not quite there yet. Photos are crudely shot with my phone X25 and X40.

shot 1 by Fortesmentum, on Flickr

image 3 by Fortesmentum, on Flickr

image 2 by Fortesmentum, on Flickr

[MicroBob]

H i Ian,
nice images! Oblique lighting often gives much contrast but is somewhat unreproducible and also produces artefacts. Your images don't seem to have this problem. So I would say this is not far from what you can get.
The pancratic condenser ist quite special and the stops will have to be cut differently than for a normal condenser for the same effect. The maxium size of the condenser aperture is quite small.

Bob

[IanW]

Hi Bob

thanks - yes I have had considerable difficulty in just cutting the stops alone - and fixing the smaller circle to the larger. Using glue was not a good idea as it caused interference. I think I have much trial and error left to go, and these results are only a start and far from satisfactory.

Any other thoughts and advice are most welcome!

[Hobbyst46]

Any other thoughts and advice are most welcome!

Hi IanW, I do not know whether it is "misery loves company", but I found the Zeiss (West) condenser and filter holder very difficult to utilize for DIY filter stops: DF, Rheinberg... even when I used a circular punch to cut color plastic circles, and tried to center them as best as I could, I would not even come close to the expected effect.
Since my phase contrast condenser is the turret type, with 2 or 3 empty ports (the others are BF, DF, Ph2, Ph3), I managed to place a DF filter stop in an empty port. The idea is that this is the same height along the optical path as the condenser iris aperture itself. The result is not great, though, probably it was not the exact size and not centered, in spite of my efforts. Combine that with the inconvenience of dismantling and taking apart the condenser just for this mission, and I abandoned the attempts.
So I wish you luck, your success will motivate me to retry!

[IanW]

Thanks Hobbyst46 -

It certainly is frustrating trying to figure out the best options and then make it work. Using a hole punch was my next step:-) but as you say, tying to make it dead central is yet another hurdle. I will keep at it for as long as my sanity allows and update here with some better quality camera photos.

Thanks again.

[75RR]

May I suggest using a compass cutter. Not only will it cut perfect circles but the pin hole will allow you to center everything with precision.

https://www.amazon.co.uk/Olfa-Compass-C ... ass+cutter

I think the first image turned out very well!

[IanW]

Thanks very much 75RR - just what I need.