How to make Gradient Universal Filter

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I saw Gradient Universal Filter (GUF) from Litonotus post on Photomacrography.net

http://www.photomacrography.net/forum/v ... b426498fd6

and post from 77RR on Microbehunter.com

viewtopic.php?t=2480


But there is no details information about size of filter and gradient area in the discussion, so I would like to share “How I make GUF filter” to someone who want to tries this.

1. Draw a rectangle using Microsoft PowerPoint, Size 3.4 cm by 6.4 cm select No fill in the rectangle.

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2. Select Format Shape, then select Gradient fill, In the Gradient Stops, use 1 Stop at 40% and 2 Stop ant 80%

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3. Copy the Gradient Fill to full page for print out.

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4. Print this Gradient pattern to your printer, if your printer can print on Transparency you may try it. But my laser printer did not print Gradient pattern on transparency very well. So I print it on normal paper and Photo copy it on Transparency using photocopy machine.
Note! You have to use transparency that matched to your printer type. For example Transparency that specific to use with Ink jet printer, and Transparency that specific to use with Laser Printer and photocopy machine. Use unmatched type of Transparency to print, it will malfunction your printer!

5. Cut out Gradient filter from your Transparency one by one to stack it together, because one layer of transparency printout is not opaque enough to block light from microscope condenser.
I stacked 4 layer of transparency together with clear scotch tape to make it opaque enough, then I use PVC Electrical insulation tape stick on the left hand side of the filter. The final filter look like this.

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6. You may try to increase or decrease “Gradient Stop” Stop 1 and Stop 2 in PowerPoint to increase or decrease Gradient area, but I am OK for the 40% and 80% that I have used.

Using UGF Filter is a trial and error approach, first step you have to fully open the condenser diaphragm and slide UGF filter in the condenser filter tray. Then slide back and forth, Left and Right until you get the optimum result. When you change microscope Objective lens, you have to adjust the position of UGF Filter again, little by little.

Sometime you may try to close microscope condenser diaphragm half way down to reduce glare, but sometime you have to let it fully open. When optimum result is show at the eyepieces, it looked like 3 dimensions image, show details of depth. It is very interesting filter to try.


This example of the same wet mount specimen, you can see that UGF filter on left hand photo show almost 3D compare to normal bright field photo on the right hand side.

[JimT]

Very informative and good illustration of the effect in the last image.

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Thank you very much for your comment JimT.

This filter work well for me with wet mount and permanent slides.

[richbart]

Can you photocopy to acetate.

[zzffnn]

Can you photocopy to acetate.

Rich, I am happy to mail you my prints, if you can wait for a week or so. Please message me.

I no longer use GUF, as I now prefer well implemented COL for NA at or above 0.65 (for low NA, the same COL mask can produce darkfield). It is just that my preference has changed; I now prefer more contrast / 3D relief enhancement (with harder dark/light division line on mask), rather than a smoother gradient.