Microcrystalline Wax Techniques?

[Frank Ladner]

Dave: I think your solution for white-balancing would work fine.

As far as the glass used, I did the same thing you are doing. Instead of spending a lot on UV filters, I got cheap ($.50 to $1.00) picture frames and used the glass from them.

Here are some of my old test images and video clips:
http://70.147.193.182/mwtest/
Notice: Video footage is uncompressed, and running on a server with a slow DSL upstream.

I tended to make my wax layers thicker than was probably necessary. This gave maybe a bit too much diffusion/softness, but I didn't really have hotspot problems.

Hope this helps!

[Frank Ladner]

Wanted to update the URL: (On port 81 now, not 80.)

http://70.147.193.182:81/mwtest/

[Tom Hall]

what do you guys use for cleaning up the wax. I had a pretty bad failure and I'd like to clean off the UV filters I used and try again.

is there some way to wash the wax off?

Also, how do I get the wax off once I do get a working GG? I am trying the bathing method in the oven but it completely submerges the two pieces of glass. so I'd like to be able to clean the wax off the outside without getting in between the two filters.

[Rich Hibner]

i use alcohol wipes. They work fine for me. try this method instead.

http://www.jetsetmodels.info/pics/ds_wax_gg.pdf

all the best,
-rh

[Frank Ladner]

I ran hot water over the glass long enough for the wax to become soft, which made it easier to remove.

[John Tracey]

Hey guys. So can anyone tell me why the physical properties of wax diffuses light so well?

In an actual ground glass focusing screen, the diffusion amount depends on the size of the grain: the bigger the grain the more diffusion you get. Well, this is obviously not the case with wax screens since you have a much smaller grain in it, but it has far better diffusion than any ground glass ever could.

Anyone know why?

Thanks!

[Bob Hart]

This is only a wildman's guess and a layman's description. Please do not accept this comment as having any validity.


With a conventional groundglass, the sides of the pits in the groundglass are the diffuser. The size of the pits sets the resolution limit. A five micron grade seems to be about the ideal for home worked groundglasses.

The effective thickness of the diffusion layer of a "ground" glass is going to be in the ballpark of upper (at surface) peaks to depth of deepest pit or scratch in the glass caused by the grinding media.

So for a five micron aluminium oxide slurry, we might assume the layer is up to five microns thick at the deepest points though there will be shallower pits in between.

That's it. The diffusion layer does not get any thicker unless you place two groundglasses face to face.

You can try a finer grade of grind and place two such groundglasses face to face to try to eliminate aerial image passthrough which causes the unwanted "ghosting" artifact.

This does not seem to work all that well as resolution seems to be about that of the coarser grade of finish as a single layer.


With wax, the microcrystals are the diffuser. They set the resolution limit to some degree. Let's speculate that the microcrystals are finer than 5 microns. In theory at least, there should be a superior resolving ability.

In practicality, like the conventional groundglass, the finer the texture, the thinner the layer, more aerial image gets through and causes the unwanted "ghosting" artifact.

However, unlike a conventional groundglass, the thickness of the diffusion layer can be varied. The resolution also does not remain as sharp if the wax layer is thickened as more microcrystals intervene and cause subsequent diffusions as the light passes through the wax layer.

However it seems to perform better than a conventional groundglass and seems to have a cleaner colour rendition and crisper whites than a conventional groundglass which seems to impart a slightly muddy cast to the natural colours.

My theory on that is in the conventional groundglass, that some colour separation and subsequent mixing may be occuring. Each peak between pits may be functioning as a microprism, separating colours into neighbouring areas of the image. There they may bounce off an adjacent pit side to mix with colours from other reflections and become less distinct to camera.

It is also likely that bits of opaque fine debris from the grinding media sit in the bottom of the pits of a conventional groundglass and are impossible to entirely remove and cause a discolouration.

A wax layer and its microcrystals remains pure.

[Oscar Spierenburg]

Bob, my guess would be as wild as yours, but I think you're probably right on most parts.
I don't know if it counts for every wax adapter, but mine has a condenser lens in front and back of the (static) wax glass (idea came from Frank Ladner). The aerial image almost disappears because the condenser 'captures' the image that passes through the wax. I noticed this for the first time (EDIT: because it has a noticeable reflective effect on highlights) in an early clip of the guerilla35, but I can't find it on the web anymore.
I'm planning to make a new adapter. To make it small, I need to find two rectangular condensers (same size as the 35mm image) I took apart two old slr cameras to get the condenser from the viewfinder, but both had the exposure markers on the glass. They are made of plastic, but nonetheless good lenses. Anyone got a better idea?

[Igor Babic]

Condenser from Nikon F gg maybe? This is in every Nikon F gg and can be very easy dismounted from its frame and does not have any markings. Markings are on plastic gg from it.
Condenser lens is multicoated on both sides.