Out of curiousity, if you were to use Loctite 358 UV curing clear adhesive to fasten the pclx lens onto the clear side of the groundglass and face the rough side of the gg towards the objective lens, would this partially solve your dust problem.

You could test by assembling the pclx hard against the gg smooth side then dabbing a dot of water onto the junction. - Just a thought.

parts list
 

It would be nice if we could buy iit as one piece,like a achromatic doublet.

big big news
 

hey everyone this could be big big news. there is a thread
'ground glass grain' chris rubin has a workflow in afteraffects to remove the grain from a static adapter .

Someone a while back also demonstrated a method of using after-effects the eliminate the hotspot with some sort of mask. That process plus the grain eliminator would be a good combination if it could be integrated into one plug-in.

Bob,

you do not need to integrate anything, because that same gg noise mask removes the hotspot at the same time it removes the grain. Remember - your gg test pattern also has a hotspot (if you're shooting it with your lens on). So the inverse of that mask acts as both grain remover and the hotspot remover.

cheers,
Chris

Chris-
I understand what your saying about the hotspot but now we are dealing with part of the image that is under exposed...Yes you will be able to make it appear "brighter" but nothing beats the quality of well exposed footage in the first place. If the hotspot is particular dark near the edges no amount of software can enhance detail that was never captured in the first place. So it sounds like when it comes to a hot spot it can help out only minor problems. Anything more and your trading in image quality for convenience. Chris test my theory out. Give it something really dark v.s. something thats properly exposed. I would be interested in seeing what happens in a real life test.

Re: parts list
 

<<<-- Originally posted by Richard Mellor : http://www.thorlabs.com/ProductDetai...roduct_ID=1481

two of thesehttp://www.thorlabs.com/ProductDetai...roduct_ID=1483

http://www.optosigma.com/miva/mercha...+%26+Apertures
you want the 50mm with 70 fl and the 50mm groundglass with 1500 grit
http://www.optosigma.com/miva/mercha...herical+Lenses
you will be able to mount the plcx directly on the ground glass
the threaded retaining rings will allow perfect focal length from the slr lens to the groundglass. -->>>

How does one go about purchasing from this company? I sent their sales associate an e-mail, but that's the only way i saw.

*edit- NM i had to use that antique thing, i think it's a telephone...

Brett,

you're right - if the light falloff at the edges of the frame is severe, then the hotspot cannot be eliminated without introducing compression artifacts and noise.

Ideally, hotspot should be removed / reduced by reducing brightness in the centre of the image and increasing it at the edges.

This would make the gg noise/hotspot mask look something like this (minus the ring and the text):

http://www.liisikoikson.com/ftp/gg_pattern.jpg

this has not been inverted yet.

Chris

I think we agree here. The hot spot in that example is so minor that I think your system would work great. I'm very impressed with your work and attention to detail. Thanks for all the extra effort and examples. You know this system can even be used for thoughs of us using moving GG because once in a while you might forget to turn on the motor and later on in post you can save the shot. Good stuff.

Does anyone know what the back focal length of 645 medium format lenses is? I need to know so I can place my diffuser in the correct place.

Just wanted to mention to you guys that are using the grain removal technique: DISABLE IMAGE STABILIZATION (Optical and Digital)

I haven't been here for a long time but I thought I would drop in with this screen technology I was going to post about some time ago, it was one of he technogies I was considering. They are called Fiber Optic Face Plates, and Fiber Optic Tapers. Plates are a cut sheet off of a bunch of carefully stacked, modeled and bonded bunch of fiber optic fibres. I think I have found the industries best with around 95% transmission rates, and upto 40 million fibrers, which should deal with any fibre problems. Alltogether probably the best available next to ones that restrict the angle of view down.

http://www.princetoninstruments.com/...beroptic.shtml
http://www.vinci.it/Fibre%20ottiche%20tutorial.htm
http://www.spie.org/app/Publications.../research.html
http://www.photomet.com/library_enc_fiberoptic.shtml
http://www.incomusa.com/products.html
http://www.incomusa.com/technology.html
http://www.incomusa.com/materials.html
http://www.incomusa.com/Faceplates.htm
http://www.incomusa.com/Tapers.htm
http://www.incomusa.com/manprocess.html

http://www.photonicsonline.com/Buyer...&VNETCOOKIE=NO
http://www.photonics.com/directory/b...categories.htm

For those with lenseless cameras (XL1 & cinema camera projects) tapers can be used to reduce a image from 35mm to whatever. Tapers are buindles bigger at one end and more squashed at the other, also a very good way to do 16:9 to 4:3 conversion. I think tapers loss a bit more light than plates dues to here design, but that may not have to be the case. They have to be bonded directly to the CCD, but if your luck your ccd allready has a a face plate on it to protec it and transfer images, so it might be possible to somehow bond it. If your sensor has some non flat version of a face plate on it, then that might cause trouble. All together a expert installation.

Capillary face plates use hollow fibres instead to increase transmsion, but I imagine hollow fibers have downsides for our purposes. While I have seen very poor looking faceplates at Surplus Shed going really cheap, places like Edmunds seem a bit expensive, and I think some of the ones listed above are significantly better.

http://www.collimatedholes.com/examples.html
http://www.collimatedholes.com/capillary_diam.html
http://www.collimatedholes.com/ltd_ratio.html
http://www.collimatedholes.com/interior_sur.html
http://www.collimatedholes.com/products.html


By the way, a note on some of these technologies, like holographic diffusers, I think you still need to use a condensor and to keep your camera's iris on manual, wide open to aviode problems. Whoever tried it before give it a go.

Very interesting idea. I also noted they have inverters for rotating an image 180 degrees...this could be quite useful.

One thing to note though is the transimission spectra...you will drop almost all of your infrareds (probably a good thing except for night vision)...and your reds will be slightly less transmitted than your blues and violets...but I imagine that's not a big deal

one thing i know about fiber optics are they are expensive..wonder how much it would cost?

well if this edmund optics place is any indicator:

http://www.edmundoptics.com/onlineca...productid=1599

assuming we can find the specs we need...which i would assume are 35mm to 1/3" or 1/3.4" ccd size with 4:1 magnification...then probably just under $1000...maybe more if a faceplace for inversion is included.

But the theoretical benefits are quite nice...no grain, higher light transmittance, non-inverted image...possible 4:3 to 16:9 conversion built in for cameras that can't do this already...as well as there is always the interesting fact that you could use those light conduits to build set-ups for some really unique shots.

Wayne: One question though...why do you think a condensor is still necessary? Isn't the device taking the exact light and placing it on the ccd...as the thing says its a "zero depth window"...to me it seems the fused ccd/taper should act almost exactly like a 35mm film plane in terms of light collection...but i'm obviously not an expert to say the least.