Dennis,
I watched the footage, VERY SHARP,

However, im still not happy with the level of diffussion your GG is giving. On the pull focus from the mans face to the trees, the trees should be far more blurred then that.

But with everything there is a compromise. Your footage is very sharp, but if it was diffused more to give shallower DOF, then it may not be as sharp. But, then again, since the whole purpose the the adapter is to give shallow DOF, which property should be compromised?

I'm pretty happy with that look Wayne...but I'm also the guy that turns up the treble, cranks contrast, and likes the sharp look.

I think the answer is a few GGs for different situations. I'm beginning (slowly) to realize there's no free lunch on the GG side. Vibrate a Beattie, there's a little chromatic aberation..but it's bright. Controlling the orbits to .2-.5 mm is beyond most DIYers. Put in a POC and you have awesome diffusion but 4 f/stops light loss.

My next test will be to try a GG with a much coarser finish to compare sharpness as it relates to light loss and I'll post those up. If I can go coarser, and still limit light loss to 1.6 f/stops, then I'm in like Flynn. Thanks for your ongoing feedback Wayne. Knowing how much work that you've done yourself on these things, your opinion has extra weight in my books.

Thanks Dennis,
I think you have made amazing progress. Your footage is very clean indeed. Only step now is to experiement with different types of GG to see what you come up with. keep at it!!!

Ok, here is an EIA1956 and frame grab with a new coarse GG. Amazingly, the GS400 (no adapter) reference chart looks almost exactly the same. So I'm getting better resolution, and still 1.6 stops light loss with the 50mm f/1.4. Of course, Wayne, you knew this all along..ha!

I'll have to do another outside shot to compare.

No adapter GS400 EIA1956 (http://www.fortvir.net/gallery/album05/GS400?full=1)
Coarse GG EIA1956 (http://www.fortvir.net/gallery/album05/coarse?full=1)
DOF screen grab (http://www.fortvir.net/gallery/album05/coarsepl?full=1)

Ok, here is an EIA1956 and frame grab with a new coarse GG. Amazingly, the GS400 (no adapter) reference chart looks almost exactly the same. So I'm getting better resolution, and still 1.6 stops light loss with the 50mm f/1.4. Of course, Wayne, you knew this all along..ha!

I'll have to do another outside shot to compare.

No adapter GS400 EIA1956 (http://www.fortvir.net/gallery/album05/GS400?full=1)
Coarse GG EIA1956 (http://www.fortvir.net/gallery/album05/coarse?full=1)
DOF screen grab (http://www.fortvir.net/gallery/album05/coarsepl?full=1)

Hmmm with all due respect, but I think this is a hoax. :)

Dennis,
Are you sure the res charts are not just the same image here? Flicking from 1 to the other thay are EXACTLY the same.

The third image proves enough for me though, the adapter is certainly there!

Alain, I'm not sure "due respect" and "hoax" should be used in the same sentence :-) Hoax suggests an attempt to deliberately deceive...and that's certainly not the case here.

Having said that, it is possible that I mistakenly uploaded the same chart twice, and I'll confirm this tonight by doing another screen grab from the footage. I'm thinking it's unlikely though as one had text overlay, and the new one didn't. I did see slight softening in the adapter chart...but only when zooming the jpegs to 150%. I also kept voice audio with the footage so I could keep track of the clips.

For my own reference (as few seem to be posting these charts), what would be a typical, if any, resolution loss with a spinning GG? Intuitively I would think that there sould be significant loss, but even with the less diffused disc, there's not much.

Alain, I'm not sure "due respect" and "hoax" should be used in the same sentence :-) Hoax suggests an attempt to deliberately deceive...and that's certainly not the case here.

Having said that, it is possible that I mistakenly uploaded the same chart twice, and I'll confirm this tonight by doing another screen grab from the footage. I'm thinking it's unlikely though as one had text overlay, and the new one didn't. I did see slight softening in the adapter chart...but only when zooming the jpegs to 150%. I also kept voice audio with the footage so I could keep track of the clips.

For my own reference (as few seem to be posting these charts), what would be a typical, if any, resolution loss with a spinning GG? Intuitively I would think that there sould be significant loss, but even with the less diffused disc, there's not much.


Dennis,

I apologize for my suggestion, it was probably too strong to say, even with the smiley attached at the end.

Now, let me explain my, perhaps out of place, suspicion. The charts uploaded have a text overlay which indicates that the possible error is not in the upload, but only possible at the editing phase.

If you download the chart images and overlay them in an image application using the "difference" overlay mode you will see that the image is the same. Not just similar, but the same image with different text. There is no softening or anything, it is just the same image. So maybe you confused which was which. Also, I thought the chart was just too perfectly framed, but that is not an impossibility, just unusual.

Then the charts have a 720x480 resolution while the rest of the imagery is at 853x480 (if I remember correctly). So I thought there was something "odd" going on with the resolution. Of course this doesn't mean anything but was an added oddity to the already strangeness of the same image chart issue.

So this is why I was suspicious of it.

It is probably a mistake and I will stand corrected.

Again, I apologize for my comment, but it was meant to be taken lightly. :)

No offense taken at all Alain, no worries. Actually I'm grateful you picked this up...I am after all looking for critiques, and the online communities certainly keep us all honest. We all can appreciate how written text denies us all the subtleties of verbal communication.

You're likely right and I confused the images in my capture folder. I use VLC (for quick grabs) which captures with some pretty obscure names. I'll confirm this tonight. GS400 output is not detected properly by VLC, hence the 720 vs 853. All of the res charts should be at 4:3 (720x480).

I know, smileys don't quite do it. We need embedded jpegs of our own facial expressions :-)

I know, smileys don't quite do it. We need embedded jpegs of our own facial expressions :-)

That just made me smile!!!! Can just imagine it!!!

I wonder if there would be any consequences in using the camera upside down like that. Maybe tape mechanism misalignment or other problems?

Michael, I doubt it. The tape alignment mechanism has to be far more precise than to allow gravity to be an issue. I could use the cam upright on those rails by lowering the plate, but I find it much more convenient in post to just capture and go. I don't like the idea of messing with footage before I even start editing it to rotate and flip.

I reposted the EIA1956 frame grab from the original footage and I'll agree it sure looks like the GS400. I did confirm from the audio recorded during the test that the coarseGG footage is indeed the correct footage, as is the grab I just redid. I'm going to redo this test altogether as I'm thinking the GS400 bare grab is incorrect.

No adapter GS400 EIA1956 (http://www.fortvir.net/gallery/album05/gs400?full=1)
Coarse GG EIA1956 (http://www.fortvir.net/gallery/album05/coarse?full=1)
Fine GG EIA1956 (http://www.fortvir.net/gallery/album05/guskers35?full=1)

Here are grabs from the second test. Alain was right, I goofed and posted two grabs from my coarse GG footage. There is some softening with the coarse and fine GGs...but not much in the way of resolution loss. I'd say it's a wash between the two surface treatments.

So I guess the question is this: Is the difference simply the look that we are trying to emulate? Both coarse and fine GG's offer what seems to be adequate resolution, and seemingly identical resolution. The only difference potentially is how out of focus areas look, right? If this is the case, then the finish on the GG could be simply another tool for a stylistic image type. To be honest, I like the look of the finer diffusion GG footage better....although I realize the coarser GG looks more like film.

Now here's a test shot with the coarse GG. The sun wasn't co-operating, but I think the change in look is evident.

Coarse GG test shot (http://www.filefactory.com/get/f.php?f=0818ab7d3a6fb618fc3ccfea)

Beautiful!!! I think this glass has much better diffusion, them trees go more out of focus then your previous footage. Footage is sharp! Well done Dennis. Question, what camcorder was it again?

Thanks Wayne. The cam is a GS400 in pro-cinema (30F) mode. The sun came out, and after a bunch more footage, I realize the GG is too coarse. Fortunately I order a full range of media grit sizes so I'm back to a bit more testing. This GG was done with very coarse media (like 20-40)

What made you decide the GG was too coarse?

The sun came out and I took a bunch of footage. You could see the spinning grain in the DV file :-( The answer lies betwixt the two.

Edit: - the grain showed at 1/250s shutter...perhaps this is OK? I don't have a 50-72 step up ring to use my 72mm filters on the 50mm lens....so I upped the shutter speed. The first test clip (http://www.filefactory.com/get/v3/f2.php?f=2597ae8b86ca0c402ebdb8f3) was partially shot at 1/250s and showed no rotating grain.

Here's what I believe to be the final GG. What do the critics think? I need to do some outside shots, with higher shutter speed. What shutter speed do most of these things start getting ugly at?

http://www.filefactory.com/get/f.php?f=4933017b44cd61e9299bcbce

Here's what I believe to be the final GG. What do the critics think? I need to do some outside shots, with higher shutter speed. What shutter speed do most of these things start getting ugly at?

http://www.filefactory.com/get/f.php?f=4933017b44cd61e9299bcbce

There is some odd halo effect going on. I like it actually, but may not be suitable for all purposes. I think it may be ghosting from the source image getting past the GG. Do a test, hold the GG without the SLR lens and check that when you look at it you cannot see anything though it. Try something with contrast like a printed page or a lightbulb or something like that. If you can see a defined shape through the GG, you are getting ghosting.

Ideas anyone?

No idea, but the light source was 1000 watts, and not diffused....so the figure and glass are reflecting pretty strongly. This GG is very diffuse...a 100 watt light bulb at about 6 feet is not visible at all. There is likely a very small wobble in the GG (like .2 mm) from a collet mount that is not completely true. I'm not sure this is the culprit.

This is a pretty tough test...but that's what I was looking for.


This from Dan's MPIC (and a much better cam too) http://dandiaconu.com/gallery/album16/candelabre2 showing a similar effect.