thanks jonathan, i'll start posting up some samples as soon as i get a second of breathing space from work-jeez, these 70 hour work weeks are starting to get to me...
-d

geaux Dino, good news for you is also good news for the rest of us. keep up the good work.

I have uploaded 9 test frames. They can be found here:

http://www.frankladner.com/testpics.htm

Thanks!

Frank, I bet if you got a Condensor AND Macro it would help out the vignette and how close you can get to the gg with your camera.

for a bit of theory see

http://www.cartage.org.lb/en/themes/Sciences/Physics/Optics/Optical/Lens/Lens.htm

and

http://homepage2.nifty.com/optas/lore-e.htm

look like we can have the condenser lens act as the gg because the way you mount the flat side has no effect on the picture.
a positive meniscus would be even better according the text, as projection of the picture on a curved plan would increase quality versus flat plane. problem is then to gg a concave surface :-)

Thanks for the links Giroud! Very informative.

Another problem I see with using a concave surface would be getting a clear focus from your camcorder. At the close distances we are dealing with, I believe you couldn't get an exact focus on the entire concave surface. (different focus planes) If I'm wrong and focusing isn't an issue, then the ground glass could be made comercially using the laser etching Canon is using for their GG mentioned earlier in this thread. I know most of us don't do laser etching in our basements but if we are all still talking about putting together a standard/manufactured version, then it might be feasible to contract a company to do it for a limited run. What would be ideal at this moment would be to have a supply of laser etched GG/condenser elements (50MM dia.) That sure beats grinding our own. Does anyone know who is doing Canon's laser etching?

Frank,
Nice images but I did notice a good bit of grain, dust and the scratch in the top right corner(or was it a hair?) Did you shoot that in the evening, in low light? I think you've proven that we need to do some finer grinding to reduce the grain. I believe a brighter image would help too. What was your video camera's iris setting? Did you try slightly over exposing the GG image to "burn out" a little of the grain. I'd be interested in your results with a bright scene. I also noticed during my own tests that opening my camera's (PD100A) iris really made the hotspot stand out but the image overall was more acceptable (sharper focus, less grain). I too am waiting for a set of condenser lenses to begin experimenting. I look forward to seeing your next set of images. Joe

Joe: That was shot in the evening. I turned my shutter speed up to around 100 and had the iris about half open. You're right about the hotspot. I tried to keep the center from being blown out, so that way, I'd have some detail throughout the frame. One trick I have done (not with these images) was to create a 720x480 black and white radial gradient in photoshop, which I would import over the footage in After Effects, setting the mode to Overlay. This would balance out the image some. I do believe, though, that if the hotspot problem gets fixed with the condenser (or some other solution), then recording a brighter image would help the grain situation.

Yeah, there are a few nice little scratches I managed to put on the ground glass. I had absolutely no problems with the 600 grit, but the 1000 seems to clump together, requiring lots of water, as you mentioned before.

Joe, where did you order your condensers from? I have not been able to find an old SLR body to get one from.

Thanks!

Frank,
I ordered the below products from Surplus Shed. Here is the link.
http://www.surplusshed.com/pages/category/educationaloptics_1.html

They have a large selection of optics at greatly reduced prices. I called on the status of my order today and the guy said that my stuff shipped on Friday (1 week after I placed my order online GRRRRRR!) I should get my lenses today or tomorrow. I'll let you know how they are as soon as I can get my eager paws on them. I ordered these initially to have a broad range of types for testing.
SKU: L1875D
EDUCATIONAL SET OF 50MM LENSES 1 12.00 12.00
SKU: L1961D
EDUCATIONAL DCV 50MM X -50MM 1 2.00 2.00
SKU: L1951D
EDUCATIONAL DCV 38MM X -50MM 1 1.50 1.50
SKU: L1574
RECTANGULAR PLANO CONVEX LENS 1 0.50 0.50

These are educational quality lenses. That means they are not of consistant enough quality for manufacturing purposes. (focal lengths vary slightly from lens to lens) But for our single unit applications, I believe they'll be perfect for testing.

Great Idea about the overlay in AE. I'm going to give it a try.

BTW, Has anyone made any progress on correcting the image orientation? I shoot a lot of sports footage and following action and focus with an inverted image would be impossible. How about a rectifying lens like in a spotting scope? I was considering a large pentaprism and mirror set up(like SLR system for a medium format camera) I personally would be willing to loose an F stop or two to gain a correctly oriented image. Anyone know where I can find an old medium format pentaprism viewfinder? (35mm is too small) Edmond Optic sells large enough pentaprisms but they're outrageously expensive. I'm willing to spend $20-$50 to experiment but not $500.
Joe

Forget prism and mirror
i did whit upside down 5"6 monitor
(119 $ )
is working perfect even on a steady-cam

Joe: Thanks a lot! I'm headed over to their website to look around.

I was just thinking, and - don't scream at me if this sounds ignorant :-) - can't you rig up a system that basically projects an image onto a solid surface, enclosed in a light-tight box, for the camera to pick up? (You know how you can hold the 35mm lens over a piece of paper and see the image projected?)

Basically, the whole idea is to pick up an intermediate image - thus the Ground Glass. But......if you can use a system of mirrors or a prism and project the image on a plain, solid surface (not sure what'd be the best surface, but the grain wouldn't be a problem any more.)directly in front of the DV camera...wouldn't that be the same principle?

Also, in the manner that the image is relayed, would it eliminate the inverted image problem?

Again, forgive me if this sounds crazy, but I was just thinking about it as I was typing this post and thought I'd throw it out there.

Thanks!

,Frank

First off, I know using an inverted external monitor is an option but I would rather save myself the time and effort of fixing orientation in post. I think a correctly oriented image is doable. Saying this,I must point out that I am not an optical engineer. In fact, I've learned almost everything I know about this subject from you all and the articles you've posted here in this and the Agus35 thread. Experts, please chime in.
Frank, I don't think you're crazy! I gave your idea about projecting onto a reflective surface with a mirror some serious thought. We Southern Boys must think alike! I didn;t throw the projection idea out completely but I do have a few concerns about it.
1. We would be talking about a front projected image, right? Well, you would have an issue with left to right orientation when compared to a rear projected image (GG) A front projected image is really a reflected image just like a mirror so left to right orientation would be reversed while vertical would remain the same. I bet that is why SLR cameras use a GG element the viewfinder assembly instead of simply focusing on a projected image.

2. I haven't come up with a simple way to orient all of the elements to make using a projected image practical

Here's my stab at a simple correct oriented image. Sorry for the poor diagrams.

Basicall, I'm proposing an optic quality mirror mounted at 45 degrees to the light path from the slr lens. The GG and condenser lens are mounted above the mirror. (which comes first GG or CL is still under debate) The video camera is mounted vertically and is focused on the GG. I have a nice short camera 9.5" from lens tip to battery pack, so the vertically mounted camera wouldn't be too awkward. My adapter wouldn't need to use a round GG or round tubing either as I would house the whole thing in a compact, lightproof black box. In a nutshell, this is identical to a top view viewfinder on a med. format camera. In fact, you could use a med. format camera body and just add your own GG and condenser. Watcha Think? Joe

_________
' '
' '
' DV '
' Camera '
' '
'--------------'
/____\

CL (___)
GG ====
' /
' /
[ SLR ] ---------'/ 45 degree mirror
Lens /
/




_______
| | |
| | |
| | |
|____ | |
/___\ | |
--------------| |
I | |
I CL (___) | |
I GG==== | |
________ I / | |
_ _ \ | SLR Lens I / | |
/ |________I / | |
______I_/_______ | |
|__________Mount_ __|
[ ]
/ / \ \
/ / \ \
/ / \ \

YIKES!!! Well, I guess my ASCI art leaves a lot to be desired. Never tried it before. Sorry. Guess my written description will have to do. Joe

LOL

Actually, Olivier and Sebastien used that same idea for their first prototype and the video turned out great. They posted pictures of that setup at http://www.originalversion.net/temp/makingof01.jpg. Also, you can check out their movie thread at http://www.dvinfo.net/conf/showthread.php?s=&threadid=21567. If you haven't already seen "Marla," its very worth the download.

frank,

you just "stoled" my idea, he, he...
i was thinking about the same thing, but never tested it in practice.
some time ago i saw slide portable projector, and i was inspired from it. the original device looks like this:

PLEASE, IGNORE THE DOTS! i was unable to "draw" it wihtout...


.....................\
......................\ <----- your eye
.......................\
........................\ big frosted GG
.........................\
..........................
small ...\.......
mirror ... \...... <------ ray () <------!! <----- lamp
..............\.................... lens.......slide

small mirror is parallel to big GG.

so if i'm right - you can use certain flat grainless surface instead of big GG. and use "system" like this...


.....................\
......................\
camera POV.......\
----------> ........\ grainless opaque surface
...........................\
..........................
small ...\.......
mirror ... \...... <--------- ()
.............\.................35mm lens



what do you think?

filip

Joe: Ha ha! Yeah, that ASCII art is quite difficult to pull off. I do understand what you're saying, though. That sounds pretty good to me, but I'm not an expert. I like the idea of using box/square stuff, because it's easier to line parts up correctly whan they're not circular.

Filip: Whew....I feel better now that some of you guys didn't laugh at my idea. What you are illustrating is exactly what I'm thinking about. Actually, it's better, because I was adding a few too many mirrors to the equation while envisioning it. :-)
That looks doable! Nice!

,Frank

he, he i was designing the whole asci drawing during yours replies...
nice to see that everyone is thinking here!

So my next question is......are mirrors just mirrors? ie. Are there certain mirrors that are better than others as far as quality? How are they rated?
Thanks!
,Frank

in my opinion (i'm not a mirrorist :),

the mirrors used must have reflecting surface on the TOP ...

(so called venetian mirrors, hm, well at least in poland)

... surface, not the bottom.

in that case you do not have reflection distorted by glass itself.

just a thought.

since projecting the image on a solid white surface seems a good idea, i am afraid that the loss of light in such process would be too big.
What about projecting the picture on a surface mirror ?
I am not sur that in that case we get the same result than with the gg, but in theory, the picture would be build the same as on the GG and in the same time reflected (and inverted) so we get the economy of several parts.
We could use the mirror of the SLR body that is just the right size.
the only problem i see with using mirror before the gg is that we could create a light path that could exceed the about 46mm that is required to focus properly.
On the other hand we usually have plenty of useless space after the GG due to the requirement needed by the macro lens.
So using here a kind of zig-zag path could be usefull to build a compact adapter.
My best guess would be to have the light comin out of the SLR lens to a 45 deg surface mirror (inverting picture) to an horizontal plano convex lens with the flat side acting as GG.
This still require to have the camera mounted vertically and the picture inverted a 2nd time.

I hate to be the bringer of bad new this time but Filip your design wont do what you want it to do. In fact it ends up having the same effect as if you had done nothing at all. Do a test with a mirror, 35mm lens a white piece of paper. In fact even if it did you still would have a problem with having the whole image in focus top to bottom. You would have to have your camera at 45 degrees so that that image plane is flat to the camera's CCD.

The rest of the last few designs ideas only do a partial correction -leaving you rendering your footage in the end anyways.

One front projection idea I had was to use a 35mm lens > forward slainted 45 degree two way mirror > white grainless projection surface > directly below the first two way mirror theres another mirror. This one is a regular one way mirror mounted at a 45mm rearward slating position > video camera.

It has two problems though. It doesnt flip the image L to R and wastes too much light. It does however makes alot of other things possible (flips the image right side up, doesnt need a condenser or ground glass, is grainless, possibly no need for a diopter either)

Personally Im still going the GG/Condenser route and simply rotating the monitor and render in post. The reasons: making my adapter much shorter, Im shooting with anamorphics, easier for steadicam work, etc.

-Brett Erskine

<<<-- Originally posted by Brett Erskine:
In fact even if it did you still would have a problem with having the whole image in focus top to bottom. -->>>

i don't understand this. why image will be out of focus? isn't it just a periscope system? if two mirrors are parrarel to each other, in my opinion (i'm not a periscopist:))) the image will be in focus all the time. i will of course make a test with a mirror and white surface, but as i remember my games with a periscope, there is no need to correct anything, everything is in focus...

oupsss...

ok. now i can see what you wroted... you are talking that the image IN THE CAMERA will not be in focus if camera itself is looking on 45 angle white screen. you are right. i just thought about the first part - mirror--->white screen parallel system. sorry, i was too fast...

<<<-You would have to have your camera at 45 degrees so that that image plane is flat to the camera's CCD. ->>>

correct.

<<<- One front projection idea I had was to use a 35mm lens > forward slainted 45 degree two way mirror > white grainless projection surface > directly below the first two way mirror theres another mirror. This one is a regular one way mirror mounted at a 45mm rearward slating position > video camera. ->>>

can you ascii this? i have problems with understanding the whole construction.

THANK YOU

I just receive my roller bearing.
the hole is 50mm dia and the external ring is just 65mm dia.
the thickness is 7mm
I will use a 50mm dia. condenser lens mounted inside with the flat side grounded with 1000 grit alu. oxide (still waiting for it) so i should not need an additional GG.
Then i got the choice to rotate it or not.
the roller bearing cost 30$, so it doesn't add to much to the price of it.
I think i will make a flange on the roller in Delrin (kind of white plastic , easy to use, very used in mechanics)
The flange will be a kind of ring, to accept inside the gg-lens and outside the way have the motor rotating it (probably a simple plastic belt)
Ideally everything clips together so there should be no need for soldering or glueing anything

Francois,

is it possible to pass somehow (somewhere) some jpgs of your roller bearing etc.
it will be nice to see that!

thanks

filip

I've been following this and the agus topics very closely for past few weeks. And you may have noticed I'm new here. One major questions for you guys is, do any of you( and mainly to those of you that live in the UK) know where to buy aluminium oxide grit in the UK? I can only seem to find it attached to paper, and even then, it's not 1000. It's only about 250, which from what I have read , would be far to coarse.

Filip-
Send me your email and I'll send you the drawing of the design. In the mean time...
A B C
35mm Lens> // ||
// ||
\\ <video camera (E)
\\
D

One front projection idea I had was to use a 35mm lens (A) > forward slainted 45 degree two way mirror (B) > white grainless projection surface (C) > directly below the first two way mirror theres another mirror. This one is a regular one way mirror mounted at a 45mm rearward slating position (D) > video camera (E).

damn that didnt line up too good. Oh well. Send the email.

I found a place nearby that sells a Hoya 58mm Closeup Filter Set, that comes with 3 lenses. I think the lenses are +1, +2 & +4 or something. Anyhow, I have heard the hoya filters mentioned in some of you guys' mini35 devices, so I wanted to get some feedback before I purchase them. I well know that an achromatic/2 element filter would be better as far as the color separation goes, but (and maybe the guys out there with a Canon GL2 can tell me) would this kit be acceptable? Also, what about when they are stacked? Does this introduce vignetting or cause chromatic abbheration to really show up?

Thanks for your help!

by the way - if you wrap up your ascii art in a
code tag (in square brackets) and end it with a /code tag in square brackets, things should line up as you expect. (testing now...)

See this page http://www.dvinfo.net/conf/misc.php?s=&action=bbcode for some info on codes.


_ ____ ____ ___ ___
/ \ / ___| / ___|_ _|_ _|
/ _ \ \___ \| | | | | |
/ ___ \ ___) | |___ | | | |
/_/ \_\____/ \____|___|___|

_ ____ _____
/ \ | _ \_ _|
/ _ \ | |_) || |
/ ___ \| _ < | |
/_/ \_\_| \_\|_|

My optics knowledge comes from what little I remember of grade 10 science; Can't a dove prism be used to properly orient the image?
http://electron9.phys.utk.edu/optics421/modules/m2/prisms.htm

Yes you are right , there are many prism that could help to have the picture in the correct position.
Unfortunately we are not at the stage where we are looking on how we could do thing (theory), but more in a stage on how we can build it. and unfortunately prism you can find easily and affordably are usually to small for a 24x36mm picture.
If you know a good source for big cheap prism...

uhhh....people, a X/Y switchable LCD is only about $120, and its easier & better image quality, I dont know why you guys are trying so hard with prisms & mirrors for this magic trick when an LCD is the best answer.

gas

I use lcd monitor is just fine
Prism éand other hare to difficult to calibrate for homemade kit

ans light loss to

i think movietube
www.movietube.com/
dont use prisme but only aadiitional viewier

<<<-- Originally posted by John Gaspain : uhhh....people, a X/Y switchable LCD is only about $120, and its easier & better image quality, I dont know why you guys are trying so hard with prisms & mirrors for this magic trick when an LCD is the best answer.

gas -->>>


John,
Where can someone find this X/Y switchable LCD monitor for $120? Can you or someone provide a link to a source?

To all,

The LCD monitor is the best solution for dealing with the inverted image (for now) but I believe an optical solution is out there. Please don't stop the flow of creative ideas. It's my guess that many of them are untested and so they shouldn't be so quickly and easily dismissed. I agree that it would be fool hardy to run out and buy a $500 prism just to test a hunch. (my pockets aren't that deep) But there's bound to be someone out there who happens to have access to one. What we need is more testing and more sharing of results. It would be nice to know exactly how many functioning adapters are out there and what those builders did to correct the common issues with this type of adapter. Hotspotting, vignetting, inverted image etc. I'm new to this forum so I'm not too savy on what is possible but could we create a survey to see who's building what. It would be nice to know which cameras are being used.
WIBN, Joe

on another note:
Has anyone ordered 5 micron grit from www.gotgrit.com yet? I just ordered some two days ago. I now believe Frank was originally right about the gray 1000 grit AO from Rock Shed. I too am noticing some varient scratches that could only be caused by a large particle. (I was being careful, following my own sugestions posted here) I don't think it is anything against Rock Shed but I now understand that the blue AO (I think that is what they call the gray colored stuff) is not consistant enough for optical work and that you need white AO. Got Grit is entirely based on telescope making supplies and only deals in white AO. After thinking about it for a minute, it makes sense that someone wanting to polish stones in an agitator isn't going to be as picky about how refined their grit is. So from here on, I think we should advise all to use only white AO for glass grinding. I'm still looking for a source for 3 micron AO. anybody have a source?

the link
http://www.portablemp3playerstore.com/stuff_you_need/special/th-5688.htm

120$ 5"6 TFT monitor

I find in europe 7" monitor for 120€

I dont think stop creativiti
but for me te mini35 it to make movie is not for losing 2 year to bild up .
If some can do whit prism etc etc...
But me for now i already use for real.

PS i even use whit Super8 camera and videotap is fantastic....

Link for AO grit 1000 in canada (only french english page is not working
http://www.aei.ca/~astronat/equinox/listeprix.htm

John,
Where can someone find this X/Y switchable LCD monitor for $120? Can you or someone provide a link to a source?

I'll second that loudly -- care to show us a link John? Please make sure it isn't 7" -- I'm looking for something in the 3-4" range...

- jim

i think movietube
www.movietube.com/
dont use prisme but only aadiitional viewier

I have take a look at this movi tube, and I am almost shure that they use a 45 degre prism.

Alain

Alain,

I'm working on your adapter for HD cam (see here (http://www.dvinfo.net/conf/showthread.php?s=&threadid=22456&perpage=15&pagenumber=2)) and have a question:

- Have you tried to use Nikon focusing screen as Ground Glass?

I found that the focusing screen (I use type D, plain matte) has a very visible grain. Do you think the grain can be eliminated by further refining the matte with the aluminum oxide powder? (I do have some on order, but they haven't shipped it yet.)

Thanks!

I haven't seen this focusing screen but I am pretty shure you can.

All the focusing screen I have seen even Hassel blad are not fine enought for that.

Alain

Alex ,

i work whit a Nikon type D focusing screen

www.sinedie.org/lickthetoad/paolo_rudelli/mini35/index.htm

www.sinedie.org/lickthetoad/paolo_rudelli/mini35/photo.htm

the grain is visible under DV camera so i think whil be even more under HD and also the screen is 36mmx24mm not 4/3 ratio

i think the materiel is plastic or somthing else so ginting whit AO i don't know if is working

Paolo

people who want the X-Y switchable LCD's, just do an eBay search for a brand called " lilliput ", make sure you buy a TFT and not an STN screen.

http://www.amazon.co.uk/exec/obidos/ASIN/B0000CBDM9/202-6704539-6752633


Its kinda funny how these are things we already discussed 2 month ago, but oh well...here we go again.

gas

Well...

It's not as if I'm about to strap a 6" LCD screen to my camera. Thanks for the links but they do me no good.

- jim

4" tft

http://www.bullnet.co.uk/shops/test/tft.htm

Please don't recomend or buy this, I have this model and this is real crap.

http://www.portablemp3playerstore.c...ial/th-5688.htm


Paolo Rudelli

the one you sugest has only
Resolution 383(H) * 234(V) DOTS
It's not good enought to be able to make focus whit this.


Alain

<<<-- Originally posted by Paolo Rudelli : 4" tft

http://www.bullnet.co.uk/shops/test/tft.htm -->>>

I guess you could just mount that one upside down.

AH HA! or Ureka...anyways, yea just mount a regular $50 4"LCD UPSIDE DOWN!

Don't know if this website is currently used by anyone in here. Thought it might be useful to someone:

http://www.einsteins-emporium.com/science/l-optics/sl215.htm

<-----Read----------Learn----------Progress----->




-Brett Erskine

TWO-LAYERED GROUNDGLASS.

For those who are following the fixed groundglass path, here is something which may be of use and someone might develop to a furthur stage than I have the time to do at present.

Whilst educating myself with microscope slides in the method of polishing glass before I turn myself loose on the real glass disks, I decided to see if I could replicate the partial polishing back of the plastic CD disks which seems to confer an improvement in the projected image.

I discovered after polishing back some of the frosted finish on glass slides to a semi-opaque condition, it would be of little use as a groundglass screen because of hot spot and some of the aerial image being apparent.

But with two such groundglasses mounted with polished-back frosted surfaces face-to-face, a more useful projection surface can be found with the finer texture remaining, therefore hopefully better resolution than with a single more opaque frosted surface of coarser texture.

The downside will likely be two internal reflective surfaces instead of one and anti-reflective coatings on the clear sides will likely be mandatory.

Has anyone ordered 5 micron grit from www.gotgrit.com yet?
Yes, I did. The guy's name is Tom. Very helpful. I got WAO 5 Micron (white). I also wanted 3 Micron but he didn't have WAO 3 at the time. I did buy some 1 Micron he had (left over from a previous special order) but from what I can tell it's a little too fine and polishes more. He did suggest trying Cerium Oxide (CEO) as a substitute for Aluminum Oxide. He said CEO was soft like WAO and might work as well. Although I didn't order any so I don't know.

Anyway, his WAO seems extremely consistent and from what I can tell, made a beautiful GG. I hope to be testing it this weekend/early next week.

I just placed an order at gotgrit.com for the following items:

Aluminum Oxide
WAO5-025 WAO 5 Micron 1/4 LB $1.75USD
Cerium Oxide
CEO-025 CEO 1/4 LB $4.50USD


I don't know much about the Cerium Oxide, but I spoke over the phone with the owner (very friendly and helpful) and he suggested it, so I'll try it out on a piece of glass or something and let you guys know how it goes.