I am still not sure why you need the frosted glass if you are going from the 35mm lens straight to the DV Camera. I understand why it is necessary if you are going through the veiw finder, bouncing off of mirrors etc. It is further from the first mirror to your eye than it would be from the point of the first mirror to the film. So the frosted glass is there the same distance as the film and you are looking at it when you look through the veiw finder. Here is a diagram: http://entertainment.howstuffworks.com/camera7.htm

It seems like the light or image will be at the film plane with or without the frosted glass. It seems like the trick is to get the DV camera focused on that plane. Would it be possible to say insert a slide with a focusing pattern and a grid showing the area that should be covered, focus and then remove the slide and block off all light. If this worked it would cut down on the loss of light because of the frosted glass.

Agus, can you focus on the frosted glass and then remove it? If so, what do you get?

The image will still be upside down. Also remember focusing on the move or follow focus will still be a problem with still camera lens because of breathing. See Charles Papert's explanation here: http://www.dvinfo.net/conf/showthread.php?s=&threadid=7713&perpage=15&pagenumber=3

Still I'm sure we can all live with these problems for this kind of DOF. Add some color correction and 24p or 30p good enough for many projects.


Paul

Once you understand why the Ground Glass work, you will know how the adapter works.

The image from the lens, create a projection in the ground glass, there is where the image with DOF is made

http://entertainment.howstuffworks.com/camera2.htm

then you shoot that image with your DV camera, pick a SLR lens and try it without the ground glass, and you wont get nothing, just an image upside down.

Wouldn't frosted glass compared to clean glass affect the image quality?

IMO:

The frosted glass is used like a projection screen, and the camcorder "film" the image produced by the 35 mm lens on this "screen". A clean glass would not preserve the focal lenght of the 35 mm lens.

Ground glass v. aerial image
 

I'm not sure of the proper optical terms here, so I hope I amd able to convey this idea...

The ground glass essentially is acting as a rear-projection element and is re-establishing your depth of focus by reimaging what you are seeing through the 35mm lens.

If you used a condenser lens, you would simply be adding the 35mm lens to your DV lens and would not be gaining the same effect. Again, I don't know the specifics, but you wouldn't be seeing the 35mm image. By recapturing the depth of focus onto a flat screen, you are able to take advantage of the optical properties of that 35mm lens.

Also, the grainier the ground glass, the more contrast you will see. As you remove the grain, the contrast is reduced. Hence the spinning ground glass.

Agus35 vs Mini35

Unbelievable Agus, i'm very impressed, currently i've done some preliminary testing of your prototype which i hope to flesh out over the next many weeks. True the Mini35 is nothing new, just a different take on the "Camera Obscura" (http://brightbytes.com/cosite/what.html). But you are ingenious, daring and ABOVE all inspiring...! That's why I want to dub your creation the Agus35.

Some quick questions... Your using the clear CD from the 25-CD pack, correct? (or is there another component I'm missing which you refer to as the "ground glass"?)or did you aquire an actual circular cut glass which you have "sanded" on one side? Else, I'm also thinking of trying to aquire an actual circular glass and using some etching acid from an arts store to frost one side for a finer "sanded" finish. Would you think that makes a difference in quality? Technically it seems it might. Also have you found an ideal place to put the rotating motor? And another, once you have adjusted the image to appear in the ground glass, the sweet spot, have you tried other lenses to check on their results? Like a zoom???

Well, yeah, if you use a cutted groud glass, made of glass and not plastic, you will have more quality, and you will loose less light steps.

Also, the ideal place for me for the motor is in the center of the spindle, it even have te same diameter to fit those very popular chinese motor toys.

I love all that about calling this adaptor the Agus35 ... heheheh

Posted by Brandt<<The ground glass essentially is acting as a rear-projection element and is re-establishing your depth of focus by reimaging what you are seeing through the 35mm lens.>>

I understand all that. I just can't picture why the light isn't at that same place, plane or distance if you focus on it. I guess the light must actually strike something to be seen.

I see how there are advantages to using mirrors, prism, etc. so as to be looking at the other side of the frosted glass and not having to look through it. That has to really cut down the light as has been discussed. Plus looking at other side it's possible to flip the image. Good bit more involved to make though.

Ok, this is quite simple, it seens that you havent even tried up the adapter, and also you seen not to understand how it works.

The adapter is way to simple to use, to build and the picture quality is amazing clear and pefect DOF... now, if you want to build another adapter using no ground glass and mirros... well... i think that is another topic.

The challenge was to build an adapter which would cost less than 10 dollars, and you could get equal image to the mini 35... i have succeded, the image is clear, i have DOF control, no vigneting... no noise...

the mini35 offers many more really advanced features, but i have adchieved the simpliest ones and the most important.

You need the ground glass.. i dont know why you are putting that you can do it, when you havent even tried. When i look at the mini 35, ithought it was just as simple to put the SLR lens in front of the DV camera, NO... it doest work that way...

So, pick up an SLR camera lens, your dv camera, and tried like you said, to use mirros, and no ground glass, the point is that this topic is about this adapter, which was built only using a 25 cd spindle, and cheap toy with an electric engine...

no means to offend, just to continue moving forward with this project.

Ground glass
 

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2968796829&category=29981&rd=1

I think this may be a way to get better ground glass. It's a 8x10 ground glass used for large format still cameras.

All you have to do is have it cut so it is round, and drill the hole in the center.

Great thread we have here.....

another test...

http://altoque.tv/35mmAdapter/kartfilm.mov

about the GG, i wonder about its weight... cause if it is too heavy it will force a lot the little engine.

Exactly. Without actually being projected onto the ground glass, you'll just be bending the light more, which will affect the DOF as if the camera was taking the picture itself. With the ground glass, it's more like your camera is taking a picture of a photograph, or of, say, a movie screen. The picture of the photo or movie screen will show the shallow DOF that the movie camera did. Your camera isn't actually getting real light that's passing through the 35mm lens, it's taking a picture of the image it's projecting, which is a completely different thing.

That's why you can get a shallow DOF on your DV camera using this even if you're zoomed in, with a small aperture, and your CCD is only 1/3"... the usual rules don't apply since you're taking a picture of a picture, not of actual things.

By the way, Agus... what sort of processing are you doing on that footage? It looks very dark, what are the settings you're using? And maybe it's just me, but I'm seeing a little vignetting on the edges... did you not zoom in like you said you were before? All in all though, that looks really good.

I was also just thinking that in a later version of "Angus35" it would be possible with maybe the use of mirrors to vertically flip the image before it got recorded onto the camera to take away from the hassle.

Jon Yurek,
Thank you. That answers my question. I guess the angle of the light changes when it hits the frosted glass.

Agus,
I do understand how it works. I have been looking into this for almost 2 years. I have not tried it yet because I lost everything to a fire some months ago before I could start. I never said that you could get away without the frosted glass only asking if you had tried and what you got. Jon's answer explains why that wouldn't work. You have the DOF and no grain but it also looks dark especially around the edges. Sorry if I got off topic but thought this thread might lead someone on another quest like earlier threads led you to this one.

Noah Posnick,
Stay tuned I am sure you will see other versions.

why are you still calling me angus ? it is Agus.. from Agustin , .. hehehe

Yeah. my comercial version will use a pentaprism to correct the image. but that will take long until it will be avaible, now you can try up the free version :)

About the vigenting Jon, in some scenes i use it as visual effect, :-) i dont see it very dark, could it be that maybe your screen brightness is too low ? (i have to admit, that while i was shooting, the adaptor move a little to the right, check the other side there is no vigneting, after a stupid kid came running and made my camera fall !!!!, that also scracted and bump my 50mm lens... damn, but i can ensure you that there is no vigneting when it is centered, i just didnt noticed.)


I tried to copy a mini35 demo video, which use motocross racers, this is not motocross actually, but you will get the idea, i use Magic bullet, and look suite, and RE smoothkit (to take out the staicases from the interlacing... my cheap TRV18 needs some help always)...

Chek the part where the guy fall, you will see that the other bikes coming in front are really blurred, and also the behind the crash the same happens, your attetion will be only with him, that is the real DOF meaning.

Agus35
 

great work Agus, the go-kart footage looks awesome, really good color.

Hi,

I made a phone call to a friend of mine that runs a panel beating shop. He said it's possible just to buy some 2mm or 3mm thick glass from a regular supplier (they'll cut it to size for you if you ask 'em nice) and then using a small and variable rate sandblaster that most panel shops have (course, medium and fine settings) you can create your own ground glass to your own specs. I haven't tried it yet to see which is the least 'grainy' result (I'm thinking 'fine') but it's a relatively inexpensive way to realise the ground glass portion of this little project.

Also, I think an 'inversion' lens whacked on the front of the slr lens may solve the shooting upside down problem. Cokin make a 'mirage' filter that inverts the bottom half of the photographed image to produce an...um, 'mirage'. I guess what is needed is a 'full version' of this kind of filter that simply inverts the image before it goes through the adapter. Does anyone know of this kind of filter?

cheers,

DW

Why invert the video, you can do it in post, shooting it... well is kinda of tricky, but once you get used to, is practically the same, myself, well i am used to now...

Hi,

yeah I was just looking for ways to NOT have to get used to shooting upside down! Obviously you have to be wary of how much light is being compromised - the more elements you put in front of the lens the more light you lose.

While I'm here; Agus you mentioned having a look at the mini-35 manual to see how this idea works - do you know where i can download this manual? On the Technik site there is more of a brochure - no schematics or cross sections - is there another manual that you can d/l?

Thanks for all your great work, it has alot of us very excited.

Best,

DW

Here
http://www.pstechnik.de/sheets/downl...l_rev_2002.pdf

Btw, i want to post some pics directly to the thread, can i use the [img ] command here ?

Agus,

I think you will probably need to get Chris' permission to attach...don't think posting pic directly into the thread is supported. Here's the attachment way:

The administrator may allow you to use the attachment feature of this board, which gives you the ability to attach files of certain types to your posts. This could be an image, a text document, a zip file etc. There will be a limit to the file size of any attachments you make, as the board should not be used as an extension of your hard disk!

To attach a file to a new post, simply click the [Browse] button at the bottom of the post composition page, and locate the file that you want to attach from your local hard drive.

Only certain types of files may be attached: these are the valid file extensions for files to be attached to this board: gif jpg png txt zip bmp jpeg.

After posting, the attachment will show up in the body of your message. To view the contents of the attachment (if it is not already displayed) simply click the filename link that appears next to the attachment icon .

I would just e-mail Chris.

Hey Agus,

I have a few questions (trying to build my own now! And I have a Sony TRV17! :-)

1. How exactly did you affix the end of the motor to the spinning CD? It seems difficult to center/stick to the CD... what did you use to do this?

2. What toy did you get the motor out of? Was it a dreamcast controller, coz if so, I have one of those lying around myself :-)

thanks!! I will take pictures of my Agus35 as well once I get it going...

paulb

hehehe you got the my little sister camera of my own.. the TRV18 and 17 are almost the same...

ok.. dont laugh, but i took a lego toy, and remove one pice that was the wheel, put it into another bigger lego piece (they are great, cause they are 100% centered) , and then make the cd to fit to that piece...

the toy was a Xmas ball that start throwing some fake snow... from there i took the switch and the batery holder as well.

let me post some pictures of it, so you can understand it more.

Some high quality images

http://altoque.tv/35mmAdapter/moto01.jpg
http://altoque.tv/35mmAdapter/moto02.jpg
http://altoque.tv/35mmAdapter/moto03.jpg
http://altoque.tv/35mmAdapter/moto04.jpg
http://altoque.tv/35mmAdapter/moto05.jpg

Yes please! If you could post a few more close-up shots of the Agus35, particularly the part where the motor is mounted to the case, where the motor is connected to the CD, etc.

thanks!
paulb

Here is a cool video !!!

Quicktime
http://altoque.tv/35mmAdapter/moto35mmfilmtest2v4.mov

Windows Media
http://altoque.tv/35mmAdapter/moto35mmfilmtest2v4.wmv

nice logo Agus ;)

Diffusion Glass
 

This could be a good source for the projection glass.

http://www.edmundoptics.com/IOD/Browse.cfm?catid=453

These guys make all sorts of good optic supplies.

Hi Agus!

Well, I finished building the first version of my Agus35 tonight... Unfortunately for some reason my computer won't see the camera as a DV deck so I can't import footage at the moment, but I will as soon as I get it working... In the meantime:

I can't seem to get rid of vignetting. I am using a TRV17, and at the closest I can place the lens to the ground glass, I still get a bright spot in the middle of the image (much like your earlier footage Agus.) If I zoom in more than about half way, it goes wildly out of focus. I think I may need to use a magnifying glass as you did in your device but Im not sure where to find that... Also, where exactly it is mounted in the device?

My problem is that I basically can't zoom in enough to cover the entire screen with the bright spot.

thanks for any help! Almost there!

paulb

p.s. I used the spindle from a broken CD player I had lying around as the motor/ground-glass axle. It works beautifully because it mounts the CD perfectly centered on the attached little plastic mount disc with ZERO vibration! A cd player with this type of motor/mount could be found at toysrus/bestbuy/whatever for less than 20 dollars.

I sent an e-mail to the UK outlet of Edmunds Optics asking if they could make a disc shaped piece of ground glass, but they only do personal commissions if the volume is large enough.. So if you've got any plans to go into production agus... :o)

On the XL1s front, I've thought of some solutions, but I won't be able to test any of them out till I get home from Uni.. That said I've spoken to some contacts in the engineering department, and I'm going to try and convince one of them to make this his coursework project.. Which would mean a fully machine worked Agus35.. But none of them know much about optics so they're reluctant, alas.

Kieran

To Kieran:

That's definitly the way to go! I know some people at engineering faculty here, too, and am about to talk them into making me one. I'd be very glad if you could share any plans with me that spawn from your project, as I want to mount
the adapter on an XL1s, too.

Agus. Do you have any idea when you will likely put up your plans?

Paul,

Were you able to use the CD player motor too? That is a brilliant idea...remove a cheap CD player's inards, replace them to a housing, and all you have to do is get the distance right on how far the "glass" is from the lens and hit "play"!!! I wonder if you can remove the CD laser(?) and still be able to hit play and it would work, then hit stop when done???? What'd you think?

Clay

P.S. Then you could also run it on two AA batteries!!!

I skipped using any of the rest of the CD player's electronics for now. My main goal in canabalizing the player was to get at the little plastic piece that the CD sits on, because this is perfectly centered on the motor and gives zero vibration (it's built to do that!)

paulb

Okay, I now have a quote for a manufactured piece of ground glass:

100mm diameter with a 10mm hole in the centre is £70 ($121 at the current exchange rate) for a one off. But bear in mind that industrial optics manufacturers tend to do bulk orders rather than one off commissions. Also I'm not sure what the thickness is, but if it's similar to edmund optics then it should only be 1mm, so it shouldn't add too much weight on the motor..

I think I'll stick with the plastic cd until one of you sees how much better the adapter performs with "proper" ground glass. After all the XL1s might cope fine with the loss of stops..

Anyway I'm getting a little ahead of myself, as my first problem's going to be getting the adapter on to the XL1s in the first place :o)

Kieran

Hey there, i got some news... unfortunaly, i have tons of works right now, seens like my tv show have been aproved for production (my first one!!! i am 21 old !).

i will try up to put the plans just after i finish making some ads for this tv channel...


About the optics, try to do what i did...

I bought a wide conversion lens, i remove the first glass (which magnify a lot), and i can take the picture of objects that are really close, like 2-3 cms... after than i can still zoom in until the half... and there.. done.

I found one cheap from sony, they cost me like 25 bucks, and i bought it before this project, may be they are lower now.

Hey Agus, this may be a bit off topic because it applies only to the TRV, but could you tell me, or take a picture of exactly what model wide angle you have? I'm going to need to get the same one to make my TRV work...

Also, which part of the lens did you remove? The glass closest to the camera lens or the one on the other side? --- EDIT: Nevermind, I think I understand now: you removed the glass closest to the camera and use that as a magnifier... is it still mounted in the wide angle adapter?

BTW Agus, CONGRADULATIONS!!! :-)

thanks!
paulb

One other thing... I've been looking into ground glass, and it doesn't look like it's too difficult to make your own. You basically take two sheets of glass, and rub them together for 15 minutes with a very fine grit and some water inbetween (apparently Bearing grit will do the trick, from an auto store). From there, you can cut the pane of glass into a circle with a circular glass cutter. Most of that stuff can be found in a stained glass art supply store, such as Hobby Lobby.

The only trick will be the fact that I can't cut a CD-sized hole small enough in the middle, coz the circular glass cutter won't go that small. Instead, what I think im going to do is cut a larger hole, and then affix the CD to the surface of the glass with glue, therefore giving me a CD sized hole :-)

paulb

yeah.. that is a excellente solution, but remember to take a close look to the weight, you cant force the little motor too much to get high spining speeds

I've been following this thread for a couple of days now-and I'm getting excited! I operate in EXTREME low budget filming and this cheap of a 35 mm solution (as far as DOF goes) looks promising. However, I am still quite naive in this field-and have a couple of questions...


-There has not been any detailed tutorial posted yet on the construction of this homemade adapter, correct? When I get some time I might get building from the info from the previous posts-but I just wanted to make sure I hadn't skipped the completed tutorial.

-I have been saving for a Canon XL1s, but am a little fuzzy on the easiest way to adapt a 35mm lens to it. The interchangeable lens feature of the XL1s attracted me-is there not a way to take a Canon 35 mm lens and stick it onto the XL1s? Or is this still relatively expensive or just not a part of the interchangeable lens design. Has anyone successfully adapted Agus's setup to the XL1s?

- For my final question I demonstrate my complete ignorance. I know little about different camera lenses-especially in price. About how much is a decent 35mm lens that could be used on this setup? Other than this (and the camera) the rest of the material could be purchased for under $10-&15, correct?

A big thank-you to all who have spent their time in posting examples, asking questions, and designing the adapter in the first place! You're inspiring.