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Old February 20th, 2004, 02:06 PM   #226
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so how many Degrees Apparent Field of View do the achromat's need to be? Has anyone found a source for these sucka's yet?

Great diagram Dino!
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Old February 20th, 2004, 02:36 PM   #227
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standard aldu35 and deluxe aldu35

okay, here's in keeping with some of the creations so far. for those keeping score at home, to the best of my knowledge the deluxe version has not been created yet but most likely would be the one that would yield the best results do the the color correction capabilities of the achromat lens. in a nutshell the lens makes the light shoot in a straight direction. the deluxe design also includes a collar for adjustment when you use other primary lenses-this is also has yet to be proven. Another question would be could you make the system with a single (just achromat lens 1) and allow it to function properly? anyone have an answer? so check the links below and if need be i can do some tweeking. i have also included what might be considered a standard concept (with the fresnel lens) already proven to be quite amazing in proof of concept.

for miniDV

http://www.dinoreyes.com/images/miniDV_standard_aldu35.jpg

http://www.dinoreyes.com/images/miniDV_deluxe_aldu35.jpg

for xl1/xl1s

http://www.dinoreyes.com/images/xl1_standard_aldu35.jpg

http://www.dinoreyes.com/images/xl1_deluxe_aldu35.jpg

keep in mind folks, the standard is cheaper to develop and inconcept the deluxe version would be the ultimate in optical quality. also, just as a reminder, what we are doing here on this thread is HUGE and may very well shake up the status quo-or at least, wake them up.

enjoy
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Old February 20th, 2004, 03:50 PM   #228
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nice work once again!
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Old February 20th, 2004, 03:55 PM   #229
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Sorry to ask this, I don't know if this as been discussed before (this thread is too big to search) but,

what is the advantage about using a nikon lens as a relay lens instead of the stock 16X XL lens with the XL1 ?
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Old February 20th, 2004, 03:56 PM   #230
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question about the fresnel

does the direction of the fresnel make a difference of the image on the gg? that is, should the "ribbed" side face the ground glass or should the smooth side?
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Old February 20th, 2004, 03:58 PM   #231
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I believe i read that the ribbed side should be facing the gg.
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Old February 20th, 2004, 03:59 PM   #232
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I'm not fully convinced that we need a second achromat behind the ground glass... muddled logic follows...

What we're really building here is a tiny little projection system. We 'project' the 35mm SLR image onto a surface (our ground glass) as accurately and brightly as possible (the need for the first achromat).

However, we then photograph this projected image as if it were a new image. The way the camcorder focuses on this very near image is through the use of the macro adapter. Quite simply... the macro adapter places focus of the camcorder right on the plane of the ground glass. I think that the second achromat behind the ground glass would just screw things up.

It is helpful to think of all of this using the 'projector' metaphor:

Let's say we built our little device differently:

Imagine that I had a hypothetical 35mm camera, which instead of a viewfinder, had an overhead projector which, lets say, shoots out some contraption on the side of the camera onto a big screen. So... whatever I aim the camera at shows up on this big movie screen to my left. It accurately portrays what the 35mm lens sees... if I change the focus on the lens... the big projected image comes into and out of focus, etc...

This movie screen is effectively the same thing as our ground glass. Movie projectors all have various ways of increasing the light and reducing spherical abberations to make a 'flat' image on the screen... this is the same thing as what our first achromat is doing.

Now - stop there for a second... the projection of what the 35mm lens 'sees' onto a projection surface (the ground glass) is one complete problem... which is solved, in our case by the 35mm lens image getting corrected by and achromat and focused onto a screen (ground glass).

Now - the second and completely separate problem...

We want to make a camcorder recording of this screen. Falling back to the movie projector metaphor... I take my camcorder and walk right up to the screen which is projecting the 35mm camera image. Lets make an assumption that I have to be 3 feet from the movie screen. (Assuming I'm transparent <grin>) I try to make a recording of the screen. However, the screen is too big - so I change my camcorder lens to be wide-angle enough that I can get the whole thing into my viewfinder.

This is analogous to our use of a special 'macro' lens on our camcorder in order to record the ground glass, which would normally be way to close to focus on. Once I have the macro and can correctly focus on the ground glass... I'm done.

Does this make sense to anyone but me?
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Old February 20th, 2004, 04:03 PM   #233
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Jean-Phillipe,
the built in 16x lens would make any lens adapter on this thread stick out over almost 1.5 ft. (1/2 a meter?) i'm guessing. not usable under any situation. i reccomend the nikon adapter out of experience building the Agus35. the lenses are cheaper, faster, and abundant for testing and using. in the diagram above i also noted a pl lens mount, but that would be for movie lenses, you could easly do with an inexpensive nikon mount, about $30 USD, and once again with any fast nikon/nikkor lens for your primary.
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Old February 20th, 2004, 04:13 PM   #234
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Jonathan, & Tavis,
in the article here, the graphic at the very bottom shows the "white light" hitting the curved side of the achromatic lens, straightening out the light, then hitting the image plain (the gg in our case)

http://www.edmundoptics.com/TechSupport/DisplayArticle.cfm?articleid=267

in the diagram i put together, could that be incorrect, should the curved side face out and the flat side of the achromat lens face the gg?

me confused still, but i do agree maybe only one achromat would be fine, the first one. thoughts?
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Old February 20th, 2004, 04:17 PM   #235
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I see what you're saying about the one achromat but i'm not entirely convinced, but i am unsure are we trying to do 1:1 imaging here? If you read here http://www.edmundoptics.com/TechSupp...?articleid=267

It says:

Quote:
we find that 1:1 imaging can be achieved with two lenses working at infinite conjugate distances. Using two achromats with convex crown surfaces facing each other, a far superior imaging system is obtained. Spherical aberration is negligible at large apertures, with the addition of color correction.
Also if you look at figure 3 on that webpage, you see the two achromats face to face, then the image plane, ie. our GG right? so it should go
SLR > Achromat1 > Achromat2 > GG...etc...
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Old February 20th, 2004, 04:27 PM   #236
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http://www.edmundoptics.com/IOD/Disp...productid=2008 at the bottom of that page there is a couple more diagrams, do they help anyone? now i'm wondering if you're right about only using one achromat. brain hurts...
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Old February 21st, 2004, 12:41 AM   #237
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Ok, Thanks Dino!
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Old February 21st, 2004, 01:20 AM   #238
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The reason for having the second achromat

The first achromat bends the light and sends it straight down the barrel (ground glass).

The second achromat picks up that light and curves it a bit more (forming a diverging cone) and sends it straight at the ccd (point of cone).

The line and angle that the second achromat sends the light is perfectly in line with the angle at which the camera (with macro lens) is looking back at it. By perfectly matching you get the most effecient system. In other words the brightest and without any hot spots.

Remember the achromats, condensers, ext. all have to be match to the focal length of all the lenses you want to end up using.

Im so glad to see everyone working hard on this again.

Brett Erskine
Director of Photography
Premiere Visions
1761 W. La Palma Ave., Suite #302
Anaheim, CA 92801
www.CinematographerReels.com
BErskine@CinematographerReels.com

P.S. BTW good diagram Dino. Thanks for doing that. Fairly similar to my adapter. One of the changes I made was to make the barrel between the ground glass and the camera adjustable as well so its works with more than one miniDV camera. Cant forget about the DVCAM's and HD as well. On the otherside it has quick change mounts to take any still, PL, or medium format lens. There are other things too but we should focus on the achromat issue first then move on.

PremiereVisions35 adapter...coming soon.
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Old February 21st, 2004, 02:35 AM   #239
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Ack - like Tavis said: "Brain Hurts". Wish I had taken the time to go and get the masters in optics :)

Makes sense, Brett. Hard to know without experimentation. Anyone who builds one... and has learns something about the effects of abberation - good or bad - drop a note here ... I'm hoping to grab my achromats and ground glass in the next week or so, and spend some serious time with them in different positions trying to find the right combination. I've been reading too much and I can't really find a definitive answer, so I'm just going to try some things. Will post results as I have them. Looking forward to having a working model, though - the footage from others looks so nice...

Sounds like you've got one built, Brett? How's it working and what was your design?
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Old February 21st, 2004, 04:20 AM   #240
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anybody have a cheap place for acromats?
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