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Old September 27th, 2007, 01:09 PM   #1
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Field of view crop factor of Letus Extreme?

What is the field of view crop factor of Letus Extreme?
Or is it full frame 36x24mm?

Thanks in advance,
T
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Old September 27th, 2007, 04:46 PM   #2
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Originally Posted by Toenis Liivamaegi View Post
What is the field of view crop factor of Letus Extreme?
Or is it full frame 36x24mm?
36x24 is a more-than-full-frame size. That's the size of a still camera, not a movie camera.

The Extreme can do either. You can zoom in to the proper distance to emulate a movie camera's field of view, or you can zoom out and get a frame about the size of a still camera's 36x24mm. That'll give you a wider angle, smaller grain, and shallower DOF, but it won't emulate the look of a 35mm movie camera.

But it's your choice, you can do either.
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Old September 27th, 2007, 05:06 PM   #3
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Originally Posted by Barry Green View Post
36x24 is a more-than-full-frame size. That's the size of a still camera, not a movie camera.

The Extreme can do either. You can zoom in to the proper distance to emulate a movie camera's field of view, or you can zoom out and get a frame about the size of a still camera's 36x24mm. That'll give you a wider angle, smaller grain, and shallower DOF, but it won't emulate the look of a 35mm movie camera.

But it's your choice, you can do either.
WIthout vignetting ????
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Old September 27th, 2007, 09:51 PM   #4
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I have noticed no vignetting on the Extreme at all. I haven't put it through intensive testing yet, but I have experimented with it and found it quite solid through and through.

It's possible to zoom so far out that you'll see the interior of the Letus' lens barrel; of course you have to zoom in enough to get past all that. But once you get to the ground glass and get some image from side to side, it's all good.

On the HVX I found that I could get a full-frame image at about 20mm, and a 35mm movie frame image at about 29mm. I checked the field of view of each with a tape measurer and cross-referenced the Panavision NZ DOF/AOV calculator.
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Old September 28th, 2007, 12:04 AM   #5
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That'll give you ..... shallower DOF.
I've never understood this... how does the zooming in on the gg affect the image that the slr lens is projecting onto the gg? Surely the zoom position on the camcorder can't change the dof of the image on the gg. That's like saying the image changes when you mask some of it off. The image on the gg doesn't know what the camcorder lens is doing.

Isn't the effect of image area on dof down to the design image area of the slr lens and nothing to do with how much of the image the camcorder is seeing?
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Old September 28th, 2007, 01:08 AM   #6
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Originally Posted by Andy Gordon View Post
I've never understood this... how does the zooming in on the gg affect the image that the slr lens is projecting onto the gg? Surely the zoom position on the camcorder can't change the dof of the image on the gg. That's like saying the image changes when you mask some of it off. The image on the gg doesn't know what the camcorder lens is doing.

Isn't the effect of image area on dof down to the design image area of the slr lens and nothing to do with how much of the image the camcorder is seeing?
In a relative sense, zooming in on the GG shows a smaller portion of the image and imitates a longer focal length. At longer focal lengths, all lenses tend to have apparent shallower DOF so it negates the effect of the adapter. The idea of the adapter is to allow shallow DOF at wider angles, something small-chip cameras can't do, and thus if you are able to achieve a bigger (=wider) image than intended by the lens, you are achieving shallower DOF than intended.
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Old September 28th, 2007, 01:12 AM   #7
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ummm yes I know what adapters do, I've built several. I'm saying zooming in or out on the image on the gg doesn't change the dof of the image. How could it? It's an image projected onto a piece of glass that doesn't change depending on how much of the image you're looking at.
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Old September 28th, 2007, 02:39 AM   #8
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Thanks,

When using 35mm photography lens it sure makes sense to know the crop factor as cinema size frame doesn`t give me the ultra wide views of 17mm manual photography prime lens for example. And there aren`t any classical manual slr lens available for the cropped sizes. My understanding is that when adapter takes only SLR lenses it should be known what size the frame is and if there`s a crop factor to it as user can not use 12mm cinema lens on it to get the FOW equivalent of 17mm SLR lens for example.
The Extreme truly is a great adapter.

Thanks again,
T
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Old September 28th, 2007, 10:21 AM   #9
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Originally Posted by Andy Gordon View Post
how does the zooming in on the gg affect the image that the slr lens is projecting onto the gg?
It doesn't. But changing the field of view that your camera is seeing will necessarily dictate a difference in your choice of lens or camera position.

The point was made poorly, but the idea is this: if you have a given adapter with a given lens on it, and you zoom in to VistaVision frame size on the ground glass, then for any given composition you will have to move closer to the subject as compared to the position you'd have to be in if you'd zoomed in to a 35mm movie frame size on the ground glass. It is the proximity to the subject that's changing the depth of field, not the amount of zooming into the ground glass.

The zoom setting towards the ground glass dictates the appropriate focal length you will have to select for any given composition, and it's those differing focal lengths that's going to affect the perceived depth of field.
Quote:
Surely the zoom position on the camcorder can't change the dof of the image on the gg. That's like saying the image changes when you mask some of it off. The image on the gg doesn't know what the camcorder lens is doing.
Your understanding is exactly correct.
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Old October 1st, 2007, 06:39 PM   #10
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Thanks Barry now I get it! :-)
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