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Old March 22nd, 2008, 10:08 PM   #1
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Super Duper Zoom with MTF adapter and Nikon lens...Why?

Is there anywhere in here where I can learn why when I use a 50mm with a MTF adapter ( or as a matter of fact any lens ) it becomes a super zoom lens?

I quite dont get it. Is there a comparison chart that says like:

MTF + 50mm nikon lens = 300mm, 400mm or 500mm?

Thanks
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Old March 23rd, 2008, 05:20 PM   #2
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The 50mm Nikon lens is designed to work with a 35mm stills camera and focus it's image onto an area the size of a 35mm film frame.
A JVC HDPro camera has 1/3'' CCD chips, a much smaller frame area. Imagine cutting a the surface area of a 1/3" CCD out of the centre of a 35mm film frame, that is what you see on the video camera.
The MTF adaptor is a mechanical adaptor that allows you to mount different manufacturers or other format lenses to your camera by converting the lens mount, they do not change the optical characteristics of the lens.
The P & S Technik, Letus etc. converters work by focusing a 35mm format image onto a focusing screen (similar to a SLR viewfinder focusing screen) within the mechanism. This focus screen image is then recaptured by the standard lens on your camera (or an intermediate lens in the case of the P & S Technik).
The JVC HZ-CA13U uses optics within the adaptor to convert the image to a 16mm film format size on the 1/3" CCD chip.
What you will see with the MTF is the same as if you zoomed your standard lens to 50mm. These adaptors work fine if you want a tele lens but are not suitable for wide angle situations.
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Old March 24th, 2008, 05:29 AM   #3
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So, you walk down your local cinema with the largest flat screen you can carry. You stand your TV in front of the big silver-screen, but it is small in comparison. The projector fires up and throws an image that covers the whole cinema screen. Only a portion of the image hits the TV.

Your TV screen is the sensor in your 1/3 inch camera. The cinema screen is the focal plane on a 35mm camera. The projector is your choice of 35mm lens of any focal length.

Light travels in straight lines.

Hope that helps.
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Old March 24th, 2008, 09:35 AM   #4
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thanks guys for such great explanation. What would happen if you used a wide lens...like a 18mm...still same deal right?
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Old March 24th, 2008, 11:18 AM   #5
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Originally Posted by Charles Barreto View Post
thanks guys for such great explanation. What would happen if you used a wide lens...like a 18mm...still same deal right?
It would have a similar FOV (field of view) as a 126mm lens in the 35mm (135) still camera format.

The crop factor for these type of adapters on a 1/3 inch chip camera is around x7. Thus, a 50mm has equivalent FOV as a 350mm. A 100-400 zoom becomes a 700-2800mm.
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Old March 25th, 2008, 09:42 AM   #6
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Keep in mind though, Charles, that an 18mm, 35mm still lens on your 1/3" chip video camera gives you the exact same FOV as your video camera's stock lens set at 18mm.
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Old March 25th, 2008, 12:16 PM   #7
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so pretty much I grab any Nikon lens and multiply it's mm by 7 and that would be the true equivalent in mm?

Also...I don't gain anything by using a nikon lens right? No awesome D.O.F?
is it better to use the Fujinon lens then...maybe it is better equipped to do HDV?
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Old March 25th, 2008, 12:55 PM   #8
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Originally Posted by Charles Barreto View Post
so pretty much I grab any Nikon lens and multiply it's mm by 7 and that would be the true equivalent in mm?
Only bother with the multiplication factor/cropping factor if you have been shooting still photos for years (35mm) and you are more comfortable thinking in those terms.

The important thing to remember with a mechanical mount is that a lens is a lens. Focal length is focal length, whether that lens is mounted on a video camera, cinema camera, IMAX camera, DSLR camera, whatever. You are still projecting an image onto a CCD, film gate, CMOS sensor and it is the size of that imaging device that determines how much of the projected image is captured. (The exception to this rule is the use of adapters like mini35/M2/Letus/Brevis/MovieTube/COPLA that 're-photograph' a projected image with a relay lens.)

The 1/3" CCD found in the ProHD cameras is smaller than your baby fingernail! Imagine taking a 35mm film negative you shot with a 50mm lens and then cropping it to that tiny size. That in essence is what happens when using small CCDs.

I've attached a graphic I created last year to demonstrate the differences in various formats. If you print it out at 1:1 the "actual format sizes" section should be accurate. Keep in mind that 35mm film SLR cameras frame the film on its side so the image size is even bigger than Super-35 cinema frame.

Quote:
Also...I don't gain anything by using a nikon lens right? No awesome D.O.F?
is it better to use the Fujinon lens then...maybe it is better equipped to do HDV?
You gain a vast assortment of long focal length Nikon lenses available around the world. A few of our members have shot beautiful long-lens nature films with 200mm or 300mm lenses mounted to a HD100.
DoF characteristics of any lens you mount with a mechanical mount adapter will be virtually identical (except for variances due to the sharpness of the lens.)
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Super Duper Zoom with MTF adapter and Nikon lens...Why?-01-relative_frame_size.jpg  
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Old March 25th, 2008, 12:58 PM   #9
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Quote:
Originally Posted by Charles Barreto View Post
so pretty much I grab any Nikon lens and multiply it's mm by 7 and that would be the true equivalent in mm?

Also...I don't gain anything by using a nikon lens right? No awesome D.O.F?
is it better to use the Fujinon lens then...maybe it is better equipped to do HDV?
No, the DOF wont change if you stick a 35mm nikkor or anything else on your cam. 18mm will be 18mm - all that changes is the FOV.

What you need to create the film like shallow DOF that I think you are after is a lens adapter like the one's made by P&S Technic, MovieTube, Red Rock and all the others - not forgetting the optical adapter from JVC mentioned above (probably the best of the lot).

Ha ha, must type faster, see above for a better explanation.
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Old March 25th, 2008, 01:15 PM   #10
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Quote:
Originally Posted by Charles Barreto View Post
is it better to use the Fujinon lens then...maybe it is better equipped to do HDV?
Depends on which Fujinon lens you are talking about. But even the 16x, in my opinion, is better "in it's comfort zone." For example from 10 to 50mm, shooting typical scenes without challenging conditions, you'll have a hard time beating it with any Nikon lens mounted. But, aim that same lens at a high contrast subject, in the same range, and you might start reaching for other options. CA is a big issue with the 16x (among other things).
Basically, the Nikons are far better, for specific shots. But the 16x is much more versatile. I use both - the 16x for up to 50mm, and for typical lighting conditions - the Nikons for over 50mm, and for very challenging lighting conditions where the 16x falls apart.
You'll see. While the lens "says" 16x on it, it's really more of a 9x.
My choice setup, for what I shoot, would be the 13x and an MTF adapter with a bag of Nikons.
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