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Old June 24th, 2010, 04:43 AM   #1
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Lenses

Hi can somebody explain the difference in Lenses

for example a 400mm and 18mm

I no about wide angle small the mm wide the angle shot is :)

Thanks
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Old June 24th, 2010, 04:56 AM   #2
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I think there's a book in there, but try these:

Photographic lens - Wikipedia, the free encyclopedia

Photographic lens design - Wikipedia, the free encyclopedia
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Old June 25th, 2010, 12:17 PM   #3
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Ollie:

As you likely know, the smaller the number, the wider the field of view for the lens. A better question is how do these lenses affect the video shoot?

If you have a video camera with 1/3-inch or smaller chips, you have a great deal of depth of field--nearly everything looks in focus. Using a telephoto lens can help separate your subject from the background and give you some depth. You just have to back up a bunch.

However; camera movement during shooting is very distracting when the video is viewed. A wider lens helps reduce camera jiggle. A telephoto lens greatly increases the likelihood of motion, so you need to avoid hand held shots at telephoto ranges, and use a good fluid head tripod that can easily support the weight of the camera and lens.
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Old June 25th, 2010, 12:41 PM   #4
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Good advice here.

I'd just note, that even the smallest sensors can be forced into a "shallow depth of field" when the conditions are right.

Anyone who's ever had to videotape a school play will have run into a situation where the lighting on a particular subject (like a child at the end of the stage) is dim, the camera position is forced to the back of the audience and even if you steady the shot on a tripod, after zooming into almost the end of the lenses reach, you're left with an uncomfortably shallow depth of field where it's difficult to keep your subject in focus.

Both the dim lighting on stage - combined with zooming in full - both work together to keep the aperturre wide open and create the narrow zone of focus.

Hope that helps clarify things.
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Old June 26th, 2010, 12:40 PM   #5
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thanks guys

hows the letus lens? is it good?

I currently have a z1 i do however a wide angle 0.7x lens.

What lenses can fit this camera? screw fits?

because z1 doesn't have interchangeable lenses unlike the z7

Thanks :)
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Old June 26th, 2010, 11:04 PM   #6
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Ollie:

Yes you are stuck with the base lens on a Z1U...which actually zooms in pretty far. A wide angle adaptor is a nice addition. I've got the the Century Optics pro series HD .7x on my Z1U, along with a filter-holding sunshade.

You can get a lens extender to make the focal length longer, but I've never heard a lot of raves about the video that way.

A Letus does work with the Z1, but it is reportedly a bit fussy and fiddly to get used to, and it will subtract some of the light sensitivity. But it gets great results once you dial it in.

Before going with a Letus, though, I'd try some experiments with zooming in a bit, and engaging one of the two ND filters on the camera, so that you are shooting with the f-stop as wide open as you can. Those two things--longer focal length and f2.8 or smaller iris-- will do a lot to shallow up your depth of field.
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