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lens change on hvx w/ 35 adapter


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#1 odin wadleigh

odin wadleigh

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Posted 19 July 2007 - 12:29 AM

I am going to shoot a music video with the hvx 200 and redrock adapter with 35mm lenses.
I heard it takes awhile to switch lenses on that camera, since the adapter goes on the end of the camera's lens. something to do with having to always adjust the backfocus?
I like to constantly change lenses while shooting and am worried this whole system might bog the shoot down.
how long should a competent AC be ablet to change lenses on that system?
thanks
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#2 Daniel Hamilton

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Posted 21 July 2007 - 07:14 AM

I am going to shoot a music video with the hvx 200 and redrock adapter with 35mm lenses.
I heard it takes awhile to switch lenses on that camera, since the adapter goes on the end of the camera's lens. something to do with having to always adjust the backfocus?
I like to constantly change lenses while shooting and am worried this whole system might bog the shoot down.
how long should a competent AC be ablet to change lenses on that system?
thanks


Should be fairly fast. You shouldn't have to adjust the "back-focus" (I assume you mean the focus of the HVX-200's built-in lens) at all when switching lenses, because you're focused on the ground-glass inside the adapter itself, which shouldn't be moving during lens changes if you've set the whole thing up properly; it's threaded onto the front of the HVX, so heat expansion should be the only factor in changing that focus. That said, it's always a good idea to check your ground-glass focus often. Personally, after every focus check I tape down the focus ring so that it can't be bumped during the middle of a shot.

Make sure you have a VERY nice monitor; this is critical for all of these 35mm adapters. You really need the monitor to be sure that you've got your focus right on the ground-glass; on the camera onboards it's damn near impossible to tell precisely. Also, make sure that your AC knows to focus on the FRONT of the ground-glass (farthest from the camera), not on the back. This is where the image thrown by the 35mm lens will land, and the ground-glass disc itself is about 1/8" thick, enough to ruin your day if you're not careful.

Also note that even with everything precisely calibrated, your image WILL be just a bit soft. You're shooting a ground-glass, not through pure optics. You're also macro-focusing like a madman to get focus on the ground-glass, so keep in mind that your plane of focus at that short a distance is not actually a plane. It's spherical, and you can see this in your image. The edges of your frame WILL be softer than the center. There's no way to avoid this with these adapters, except by closing down a couple stops. But if you're going to do that, you lose all the depth of field you spent all that money on those 35mm lenses for anyway.

Don't blame your AC. :)
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