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Arri ST mount adapter

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Aaron Page
Arri ST mount adapter
on Apr 27, 2009 at 1:12:46 pm

I'm relatively new to video as well as this forum and wanted to know if anyone has any experience with an Arri St mount adapter for the JVC hd200. I found it on ebay for really cheap which instantly made me skeptical, but its only a ring. How bad can it be? here is a link to a site that carries it. http://www.cineadapter.com/shop/step1.php?number=612

any help and input would be greatly appreciated.


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Scott Erlinder
Re: Arri ST mount adapter
on May 28, 2009 at 3:10:45 am

Aaron,

The adapter gives you better glass but does not decrease depth of field like the "cine adapters" do- and being that the CCD chips are so small, you'll have a hard time finding 16mm lenses that give you wide angle (The widest common lens for 16mm is a 5.9 Angineux).
Look at the lens/chip relationship like a cookie cutter- the smaller the chip, the less area of the lens is used, so what was wide angle in 16mm would be a "normal" lens in 1/3" CCD



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Aaron Page
Re: Arri ST mount adapter
on Jun 16, 2009 at 2:15:26 pm

Thanks for the reply, but why would I not get a shorter DOF? Also, do you know what exactly Arri ST mount is? I assume it is Arri Standard bayonet mount. Please correct me if I'm wrong.


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Scott Erlinder
Re: Arri ST mount adapter
on Jun 17, 2009 at 11:41:56 am

The depth of field is determined on any photographic system by the imager size and acceptable circle of confusion. The only way you get around this with the mini 35 adapters is by rephotographing the image projected inside the adapter by the video camera.
JVC makes a $4000 relay lens which doesn't do that, but instead, uses a "relay" lens to squeeze the 16mm lens image down to 1/3 inch imagers, which gets you roughly 16mm depth of field. Without the relay lens, you are just putting another piece of glass on the camera, not creating a different DOF. (go here and I think you'll see what I'm describing:
http://www.snodart.com/tutorials.php )

The Arri St mount is a very old style mount (pre-bayonet, but will work in a bayonet mount) that looks like a tube at the back of the lens. Be careful though, there are some very cheap versions that are machined aluminum rather than Stainless steel- don't buy those. In the old "S", they physically rotated in the mount for focus. These will not work with adapters in newer systems. Look for Distagon and/or Planar models from Zeiss, stainless steel for the rear mount.



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Aaron Page
Re: Arri ST mount adapter
on Sep 5, 2009 at 5:43:59 pm

Hey, Never thanked you for the info. I have done a lot of reading since then, but unfortunately I got your response after I already purchased the adapter. It's pretty much useless. It is however a decent piece of machined aluminum that I may try and use as a platform to build a relay adapter.


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Averill Townsend
Re: Arri ST mount adapter
on Sep 7, 2009 at 9:50:33 pm

I just stumbled across this thread. I'm curious why your adapter is 'Useless' ? I have a new HPX300 and I would love to use an occasional Arri ST Prime or even my 'ol 12-240!

What did you do or try to arrive at your conclusion?


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Aaron Page
Re: Arri ST mount adapter
on Sep 8, 2009 at 2:44:27 am

I should rephrase what I said. It is not useless, it just didn't do what I wanted it to do. I was hoping I would be able to slap on 16mm lens and get 16mm DOF, but I have since learned it doesn't work that way. I already own some 35mm adapters, but was hoping to lose the focusing screen. So,in conclusion it's like Scott said. It will allow you to use better glass, but you won't get shallower DOF. Scott pointed out some pretty good reading on the matter and it pretty much comes down to sensor size.


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