Re: 50mm vs 38mm

From: Ron Toole (email suppressed)
Date: Thu Apr 08 2010 - 09:22:24 PDT

Here's a trick I learned after installing Paul Sharits' 'Shutter Interface' here at the Hirshhorn museum in washington, dc, and this came directly from the source of the equipment that was included in the purchase, which was the front element of a standard Eiki 50mm lens removed, giving the lens a focal length of approximately 25mm. Shutter Interface is four projectors running simultaneously with images overlapped and it's evident in the projection that this process (of removing the front element) is very unscientific as one of the lenses is more like 27mm but for those of you looking for a 25mm lens and having an extra 50 around this is a viable option for you.

Not much visible difference in brightness / sharpness / lens clarity when comparing the custom 50 to a 25 I had laying about, but the conditions under which this examination was performed weren't the best.

Anyone have an opinion regarding lens brightness / sharpness when removing a front element?
Ron Toole washington DC

--- On Wed, 4/7/10, Ed Inman <email suppressed> wrote:

From: Ed Inman <email suppressed>
Subject: Re: 50mm vs 38mm
To: email suppressed
Date: Wednesday, April 7, 2010, 8:04 AM

At you can download a simple lens calculator.
First click on "Manuals" on the left side of the screen, then download the calculator under the "Miscellaneous" heading.
Additionally, if some of your lenses are the older type measured in inches, you can do a simple inch to mm conversion here:

-----Original Message-----
>From: Ed Halter <email suppressed>
>Sent: Apr 7, 2010 9:10 AM
>To: email suppressed
>Subject: 50mm vs 38mm
>Simple question but I can't seem to find the answer online -- anyone 
>know exactly what percentage bigger image a 38mm 16mm projector lens 
>produces vs a 50mm? Offlist is fine if you prefer to be discreet in 
>such matters.
>For info on FrameWorks, contact Pip Chodorov at <email suppressed>.

For info on FrameWorks, contact Pip Chodorov at <email suppressed>.

For info on FrameWorks, contact Pip Chodorov at <email suppressed>.