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-   Sony XDCAM EX Pro Handhelds (http://www.dvinfo.net/forum/sony-xdcam-ex-pro-handhelds/)
-   -   Lens is a 2.8 at Full Telephoto (http://www.dvinfo.net/forum/sony-xdcam-ex-pro-handhelds/109754-lens-2-8-full-telephoto.html)

Eric Pascarelli December 7th, 2007 10:56 PM

Lens is a 2.8 at Full Telephoto
 
This is not really a big deal, but I thought I'd pass on something I noticed while doing some tests on the EX1 today.

At 81.2mm there is no measurable difference in brightness (using a grey card) between 1.9 and 2.8 on the lens.

In fact, above 25mm, at f/1.9 the brightness begins to fall off. It goes down by 1/2 stop at 32mm and one full stop at 81.2, as stated above.

Of course I'd be curious to know if everyone's camera does this or is this more pronounced on my vignette prone beauty, #122.

It's simple to do, really. Aim the camera at an evenly lit, neutral field of color (exposed so it's not clipping), turn on "Brightness Display" Start at full wide at f/1.9 and watch the number on the brightness display as you zoom in. It should start to go down at 25mm if your camera is like mine. When zoomed all the way in, at 81.2, close the stop to 2.8 and see if the brightness number changes. Mine does not.

Piotr Wozniacki December 8th, 2007 07:21 AM

This is what Simon was reporting, as well. Strange though that specs do not reflect it, and I take it the aperture reading doesn't change, either?

Would Sony think they could hide an obvious ramping like this? Strange...

My V1E ramps from 1.6 to 2.8, but over the much longer (20x vs 14x) zoom range!

Eric Pascarelli December 8th, 2007 09:23 AM

Piotr,

At full telephoto the aperture reads T1.9 on the display even though it does not seem to open that wide (in terms of light transmission).

Chris Hurd December 8th, 2007 10:20 AM

I guess we need to revisit this thread then?

Re: http://www.dvinfo.net/conf/showthread.php?t=109110

Piotr Wozniacki December 8th, 2007 10:29 AM

Chris,

I guess it's possible that Alexander based his opinion on the aperture read-out as presented on the LCD/EVF; in consistency with the specs, it does *not* change while zooming in. Of course we still only have two persons reporting it actually does ramp; I cannot confirm it as I'm still waiting for my EX1.

What I don't understand is that if Sony could openly admit the ramping with the V1, why not with the EX1?

Brian Drysdale December 8th, 2007 10:58 AM

Quote:

Originally Posted by Piotr Wozniacki (Post 789274)
Chris,

I guess it's possible that Alexander based his opinion on the aperture read-out as presented on the LCD/EVF; in consistency with the specs, it does *not* change while zooming in. Of course we still only have two persons reporting it actually does ramp; I cannot confirm it as I'm still waiting for my EX1.

What I don't understand is that if Sony could openly admit the ramping with the V1, why not with the EX1?

Almost all the manual zoom lenses used on the high end cameras ramp. However, the specs given for these lens make no mention of it occurring.

With the demand for constant aperture lenses for HD dramas etc. there have been zoom lenses manufactured with this feature. However, the lenses are much larger than the traditional video zooms, which are a compromise in size, wieght and cost due to the market demand for these features.


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