Aperture 'OPEN' on VX2100E at DVinfo.net

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Sony VX2100 / PD170 / PDX10 Companion
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Old May 11th, 2006, 02:00 AM   #1
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Aperture 'OPEN' on VX2100E

Hello,

This is a long overdue question for me regarding my VX2100E:

When using the manual exposure ring you are able to set the aperture at 'OPEN' (just before turning on the gain).

What f-stop does 'OPEN' represent and when should it be used if ever?

The reason that I ask is that if you are using the Aperture Priority AE the widest aperture that you are able to select is f1.6 at full wide angle or f2.4 at full telephoto zoom positions - 'OPEN' is not a choice.

Also - the zoom position does not seem to affect the manual exposure setting set with the manual exposure dial i.e. at full wide angle or full telephoto zoom positions the manual exposure setting is not automatically altered or limited as it is when using the AE modes. In other words - using the manual exposure dial you are able to be at full wide angle or full telephoto zoom positions with the iris set to 'OPEN' using the manual exposure dial.

Also, strangely enough, the next available setting is f2.8 when using the manual exposure dial i.e. f1.6 and f2.4 are not available options and going the other way turns on the gain.

I have a TRV27E that also has an 'OPEN' position but my FX1E does not allow an 'OPEN' setting. Is this the very reason that the VX2100E is superior in low light conditions (assuming that you use this 'OPEN' position setting)?

Regards,

Dale.
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Old May 11th, 2006, 07:55 AM   #2
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For some reason Sony chose to display OPEN instead of the actual F-stop because (as you noticed) that number changes depending on the zoom setting. This is a design factor of the zoom lens, and every fixed lens camcorder will show this same behavior. To see what the actual iris opening is, record some footage and play back the tape with the data code option turned on.
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Old May 11th, 2006, 11:39 AM   #3
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Thanks for the reply.

I thought I had already checked that - but - you are right:

It displays 'MANUAL' and is at f1.6 / f2.4 at wide / tele - same as using Aperture Priority AE.

Thanks.

Regards,

Dale.
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Old May 11th, 2006, 01:00 PM   #4
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Boyd's right - 'open' simply means maximum aperture. This varies by a whole stop as you zoom from wide to tele, and on the FX1 it varies by a stop and a half. This does indeed help to make the 2100 more light sensitive than the HDV cam, but it's superiority in low light has more to do with the big pixels that can be used with SD.

So on your 2100, if you're shooting at 'open' at the wide end, you'll be shooting at 'open' and +6dB of gain up at the tele end - all other things being equal. The FX1 will be at +9dB if the same conditions are met, but as it's a good stop less light sensitive, it'll be at +15dB in the same conditions.

tom.
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Old May 11th, 2006, 01:56 PM   #5
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Quote:
Originally Posted by Tom Hardwick
So on your 2100, if you're shooting at 'open' at the wide end, you'll be shooting at 'open' and +6dB of gain up at the tele end - all other things being equal. The FX1 will be at +9dB if the same conditions are met, but as it's a good stop less light sensitive, it'll be at +15dB in the same conditions.tom.
Hi Tom
But does this mean video at equal quality..in view of the FX/Z1's better gain settings?

Gareth
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Old May 12th, 2006, 01:41 AM   #6
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'Video at equal quality' - well that's a difficult one Gareth.

Let's take a gloomy room. The VX/PD is at maximum telephoto, zero dB gain. In the same light the Z1 has a lens that's a half stop slower and the chips (due to their much smaller picture-elements [pixels]) are a good stop slower. The lens is noticeably less telephoto as well, so the camera will have to be moved closer to the subject.

We'll forget the aspect ratio differences for now, but you'll see that the Z1 is shooting at maximum aperture and +9dB of gain up. I know the Z1 is amazing clean in its gain-up mode, but you've only got to access the hyper gain so understand what gain is doing to your image.

Yup, it's diluting the contrast, losing the colour and adding electronic noise. The fact that small doses of gain-up aren't really noticeable is a plus, but your MPEG2 encoder sees and knows all. If you can avoid gain, so much the better for your DVDs.

tom.
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Old May 15th, 2006, 12:41 PM   #7
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2100E? What is the dif. bewteen VX2100 and the "E"?
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Old May 15th, 2006, 01:41 PM   #8
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I believe it's the PAL model, as sold in Europe....
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Old May 15th, 2006, 06:52 PM   #9
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