PDW530/DSR450/BVW400 Sensitivity Comparison

[Ralph Oshiro]

Was at a premiere tonight and had a chance to have these three cameras in the same "room" at the same time:

1. Sony PDW530 2/3" 16:9, 24PsF, XDCAM SD
2. Sony DSR450 2/3" 16:9, 24PsF, DVCAM SD
3. Sony BVW400A 2/3" 4:3, 60i, BetacamSP

In a VERY quick and dirty sensitivity test, we irised all three cameras on someone's face lit by the equivalent of a DivaLite 400. The surprising thing was that the DSR450 did NOT seem to change sensitivity when changing from 60i to 24P or 24PsF modes.

1. Sony PDW530 2/3" . . . . . . .f/11
2. Sony DSR450 2/3" . . . . . . . f/8
3. Sony BVW400A 2/3" . . . . . .f/5.6

The PDW530 was a full two stops faster than the 10-year-old Betacam BVW400A, and a full stop faster than the 2/3" DSR450 (in all modes). Again, surprisingly, the DSR450 was only one stop faster than the BVW400A. Even in 60i, with the shutter off. I'm a bit surprised by this, and hope to have the opportunity to retest the DSR450's sensitivity with the BVW400 again sometime soon. All cameras, with the exception of the DSR450 which had the same sensitivity in all scan modes, were in 60i, shutter off. Also, note that this was a very quick and dirty test--all three cameras had very different lenses mounted.

[Simon Wyndham]

The reason the 450 didn't change sensitivity in progressive scan modes is because the shutter was probably still off. To be the equivilent of a 180 degree shutter you will need to switch the shutter on, and change it to 1/48th. The sensitivity will decrease by around a stop. Same should go for the 530. My 510 retains the same sensitivity in 25PsF mode as it does in 50i mode until I turn the shutter on to 1/50th.

The 450 should have the same sensitivity as the 530. I know this might seem like a really stupid question, but you didn't accidentally have -3db gain on did you?

[Simon Wyndham]

Incidentally a good compromise between the loss of sensitivity and blurriness of movement in lower light situations when using PsF modes can be to use the 1/33th shutter. Not quite as smeary as with the shutter turned off, but not as much light loss as 1/48th or 1/50th (NTSC/PAL).

[Ralph Oshiro]

No, I checked. Yeah, I deliberately kept the shutter off to compare interlace vs. progressive "read-out" sensitivity boost, when in interlace mode. I specifically checked the gain display on the DSR450 and it was at 0dB. All shutters off. All cameras at 0dB gain.

[Ralph Oshiro]

Simon, is it possible for you to borrow a DSR450 (or whatever the UK equivalent is called) and do a more formal, side-by-side sensitivity test with your PDW5XX sometime?

[Simon Wyndham]

Yep. If the shutter was off this is why there was no change in sensitivity. Other cameras with progressive scan functions will often automatically change to a 1/48 or 1/50th shutter, thus reducing sensitivity. If you turned the shutter on on the 450 and adjusted it to the correct speed it would show the same loss of sensitivity as any other progressive camera.

The 530 should have behaved in the same way. If it didn't I am puzzled as to the reasons.

If I can get hold of a 450 I'll give it a go. Certainly I know the official specs between the PDW and DS450 is the same.

Got my hands full this weekend though with an XDCAM HD :)