On the Road with the HVR-V1U, Part 8

My “V1-FX7 Handbook” is selling very well (www.knowledge-download.com/V1-FX7), but for those of you who haven’t yet bought it, in this report we will see how much gain we can use without introducing noise when shooting with a V1 or FX7.

 

Minimum V1 and FX7 sensitivity is rated at 4-lux; 1-lux lower than the CCD based Z1 and FX1. What is the reality of this sensitivity? There is a movie screen in the upper-right corner of this screenshot of a restaurant in Malaysia. Although the screen was very dim, the V1 captured it. And, note the bright yellow sign did not blow-out. This is a perfect example of how wide latitude supports high picture quality.

 

Video gain can be set to 0, 3, 6, 9, 12, 15, and +18dB. There is, however, no simple relationship between gain and noise because noise is typically visible only in medium dark areas. I found I could use +9dB gain without adding noise—although in many situations I used +15dB, as shown below.

 

 

 

Below you can see how dark the scene actually was.

 

 

 

 

 

 

 

 

 

 

 

 

If one wants no noise added, limiting gain to +6dB is the correct tactic. However, the histogram shows the signal bunched-up against the left-edge and not reaching much past the mid-point. This is not a good quality video signal. And, you can see the frame really doesn’t look great.

 

 

 

The histogram shows the highest signal point is almost near the right edge. You can see the frame looks better. Noise it very low.

 

 

The histogram shows the highest signal point is at the right edge. This is a much better quality video signal. And, you can see the frame looks good. Noise it still low.

 

This is the gain set by the camera’s AE system. Even in this situation, using automatic functions produces an optimal image. Interestingly, this is the gain I would have set using the camcorder’s on-screen histogram.

 

 

 

Pushing gain to +15dB reveals more shadow detail. The histogram shows the highest signal point is now above 100IRE. Noise appears primarily in shadow areas so if there is action in the brighter areas, an audience will likely not see the noise. Noise is moderate.

 

 

 

At 18dB, the image is about as bright as the human eye sees it. The histogram shows the highest signal point is well above 100IRE. The excessive image noise appears primarily in shadow detail, so you can engage Black Compress to push dark shadows into black so noise will be less visible.

 

If, as in the scene I was shooting in a night market in Malaysia, there is little rapid movement, you can decrease shutter-speed so the CMOS sensors have more time to gather light. By dropping the shutter-speed by half, 6dB less gain need be used.

 

A wide shot is best when you need to lower shutter-speed. (The smaller a moving object, the lower its “motion vector.” That simply means objects will move less within the frame, which will reduce motion blur from the slower shutter.)

 

Also, do not pan or zoom at slow shutter-speeds. And, if at all possible, use a tripod.

In Report #9, we will learn more about White balance.

 

 

Steve Mullen owns Digital Video Consulting that offers eBooks on HD production. Currently, DVC (www.mindspring.com/~d-v-c) offers three eBooks: the Sony HVR-V1 and HDR-FX7 (Review, Specs, Recent News, $2599) Handbook, the Sony HDV Handbook, and the JVC ProHD Handbook. In July, DVC will offer A Guide to Low Cost HD DVD Production.