Fred Miranda Offline Admin Upload & Sell: On
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Continuing our discussing on this subject that started here.
It's documented on the Sony's A7RII Help guide that resolution is limited to 12 bits when using the following shooting modes:
*My commentary below the modes.
- Silent Shooting
*I would turn this mode OFF for critical work
- Long Exposure NR (when the camera automatically captures a black frame after the exposure)
*I would turn this mode OFF and capture a black frame instead
- Bulb (more than 30 sec. exposure)
*Once you pass 30 seconds your files will gain 1-stop more noise and have 1-stop less dynamic rage. If you are doing Nightcapes and need ISO 400 or higher, the noise increase from the bits reduction will be unnoticeable according to the article below. Another workaround is to take several 30-second exposures and stack them in Photoshop as Smart Object –> Stack Mode -> Summation. So (2) 30-seconds stacked this way will end up looking the same as a 1-minute exposure.
- Continuous Shooting. (Including Bracketing continuous shooting)
*When using Bracketing, do not set the camera to continuous shooting
Jim Kasson put this to test with the A7II and was able to verity something that we had suspected from the initial A7RII online samples. 12 bits will make your shadows worse by about 1 stop and the image will also lose about 1-stop of dynamic range. It's very noticeable when recovering shadows in post-processing.
Here is an excerpt from the article:
"When the shutter is not set to bulb, and the shutter mode is set to continuous drive, speed-continuous drive, continuous bracketing, A7s’s silent shutter, and any possible combination of these, the linear, pre-tone-curve, bit depth of the camera is 12 bits. With all other settings, including single bracketing, the linear bit depth is 13 bits.
The loss of precision associated with the affected shutter modes causes an increase in the read noise by about one stop, a decrease in the dynamic range by about a stop, and more shadow noise, as can be seen in this photon transfer curve of the a7II’s performance in the two modes."
Read Full Article
For landscape photography the only real issue will be Bulb mode as other modes can be avoided. The good news is that the loss of precision associated with the Bulb shutter mode can only be really noticed at base ISO. The higher the ISO setting the less noticeable this side-effect will be since there is little analog read noise to dither the ADC signal.
Your thoughts?
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