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Archive 2015 · A7RII 12-bit mode. How to avoid it.

  
 
flash
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p.2 #1 · p.2 #1 · A7RII 12-bit mode. How to avoid it.


vario1 wrote:
Snapsy
Can you give me an example where Sony is actually packaging a non-native lens adapter with the camera, not the camera store?
I have yet to see that, but, YMMV.


In Oz we get a choice of a free adaptor by redemption from Sony. We choose between the LEA3, LEA4 or a selection of metabones adaptors. Each body comes with a card in the box. It's not available with kits (eg: A7+28-70kit).

Gordon



Aug 03, 2015 at 03:11 PM
pcho
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p.2 #2 · p.2 #2 · A7RII 12-bit mode. How to avoid it.


retrofocus wrote:
It was done with the original A7 series in Australia (with Metabones III adapter) - unfortunately not here in the US or in Europe.


I was a late adopter to the A7 series and by the time I purchased the A7r and the A7s I got Metabones lV for both of them for free here in Aust.
Perry



Aug 03, 2015 at 03:16 PM
jamato8
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p.2 #3 · p.2 #3 · A7RII 12-bit mode. How to avoid it.


Fred Miranda wrote:
True, I went through 3 adapters to find a centered one. Reminded me of the pain of buying a Samyang lens.


Has there been the issue of off center with the Metabones IV that you know of?



Aug 03, 2015 at 03:29 PM
jhinkey
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p.2 #4 · p.2 #4 · A7RII 12-bit mode. How to avoid it.


By "centered" do you really mean that the mounting flanges are not parallel?

I had a cheap Fotasy F to E mount adapter that had perfect parallelism (to less than 0.0001 inch variation in flange-to-flange distance at any point) while my much more expensive Metabones F to E mount adapter was off by up to 0.002 inch along one side.



Aug 03, 2015 at 03:41 PM
jhinkey
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p.2 #5 · p.2 #5 · A7RII 12-bit mode. How to avoid it.


Fred Miranda wrote:
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.
  1. Silent Shooting
    *I would turn this mode OFF for critical work

  2. 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

  3. Bulb (more than 30 sec. exposure)
    *There is no way around this one. Once you pass 30 seconds your files will gain 1-stop more noise and 1-stop less dynamic rage. If you
  4. 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, A7sís 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 a7IIís 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?
...Show more

These are good examples of those "little" things that Sony needs to fix before they can seriously threaten my D800 for high dynamic range shooting. I use all those except continuous shooting and want the max. dynamic range. I would be much happier if Sony did not include 4K, stayed at 36MP, added all the goodies that it did, and was able to have true 14bit in any of those above modes.


Aug 03, 2015 at 03:48 PM
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p.2 #6 · p.2 #6 · A7RII 12-bit mode. How to avoid it.


Metabones is expensive for its build quality and features. I don't believe they have a good quality control. (tolerance)

How do you test 0.0001 to 0.002?

My tests have been with resolution charts mounted perfectly parallel to the sensor. When the adapter mounting flanges are not perfectly parallel, it's very noticeable on some extreme edges.



Aug 03, 2015 at 03:49 PM
jhinkey
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p.2 #7 · p.2 #7 · A7RII 12-bit mode. How to avoid it.


Fred Miranda wrote:
Metabones is expensive for its build quality and features. I don't believe they have a good quality control. (tolerance)

How do you test 0.0001 to 0.002?

My tests have been with resolution charts mounted perfectly parallel to the sensor. When the adapter mounting flanges are not perfectly parallel, it's very noticeable on some extreme edges.


Uh, I measure it with a 0.0001" accuracy micrometer . . .



Aug 03, 2015 at 03:52 PM
hiepphotog
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p.2 #8 · p.2 #8 · A7RII 12-bit mode. How to avoid it.


jhinkey wrote:
By "centered" do you really mean that the mounting flanges are not parallel?

I had a cheap Fotasy F to E mount adapter that had perfect parallelism (to less than 0.0001 inch variation in flange-to-flange distance at any point) while my much more expensive Metabones F to E mount adapter was off by up to 0.002 inch along one side.


Count yourself lucky. There were talks back in the day how Metabones was trying to get as close as possible, but I guess their machines can't. Phigment adapter maker also shared his experience on how to get these adapters in spec, and generally, it's not easy. You also have to consider your camera mount-to-sensor and lens-to-mount parallelism as well.



Aug 03, 2015 at 03:53 PM
hiepphotog
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p.2 #9 · p.2 #9 · A7RII 12-bit mode. How to avoid it.


jhinkey wrote:
These are good examples of those "little" things that Sony needs to fix before they can seriously threaten my D800 for high dynamic range shooting. I use all those except continuous shooting and want the max. dynamic range. I would be much happier if Sony did not include 4K, stayed at 36MP, added all the goodies that it did, and was able to have true 14bit in any of those above modes.


I think with the current technology, Sony is forced to do those because of the smaller, thinner profile of their tech-packed A7 body. Space and heat are always the issues. IIRC, the A99 doesn't have this downgrade problem in some of the above modes, either the continuous shooting or bulb above 30sec.



Aug 03, 2015 at 04:05 PM
johnctharp
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p.2 #10 · p.2 #10 · A7RII 12-bit mode. How to avoid it.


hiepphotog wrote:
I think with the current technology, Sony is forced to do those because of the smaller, thinner profile of their tech-packed A7 body. Space and heat are always the issues. IIRC, the A99 doesn't have this downgrade problem in some of the above modes, either the continuous shooting or bulb above 30sec.


For all of the reasons for Sony to implement a degraded capture mode (and for all of the reasons they hard-wired lossy compression), there's still literally no reason for them to not include the option to disable these functions and let the photographer deal with the inconvenience of having to wait on the camera to chew through each shot a bit longer while making the maximum quality that the sensor is capable of available.

Every time I read about one of these issues, I remember that neither Nikon (with Sony's sensors!) nor Canon (also with Sony's sensors!) do this.



Aug 03, 2015 at 04:21 PM
AmbientMike
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p.2 #11 · p.2 #11 · A7RII 12-bit mode. How to avoid it.


It's easy to freak out over stuff like this, but I got some really nice stuff shooting jpegs, which are 8 bit, I believe, on a Rebel XT. I don't think the RAW was that hot on that camera, and the cards were smaller then, so I didn't want to shoot RAW.


Aug 03, 2015 at 04:30 PM
tn1krr
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p.2 #12 · p.2 #12 · A7RII 12-bit mode. How to avoid it.


hiepphotog wrote:
I think with the current technology, Sony is forced to do those because of the smaller, thinner profile of their tech-packed A7 body. Space and heat are always the issues. IIRC, the A99 doesn't have this downgrade problem in some of the above modes, either the continuous shooting or bulb above 30sec.


A99 has the very same limitations as current A7-series, see page 140 in A99 manual below

https://docs.sony.com/release/slt-a99_a99v_handbook.pdf



Aug 03, 2015 at 04:51 PM
hiepphotog
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p.2 #13 · p.2 #13 · A7RII 12-bit mode. How to avoid it.


tn1krr wrote:
A99 has the very same limitations as current A7-series, see page 140 in A99 manual below

https://docs.sony.com/release/slt-a99_a99v_handbook.pdf


My bad, I mixed it up with the lossy compression. A99 is the only current Sony FF with lossless 14-bit raw. And there goes my theory about hardware limitation due to size .



Aug 03, 2015 at 04:59 PM
tn1krr
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p.2 #14 · p.2 #14 · A7RII 12-bit mode. How to avoid it.


hiepphotog wrote:
My bad, I mixed it up with the lossy compression. A99 is the only current Sony FF with lossless 14-bit raw.

RAW format is ARW 2.3 in SLT-A99, the very same lossy-compressed as in current A7-series. All SLT-cameras have the compressed RAW. A900/A700 had lossless but they were 12-bit () only




Aug 03, 2015 at 05:05 PM
RobDickinson
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p.2 #15 · p.2 #15 · A7RII 12-bit mode. How to avoid it.


Sony, always a gotcha sadly. Owned and run by engineers who think this kind of thing is good enough.

Will stick with my a7r (I know..)

and yes I got a free metabones mk4 from Oz.



Aug 03, 2015 at 05:09 PM
Pixel Perfect
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p.2 #16 · p.2 #16 · A7RII 12-bit mode. How to avoid it.


Fred Miranda wrote:
Long exposures are not affected. Only when they exceed 30 seconds (Bulb mode)
In Bulb mode, base ISO makes the bit reduction more noticeable as the article demonstrated. So actually we should avoid shooting at base ISO in Bulb mode.



But if I want to shoot say a twilight seascape with very long exposure say 3 minutes and I need base ISO to achieve that, then what? It's rare I'd use bulb with a high ISO, but maybe I don't use it enough.



Aug 03, 2015 at 05:49 PM
goto_dengo
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p.2 #17 · p.2 #17 · A7RII 12-bit mode. How to avoid it.


Fred Miranda wrote:
*Shoot at ISO 400 or higher where the effects of precision loss won't be as noticeable.


I'm not sure this makes sense.

The effects won't be noticeable, because by dropping to 400 ISO you're introducing the very things you're trying to avoid with 12-bit mode--diminished dynamic range and increased noise!

The reason, in other words, 12-bit appears to exact no penalty at 400 ISO is precisely because 400 ISO quality has already fallen off significantly from 100 ISO. The A7R has 14 stops of DR at 75 ISO; at 400, it has just 12. Noise is significantly higher at 400 as well. No thanks.

So there appears to be no way to get top notch, base-ISO noise and DR with bulb. So, bulb is basically out. The others can be avoided, but for super long exposures, there's no great answer.



Aug 03, 2015 at 06:02 PM
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p.2 #18 · p.2 #18 · A7RII 12-bit mode. How to avoid it.


Pixel Perfect wrote:
But if I want to shoot say a twilight seascape with very long exposure say 3 minutes and I need base ISO to achieve that, then what? It's rare I'd use bulb with a high ISO, but maybe I don't use it enough.


The 12-bits Bulb limitation is indeed a big deal for landscape photography. What if I want to capture an image in very low light with a strong ND filter? It's easy go into Bulb territory.
For night photography it gets better because we always bump ISO and the noise increase would not be as apparent because we would have more analog read noise to dither the ADC signal. However, there will always be more read noise by about one stop, a decrease in the dynamic range by about a stop, and with that, more shadow noise.

This is not something new to the A7RII as all previous A7 series bodies have the same limitation. At least Sony documented this issue instead of just reducing the bits and stay quiet about it. Photographers can now decide if this camera or any other A7 series camera suit their needs.



Aug 03, 2015 at 06:13 PM
RobDickinson
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p.2 #19 · p.2 #19 · A7RII 12-bit mode. How to avoid it.


Almost all my long exposures are ISO 100 or 200.

Bumping ISO to 400+ to avoid the issue just means I will be limiting either my shutter length or my dynamic range (again) by higher ISO.



Aug 03, 2015 at 06:21 PM
snapsy
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p.2 #20 · p.2 #20 · A7RII 12-bit mode. How to avoid it.


Not sure what technical reason Sony has to switching to using 12-bits for bulb exposures. Might have something to do with DSNU or hot pixels though not sure why those would warrant 12-bit operation.


Aug 03, 2015 at 06:31 PM
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