A7S banding at higher iso

[Michael Markey]

Hi ,I`ve searched the various threads here (well most of `em) and can find no ref to what I`m experiencing at higher iso with my A7S.

There`s a definite banding evident.
Wonder if anyone has any ideas.

Thank you in anticipation.

 

[sevo]

It is the regular artefact that appears whenever a rolling shutter is used at high shutter speeds (narrow slit width) with a AC grid powered lamp with no (or small) afterglow (like discharge lamps, or LED lamps with a low grade transformer).

Pro studios, motion picture stages etc. use "flicker-free" illumination to stay clear of that effect - but that stuff is heavy and expensive (where mobile, usually transported by truck and installed by a crew of experts).

Blame George Westinghouse for the AC, and hold your breath until non-rolling electronic shutters make it into SLRs (as of now, you will only find professional quality non-rolling shutters in video and motion picture cameras). For now, use long exposure times (1/30s or longer) when confronted with artificial light of questionable quality.

 

[Michael Markey]

Thank you so much.
I thought it looked like a shutter artifact and had some notion that lighting might be playing its part but beyond that hadn`t a clue.

I can still handhold at 1/30 🙂

 

[Larry H-L]

If you are using the silent electronic shutter, try switching to the fully mechanical shutter and it may eliminate some of the banding. For some reason, the Sony a 7S shows much more banding than my Panasonic micro 4/3 cameras, in the same lighting situation.

I once asked a Sony representative about this problem, and they suggested that upgrading to the latest firmware may help somewhat.

 

[Alfonso B]

That's what they say when they have zero clue, fw update isn't going to help. Edit🙁 it might help with electronic shutter). Mechanically your micro 4/3:rds shutter curtain has to travel a shorter distance so smaller percentage of shutter actuation time is spent with one of the curtains partially blocking the sensor. It might even have a faster curtain speed because shutter has less mass.

 

[Michael Markey]

Thanks Larry .... I am indeed using the silent shutter mode .
I`ll check the firmware status ....cheers.

 

[willie_901]

Electronic shutter usage has significant disadvantages. While electronic shutter technology is steadily improving, using the ES with existing still-cameras should be a last resort. Sooner or later, gratuitous ES use will cause disappointment.

The banding seen above is common with ES use and is caused by modulated light sources such as fluorescents (particularly older fixtures), some LEDs (usually those with color control) and certain types of indoor arena lighting. I don't think this type of rolling shutter banding has anything to do with ISO.

Another source of banding is sensor fixed pattern noise causes banding. Fixed-pattern noise is always present in all cameras. Fixed-pattern noise becomes more obvious as the signal level (exposure) decreases. So, fixed-pattern noise will become visible as ISO increases. Firmware updates can minimize banding effects from fixed-pattern noise and other correlated sensor noise sources that have nothing to do with the ES.

To be complete, it is possible high frequency electronic interference from ES circuitry could cause fixed-pattern noise artifacts. It is also possible firmware could change the interference signals' characteristics. I think this is unlikely.

 

[mcfingon]

I can confirm I've seen the banding on my A7S with some types of artificial light with the silent shutter. It doesn't happen often, luckily. Sony are claiming that the new A9's faster electronic processing has almost eliminated the rolling shutter effect, so maybe that will get rid of the banding too. I doubt that firmware changes on the A7S will solve the problem.

 

[sevres_babylone]

I have the A7SII and also have seen banding at times with high ISOs. Thank god for chimping🙂 In one instance, it was, I think, in a situation where there flickering fluorescents our neon; the other was where there was pulsating stage lighting. The first was more subtle, and I actually didn't notice the banding till afterwards. I continued using the silent shutter and the rest of the shots were okay. So a bit of a mystery. The second time, I did chimp and noticed it after a couple of shots. I did switch away from the silent shutter. I guess if the music is so loud I need earplugs, I don't really need the silent shutter anyway🙂

 

[Michael Markey]

Thanks for the responses chaps .
I`m going to be careful in future when and where I use that silent shutter

 

[willie_901]

...The first was more subtle, and I actually didn't notice the banding till afterwards. I continued using the silent shutter and the rest of the shots were okay. So a bit of a mystery. ...

Not much of a mystery but there are several variables which makes it difficult to predict when ES artifacts will be problematic.

The amount of light from modulated sources plays a big role. So changing the composition can make a difference. If the modulated light is reflected, a small change in angle might be important.

The light source modulation rate and the shutter time affect the banding. So even a small change in shutter time might have an effect.

Things get more complicated when the light modulation rate changes or when there are two sources with different modulation rates. Contemporary LED venue lighting creates different colors by changing the electrical current ratios of red, green and blue LEDs using modulation. So when color changes the modulation responsible for the banding changes.

Increasing ISO increases both the signal and the noise amplitudes after the shutter closes. So ES banding is independent of ISO.

Banding from coherent electronic camera noise is different. When ISO is low (and you do what the meter tells you to do) the exposure is high. More light hits the sensor. This means the signal-to-noise ratio is high. Now the coherent electronic noise levels are much lower than the light signal levels. The noise responsible for the banding is not digitized.

As ISO increases, exposure decreases. At some point the coherent electronic noise levels becomes similar to the light signal levels. Now the banding artifacts are digitized.

 

[sevres_babylone]

Not much of a mystery but there are several variables which makes it difficult to predict when ES artifacts will be problematic....

Thanks for taking the time to give this detailed explanation.

 

[Michael Markey]

Thanks from me also for the detailed explanation ...
I seem to have solved the problem by switching to the normal shutter rather than the silent shutter.

So far ,so good.

 

[willie_901]

To both Serves and Michael - I appreciate your follow up messages.