a7rii long exposure color noise - quick rudimentary test

[bbphoto]

I had read about these Chinese tests and a few others indicating poor performance by the new camera with long exposures. This concerns me as I do a bit of nighttime astro and landscape stuff. I wanted to check it out before getting to bed so here's a couple RAW crops showing what I think is chroma noise in shadows. You can see my adjustments on the right. I haven't really seen such noise before. Not sure what's causing this, but I hope it's something that can and will be addressed via firmware. I never had anything like this with my Nikon. The JPEG versions, i'll note, are so compressed that banding happens far sooner than would have on the Nikon /:

 

 

[bbphoto]

Here's same shot at ISO 800 rather than 100. After pushing both files, I found that the perceived chroma noise is fairly equally pronounced.

 

 

[bbphoto]

Crop from last shot (800 iso) for reference:

 

Honestly, everything looks great so far except this chroma noise. Really hope it's addressable. It's not quite a deal-breaker, but it's close (not sure i have a choice at this point anyway)!

[itsskin]

Any chance to see the pictures?

[bbphoto]

Apologies! I uploaded a minute before going to sleep and thought the images uploaded. 

 

 

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[bbphoto]

ISO 800 and zoomed crop here.

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[itsskin]

Thank you! Were they shot with NR on or off?

[bbphoto]

@itsskin, NR and LE NR turned off. You reckon this is indeed just a type of chroma noise? It's so dispersed...hmmph. 

[itsskin]

Does not look good...

Though here people are saying everything is ok... 

http://www.getdpi.com/forum/sony/55683-a7rii-less-than-ideal-long-exposures.html

[bbphoto]

Seems as if that chroma noise may be hot pixels? Yeah, still early to tell, but I'm just seeing stuff that I can't find in my equivalent Nikon D750 shots. It feels like a witch hunt, but honestly after making the switch to Sony and welcoming mirrorless with open arms...it's of some concern.

[maple888]

I am seeing the same thing done a few test shots starting at 2s right through to 30s at iso 800 in the dark in the back garden and the colour noise really starts to get bad after around 5s.Turning LE NR on gives a perfectly clean image.This seems to be a similar problem that people complained about when they upgraded from the Olympus OM-D E-M5 to the Olympus em1, the em1 had this colour noise in the shots unless LE NR was set to on where as the em5 was much cleaner without having to have the NR on. I repeated the test with my A7r and its no where near as bad as the A7rii.

[Singingsnapper]

What you are seeing is hot pixels. I had it not too dissimilar to that on the 645D and that didn't allow LENR to be turned off - so you got the double exposure wait and no reprieve from the hot pixels.  It's worse but not massively so.  I find that using the hot pixels part of Dfine gets rid of it nicely without softening the shot much.  I shot several long exposures here:

 

http://www.sonyalphaforum.com/topic/1343-out-on-the-gower/

 

and not one speck of hot pixel to be seen.  I have processed carefully because the last glow of sun is on the left and this is an edge that I have found the posterisation to be a risk with my 645Z.  

[itsskin]

@bbphoto would you be so kind to share couple of raws with this issue? I waned this camera for night photography and need to see how bad it is....

[ViRuS X]

Seems as if that chroma noise may be hot pixels? Yeah, still early to tell, but I'm just seeing stuff that I can't find in my equivalent Nikon D750 shots. It feels like a witch hunt, but honestly after making the switch to Sony and welcoming mirrorless with open arms...it's of some concern.

You should send it back , it looks like a hot pixels issue.

[bbphoto]

I'll try and upload Raws for you tomorrow still on phone. @virusx, so you think this looks like a defect? I'm not familiar with hot pixel issues and wasn't sure if it's normal behavior for this camera or my copy.

[ViRuS X]

It's obviously a defect , I haven't seen anything like this before using any Sony camera, your copy is defective , just send it back and try not to accept repair, try to get a new copy

[maple888]

I dont think its a defect i think its a inherent trait of this new sensor.Im seeing other reports on more forums.

[Singingsnapper]

Hot pixels aren't necessarily a defect.  I had them with the D800 and E and get them with the 645Z.  With all three cameras  I have always kept LE NR off (though 645Z has an auto feature which if you are using ISO100/200 and generally under 3 minutes, it doesn't come on unless the sensor gets hot).  Reason I always have it turned off is as a landscape photographer I am often shooting at twilight or dawn, and if I had to wait another 3 mins, the required exposure may have doubled or halved respectively.

 

Hot pixels are a consequence of not using LE NR.  The sensor will get hot on longer exposures,leaving hot pixels which the dark slide eradicates. If the hot pixels are come on within a short period of time then there may well be an issue.  I don't see it on my Sony censored 645Z on exposures below 4 mins unless I have done a number of long exposures.  At 100ISO and the first 4 min exposure I generally see no hot pixels.  

[itsskin]

Yeah, but we are talking 8 and 20 seconds here.

[bbphoto]

Hmm I suppose I need to see if others are having same issue. The 8 and 20 second shots I took were 2 of only 5 shots I took in a 5 hour period of time. The second shot was the 20 second so I can't imagine sensor had been too hot?

[itsskin]

Sure. You need to be shooting timelapses to make sensor hot.

[itsskin]

Here is the other case http://www.fredmiranda.com/forum/topic/1380165/0#13141850

[bbphoto]

Interesting. So it sounds like it's thermal noise or hot pixels officially. Something the 810 apparently suffered from and was addressed shortly after release by Nikon via service recall and eradicated on later shipments of the camera. (https://photographylife.com/nikon-confirms-the-d810-thermal-issue-and-offers-a-solution)

Probably worth mentioning, if related, that when I first turned on the new a7rii (very first time- no lens on it at the time, just cap) I saw a number of very noticeable hot pixels, red and green, floating on the LCD display. I shut it off and turned back on and did not see them second time. Is that normal behavior? My a6000 does not do that.

[itsskin]

Probably won't help, but you can try to force-remap hot pixels. Change the date several month to the future and switch off the camera. You should hear shutter clicking - thats the remap process. BTW, any chance to see RAWs? Are you off your phone already?

[bbphoto]

Oh yea maybe i'll try that. Here's link to raws and another screen grab where I did 20 seconds ISO 100 with lens cap on. 

 

https://drive.google.com/folderview?id=0BzN_BO2D-YtGfldHQ2lrUkZkMG9rTGlOQ0pRVU51Ym1lOG1kVlQ5akF4QnNZR2pEeEJMd00&usp=sharing