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11 hours ago, David McGill said:

Mark - here is a link to Mr/Ms Squirrel at 100% - http://davidmcgill.co.uk/100-squirrel it does look a little bit soft to me.

 

Looks very different to the original full frame image you posted which appears more contrasty and sharpened?

Anyway, with respect to noise in the 100% crop, I don't see any problem. But, as Space Cadet says, I would probably increase contrast or clarity a bit.

 

Mark

Edited by M.Chapman
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12 minutes ago, geogphotos said:

 

Yep. One today for noise - where I tried to lift dark shadows. 

 

Is there any chroma noise? I think they're stricter on that than just uniform "grain" caused by luminance noise. 

 

12 minutes ago, M.Chapman said:

 

Looks very different to the original ful frame image you posted which appears more contrasty and sharpened?

Anyway, with respect to noise in the 100% crop, I don't see any problem. But, as Space Cadet says, I would probably increase contrast or clarity a bit.

 

Mark

 

The full image is, in my opinion, very heavily sharpened. I am avoiding using the term "oversharpened" but it is heavy. I would advise the OP not to submit an image sharpened to that level as it may well fail - there are halos around the squirrel's ears where the sharpening mask has increased local contrast substantially.

Edited by Cal
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23 minutes ago, Cal said:

 

Is there any chroma noise? I think they're stricter on that than just uniform "grain" caused by luminance noise. 

 

 

Don't know about 'chroma noise'. Carelessness on my part. Failed for 'Noise'.

 

I00004.efOIV6btk.jpg

 

 

 

I0000rIBbG_C4AG8.jpg

 

 

 

I0000feQDAbhRDPE.jpg

 

 

Edited by geogphotos
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1 hour ago, geogphotos said:

 

Don't know about 'chroma noise'. Carelessness on my part. Failed for 'Noise'.

 

I00004.efOIV6btk.jpg

 

 

 

I0000rIBbG_C4AG8.jpg

 

 

 

I0000feQDAbhRDPE.jpg

 

 

 

Yes, there's definitely chroma noise there, you can see the little colour splotches in the road and the other darker areas. Make sure when processing your image in lightroom you have the "colour" noise reduction slider up. Default usually starts at 25 which for me removes all but the most stubborn chroma, a particularly stubborn photo might need 50, 60 but beware using values higher than that as it can actually remove genuine colour from the image. From my experiences of QC fail in the past they are REALLY strict on chroma. Hope this helps.

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Ironically, last year I uploaded a bunch of images from Louisville, Kentucky. The batch included images shot at night  in downtown Louisville at ISO 2500 with my Sony A7rii which are amazingly noise-free as well as a bunch from Churchill Downs shot at ISO 100. One at ISO 100 failed for noise (I asked for a review since I believe they mistook black sand mixed with white sand in the high definition image of the racetrack for noise, but it failed again, so it's on sale elsewhere), but they took longer to review the other images including those shot at ISO 2500, so I assume they got a good look and they all passed. I've licensed most of these a few times elsewhere and sold prints too. I was going to include a couple from that group, but the Alamy search keeps timing out when I search Louisville Kentucky and searches by number show no images even if I switch from "Creative" (where they used to show up) to "Relevant" so I'm guessing search by file number isn't working today?

 

The Sony has been a game-changer for me in terms of shooting at high ISOs. With my Nikon D700 which was the standard bearer for low noise for years, I rarely shot as high as ISO 800, usually keeping my images at 400 or lower, and using a tripod at night, whereas I rarely use a tripod with my Sony. 

 

With my other mirrorless camera, the Olympus OMD-E1, I am less likely to push the ISO, although the night that I got it I shot a fire two doors down from me at ISO 1500-2500 and found the jpegs to be quite good, but I rarely push it past 800. The shake reduction technology in the Olympus is second to none, so I can handhold at much lower settings. 

 

When the search is working again, I'll add some images so you can judge for yourself. 

 

 

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Regarding noise, ISO, and chip sensitivity.

 

A digital camera sensor has a sensitivity of only one ISO. In my Canon it is ISO 100. If I set my camera at an ISO of 200 then the camera exposure meter chooses a F number/shutter speed combo that underexposes the ISO 100 chip by one stop. The camera knows this. The camera internally boosts the underexposed information coming from the ISO 100 chip by one stop. This makes the final boosted signal correct to ISO 200. The Camera then saves the ISO corrected information to a RAW or a JPG.

 

However in boosting an underexposed signal from an ISO 100 chip to ISO 200, it also boosts the insignificant noise that is in the signal coming from the ISO 100 chip.

For most images, I find that I can set the camera exposure ISO to 400. When the camera boosts to ISO 400 the information coming from an ISO 100 chip, the noise is there, but difficult to detect at 100% on a monitor.

 

In a ISO 100 chip signal, boosted after the exposure in camera to ISO 800 and higher, the noise becomes obvious.

 

The chip always sees at ISO 100. By setting the camera ISO to 200 you are not boosting the sensitivity of the chip to light. You are telling the camera to boost the underexposed information coming from the ISO 100 chip, after the exposure is made.

 

Most internet sites dealing with ISO, give the impression that increasing the ISO setting makes the chip more sensitive to light. That is wrong.

 

Camera brands can vary as to noise at higher ISO. However it is not so much the chip, but the in camera software doing the boost after the underexposure.

 

It took me a long time to get my head around this, but it can be very powerful information when dealing with high dynamic range situations.

 

Go to the Cambridge in Colour site on this page:

https://www.cambridgeincolour.com/tutorials/image-noise.htm

Chip speed and ISO settings are dealt with in passing under, Terminology: ISO Speed.
 

Edited by Bill Brooks
clarity I hope
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This is called ISO Invariance and is demonstrated with examples for the Fuji X-Pro2 here:

 

https://www.dpreview.com/reviews/fujifilm-x-pro2/6

 

However, according to this article some cameras are more ISO Invariant than others:

 

https://improvephotography.com/34818/iso-invariance/

 

I've no way of telling how true their conclusions are, just glad that Fuji cameras seem to be among the winners here.

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On 15/11/2020 at 21:32, Bill Brooks said:

Most internet sites dealing with ISO, give the impression that increasing the ISO setting makes the chip more sensitive to light. That is wrong.

+1

 

On 15/11/2020 at 21:32, Bill Brooks said:

Camera brands can vary as to noise at higher ISO. However it is not so much the chip, but the in camera software doing the boost after the underexposure.

 

Or more likely boosting the electronic signal gain (using switchable analogue amplifier gain) before the Analogue to Digital conversion stage. The benefit of doing this (rather than using in camera software after A/D conversion) is that the bit depth is preserved, even if the lower bits may become noisy, but that's still better than them being empty.

 

Mark

Edited by M.Chapman
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11 minutes ago, Harry Harrison said:

This is called ISO Invariance and is demonstrated with examples for the Fuji X-Pro2 here:

 

https://www.dpreview.com/reviews/fujifilm-x-pro2/6

 

However, according to this article some cameras are more ISO Invariant than others:

 

https://improvephotography.com/34818/iso-invariance/

 

I've no way of telling how true their conclusions are, just glad that Fuji cameras seem to be among the winners here.

 

 

i have done a few test and it seems to hold on Fuji.   what i am still struggling is the counter intuitive that the noise drops from 500 to 800...

 

 

this video had lots of information on Fujifilm ISO invariance 

 

 

https://www.youtube.com/watch?v=rR8wz0Zroio&ab_channel=pal2tech

 

 

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Personally I don't think what other people do or don't do makes much difference unless they are shooting with the same camera. I think what it comes down to is how good your camera is at handling noise and how good your software/processing skills are at removing noise.

 

The Z6 is about as new as camera technology comes (I can only dream of having one of these) so I would like to think that you can push it to higher ISOs and get good image quality.

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On 16/11/2020 at 00:16, Matt Ashmore said:

The Z6 is about as new as camera technology comes (I can only dream of having one of these) so I would like to think that you can push it to higher ISOs and get good image quality.

Matt, I have been impressed so far with the quality of the images I have obtained with the Z6. I took a "gamble" and uploaded the squirrel and mushroom images at 1600 and 6400ISO respectively referred to in my earlier post together with others shot at 200ISO. The submission passed QC so I am happy to upload higher ISO images in the future.

 

David

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High ISO images are fine so long as you deal with the noise properly. I have over 100 images at ISO 8,000 or above, including at least 9 at ISO 25,600.  Most of these were taken with a Canon 1DX Mark II. 
 

Ironically, one of my last QC fails was for noise in the shadow areas of a well-lit outdoor image at ISO 100.  
 

Graham

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On 16/11/2020 at 00:16, Matt Ashmore said:

Personally I don't think what other people do or don't do makes much difference unless they are shooting with the same camera. I think what it comes down to is how good your camera is at handling noise and how good your software/processing skills are at removing noise.

 

 

I think this is really worth repeating. Generalisations can be very misleading. Whatever the technology behind luminance noise control, different cameras have greatly different abilities, all else being equal. Post-processing skills are also very important (the assumption being raw images only). In addition, unless you upload high ISO images only in a single batch, it is not possible to say what is acceptable as it may not have even been seen in QC. 

 

A tip: I'm surprised nobody appears to have mentioned this but downsizing the image at the final stage to the minimum required by Alamy (3000x2000 pixels approx) can really help to reduce noise in high ISO images. The Z6 has plenty of room for downsizing. Also it goes without saying but make sure to do all the noise reduction on the raw file and not in Photoshop (not including ACR in this which is pre-Photoshop). 

 

Finally luminance noise can be very subjective depending on the person viewing and, very importantly, the monitor used to view the image on. High res screens, particularly retina screens, tend to conceal luminance noise to some degree. 

 

 

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And don't do what I have just done - send a cruddy old slide copy ( see other thread) by mistake as stock! 

 

Mr 3 Stars now after my recent series of careless errors. 

Edited by geogphotos
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