Strange artifacts on 7D

I am seeing strange artifacts I have not seen before with my 7D. Zoomed in screenshot of an image shot at 420mm (300f4 with 1.4) at f4, 1/1000 ISO 800. I have shot at much higher ISO's. Cannot figure out what this is. Any help appreciated.

www.flickr.com/photos/​njwight/5395360241/

thanks
NJ

I'm interested in the cause of this as well. one of my friends has a 7D, and a similar artifact issue, though his doesn't appear to be as bad. It seems related to cold though.

Raw or JPEG? Can you compare other variables, like a different lens, different ISO, different aperture, different shutter, different exposure level? Also, can you post the actual photo rather than a screenshot?

1) Raw processed through DPP or using custom picture styles for JPG?
2) What are your picture style sharpness settings if you are using a custom style?

This happens alot if you sharpen the JPG in camera or through DPP (picture style or in DPP itself). Keep your sharpness down and process sharpness in post processing later.

Skaperen wrote in post #11732034
Raw or JPEG? Can you compare other variables, like a different lens, different ISO, different aperture, different shutter, different exposure level? Also, can you post the actual photo rather than a screenshot?

Agree - we need more info. Among other things, it would be helpful to know how much sharpening was done, either in camera or in post processing.

Looks to me it was underexposed and pushed back up in post and sharpened, therefore, enhancing the noise as well. But I could be wrong. I just see the flickr exif showing -0.33 EC.

It looks like the mazing pattern you get with the 5D2 and 7D if you do just the right combination of camera settings and raw processing/DPP, etc. Perhaps take a 100% crop that is about 800x800 and attach it to the original post?

I agree with jwcdds, looks like the result of excessive post processing manipulation.

I saw something similar on another forum from a 7D, the user had taken a photo at ISO 5000 and underexposed it, noise reduction was also set to "low" in the camera. This was also from a 7D.

Someone far cleverer than I am replied with this:

"the example you posted was shot at 5000 ISO and is underexposed. Well, it may not appear underexposed to the eye, but you have fallen a good 2+ stops short of saturating the sensor. This is a long way removed from an "ETTR" exposure, which I would normally strive for. Shooting at 5000 ISO and underexposing by 1 stop is like shooting at 10,000 ISO. Underexposing by 2 stops is like shooting at 20,000 ISO. You're going to see noise!

think for a moment what is happening when you shoot at high ISO. If you were to shoot at 100 ISO and expose fully to the right you would have pixels in the frame that were fully saturated and essentially noise free. But, up the ISO to 5000 and even the brightest pixels will be exposed to only 1/50 or 2% of their capacity. Other pixels will be even less well saturated. If your exposure is 2 stops under then the brightest pixels will only be receiving 0.5% of the light. If you crop the image to 1/4 of the frame then you've thrown away 3/4 of the light you captured, leaving you with just 0.125% of the light in that crop. It's not much to work with."

In other words underexposing and high ISO is fatal for IQ. It may be different in your case, but its worth checking. What does the histogram look like ?

I posted on your flickr wall with my response i had same issues till i got rid of one lens...

I dont look for exif's but if its as as said above thats most likely your issue

Don't take this the wrong way but based on the information available I would say the issue is primarily with you.

I can think of absolutely no logical reason to be shooting F/14, ISO 800, Shutter 1/1000, -0.3 ev with that camera and lens combo other than attempting to get a hand-held landscape shot of an area you can't approach very closely due to physical barriers. However, in that case such artifacts would be irrelevant because you don't need to zoom in on landscape shots to the point where you can see that kind of thing.

What people don't always get at first (or ever in some cases) is that, aside from sensor size, noise (and your main problem is almost definitely excessive noise) is based almost entirely on how much light reaches the camera's sensor, and only changes in shutter speed, aperture value, or the amount of light on the subject will change how much light reaches the camera sensor.

So in this shot you have almost no light getting to the sensor, and that causes noise, which causes what you are calling "artifacts". You should have used F/7 to allow twice as much light to reach the sensor (and also to get a sharper image) and dropped your ISO to 400 to increase the exposure level by a full stop to effectively +0.6ev (according to your cameras internal metering). This would have cut the amount of noise by quite a bit, resulting in a cleaner looking shot.

However, even this wouldn't fully resolve the issue. The next issue is that you took the shot from so far away that the only way to get the bird to fill the final crop was apparently to do a 100% crop. You need to get a longer lens or physically closer to resolve this issue. A 100% crop, or even a 50% crop, on a crop camera in mediocre lighting is always going to have noise issues.

Also you can't trust your camera to meter properly when your subject is small and against a bright background. The camera will underexpose the subject in order to avoid overexposing the background, which takes up much more of the image. In a case like this a blown background is not that big a deal because it will be all white either way. So you could probably afford to go +1.6ev on a shot like this. Maybe use a grey-card to get your exposure settings.

So, to sum up.

Faster aperture, more exposure, closer to subject, don't always trust your cameras exposure meter.

Thanks for all the comments. I am actually trying to find other examples. It is a RAW image with some adjustments in Aperture 3-but not a great deal. It could be sharpening. When I get back to my desk I will pull up a new master and compare. I have seen noise on many of my photos-it never manifested itself like white flecks though. That is what confused me.

Arentol, I have no issue confessing, it is most likely me! But thanks for being gentle. I actually prefer thinking it is me than blaming my equipment. You are right, I was trying to come back from having the background fully blown out, but as you say, it is white anyway! Thanks for suggesting the other settings. In fact, i checked other images at f/14, 1/250 and the noise is not there. I get very confused with how to deal with these conditions-white overcast sky and dark subjects. I know the sensor doesn't have the range to cover that. I also get confused with what metering method to use, so if anyone can help there, I am a willing student.

I really appreciate the guidance.

Thank-you all.
Nancie

jwcdds wrote in post #11732361
Looks to me it was underexposed and pushed back up in post and sharpened, therefore, enhancing the noise as well. But I could be wrong. I just see the flickr exif showing -0.33 EC.

This would be my guess...I didn't even see the exif setting. But is pretty classic of the noise that shows up when you push up an underexposed image; or, at least when *I* push up an underexposed image

As far as flat, overcast skies behind your subject; my usual operation would be Spot metering on the subject itself and just let the sky blow out. There isn't any detail there anyway, so why worry about it.

njwiggit wrote in post #11734135
* * * I get very confused with how to deal with these conditions-white overcast sky and dark subjects. I know the sensor doesn't have the range to cover that. I also get confused with what metering method to use, so if anyone can help there, I am a willing student.

I really appreciate the guidance.

Thank-you all.
Nancie

If you get to the point where your camera cannot capture the entire dynamic range of the scene, you have to decide what's most important and expose for that (expose in such a way that the most important part of the scene is exposed to the right, not under-exposed). The key is to make sure that you "expose to the right" for what's important in the image, even if you lose detail in the brighter regions. I've found the approach described here http://daystarvisions.​com/Docs/Tuts/DCExp/pg​1.html to be invaluable in getting better exposures. I don't use it all the time, but it's really helpful for high dynamic range scenes. You can use this approach to spot meter on the brightest area in which you wish to retain detail, then up the exposure according to the highlight "headroom" you've established for your camera using his method. This will "expose to the right," which will minimize noise. He also has a good general tutorial on metering at http://daystarvisions.​com/Docs/Tuts/Meter/in​dex.html. Another way to handle this type of issue is to bracket the exposure and combine the multiple exposures in post processing software to get more dynamic range than you could capture in a single image.

set your highlight feature in the custom settings it at least keeps you from going nuts and learn the shoot to the right thing unless you have your camera set up diff?

I find people not using flash will have noise as well bang on.
Once i started to use the flash (because its needed 99% of the time) noise is gone.
If not using flash had better be great lighting... otherwise you will dig up noise somewhere in the image

arentol wrote in post #11734078
So in this shot you have almost no light getting to the sensor, and that causes noise, which causes what you are calling "artifacts". You should have used F/7 to allow twice as much light to reach the sensor (and also to get a sharper image) and dropped your ISO to 400 to increase the exposure level by a full stop to effectively +0.6ev (according to your cameras internal metering). This would have cut the amount of noise by quite a bit, resulting in a cleaner looking shot.

f/14 to f/7 doesn't allow twice as much light to reach the sensor. It allows four times as much light (2 stops difference).