Dithering effect in 7D images

[Vertigo1]

I've noticed that, when viewed at pixel level, the images from my 7D are often displaying a kind of dithering effect. It's most noticeable in areas which are out of focus.

Here's an example, taken from a straight screen-grab from Lightroom on an image viewed at 3:1 magnification:

What is this? Is it noise? A limitation of a crop sensor that only going FF would fix? This image was at ISO100 so surely noise shouldn't be an issue even on a crop - there was no shortage of light.

 

[seriousrikk]

That looks to be magnified well above 1:1 to me.

But yes, I found my 7D would benefit from a little noise reduction even at ISO100

 

[Vertigo1]

It's 3:1, as mentioned in the original post Only to make the issue I'm talking about as visible as possible of course - I don't routinely pixel peep at 3:1!

 

[stu.artd]

Looks like it could be image noise.
As you say it's 3:1, are you really viewing at 300% ?
That's more than pixel peeping!
Is the effect visible at 100% or when printed?

 

[seriousrikk]

My bad, missed the bit where you mentioned 3:1

Do you have any sharpening applied? I found this effect would be made more prominent when the images were sharpened. So much so that often I would bomb out to photoshop and use a mask to ensure the background does not recieve any sharpening.

 

[Vertigo1]

Ah - bloody sharpening. I didn't think I had any applied but forgot that there is some in the preset I used when importing. If I remove the sharpening the dithering reduces massively so that's obviously it. My bad

It was noticable at 1:1 - I don't usually even pixel peep at 1:1 to be honest as most images are down-sized when exported. I was only viewing at 3:1 or 300% to ease visibility in this example

 

[tdodd]

Try using the sharpening mask. It can help reduce this abomination on plain or OOF areas and let sharpening get to work only on more sharply defined edges. In fact the mask is often the first adjustment I will make in the detail panel, so that I can avoid sharpening the sky, for example, and then I am better placed to see how much sharpening I can get away with on the important bits of detail.

 

[Andy_S]

I've found the preview in LR to sometimes lack in quality, unsharp/grainy. Changing the zoom level sorted it out and the image was fine on export.

 

[hollis_f]

Would you normally print out your images 15 feet wide then examine them from 10 inches away? Because that's the equivalnet of what you're doing.

 

[seriousrikk]

Would you normally print out your images 15 feet wide then examine them from 10 inches away? Because that's the equivalnet of what you're doing.

Did you read the bit about 3:1 to show the effect? I has been mentioned more than once now...

 

[hollis_f]

Did you read the bit about 3:1 to show the effect?

Yes, I was just pointing out that showing an image at 3:1 to show an effect is just as sensible as printing an image 15 foot wide just to be able to see some effect.

If the only way you can see the effect is to carefully examine a billboard-sized image then the effect has absolutely zero impact on real-world images.

 

[Vertigo1]

Yes, I was just pointing out that showing an image at 3:1 to show an effect is just as sensible as printing an image 15 foot wide just to be able to see some effect.

If the only way you can see the effect is to carefully examine a billboard-sized image then the effect has absolutely zero impact on real-world images.

I did say the effect was visible at 1:1 also and would thus be clearly visible in final output if it was large or heavily cropped or both. It was the fact that I'd noticed it in such final output that lead me to investigate in the first place and zoom in to 3:1 to examine the effect in detail and try to work out what was going on.

 

[Orville]

Having recently acquired a Nikon D800e and having used a 5D Mk III. It made me realise how bad the 7d is for what I use it for!

Don't forget that you are comparing a 4 year old crop body to two current and much more expensive FF bodies. It's almost like comparing a 7 year old high-end compact to the 7D in terms of sensor size and price difference.