Mon 04-Feb-13 12:17 AM | edited Mon 04-Feb-13 12:18 AM by aolander
That's not pixelization, it's noise. The ISO you used wasn't very high (which will cause noise), but did you crop these photos a lot? They aren't that sharp like you cropped the bird out of the center of an image. Enlarging the image (by cropping) will make noise more visible.
To me your pictures do not look like they are in focus. I dont see noise as the main problem.
Lighter colors may show up noise more but I think in this case you it just may be grain for 100% and being slightly out of focus. Trying shooting some bigger obbjects where you know the focus is correct.
>I have taken over 5,500 pictures with my D7000. Over the last >two weeks, all the pictures with ISO over 400 are pixelated. >This was never an issue before. Any suggestions?
Small birds are a serious challenge to photograph. They move very rapidly - even with shutter speeds faster than 1/1000 images can be blurred by motion. I've had plenty!
You were shooting in fairly poor, low contrast light at elevated ISOs and cropping severely. Any applied sharpening will cause pixelation because you're actually seeing individual pixels. The last image, although larger has the plane of focus on the tree in front of the nuthatch. This is another challenge when photographing small birds from a distance - being sure that you're focusing on the intended subject.
The only real options to get good, crisp shots of small birds are to buy a big lens and get close, or use a smaller lens and get REALLY close.
All of these were shot with a 500mm on a D7000 at 8m or closer and most of the smaller birds still involved some cropping. The starling was shot at a little over 4m. The MFD for my 500mm is 4m.
One approach to getting close would be to set your camera up on a tripod close to the feeder and trigger it with a long cable release or radio-controlled release. The birds will get used to it quickly and soon ignore it. There are also very clever low-cost tethering options. I can tether my camera to my PC, and control the camera over my home wireless network with my phone to take photos of birds in the garden as well. You could also use a hide to get you and your camera closer to the feeder.
Using an off-camera flash fired though a small umbrella would give extra light and allow you to get your ISO down to 100 as well.
I'm still a novice, but have quickly learned that photographing wildlife is very challenging, and requires patience, persistence and guile to get close to your subject. It's one of the most frustrating areas of photography, but also one of the most rewarding.
What's the minimum focus distance on your 200mm? I'd try to find ways of getting closer first, and then maybe try the TC if you still can't get close enough. A TC isn't a panacea, and will cause some degradation in image quality and take your maximum aperture up to f/4. The lens/TC combo probably won't reach best performance until you stop down to about f/5.6.
I use a 1.4 TC on my 80-200 AF-S from time to time - the results are pretty good, but not really on a par with the bare lens.
Small birds just need a long focal length. The 70-200 is a good lens, but nothing will make it a lens of choice for small birds. I'd consider the lens with a teleconverter better for large mammals or large wading birds - not small birds.
The other challenge you run into with cropping is the backgrounds are not smooth enough. A longer lens provides better subject isolation and smoother backgrounds.
Take a look at lenses like the Sigma 50-500 or 150-500 as good compromises. I have a Tamron 200-500 which is quite good at close range.
As mentioned above, you need good light. 1/1000 sec and ISO 200 would be the starting point. As you move to higher ISO levels, you increase noise but you also lose contrast and detail.
Also take a look at your post processing. Sharpening, contrast, and saturation can all add pixelation - especially on a cropped image. In some situations you can crop and then resize to a larger image size at the start of editing to reduce pixelation. You can also apply noise reduction selectively to the background.