The Nikon D7000 is equipped with a brand-new 39 Point AF System with 9 cross-type sensors. As I pointed out in my DSLR Autofocus Modes article, the higher the number of cross-type sensors, the better. In comparison, the Nikon D90 has 11 focus points and only 1 cross-type sensor, while the Nikon D300s has 51 focus points and 15 cross-type sensors. During the month of testing the camera, I used it in various environments and have a few things to talk about in regards to its performance and accuracy. Let’s talk about autofocus accuracy first.
I know that some of the Nikon D7000 owners have complained about autofocus accuracy and reported having back/front focus issues. I also know that many of the visitors that read this review will focus on this part of the review more than any other, mostly due to the number of complaints they have seen on various online forums. Let me start off by saying that the Nikon D7000 does NOT have a back focus problem. Before some of the readers who were directly impacted by a D7000 back focus problem start throwing tomatoes my way, let me first explain this in more detail.
There are many variables that affect autofocus accuracy and a number of reasons why images from the D7000 might appear softer compared to older generation cameras. Many photographers who just got the D7000 as their first DSLR or moved from an entry-level DSLR like D40 to a D7000 simply do not have a solid understanding of how to use different focusing modes to obtain accurate focus. Without doing much reading and learning how to use the different AF modes on the camera, they just take pictures hand-held, expecting the D7000 to produce tack-sharp images.
There are tons of photographs of blurry dogs and cats on the Internet photographed in Single Servo (AF-S) mode while they are in motion, with photographers blaming the equipment for out of focus images. In other cases, you hear some photographers say stuff like “my Nikon D40 was much sharper and I never had focus problems with any of my lenses on it”. Wait a second. Before they were viewing a 6 MP image at 100% on their computer screens and now they are viewing a 16 MP image at 100% and are expecting both to look equally sharp? Of course, they are! But they do not seem to understand the following:
- High resolution sensors need better lenses that can resolve more detail. Do not expect your old crappy DX kit lens to give you super sharp images on the D7000.
- Camera shake is more noticeable on high resolution sensors when images are viewed at 100%.
- Even slight autofocus errors are quite visible on high resolution sensors.
So, going back to viewing a 6 MP image versus a 16 MP image at 100%, if those photographers resized the 16 MP image to 6 MP in Photoshop, they would not see much difference in sharpness between the two 6 MP images. Take a look at the following examples:
The first image is a 100% crop from a 6 MP image, while the second one is a 100% crop from a 12 MP image. Looking at the 6 MP image, I can say that it looks acceptably sharp to me and if I add a little bit of sharpening in Photoshop, I will get a very usable image. Now take a look at the second image – this one looks soft/blurry in comparison. Both are taken from the same image and one is simply resized to a smaller resolution. That’s why if your lens is not very sharp or if it slightly front/back focuses, you would not normally notice any problems when it is mounted on a low-resolution camera. Many photographers did not even know about front/back focus issues until they tried out the D7000 or saw hundreds of messages on online forums. Simply put, Nikon opened a can of worms with a high-resolution sensor and people all of a sudden started discovering focus problems with their lenses.
Front/back focus issues are mostly related to lenses, not camera bodies. Again, as I have pointed out above, a slight focusing problem of a lens might not be noticeable on a low-resolution sensor, but will certainly show up at high resolutions. Add camera shake and motion blur at slow shutter speeds and the situation is worsened even more. Not all lenses are perfectly calibrated when they leave Nikon factories, as can be seen from some of my Nikon lens reviews, so you should not be surprised if your lenses are not 100% accurate. If you did not notice a focus problem with your lens before, it does not mean that it did not exist.
Now, this all does not mean that a DSLR body cannot have any issues. I’m sure a number of Nikon D7000 camera bodies actually had some focusing problems – a normal problem that occurs when a product is manufactured. Some experienced photographers have clearly demonstrated DSLR autofocus problems and I am not going to argue with them. However, the number of people who truly had an autofocus problem with a D7000 body is extremely small. Inside the DSLR body, AF problems could be caused by badly aligned internal components and other calibration issues that are easy to fix by the manufacturer. If all of your lenses have focus issues that are not present on a different DSLR body, then you might have one of those defective DSLRs that need to be repaired/recalibrated by Nikon. Don’t try to repair or recalibrate the camera yourself. There are some people who advise using a hex wrench inside the camera chamber to fix the focus problem, but it is not a good idea for two reasons – you might damage your camera and you might make AF accuracy even worse. Nikon uses specialized computer equipment to calibrate cameras and lenses and you should let them handle that instead.
Another reason why we hear so much about back focus issues on the D7000 is that Nikon gave the ability to use AF Fine Tune on the D7000 (Nikon D90 and entry-level DSLRs do not have this feature). Many photographers, especially newbies, experiment with AF Fine Tune too much and they end up with even worse results. Tweaking AF Fine Tune values requires careful testing using special charts for accurate results, so I would not just use any arbitrary number and hope it will work. Obviously, using other people’s AF Fine Tune values is no good either… Lastly, autofocus problems on DSLRs and lenses have been known for many years now, pretty much since the day autofocus was invented. If you search for “backfocus test” in Google, you will find articles from 10+ years ago. So it is NOT a new problem on the D7000 – there were back focus issues even back in the film days.
I hope this clears things up. Let’s get back to the Nikon D7000 AF system and what I think of it.
The new 39 point AF system behaves similarly to the 59 point AF system used in higher-end Nikon DSLRs. While it might not be as good for fast-moving subjects, it performs quite well in most situations. If you are used to the simple Nikon D90 AF system, you will find the AF system on the D7000 to be a huge upgrade and overall a much better, more reliable and more responsive AF system. In bright conditions outdoors, the Nikon D7000 snaps into focus very fast. Lenses with fast AF motors like the Nikon 24-70mm f/2.8G and Nikon 70-200mm f/2.8G perform exceptionally well on the D7000.
In low-light conditions, the AF accuracy starts to suffer depending on the amount of ambient light. I had a few cases where the D7000 indicated that focus was acquired properly, when in fact it was not. Switching to the center AF point indoors certainly helps a lot and AF performance gets more reliable though (you have to be careful about focusing and then recomposing when shooting at large apertures and shallow depth of field, because you could end up with an out of focus image, due to a change in focus plane). If you have been using an entry-level DSLR or a D90, you will definitely like the D7000 AF system. However, if you have been using a pro-level DSLR like Nikon D700/D3s, you will find the low light AF performance to be a little weak in comparison. Once you get used to how the D7000 autofocuses, you will be able to get great results, even indoors.
Here is an example of a portrait that was shot indoors in low light with the Nikon D7000:
Here is the full-size version of the above image (4.8 MB JPEG – RAW to JPEG conversion performed in Lightroom, some sharpening was applied to the image – Amount: 50, Radius: 1.0, Detail: 50, Masking: 20). Focusing was performed in ambient light (Single Servo/AF-S) and the shot was taken with a single off-camera flash positioned on the left of the subject, shot through an umbrella. Shot with Nikon D7000 + Nikon 70-200mm f/2.8G VR II @ 112mm, f/2.8, 1/20, ISO 200, VR On. The rest of the EXIF data is embedded in the file.
Here is another example, shot in a studio in good light:
The full-size version of the above image can be downloaded from here (1 MB JPEG – RAW to JPEG conversion performed in Lightroom, some sharpening was applied to the image – Amount: 50, Radius: 1.0, Detail: 50, Masking: 20). Continuous Servo/AF-C mode with two studio lights using an octabank (main light on the left) and a softbox (positioned to the right as fill light). Shot with the Nikon D7000 + Nikon 50mm f/1.4G @ f/5.6, 1/125, ISO 200. The rest of the EXIF data is embedded in the file.
Overall, I am very pleased with the new AF system on the D7000.
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