When we reviewed the Canon EOS 300D (Digital Rebel) I added this page which attempts to check the accuracy of auto focus both of the camera and lens used. This test is designed to check for front or back focusing defined as:
Where the camera indicates an auto focus lock but the actual focus position produced is slightly in front or slightly behind the actual ideal focus position. This can be caused by errors in the camera or a problem with the lens.
AF Test Target
For this test we are using a variation of various 45 degree tests seen elsewhere. Ours uses a simple rule print with a focusing target placed at 45 degrees from the rule and facing the camera directly. This target was designed to be easy for the camera to pick out as well as being large enough (3 x 2 cm) not to allow the AF sensors to pick up background detail. The camera is placed at exactly 45 degrees from the chart (facing the AF target) at a distance of 0.5 m (from the AF target to the focal plane).
The chart is then shot at both wide angle and telephoto at a large aperture (to keep the DOF as small as possible) with center point AF selected. It is then possible to examine the image and see whether the AF target is in focus, it is also possible to see the DOF on this chart. Each small line on the ruler is 1 mm, larger line is 10 mm. Each crop is produced by reducing the image by 50%* (to allow more of the image to be visible).
* Except the 18 mm crop which would have been too small if reduced
Nikkor AF-S DX 18- 70 mm F3.5 - F4.5G
|At 18 mm (F3.5): Too small to tell, possible back focus *(not reduced in size)*|
|At 55 mm (F5.6): Slight back focus|
Nikkor AF-S 28-70 mm F2.8 ED
|At 28 mm (F2.8): Good (DOF more to the back)|
|At 70 mm (F2.8): Good|
Nikkor 50 mm F1.4 D
|At 50 mm (F2.8): Back focus|
Nikkor 50 mm F1.4 D (Manual Focus)
|At 50 mm (F2.8): Back focus|
The results were interesting but not unsurprising, I had noticed the 18-70 mm back focus while taking some test shots and had switched to manual focus for some of them. The 50 mm back focus was more surprising although generally I use this lens at small apertures (F9 or smaller) so this amount of back focus would be soaked up by the depth of field. As I would also expect the 28-70 mm F2.8 performed the best, clearly showing that this isn't a necessarily camera problem.
Other lens tests (on the AF-S DX 18-70 mm)
We wouldn't normally perform these tests in our digital SLR reviews but because the new AF-S DX 18-70 mm is being bundled with the camera and it is likely to become the primary lens for many D70 owners we have chosen to test some other lens characteristics.
The AF-S DX 18-70 mm isn't and doesn't really pretend to be a macro lens, its closest focus distance of 38 cm (15 in) produces a frame coverage of 133 x 88 mm. Obviously there are a wide range of dedicated macro lenses available for the Nikon lens mount. Each grid line on our macro test chart is 10 mm, the shot is taken at shortest subject distance in macro mode (if available).
|Wide angle (18 mm) -
353 x 235 mm coverage
9 px/mm (216 px/in)
Corner softness: n/a
|Telephoto (55 mm) -
133 x 88 mm coverage
23 px/mm (572 px/in)
Corner softness: None
Barrel and Pincushion Distortion
The AF-S DX 18-70 mm lens exhibited 1.4% barrel distortion at full wide angle, slightly more than I had expected although not that surprising considering the focal length at moderate cost of the lens. At telephoto pincushion distortion was very low at 0.3%, so low that it would simply not be visible in normal shots.
Wide angle (18 mm)
Telephoto (70 mm)
Vignetting / Lens Shading
At full wide angle and maximum aperture (18 mm / F3.5) the AF-S DX 18-70 mm lens exhibited a surprising amount of lens shading although this was tamed by stopping down the aperture, we would consider the amount of fall off seen at maximum aperture as noticeable.
Our vignetting measurement is made by taking the average luminance value of the darkest corner of the image and comparing it to the average luminance at the center of the image, any difference greater than 15% may be visible in everyday shots.
|Dirt Hose by poppyjk|
|European bee-eaters by drvanger|
from A Big Year - birds
|Fat Is Beautiful Guinea 2008 DP by MarioSS|
from - Fat is Beautiful - (Woman's Portrait n Black and White+ A Border)
As summer really gets going over here in the Northern hemisphere, the team at Imaging Resource has put together a list of the best cameras for backpacking.
The Ukrainian Parliament banned statues of Lenin in 2015. Two years later, the monuments no longer adorn public buildings or stand watch over town squares, but they're still there.
If you had to choose one camera to bring along for the ultimate West coast road trip, what would it be? DPR's Sam Spencer choose the X100F. Read more
The a9 boasts impressive capability. As more examples of it in practice pour in, Sony's claims hold up. Watch the a9 track and maintain focus on a rapidly approaching basketball.
Last week, more than a million tonnes of Californian coastline slid into the ocean, taking part of Highway 1 with it. Check out the remodeling in photos taken before and after the landslide.
Even after eighteen months of reviewing the latest, greatest, shiniest and must-buy-me-est new gear, DPReview staffer Carey Rose has continued to use older DSLR cameras for his freelance work. But now, that might be changing. Read more
Sony is the world's leading mirrorless camera brand but remains third for ILCs overall, it's said in a presentation to investors. A focus on high value cameras and lenses should boost operating income, it says. Read more
It's nicknamed the 'Cycloptic Mustard Monster,' and is a 3D printed medium format camera. Read more
The new NanGuang LED lights are battery powered and come with accessories including filters and diffusers.
Have you been telling yourself, "Hey, I really need one of those 8K displays?" A video about Dell's new 8K monitor shows you what to expect. Is it really that much better?
Tamara Lackey, a Nikon ambassador USA and pro shooter, discusses embracing self-consciousness as a means of connecting with subjects.
There's a new Spiderman movie coming out and the poster been generating a lot of online chatter. Mostly about how it looks like the creation of a fevered teenager that just discovered Photoshop.
An honest defense of the system's merits, with photos as proof.
Copyright disputes are no fun at all. 'Binded' is a new startup that aims to simplify the process of registering - and enforcing - copyright for photographers. Read more
Not everyone wants to pay a premium for a long zoom camera. Thankfully, there are many reasonably priced cameras available, though they won't offer the same image quality as enthusiast models. In this updated roundup we look at big zoom cameras with more consumer-friendly price tags. Read more
Think Tank Photo has updated two of its popular bag lines with improvements to functionality. Read more
We’ve all seen Bob Jackson’s Pulitzer Prize winning photo, but there's another.
The sample footage looks good.
It will automatically pick the best camera settings depending on shooting conditions. It even promises enhanced functionality for your camera, like exposure and focus stacking. It already supports many cameras from Canon, Fuji, Nikon and Sony. Read more
As if $13,950 wasn’t enough to pay for a special edition lens, the Leica Store in San Francisco is offering a prototype of said lens for $24,995. Read more
Make those old photos disappear without deleting them forever.
Firmware updates enable 10 fps shooting with adapted A-mount lenses, and faster startup times and better compatibility for 20 fps shooting when using native lenses on the a9.
Fujifilm has released firmware updates for its camera models X-T2, X-Pro2, GFX 50s, X-T20, X100F and X-T1 and updates to three of its software products.
A 22 year-old Romanian photographer uses his DJI Phantom 4 drone to capture unique perspectives of the city where he now lives.
What's it like to ride the waves with champion surfer Kelly Slater? This VR video from Teton Gravity Research gives you a taste.
When Nikon released the full-frame D3 in 2007, it changed the professional photography industry. In this week's Throwback Thursday, Barney remembers a legend. Read more
The new stuff should have better red hues, improved sensitivity and finer grain - but don't worry - will still shift blues to green, greens to purple and yellows to pink.
Ricoh has introduced a new rugged compact camera with a 16MP CMOS sensor, 28-140mm lens, 2.7" LCD and built-in LED macro lights. Read more
This compact drone can shoot HD video using a 2-axis stabilized 12MP camera. Read more
The new Prynt Pocket can print a photo directly from their iPhone simply by inserting the phone into the printer, then snapping a photo. Each print will cost about 50 cents. Read more