Showing posts with label lens. Show all posts
Showing posts with label lens. Show all posts

Thursday, October 23, 2008

Canon SX110IS review: 10x zoom lens performance in the real world

The Powershot SX110 has a 10x zoom lens, which is quite a step up from the compact cameras which typically only have 3-5x zoom. In this section, I'll show some real-world pictures demonstrating how much difference 10x zoom makes compared to a 4x zoom, and also show how usable 10x zoom is in moderate indoor light (answer: not so much).




At right is a wide-angle picture ("0x zoom") taken on a nice sunny day, at ISO 80. You can click on the image for a full-sized version. Note that the bus was a bit over-exposed so I had to adjust the brightness down a bit by pre-focusing on the sky, (IE holding the shutter button down halfway), and then reorienting on the bus. This is why the rest of the picture is a bit dark, but it was necessary in able to preserve detail on the bus, which I will zoom in on next.




This shot is taken at 10x zoom. Much less light is hitting the sensor because we have zoomed in all the way, but as you can see the image is still very clear and low-noise, with no blur, even though the camera is still in ISO 80. You can click on the image for a full sized version.


What would 13x zoom look like? I took advantage of the fact that the camera can do interpolation-free zooming if you take your picture at a lower megapixel setting; in this case zooming in past the optical limits of the lens is identical to cropping the image down to a smaller size. If you shoot in 4 megapixel mode this allows the 10x zoom to become a 13x zoom. As you can see in the picture at left, 13x doesn't make much of an improvement on 10x, but it's a nice feature if you tend to shoot in less than 9MP mode, as I do (9MP files are much bigger, and most of the time I'll never have a need for all those extra pixels). Note: the image at left has been resized down to 25% of its original size to save server space.



So far we've seen that the zoom functions great outdoors. What of indoors, where the light level is typically much, much lower? I took the next series of shots in the kitchen, with all the lights on. The room is pleasantly lit with 2 conventional 60 watt bulbs, and is far from dark, but isn't as bright as an indoor room with a large sunny window would be. At left we have the 0-zoom shot. It's already dark enough that I had to use ISO 400 to get a sharp shot. Detail is OK, but but Hi-ISO noise is certainly visible. On the upside, there's no blur.



At ISO 400 and full 10x zoom the result is a blurry mess. I tried taking several photos in case my hand just happened to be shaky, and couldn't do much better.



It wasn't until ISO 1600 (!) that the blurriness went away. Unfortunately, as you can see, most of the detail is now lost in CCD noise.



For comparison, I also took the same shot with my more compact Powershot SD850IS, also zoomed in to its max(4x), at ISO 200. This shot is interesting for 2 reasons. First, it shows the difference in scaling between a 10x zoom and a 4x zoom. It's definitely clear that a 10x lens takes you a good bit further in. It's also interesting because it shows how much more appropriate a 4x zoom is for indoor shots than a 10x zoom is. Now, you don't have to use the full range of a 10x zoom lens, and if I took this shot with the SX110 at 4x zoom, I'm sure it would look much better than at 10x zoom (unfortunately, the SX110 doesn't report zoom level, so I couldn't easily create such a shot for this webpage). The point is that all of the extra range that the SX110 offers is of little advantage if you'll be taking medium-light indoor shots like this one. On the other hand, zoom isn't really needed indoors. All of your subjects are close enough that you can just walk the 2-5 feet closer needed to get the proper framing. It's only outdoors where the long zoom becomes truly useful.

So, in conclusion, the zoom lens works great on this camera, in bright daylight. The difference in zoom between 4x and 10x is quite noticeable, and will allow you to get much closer to your outdoor subjects that you can't just walk up to.

Later in the day, and for moderately lit indoor shots, however, it's not really much more useful than the 4x zoom lens you would get on a good compact camera.

This post is part of a series that reviews the Canon SX110IS.

Monday, October 20, 2008

Canon SX110 Review: lens distortion - lab tests and real world images

The SX110 has a 10x zoom lens. With such a wide range you might be concerned that image quality might be compromised either at the wide or telephoto setting. On the whole, however, image quality is good throughout the whole zoom range.


At right is the camera at its widest zoom. Some barrel distortion is visible (IE, curved lines which should be straight), but it's not bad. Note, however, that most cameras have this to some extent. On the positive side, the corners of the image are just as sharp as the center. Many cameras, particular more compact models, have blurry corners. Many Canon SD cameras exhibit this problem fairly clearly, such as last year's SD850IS. It's nice to see that the SX110 does not.



Next is the lens at the other extreme of the zoom range, in full telephoto. Here, there is no indication of the barrel distortion seen at the wide angle setting. Again, there is also no corner blur. Thus, the lab tests show that the lens performs quite well.  What of real-world shots, however? In particular, does the wide-angle barrel distortion show up in photos of the real world? See the next few pictures. 



In this picture, which is designed to highlight the problem, it is possible to see distortion. Even so, it's not nearly as obvious as in the lab test. Given that you are unlikey to take a picture like this unless you are trying to show off the flaws in the optics, it's not too bad.



This picture is perhaps more representative of the real-world images which would show off this problem. The support columns clearly bend out toward the middle, whereas in real life they are as straight as your typical 2x4. Whether or not you find this objectionable is really a question of taste, but I personally don't notice it unless I'm looking pretty carefully.

This post is part of a series that reviews the Canon SX110IS.