Monday, February 08, 2010

Zoom Zoom Zoom Zoom

I've always said you can never have too much zoom lens on your camera. Problem is, the more zoom you have, the harder it is to get a quality picture. Here's a little example I shot this evening with an old lens I had and a couple of new fancy Canon Extenders I found at the pawn shop for a good price. Unlike the cheap 400mm lens, these extenders are top of the line. They'll find a place in my camera bag while I wait to be able to afford a nice long prime lens. Anyhow, the shot above is from one end of my living room to the other with just the big 400mm zoom telephoto lens. With the 1.6x crop factor of my 7D, that makes this shot about 640mm. At that kind of zoom, I can't come close to hand-holding it, so I've got it on a tripod and I'm triggering the shot with a remote. I guess I should learn how to lock the mirror up and take the shot, but I'm not quite there yet. Take a close look at the Justin Wilson LP just right of center.

Here's the next shot with a 1.4x extender thrown into the mix. Notice that in addition to giving more zoom, it's also darker. The 35mm equivalent zoom here is 896mm. That's pretty big. This is also the last exposure that the camera would autofocus on and really didn't think it would, but it did. All the remaining shots are manual focus. See that Justin Wilson LP? Not the one left of center in this shot but the other one, still to the right of center. Look close and you're beginning to see a lot of Chromatic Aberration. That means the different colors of light are traveling differently through the lens, and they aren't coming together quite right on the image sensor.

And here's a shot with the 2x Extender in place, making a 1280mm shot. Way, way, way long, and way too dark. I think I shot this one at a full stop more than the camera wanted, and I still had to brighten it up a little. Look close at our Justin Wilson title and you can see it's getting a lot worse. This is in pretty poor lighting, so maybe it wouldn't be so bad in daylight, but it still wouldn't get you into National Geographic.

Last but not least, this is the 400mm lens plus the 2x extender plus the 1.4x extender plus the 1.6x crop factor, making for a total 35mm equivalent of 1344mm! That's a lot of zoom! However, this is clearly the worst picture of the lot. It's almost to the point where you can't read the lettering on the Justin Wilson LP. If you were a double naught spy, though, this would certainly get you some incriminating photographs. Now, if I only had a nice 400mm L series f/2.8 prime lens to try this little test on...

So what happens when I put all these together? The collage above shows all the pictures crammed into one, with the lens alone at the bottom, followed by 1.4x, then 2x, then 1.4x and 2x on the top. I blew up each picture by the same factor as the missing extenders to get the scale the same in each shot. I also tried to fudge the levels a bit to get the brightness levels the same, but I didn't go crazy with it. (You can see where the camera shifted slightly between shots, I must need a heavier tripod.) Anyhow, you can see that I'm probably just as well off zooming the photo digitally as I am by having all that extra glass. I think if I had started with better glass, there would be fewer flaws to amplify, but it would still be a trade-off. I have a lot to learn when it comes to such things. Maybe I should just go back to a point-and-shoot with a 10x zoom and quit worrying about such things. Sure would be cheaper.


Buster said...

Being ancient and all, I learned to shoot on Pentax SLR with no built-in light metering, followed by a Nikon with several lenses (35, 50, 85, and 135, I think). This was like 40 years ago.

Now, I'm all about point and shoot with a 10X zoom - that's me for sure!

Oracle said...

Buster and I meet again.

Anyway. Nice collection of Firesign Theatre.