Mokka mit Schlag » Photography

I was reading Arthur Morris’s blog today when I noticed that he was shooting with wildly different settings than I was. He seemed to be using a wide open aperture, and a relatively high 400 ISO even in sunlight, while relying on the camera to eliminate grain. This let him shoot with shutter speeds as fast as 1/2000 of a second. He had much better lenses than I did, but I still thought it might be worth a try, so I took a quick spin around the ponds at Mason Park in the late afternoon and see how this did. My lens would only open up to f/6.3 at 300mm–his could get as wide as f/4–but it did make a big difference as seen in this photo of a Western Bluebird:

Western Bluebird
Tamron 28-300 Di VC on an EOS 50D body, ISO 400, f/6.3, 1/2000s

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I’ve had it for about six months now and given it more than a fair shake, but ultimately I’m not happy with the Tamron AF28-300mm F/3.5-6.3 XR Di LD Aspherical (IF) I got for my primary lens for the EOS 50D. When I put this lens on, I want to be able to shoot at the long end, and I spend a lot more time there than at the short end. Unfortunately it’s just not nearly sharp enough for my tastes at 300mm. Even on a tripod with image stabilization turned on, it needs a shutter speed below 1/400s, ISO no bigger than 200, and aperture f/8.0 to f/11.0 or thereabouts to achieve adequate sharpness. That’s just too limiting. Even then, it’s far from perfect. I’ve gotten a few good shots with it like this Snowy Egret in Mason Park in March, but that’s about it:

Outside direct sunlight, it really doesn’t perform well at all. In fact, this image stands out precisely because it is so sharp. By contrast, I routinely get images that sharp while handholding my non-stabilized Canon EF 100mm f/2.8 Macro USM, like this Great Blue Heron from San Joaquin a few months later:

Most of my Tamron shots end up looking like this American White Pelican from the Salton Sea instead:

So I think it’s time to look for a new general purpose zoom lens. What are my options?
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It took some time and a learning curve, but I am now more or less happily using Adobe Lightroom 2.4 to manage my more serious DSLR nature photography. (I still use iPhoto for point-and-shoot family photos and the like.) Lightroom’s ability to correct exposure problems is nothing short of magic, and has rescued many photos. Here are some updates on things I’ve talked about in the past, as well as some open questions.
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I know the EOS50D is saving a JPEG with each raw file because Lightroom finds and displays them before switching to the raw image. However after mounting the memory card in the Mac Finder, all I see are raw images:

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I shoot raw images with an EOS50D. I load them off the card using Lightroom 2.0. Then I start paging through them. The first time I see a photo it’s a plausible, nice neutral tone. Then Lightroom thinks for a few seconds while displaying the message “Loading…”, adjusts something, and the whole photo is suddenly a lot redder than it should be.

How do I tell Lightroom not to do this? Whatever it’s doing, it’s screwing with the proper color balance of the photos. The photos seem clearly better before Lightroom mucks with them. I can usually get back to some semblance of what the photo should be by adjusting tone and temperature and such in the Develop mode; but why should I have to? The photos started out fine until Lightroom mangled them. Any ideas?

Allegedly my Tamron zoom lens has a 1:3 macro capability. That is, at maximum telephoto and minimum focusing distance (0.49 meters) objects should be imaged on the sensor at 1/3 their actual size. Let’s check that out.

The sensor in a Canon EOS 50D is 22.3mm by 14.9mm. A U.S. quarter has a a diameter of 24.26 mm. I extend the lens to 300mm and switch it to manual focus. Then I set the focus on the lens to 0.49m (the minimum). I move the camera until the quarter comes into focus and snap.

At 1:3 the quarter should occupy 24.26/3 mm == 8.087 mm. 8.087 mm/ 22.3mm = 0.36, just a tad more than a third the width of the picture. Actually it could be a little smaller than that if I didn’t shoot it head on. The raw image is 4752 pixels wide, so the quarter should be about 1710 pixels wide. Let’s open it up in Photoshop and find out.
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