Photo Class 2/30

Jupiter

This is lesson 2 of the photo class. But first, an explanation of the picture above. I set out to capture an image of the Moon and Jupiter, since they were really close together in the sky the other night (Jan 21). I wasn't very successful, though maybe someday I'll make a composite picture since I got decent exposures of the moon, and of Jupiter, but not of both together. I suppose it's a dynamic range issue, since the moon is significantly brighter than Jupiter. Anyway, back to the photo. It's not remarkable except for the little dots that look more like sensor dust than anything. Jupiter looks awful, I think it's overexposed and the wind was blowing more than my pitiful cheap tripod could handle so it's elongated too. This may be the engineer in me or maybe it's the astronomy nerd, but this photo is still awesome. That's because three of those dots are moons. Below and to the left is Ganymede, on the opposite side of Jupiter but about the same distance away as Ganymede is Io. Up and to the right from Io is Callisto. Finally down and to the right from Callisto is a star, Omega 2 Tauri. I'm still amazed that I captured this with my camera, even if it is kinda crappy from a photography perspective.

Anyway, now on to the boring part, since the rest of this post is probably really only of interest to me. The assignment for this class was pretty much to identify my camera's specifications and then to compare it with another camera. Not too difficult, because I'm a tech geek and the comparisons are something I've been doing anyway since I've been contemplating a new camera body for better low light capabilities. I've also been lusting after a fixed aperture lens.

Camera sensor/body stuff (Currently own a Canon Rebel XS, comparing to a Canon EOS 60d):

• Resolution - Rebel XS is 10 megapixel, the 60d is 18 megapixel
• Sensor Size - Essentially the same. XS is 22.2mmx14.8mm, 60d is 22.3x14.9
• Sensor Quality - They're both APS-C CMOS sensors. The 60d is a generation or two newer, and has better low light capabilities (wider ISO range, and less high ISO noise)
• Shutter - max shutter speed for the XS is 1/4000s, 1/8000s for the 60d. Flash 
• Light Meter - the XS lacks spot metering, the 60d also has a better evaluative metering system (35 zone vs 63 zone)
• Focus Detector - both use phase detection. 60d has more autofocus points (9 vs 7) as well as more capabilities for each autofocus point
• Image Storage - both use SD cards, though the 60d can use the newer SDXC cards
• Framing - viewfinder magnification is .81x vs .95x, the mirror system is pentamirror vs pentaprism and the coverage is .95x vs .96x so the 60d would have a brighter and more magnified viewfinder

Lens Stuff (currently own a few, but comparing the Canon 18-55 f3.5-5.6 IS to the Canon 17-55 f2.8 IS):

• Focal Length - Same on the telephoto end, but the 17-55 has a 1mm focal length advantage on the wide end. That turns out to be a little bit significant, it's a 4 degree increase in the field of view
• Aperture - The 17-55 has a fixed 2.8 maximum aperture so it lets in more light all through it's range. Especially significant at 55mm focal length, where it's 4 times as much light. The 18-55 has a smaller minimum aperture through some of it's range, but I don't think there's too much reason to ever shoot below f22.
• Focus System - This is a big difference. The 18-55 has a micro-motor for focus. The 17-55 has a ring USM motor, which is faster, quieter and allows for focus adjustment even when autofocus is enabled.
• Stabilization - The 18-55 finally wins! 4 stops of stabilization vs 3 for the 17-55
• Other Features - The 18-55 focuses closer, so it has a higher maximum magnification for close-up pictures. The 17-55 also has some fancy coatings and lens elements that I don't understand.