 Kathy Zavatson |
why can't I set lens to 1.4? I just bought a Canon 24-105mm 1.4 L IS lens. I use it on my Digital XTI and when I set the mode to AV and try to shoot as wide as it will go it won't go lower than 4.0. Why is it doing this or am I setting it up wrong? Also, I was trying to test it in a low light setting and some of my pics still came out blurry. Why? I'm trying to learn this lens b/c I will be shooting my friends birth and need a good lens. I also plan on using my 50mm 1.8. Should I just stick with that and stay away from my new lens? Any advice would help. thanks!
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- Gregory LaGrange Contact Gregory LaGrange Gregory LaGrange's Gallery |
Because that lens is a f/4 lens. http://www.usa.canon.com/consumer/controller?act=ModelDetailAct&fcategoryid=149&modelid=11924
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Alan N. Marcus |
Hi Kathy, As you know, we state the light gathering power of a lens using the f/number system. Mathematically f/numbers are ratios. We calculate them by division. While the f/number system is confusing it remains useful because a ratio is devoid of dimension. This declares that all lens systems set to the same f/number will perform the same as to image brightness regardless of make or model or size etc.. This is a good thing otherwise we would have disorder. We generally write f/numbers using a slash which indicate division. Examples are f/4 or f/5.6 etc. Since the maximum value or f/number of a lens is a good selling tool, lens makers tend to engrave it in the space surrounding the lens. In your case the maximum aperture is f/4 however lens makers prefer to write this value as a ratio using this notation 1:4. Note the use of the colon which is a valid usage to signify a ratio. In this case 1:4 is the same as 1/4 meaning the working diameter divides into the focal length 4 times. Its this notation caused you to believe you f/4 lens was a 1.4. Sorry about that! Alan Marcus
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W. |
Even NASA sometimes gets confused. And then a 250 million bucks spacecraft crashes into Mars, like a couple years ago...
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Kathy Zavatson |
THank you all for responding. Yes, I figured this out a little too late. I was reading it wrong. I still like the lens I just most likely be able to use it during my friends birth since the lighting will be low. I will do a couple of test shots since it does have IS maybe it won't be a problem.
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- Carlton Ward Contact Carlton Ward Carlton Ward's Gallery |
Kathy, you may also set your ISO setting to 400, 800, 1600 or higher to get a fast enough shutter speed to capture a focused shot. I bump up my ISO setting often in low light conditions when using a flash is inappropriate. With the higher ISO settings be sure to check your histogram to see that you are dialed in because if you have to lighten the image very much, you will get noise By setting your ISO higher you may possibly be able to select more Depth of Field as well(f/5.6, 7.1, and up) as long as you don't sacrifice the shutter speed too much to capture a moving subject.
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