 Jennifer A. Feeney |
28-200mm zoom and noise I am borrowing a friend's old Tamron lens (for Canon) and using it on my Rebel xti. I have noticed a lot of noise with this lens as compared to my 18-55mm kit lens. Even when the ISO is set at 100 and there is plenty of light (shutter speeds of 350+)I have a tone of digital noise in the pictures. Is this a typical problem with zoom lenses, poor quality lens, incapatability with my camera, or what? I'm saving up to buy the Canon 70-200mm IS zoom, but will think twice about investing 1600 in a lens if I will always have noisy pics.
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Todd Bennett |
Jennifer, Can you post a pic that shows the noise? A piece of glass (a lens) should have no affect on noise. The ISO/film speed is what induces the noise or graininess into the picture.
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Jennifer A. Feeney |
That's what I thought. Unfortunately, I don't have pics (I deleted many and removed the noise from the rest). Could it be that low amounds of noise that you would not normally see with a wide angle lens become magnified with a zoom?
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Todd Bennett |
Jennifer, I don't think a lens has any effect on noise. The noise comes from the sensor and the ISO setting. The lens quallity is only going to affect the clarity of the picture. Try looking at this post: http://www.betterphoto.com/forms/QnAdetail.php?threadID=28798 You'll have to weed through some garbage; but, it may help. Chris has a good test he mentions in there.
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Jennifer A. Feeney |
OK, I went back and looked at my photos and it turned out that the ISO was 400 (not 100, as I thought). I just took some shots at 100 and got no noticable noise. Now, I often shoot at ISO 400 with my standard lens and don't get the kind of noise I got with the different lens. Wondering just what causes digital noise, I did a quick search and found the following article (Digital Noise - What Is It? What Causes It? And How Can I Get Rid Of It?http://searchwarp.com/swa82244.htm) I it goes into a bit more detail and is very understandable. ISO (digital sensor sensetivity) is directly related to noise, but so is the amount of light you are exposing the sensor to. With slow shutter speeds you also get noise because the sensor is "integrating more light per pixel...some pixels will appear as noise because for these pixels the amount of noise integrated is significantly close to or higher than the actual light measured." What does this mean for me and my pics? I was shooting outside in late afternoon sun. While not the intense sun of high noon, still a significant amount. I wanted to eliminate the chance of camera shake so set the ISO to 400 so I could use fast shutterspeeds. Problem was (I think) that this setting was just too sensetive for the amount of light. So I got a lot of noise. I am often shooting indoors, for which a more sensetive ISO is appropriate. In these images I get very little noise.
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