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04/26/2006 03:58:48 PM · #1 |
I'm looking at buying a wide angle zoom lens, but I'm not sure which one is better.
I have a Canon 10D, and one, in the description, says is a F2.8-4 and the other is a F3.5-4.5. The 2.8 is a bit better cause it lets light in faster, right??? Its a bit confusing to me.
Also, on the lens specifications, they both say minimum apeture F22. I know what the apeture is, but is that the max the lens can go? I don't think the 10D goes past 22 anyway.
Im confused. Can someone please let me know what these things mean when purchasing a lens??? |
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04/26/2006 04:09:25 PM · #2 |
IT may all seem backasswards but it will make sense, i hope. the max f/stop is always the smallest number. So yes a 2.8 lens is good because it will let in more light. Then min f/stop is how small the lens will close down, ie f/22 or f/32 and so on. When you are shooting open, say f/2.8, you will let in lots of light, you will be shooting at a higher shutter speed and will have min DOF. Conversely if you are shooting at f/22, you let less light in and will shoot at longer shutter speeds and have max DOF. How the Navy taught me to remember this was a saying "close down, slow down, open up, speed up. I hope this all makes sense and helps you.
chris
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04/26/2006 04:17:44 PM · #3 |
2.8 is usually better/faster but with a wide angle that isnt always the case. You have to look at what you're going to be shooting with the wide angle and then see if that's something that needs to be faster with that shallow enough dof. Wide angle lenses are used a lot for landscapes and you dont really need a fast lens for landscapes nor do you really need to have the shallow dof.
Of course I could be wrong but thats what I've been told. |
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04/26/2006 04:20:26 PM · #4 |
| The 2.8 is likely going to have higher quality optics in addition the wider aperture. You may not use it wide open but in all likelihood you'll notice significant differences in color, contrast, and sharpness. It really depends on the specific lenses though so you may want to check out reviews. |
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04/26/2006 04:24:39 PM · #5 |
| I would think the same thing. Unless you're capturing a landscape at dusk or later, I wouldn't think you'd need that wide an aperture. During the day 5.6 - 22 (I try not to go that small because all the dust particles come out!) probably would be used. However, maybe if you're using a super fast shutter speed you'd open the aperture??? |
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04/26/2006 04:51:27 PM · #6 |
Originally posted by pottersclay75:
I'm looking at buying a wide angle zoom lens, but I'm not sure which one is better.
I have a Canon 10D, and one, in the description, says is a F2.8-4 and the other is a F3.5-4.5. The 2.8 is a bit better cause it lets light in faster, right??? Its a bit confusing to me.
Also, on the lens specifications, they both say minimum apeture F22. I know what the apeture is, but is that the max the lens can go? I don't think the 10D goes past 22 anyway.
Im confused. Can someone please let me know what these things mean when purchasing a lens??? |
1. As a rule (and this is not universal but it's pretty true) zoom lenses with f/2.8 maximum apertures are better built and optically superior to ones with smaller maximum apertures.
2. As a rule, any lens performs better stopped down one or two stops from its maximum aperture. So the f/2.8 lens will perform better at f/4, say, than an f/4 lens would (unless you stopped it down to f/5.6). This is a generality, but a fairly valid one.
3. f/stop is defined as the ratio between the physical diameter of the aperture and the focal length of the lens. A 25mm aperture on a 50mm lens would be f/2; a 25mm aperture on a 100mm lens would be f/4. A 25mm aperture on a 200mm lens would be f/8. So the "aperture number" is the inverse of the physical size of the aperture, basically. THEREFORE, the easiest way to visualize the relationship is to realize that f/2.0 is 1/2, f/4.0 is 1/4, f/8.0 is 1/8.... f/22 is 1/22. Obviously, a half is bigger than a quarter is bigger than an eighth... you get the idea.
4. Your 10D does not limit the minimum f/stop to 22. It doesn't care one way or the other. If it "stops" at f/22 that's because the lens mounted to it doesn't go any further. F/22 is a common minimum aperture for these lenses. F/32 is relatively common, f/45 is very rare, and I don't think I've ever seen one smaller than f/45 in the 35mm lens lineup. With my old view camera, on the other hand, f/64 was nearly universal, and f/128 was occasionally seen in some of the expensive Copal shutter assemblies, but that's a whole other story.
Robt.
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04/26/2006 05:12:12 PM · #7 |
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04/26/2006 06:01:28 PM · #8 |
Of the lenses you listed, the Sigma 17-70 is what I'd use. You may also want to check out the Sigma 18-50mm F2.8 EX DC (the EX means top of the Sigma line).
IMO, you may need to be wider (like the Sigma 10-20 or Canon 10-22), or you may have to stitch photos together.
If you shoot house interiors, you should have a good tripod, and use a hot shoe level because even the slightest tilt can make things look funny. (E.g. a slight downward tilt of the camera leads to keystoning in your image.) This is a good one: //www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=263729&is=REG&addedTroughType=search
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