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Old 02-04-2009, 07:56 PM
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Tilt (Michael)
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Wide angle lens

Hi Guys,

I'm heading over to Japan next week, and I may very well get tempted into buying a new wide angle lens while I'm there for my 50D. So what do you think, 17-40L F4 perhaps? maybe something else? I currently have the Canon 17-85 IS F4-F5.6 and it has some barrel distortion at 17mm, it would be nice to have a lens that doesnt do that.

Michael
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Old 03-04-2009, 06:12 AM
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Not sure what focal lengths you shoot at normally, or if you intend to upgrade to a full frame camera like the 5D or 1D series in the near future, but IMO the best walkaround lens suited to the 50D would be the EF-S 17-55 f/2.8 IS. It's sharp as, fast aperture, and IS. It's slightly more than the 17-40, so you'd have to weigh up whether you think the extra stop and IS is worth it. It's not an "L" series either, but the build quality is very good.

In addition, I find that if I want "wide" I usually go very wide and have the 10-22 also. It's a great lens, but in hindsight I'd have gone with the Sigma 10-20 probably (cheaper and just as good quality). Believe there is a new Sigma lens 10-20 or thereabouts being release soon that's f/3.5 constant aperture too.

If you consider 17mm wide enough, I'd go with the 17-55. Great combo with your 70-200 f/2.8L
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Old 03-04-2009, 07:08 PM
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I keep seeing very favourable reviews of the Tokina AT-X PRO DX AF 11-16mm f/2.8.

Build quality appears to be very good and more importantly, it produces very sharp and nicely contrasted images.

The magnification range isn't as good as the 17-40...but it goes wider and performs better in low light conditions and is a little easier on the pocket compared with its Canon cousins.

Food for thought
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Old 03-04-2009, 11:32 PM
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Tilt (Michael)
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I got my 50D today! Wow, what an upgrade from the 350D

Thanks for the input, you've given me some options to think about. The full frame DSLR in the future is certainly an option, therefore I'd probably need to look at something away from EF-S.

Michael
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Old 04-04-2009, 06:45 AM
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Congrats on the 50D! I'm very jealous.
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Old 20-04-2009, 10:23 PM
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Currently in Japan. No wide angle lens for me at this stage (weak AUD makes for no bargains), although this has given me more time to consider a prime L series lens rather than a zoom. I was in a camera store yesterday checking out the 24mm, 35mm and the 50mm prime Canon lenses. There was a cool chunk of raw Fluorite crystal sitting in the cabinet too displaying the material that goes into an L series lens.

Michael
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Old 21-04-2009, 06:35 PM
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If you're intending on going full frame in the near future the 17-40 F4L would be nice.
Reviewers claim it still has some barrel distortion at the wide end but is easily corrected in software (the 50D software bundle has correction for many lenses).

If you're staying with the 50D for a while I'd look at the 12-24 Tokina, a very nice lens for not a lot of money. When and if you go full frame you will not lose much on resale.

One thing you will miss if you go full frame, is the reach of your telephoto lenses; the 1.6 crop factor of the 50D makes your 70-200 reach a whole lot further.
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Old 21-04-2009, 06:56 PM
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Quote:
Originally Posted by acropolite View Post
One thing you will miss if you go full frame, is the reach of your telephoto lenses; the 1.6 crop factor of the 50D makes your 70-200 reach a whole lot further.
Here's the way it was explained to me: One often reads this about the 1.6 crop factor effect, but the focal length of a lens does not change, whatever camera one uses with it. Therefore, the actual magnification or 'reach' of a particular lens remains the same.

The APS-C sensor merely crops the centre image, thereby giving a larger apparent magnification.

What we're really talking about is the angle of view offered by a particular lens, which does change with a smaller sensor.
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Old 21-04-2009, 07:17 PM
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Quote:
If I may quote a reliable source on this issue: one often reads this about the 1.6 crop factor effect, but the focal length of a lens does not change, whatever camera one uses with it. Therefore, the magnification or 'reach' remains the same.
Matt it doesn't matter how you phrase it, magnification relative to the image ratio is real and the reach of your lenses on a FF sensor, as compared with a crop sensor, is less.

I have owned a 20D, 50D and now 5DII and I can assure you that the Tele lenses (and all lenses for that matter) have less reach on FF sensor.

To put it simply the image scale of a 200mm lens on a crop sensor will be 1.6x greater than that of the FF sensor; that is to get the same image scale or FOV on a FF sensor you will need a lens of 320mm which oddly enough equates to 1.6 x 200.

On the reverse side your wide angle lenses have much wider FOV's on a Full frame sensor although that's not really an issue as 10-22 etc lenses have approximately equivalent FOV to 17 on a FF sensor.

With Tele lenses however longer+quality=$$$$

Try pricing an L series 600mm.

Last edited by acropolite; 21-04-2009 at 08:28 PM.
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Old 28-04-2009, 02:52 PM
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Just got home from Tokyo (so very tired)... No additional lens in my bag, maybe next time. I also found the time to drop into the Tak shop in Akihabara before I left, I asked my wife (who was in the store with me at the time) if she minded that I purchase the TOA-150 that was there

BTW Phil I did price a 600mm L series lens a few days ago. It was over 1,000,000 Yen.

Michael
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Old 28-04-2009, 04:35 PM
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On crop factor etc:

The only thing that matters is FL.
From there, anybody can calculate the scale of that particular lens, that means how many mm per arcsec. Or, how many pixels one arcsec uses at that particular sensor.

The FOV of the camera depends on the physical size of the sensor.

The so called "crop factor" is misleading term and should never be used, at least not among people who understand the basics of camera geometry. Because it was "invented" by some companies to make it simpler for people used to conventional 35mm film cameras.. thus creating only a confusion among other users.

To extend my point: What if someone is using Canon lens mounted on webcam? Crop factor is then 3, 4 or even higher, depending on the size of the sensor.. referred to 35mm film size, of course.
If someone is used to 22mm sensor (most cheaper Canons) , then crop factor relative from those is again different (1.6x smaller)..

In earlier days of astrophotography (when plates were used), the term used was "scale", expressed as arcsec/mm, as mentioned at the beginning of this post. It did not matter what size of film or plate was used, because this number was lens dependent, thus constant.

Last edited by bojan; 28-04-2009 at 05:36 PM.
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