What lenses do you use for group shots?

To cloudwalker:

Being new to digital and having no wide angle lenses yet, I would worry that that 24mm will give me all the distortion while working as a 38mm.

Just think of it as what you already know about different film formats... how it all relates to normal focal length. If you fitted your 55mm lens from your roll film system onto a 35mm film camera, it would act just like a normal lens... distortion and all. But if you mounted it on a 4x5, well... I'm sure you know.

-Pete

So, are you saying that the distortion has nothing or little to do with lens design but is rather a question of how the focal length relates to the format? Tbh, I had never given it any thought until this thread :(
 
Sigma has 2 versions of the 10-20 now. The 3.5 just came out so that should puch the price of the 4.0-5.6 down. still a good lense. I have not decided wether to go canon 10-20 or sigma. Does anyone know if the 50D has the correction information for the Sigma lenses? Not trying to steal the intent of this thread ;)
 
Sigma has 2 versions of the 10-20 now. The 3.5 just came out so that should puch the price of the 4.0-5.6 down. still a good lense. I have not decided wether to go canon 10-20 or sigma. Does anyone know if the 50D has the correction information for the Sigma lenses? Not trying to steal the intent of this thread ;)

My Sigma 10-20 f/4-5.6 works fine on my 30D and my 7D, so I would imagine it would work on a 50D. (... love that lens...)
 
To cloudwalker:

Being new to digital and having no wide angle lenses yet, I would worry that that 24mm will give me all the distortion while working as a 38mm.

Just think of it as what you already know about different film formats... how it all relates to normal focal length. If you fitted your 55mm lens from your roll film system onto a 35mm film camera, it would act just like a normal lens... distortion and all. But if you mounted it on a 4x5, well... I'm sure you know.

-Pete

So, are you saying that the distortion has nothing or little to do with lens design but is rather a question of how the focal length relates to the format? Tbh, I had never given it any thought until this thread :(

There are different kinds of distortion. Perspective distortion is related to focal length:

"http://en.wikipedia.org/wiki/Perspective_distortion_(photography)"
 
There are different kinds of distortion. Perspective distortion is related to focal length

Although focal length does play a role in perspective distortion, it is actually a natural phenomena. If you stand at the foot of a skyscraper looking up, the top will look smaller than the base just like it would with any lens.

I am talking about radial distortion which I believe is particular to lenses and much more of a problem with wider focal length. Of course, I could be wrong :D
 
...a question of how the focal length relates to the format?

Doesn't that seem right to you? Gee... maybe I'm the one who's thinking wrong.

I figure the lens is making a circular image, and the closer the edge of the frame comes to the the edge of the circle, the more we see the distortion. If it goes far enough, you get the edge of the image (vignetting).

That's how I reasoned it out.

Please.... someone jump in if I'm steering folks wrong.

-Pete
 
...a question of how the focal length relates to the format?

Doesn't that seem right to you? Gee... maybe I'm the one who's thinking wrong.

I figure the lens is making a circular image, and the closer the edge of the frame comes to the the edge of the circle, the more we see the distortion. If it goes far enough, you get the edge of the image (vignetting).

That's how I reasoned it out.

Please.... someone jump in if I'm steering folks wrong.

-Pete

Absolutely not trying to say you are wrong. Just trying to understand. I am not much with science but I am pretty good with common sense and what you say about the circular image is, to me, common sense. And, I have seen the same thing mentioned on several sites/blogs.

Although most tests of distortion are done with straight lines, some people/sites/blogs seem to think it should be done with circles. To me it makes sense but, again, I don't really understand any (much) of it. My reactions have more to do with common sense than science so...

I guess I'll just go to the store and try a few things :D
 
Sigma has 2 versions of the 10-20 now. The 3.5 just came out so that should puch the price of the 4.0-5.6 down. still a good lense. I have not decided wether to go canon 10-20 or sigma. Does anyone know if the 50D has the correction information for the Sigma lenses? Not trying to steal the intent of this thread ;)

My Sigma 10-20 f/4-5.6 works fine on my 30D and my 7D, so I would imagine it would work on a 50D. (... love that lens...)

Sorry I meant Periphial Illumination Correction information.
 
Absolutely not trying to say you are wrong. Just trying to understand.


Oh, me too. I could be absolutely wrong. In fact, after I made the post, I began to ponder that the image produced by a lens is likely not merely circular, but spherical... like a contact lens. Film, and I presume sensors, are flat, causing the distortion. Hey... maybe we're on to something. Should we start producing curved sensors?
 

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