is the field of view always smaller on shorter lenses? (ex 28mm vs 35mm)?

[brentw505]

i have a tamron 28-200mm macro lens with a 10d right now... was wondering if the tamron lens, on 28mm, would have a wider view than the 35mm 1.4L wide angle lens. does longer always mean shorter view of anlgle? or is that just usually what it is?

another question: what is a 35mm camera? is that always a film camera? what is the 35mm refering to?

[Persian-Rice]

narrower field of view, not shorter heh.

You are comparing a 28mm to a 35mm? I'm confused, what are you trying to ask?

The shorter the focal length the wider the field of view, 17mm is not going to be"wider" then another 17mm, unless you have some extra stuff going on like cropping. 28mm will be wider then any 35mm. Where did you get the idea it would otherwise? just wondering.

Are you talking about physical dimensions? because that will have nothing to do with it, just the design of the lens. The Tamron 28-75 is much smaller then the Canon 28-70. But they pretty much show the same thing.

I hope I covered it somewhere in there.

[Persian-Rice]

35mm is the dimension of the film........Most sensors on dSLRs are smaller, other then 1Ds series. That's why you get crop factor. Don't be confused by 35mm, 4x5, 6x4.5, or 6x7.

Those refer to the size of the film or in digital's case the sensor. Don't mix them up with lens focal length.

[brentw505]

i never really knew what those numbers really meant... i just thought that it was the length of the lens... didnt know if every 25mm lens has the same field of view as any other 25mm lens

[Persian-Rice]

http://www.millhouse.nl/digitalcropfactor.html

[Persian-Rice]

Yes, the designs are what makes the actual physical dimensions of the lens. In terms of advertised focal length, they will be as advertised. Referring the link above, all D series digital SLRs are 1.6 crop factor because the dimensions of the sensor are pretty small.

[rent]

the mm number is the "focal length" of a lens. shorter focal length = wider field of view for any given camera format. camera format is determined by the size of the imager (film, or digital sensor).

so yeah, for the 35mm format (35mm film, or the 1Ds series), all lens with the same focal length has the same FOV.

with a smaller imager format like the sensor on the 10D/20D/DRebel, a lens would give a smaller FOV on such cameras as it would on a larger format. this is known as the crop factor (which tends to lead to very long threads, especially when mixed with other technical terms, LOL).

good luck and welcome to the forum!

-alex

i never really knew what those numbers really meant... i just thought that it was the length of the lens... didnt know if every 25mm lens has the same field of view as any other 25mm lens