Which lens should I get - Focal Length Comparison


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CS TAN

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Sep 3, 2007
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#1
A lot of threads in CS is about which lens to get for landscape, portraiture, wild life, etc...

I think the question has a lot to do with people not understanding the focal length and what they would be getting within the frame when using a particular focal length lens.

I found this on the web which I feel is quite useful myself so just want to share with others here:

http://www.juzaphoto.com/eng/articles/focal_length_comparisons.htm
 

hwchoy

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#4
however I should hasten to mention that such a way of comparison only works for close-by focal lengths (eg comparing 300mm against 400mm). it is not valid if you compare say 50mm to 200mm as the perspective changes with the focal length. a short lens shows you a lot of background, whereas a long lens gives you a "barrel" effect.
 

grantyale

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Oct 4, 2004
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#5
however I should hasten to mention that such a way of comparison only works for close-by focal lengths (eg comparing 300mm against 400mm). it is not valid if you compare say 50mm to 200mm as the perspective changes with the focal length. a short lens shows you a lot of background, whereas a long lens gives you a "barrel" effect.
:nono: No that's not true.

Besides, Juza's article seems to be talking about focal lengths on APS format only, and yet he mentions FF here and there - which isn't exactly helpful. For example, he says
17-55, 17-85 and similar zooms, created for APS-C cameras, offers a pretty wider angle of view than standard zooms for FF cameras, as the Canon 24-105 L IS.
Well. It doesn't matter if 24-105 is a FF lens or not, it's simply 24 vs 17 compared on the same format.
 

hwchoy

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#6
:nono: No that's not true.

Besides, Juza's article seems to be talking about focal lengths on APS format only, and yet he mentions FF here and there - which isn't exactly helpful. For example, he says

Well. It doesn't matter if 24-105 is a FF lens or not, it's simply 24 vs 17 compared on the same format.
what do you mean its not true? cropping a 300mm lens image down will not give you the same picture as one that is produced by, say, 100mm.

a 24mm FF lens on an FF sensor will not produce the same image as a 15mm FF lens on APS-C sensor, for the same reason. it could be close but not the same.
 

CS TAN

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#7
I believe the website is best use for focal length comparison between two close focal length lenses. e.g. how much wider is 16mm as compare to 17mm. How much area will I be missing if I go for 24mm instead of 17mm. The website give you a visual aid to "see" so as to help you decide.
 

grantyale

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#8
a 24mm FF lens on an FF sensor will not produce the same image as a 15mm FF lens on APS-C sensor, for the same reason. it could be close but not the same.
:bsmilie: Tell me how it won't.
 

Reim1o

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#9
The compressed/exageration effect would be different. Imagine you have a huge a55 sensor that you can mount a 135mm lens and it will give you the same view as a 24mm on a full frame.
With the 24mm full frame you will get that impact, whilst the larger sensor will have more compressed picture.
 

YSLee

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#10
It will be the same if you maintain the same subject magnification ratio.
 

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