50mm normal lens = 85mm on a DSLR?

[jenni_orwick]

I just read an article on normal lenses and the author explained that-

"a 50mm normal lens on a Canon EOS-10D camera renders an image equivalent to an 85mm lens on a film body. On

these cameras, the focal length that best equates to a "normal" perspective is the 35mm, becoming an effective

52-56mm lens on a typical digital body."

 

does this apply an XTi as well? As some of you might know from a previous post, I'm searching for a nice prime

for low light photography, but should I look for a good 35mm instead of an EF 50mm F/1.8 now?

[Matt Laur]

<i>does this apply an XTi as well?</i>

<br><Br>

Yup.

<br><br>

<i>should I look for a good 35mm instead of an EF 50mm F/1.8 now?</i>

<Br><Br>

Depends on what you want. A 50mm will feel like a short telephoto lens. If you're using a 50mm on your XTi, you'll have to stand approximately 15 feet away before you'll be able to fit an entire standing person into your frame.

<br><Br>

Do you have a kit zoom lens? If so, the zoom markings on it will tell you exactly how a given focal length will appear to your camera. That's a great way to judge what length you need.

[akajohndoe]

There is an explanation of this "crop factor" effect <a href="http://en.wikipedia.org/wiki/Image_sensor_format" rel="nofollow">here</a>. On a 1.6x camera 50mm seems more like 50*1.6, or 80mm.

[g dan mitchell]

<p>Almost.

 

<p>If you put a 50mm lens on a 1.6x Canon cropped sensor camera the camera will capture images with an angle of

view equivalent to using a <b>80mm</b> lens on a 35mm SLR or full frame DSLR.

 

<p>If you are familiar with the way that particular focal lengths worked on 35mm SLRs, this is useful information that

can help you determine what focal length to use on your cropped sensor camera.

 

<p>If you remember liking a particular focal length on 35mm and you want to know what focal length will provide the

equivalent angle of view on your cropped sensor DSLR, <b>divide the focal length of the former by 1.6 to find the

equivalent focal length on your DSLR.</b> Example: If you liked a 50mm lens on 35mm SLRs you would get the same

angle of view from a 31.25mm lens on your cropped sensor camera because 50mm/1.6=31.25mm.

 

<p>If you have a given focal length lens on your cropped sensor DSLR and you want to know what the equivalent focal

length was on your 35mm SLR, <b> multiply the focal length of the former by 1.6 to find the equivalent 35mm SLR focal

length.</b> Example: If you put a 100mm lens on your cropped sensor camera it will provide the same angle of view that

you would have gotten from a 160mm lens on your 35mm SLR because 100mm x 1.6=160mm.

 

<p>Whew...

 

<p>Dan

[jenni_orwick]

"Do you have a kit zoom lens? If so, the zoom markings on it will tell you exactly how a given focal length will appear to your camera." - Matt Laur

 

oh okay, so it'll look the same as the kit lens. I thought the author ment that the 50mm prime would shoot as an 80mm on any other zoom lens. But you're saying that the ratio is the same as a kit lens right?

[jenni_orwick]

I havent used an SLR before, if the 50mm prime on an XTi looks the same as the 50mm on the kit lenses, then i'm content. Someone please confirm this? for give my ignorance i'm not a photographer, I'm trying to by a gift =)

[sarah_fox]

Yes, for any given camera body, one 50mm lens will give you approx the same magnification as another 50mm lens -- or even a zoom lens set at 50mm. (Is that what what you are asking?)

 

If you have ANY lens set at 50mm on a 1.6 crop frame camera like the XTi or 10D, it will give you about the same field of view (or magnification, or whatever you want to call it) as an 85mm lens on a full frame camera (like a 35mm film camera). A 50mm lens would be considered a "mild telephoto" on a crop frame camera. It would be well suited for portraiture, as it would avoid the distortions (e.g big noses, shoulders, knees, or whatever sticks the farthest out front) that would sometimes be seen on a "normal" lens, which would be about a 30mm lens on a 1.6 crop camera.

 

For a full frame camera (e.g. a 35mm film camera), a 50mm would be a normal lens, and an 85 (or more ideally a 105) would be portrait length.

[gaylon_morris1]

For a given sensor, a focal length is the same regardless of lens it comes off of, so yes - a 50mm prime will look the same, from a 'fills the viewfinder' standpoint, as the kit lens set to 50mm.

[g dan mitchell]

<p><i>"For a given sensor, a focal length is the same regardless of lens it comes off of, so yes - a 50mm prime will look the

same, from a 'fills the viewfinder' standpoint, as the kit lens set to 50mm."</i></p>

 

<p>Huh?

 

<p>While it is true that a 50mm lens is still a 50mm lens no matter what camera you put it on, it is not true that the image

captured in the different formats will be the same. It is <i>very definitely not true</i> that a 50mm lens will "fill the viewfinder" the same

[sic] on

full frame and cropped sensor cameras.

 

<p>In terms of angle of view, photos captured by a 50mm lens on a crop sensor camera and a 80mm (not 85mm) lens on a

full frame (or 35mm SLR) camera will look the same - e.g. they capture the same angle of view.

 

<p>To offer a direct answer to the OP's question about the 35mm lens on the XTi or other 1.6x cropped sensor camera...

a 35mm lens on these cameras provides the same angle of view provided by a <b>56mm</b> lens on a full frame

DSLR or a 35mm SLR.

 

<p>If you are trying to emulate the effect of a 50mm "normal" prime on the 35mm film SLR on your new XTI, the exact focal

length you want is <b>31.25mm</b>. The closest approximation comes from third-party 30mm primes - or, of course, from a zoom that

includes that focal length. Close alternatives from Canon include 35mm primes (which will seem a bit longer than you want) and 28mm

primes (which will seem just a bit wider).

 

<p>Dan

 

<p>(Yes, I know about the DOF issues, but let's not go there in this thread, OK? :-)

[richard_oleson]

I think that's exactly what Gaylon meant by beginning that sentence with "For a given sensor...", Dan. A "given sensor", in my book, would not incorporate different format sizes.

[jenni_orwick]

thank you all so very much. please take care.

[benbangerter]

Jenni: Finally, understand that "perspective" is not a characteristic of a lens - it is solely determined by the position of the camera relative to the scene. A lens has a "field of view" which is determined by the extent to which the sensor (or film frame) crops the circular image projected by the lens. With your digital SLR, you now have a tiger by the tail. Enjoy the ride!

[skipd]

I also think that Dan Mitchell's post is based on a misunderstanding of Gaylon's post before it.

 

What Gaylon was saying is that any lens of the same focal length used on any particular camera will provide the same field (angle) of view. As an example, a 50mm prime, a 24-70 set to 50mm, or an EF-S 18-55 set to 50mm will all provide precisely the same size image on a 40D.