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t2i for action scene

dlevanchuk

dlevanchuk

Looking to get a camera for my first project.

Woudld t2i be a good choice for fast paced action scene, like a person running through the street, where there is a lot of focus change? I've read that t2i doesn't have autofocus, so it kind of worries me :-S
 
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chilipie said:
For day exteriors, an f3.5 is absolutely fine, but I usually like to open it up a bit when I'm inside as I like the effect of it.

One thing that's worth bringing up here is the fact that lenses usually look their best when stopped down a little - a lens that's wide open at f3.5 will generally look a fair bit sharper at f4. I did an exterior night shoot recently, with relatively low wattage lighting, using a Canon 50mm f1.4 - I don't think I ever opened it up more than f2/f1.8 or so, so I could have got away with the Canon 50mm 1.8, which is substantially cheaper (though the 1.4 isn't my lens), but having the extra two-thirds of a stop on the lens meant I could have a sharper image.

Of course, if it's the difference between getting a shot and not then open that lens up as wide as it'll go - but a faster lens does more than just let you shoot in lower light.
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I remember reading that somewhere and had totally forgotten about it! That's a good bit of advice.
Btw I thought I'd mention, if you do get a T2i, it has a cropped sensor of a factor of 1.6 (I think that's what they call it), meaning a 50mm lens would look like an 80mm...Or so I hear.
 
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sina12345 said:
I remember reading that somewhere and had totally forgotten about it! That's a good bit of advice.
Btw I thought I'd mention, if you do get a T2i, it has a cropped sensor of a factor of 1.6 (I think that's what they call it), meaning a 50mm lens would look like an 80mm...Or so I hear.
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Yep, the T2i/550D has an APS-H sensor with a 1.6x crop factor. However (and I know I've got mixed up with this before), the crop factor does not change the focal length of the lens, just the angle of view. A 50mm is still a 50mm, and the characteristics of the lens do not change, but the recorded image is cropped to the same field of view as a lens 1.6x longer.
 
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sina12345 said:
I remember reading that somewhere and had totally forgotten about it! That's a good bit of advice.
Btw I thought I'd mention, if you do get a T2i, it has a cropped sensor of a factor of 1.6 (I think that's what they call it), meaning a 50mm lens would look like an 80mm...Or so I hear.
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True, but that's only if you're using an EF lens. Chilipie is surely talking about EF-S lenses, which are designed for this particular sensor, and no funky math is needed.

EDIT: Doh! Spoke on chilipie's behalf, while chilipie was typing.
 
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Cracker Funk said:
True, but that's only if you're using an EF lens. Chilipie is surely talking about EF-S lenses, which are designed for this particular sensor, and no funky math is needed.

EDIT: Doh! Spoke on chilipie's behalf, while chilipie was typing.
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Not quite :) A 50mm EF-S lens has the same AOV on a 550D as a 50mm EF lens does (i.e. the AOV of an 80mm lens on a full-frame sensor) - the EF-S lens is just designed for the smaller sensor, projecting a smaller image (which is why you get vignetting with an EF-S lens on the 5D), and thus can be smaller, lighter and cheaper than its EF equivalent.
 
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chilipie said:
Not quite :) A 50mm EF-S lens has the same AOV on a 550D as a 50mm EF lens does (i.e. the AOV of an 80mm lens on a full-frame sensor) - the EF-S lens is just designed for the smaller sensor, projecting a smaller image (which is why you get vignetting with an EF-S lens on the 5D), and thus can be smaller, lighter and cheaper than its EF equivalent.
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Okay, say that again, but this time speak English!

:huh:
 
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Cracker Funk said:
Okay, say that again, but this time speak English!

:huh:
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Heh :) I'll do my best…

A lens does not change focal length when put on a different-sized sensor. What does change is the angle of view (AOV) of the image being recorded. A 50mm lens on a 550D has the same AOV as an 80mm lens on a 5D.

EF-S lenses can only be used on sensors the size of the 550D's because they project a smaller image onto the sensor. You know how the image from an EF lens is effectively cropped when used on a 550D? An EF-S lens gets rid of the extraneous glass that is focusing the light into the area around the 550D's sensor that isn't being recorded (hence the smaller, cheaper, lighter).

A 50mm EF or EF-S lens can be used on the 550D with no change in the AOV - all the EF-S lens does differently is to "pre-crop" the image being projected on the sensor, which accounts for the vignetting when an EF-S lens is used on a full-frame camera such as the 5D.

I hope that was clearer… I get a bit carried away with myself sometimes :D
 
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What chilipie said is correct.

lets c if i can make it simpler (or make it come sound even more complicated lol)

Lenses are circular.

Sensors are rectangular.

EF lenses are large circles that fit around a FF rectangular sensor.

EF-S lenses are smaller circles that fit around smaller (1.6 crop) rectangular sensors.
 
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Remember the caveman lawyer from SNL?

cavemen-unfrozen-lawyer-web.jpg


That's how I feel right now. I'm just a caveman. I don't understand your big words, or your fancy cameras.

So, let me break this down into something even a caveman could understand -- pictures. This is how I envision it in my head. Let me know if I've got it right, or if it needs tweaking.

eflens.png
 
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I stopped in to a camera shop the other day, and played around with EF lenses, and asked a bunch of questions. FINALLY, I understand the crop factor and conversion stuff, and I finally understand why it confused me.

It doesn't apply to me. Not even slightly. It's only for other people to worry about -- namely, people who are accustomed to what a particular focal length will look like on 35mm film. Conversion math is necessary for photography converts working with the T2i/7D. Cuz unfortunately, these cameras won't get them the look they see in their heads, when thinking about a particular focal length.

I don't have that problem, cuz I'm a miniDV convert. I don't have any image in my head telling me what a 50mm lens will look like, etc. So, I've edited my beautiful diagram, so that all the other cavemen out there can finally understand this concept.

eflens.png
 
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Cracker Funk said:
I stopped in to a camera shop the other day, and played around with EF lenses, and asked a bunch of questions. FINALLY, I understand the crop factor and conversion stuff, and I finally understand why it confused me.

It doesn't apply to me. Not even slightly. It's only for other people to worry about -- namely, people who are accustomed to what a particular focal length will look like on 35mm film. Conversion math is necessary for photography converts working with the T2i/7D. Cuz unfortunately, these cameras won't get them the look they see in their heads, when thinking about a particular focal length.

I don't have that problem, cuz I'm a miniDV convert. I don't have any image in my head telling me what a 50mm lens will look like, etc. So, I've edited my beautiful diagram, so that all the other cavemen out there can finally understand this concept.

<snip>
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C'est parfait! I'd never paid any attention to focal length (numbers wise) while doing video until I started using the Canon DSLRs, but I'd done enough stills photography for it to be worth the mental conversion when it came to the 550D :)
 
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Never thought about that Cracker. It's true. My DP (and I) think in focal lengths. Ok, so 50mm for that shot, 85 for that shot, 28 for this master. If you don't already have that in your head it's not as "confusing".
 
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Gonzo_Entertainment said:
Never thought about that Cracker. It's true. My DP (and I) think in focal lengths. Ok, so 50mm for that shot, 85 for that shot, 28 for this master. If you don't already have that in your head it's not as "confusing".
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Well, the thing that confused me was that I couldn't figure out, for the life of me, why I had to do conversion math. I felt like I was getting conflicting answers. One guy would tell me that because of the crop factor, a 50mm will look like an 80mm, or something like that. Then another guy would tell me that an EF 50mm would look exactly like an EF-S 50mm. And I was like, damn, which is it? What I finally understand is that we aren't doing any conversion math with lenses -- only the sensors. And so, the people who are accustomed to full-frame, it makes sense that they have to do conversion. But people who aren't accustomed to anything, there's no math necessary, whatsoever. All those guys who kept telling me to do the math were assuming that I had a preconceived notion of what a particular lens looks like, on full frame sensors, or 35mm film. I don't. So I don't need to worry about it. They're all the same to me.
 
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