Crop Sensor/Full Frame Confusion.

[knwnasrob]

Alright so I have a T2I right now and want to upgrade my kit lens (18-55), I want something that is better quality and has more zoom BUT keep the 18 or less focal length *I go to slot of car shows so it isn't easy taking pics far away when oblivious people alway walk by lol*
So I am looking and see the 18-135mm canon lens and it says in the description:
For use with APS-C cameras
35mm equivalent to 29mm-216mm focal length

Confusion! If the T2I is APSC then shouldn't it be 18-135mm and not 29-216???
So how would I know which lens really is the same low focal point as my 18-55 set at 18mm?
Sorry if I sound clueless...but I really am!

 

[enzodm]

18=18, so if you set it at 18mm you will have the same focal length and the same field of view. The latter being equal to what you would see at 29mm on full frame (with both lenses).
Focal length is independent on the sensor size, so the numbers you read are always comparable on the same camera. What changes is the recorded area, smaller in APS-C so giving you a smaller field of view than FF.
There is a thread just badly finished on this specific topic.

 

[WesternGuy]

Have a look at this page an see if it helps you understand this situation. The difference refers to the field of view or what the camera sees with the lens on it. As enzodm has indicated, the difference is not in the focal lengths themselves, but in the field of view that is captured by your sensor. Putting an 18-135mm lens on a APS-C sensor camera gives you the same field of view as putting a 29-216mm lens on a full frame (35mm) camera. Hope this helps.


Full Frame Sensor vs Crop Sensor – Which is Right For You?

Cheers,

WesternGuy

 

[ann]

At the low end it is the same

 

[tirediron]

At the low end it is the same

No, it's not.

 

[DiskoJoe]

With your current 18-55mm lens on an apsc you are actually seeing the view in a range of 27 - 82.5. You will only get the true range of 18-55 if you have a full frame camera. Keep this in mind when buying lenses.

 

[Dao]

Confusion! If the T2I is APSC then shouldn't it be 18-135mm and not 29-216???
So how would I know which lens really is the same low focal point as my 18-55 set at 18mm?
Sorry if I sound clueless...but I really am!

When you shop for new lens for your camera, do not worry about too much on the 35mm equivalent. It really don't mean much since you are not going to use the lens with a 35mm film body nor a full frame digital body. (Maybe later)

It is like, this vase worth US$100 or equivalent to Japanese Yen 7,645 In some case, the exchange rate may mean something such as you are used to Japanese Yen so you know if the vase cost 7645 yen is expensive or not. However, if you only use US dollars then you don't really need to know how much it is in Japanese yen.

 

[Big Mike]

35mm equivalent to 29mm-216mm focal length

This is the part that everybody seems to miss...The only reason they give you a crop factor or say that it's "equivalent to...", is because 35mm film cameras, used to be the standard tool for photographers. So now, they just compare everything back to 35mm film cameras.

If you are not very familiar with 35mm SLR cameras...then the crop factor is probably, completely irrelevant to you. So Don't Worry about it.
18mm on your camera may be equivalent (FOV) to 29mm (on a 35mm film camera)....but 18mm will always look the same on your camera...no matter what lens you use.

People keep getting confused, and there is so much mis-information going around....when really, most people should just forget that they ever read anything about the crop factor.....I feel like I'm taking crazy pills.

 

[knwnasrob]

Thanks for the help guys!

 

[ClickAddict]

At the low end it is the same

No, it's not.

I might be wrong tirediron, but I believe what ann meant was that at the low end (18mm, which is what the op is interested in since the op tends to shoot at 18 alot for car shows), the 18-55 (the one the op has) and the 18-135 (the one the op is interested in) will both be the same on the op's camera. (Field of view wise). Since the OP was worried about loosing out at the lower end.

 

[ann]

18mm is going to be 18mm regardless of the other focal lengths. As Click indicates the op was concerned about that end of the lens, not the other. How is that wrong?

 

[Village Idiot]

OP. Don't worry about field of view difference between full frame and crop sensor cameras until you either buy a full frame camera or buy a camera with a different sensor size. That will solve your problem entirely.