Lens question

[kharypayt37]

I currently have a t6i body with a 55-250mm lens. I mainly take sports pictures/videos (American football), and I am wondering which lens I should upgrade to. I am looking for an investment piece that will suit me down the line should i upgrade my camera. From research the past few days, i have focused on the 70-200mm f/4 IS II. This has been the clear-cut favorite (according to the sources ive looked at). However, i am not sure if i should opt for a lens like the 300mm as my current lens can deal with those closer shots.

i appreciate any advice!

[shadowsports]

Greetings,

One important detail.

The 70~200 f4 is a EF lens

Your T6i is APS-C and is designed primary for EF-S lenses.  You can however use EF lenses with it, but note that the effective focal length will be 112~320mm (not) 70~200.  

[kvbarkley]

And the (35 mm equivalent view) effective focal length of his current 55-250 is 88 to 400.

[shadowsports]

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@kvbarkley wrote:

And the (35 mm equivalent view) effective focal length of his current 55-250 is 88 to 400.

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The 55~250 is EF-S (true APS-C)

@Mike...

Crop factor...  It doesn't apply.  

He's got an APS-C body and is considering an EF lens.  (70~200)

[MikeSowsun]

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@shadowsports wrote:

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@kvbarkley wrote:

And the (35 mm equivalent view) effective focal length of his current 55-250 is 88 to 400.

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The 55~250 is EF-S (true APS-C)

@Mike...

Crop factor...  It doesn't apply.  

He's got an APS-C body and is considering an EF lens.  (70~200)

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It doesn't matter what lens you use. Crop factor ALWAYS applies when you use a crop camera. It is a basic fact that is often misunderstood.  

[shadowsports]

I believe his intention is to improve the quality of his glass.  now and in the future.  He indicated he was conidering the 70-200, but then stated that a 300mm lens was also in contention, recognozing that his 55-250 would already be covering this focal length.  

I was merely pointing out that using an EF lens with his body will yield the following FL, not what range on the lens shows.  What going to change is the FOV and amount of light an EF lens will let in.  The image circle is going to be smaller on the crop body regardless of the lens being used.  I'm aware of this.  Maybe I didn't express this correctly.     

[kvbarkley]

No. Just no. The focal length of a lens is the focal length of the lens, it is an intrinsic property of the design. It does not change because of the size of the sensor.

What changes is simply the field of view. And that applies to EF and EF-S lenses. there is no reason to point out the 1.6x field of view of the EF-S lens, and not point out the same for the EF lens.

Besides, if our OP has never used a 35mm film or full frame DSLR, the comparision is meaningless.

[ebiggs1]

"Besides, if our OP has never used a 35mm film or full frame DSLR, the comparision is meaningless."

Bingo!  

Crop factor is the most ridiculous and misunderstood term in photography. Rick is not alone in that confusion. The thing to take away from this is, once a lens is made, its FL can not change.  No matter what camera it is used on. You could take the very same 55-250mm lens and mount it on a medium format camera body, if such an adapter were possible, and its FL would still be 55-250mm.

[rs-eos]

It isn't meaningless though.  e.g there is much documentation out there on what designates a wide angle lens, what is standard, telephoto, etc.

If someone is specifically looking for a standard lens (in terms of field of view), they do need to look at focal length and understand that a 50mm is standard FOV on full frame, but short telephoto on APS-C.

Same for folks looking for super wide angle.  You'll want to say get something closer to 14mm instead of a 24mm if working with APS-C.

[ebiggs1]

"If someone is specifically looking for a standard lens (in terms of field of view), they do need to look at focal length and understand that a 50mm is standard FOV on full frame, but short telephoto on APS-C."

Ricky this is where it goes south. Unless you are comparing and 'thinking' in FF camera theory and terms the crop factor is meaningless. Not how does it work on somebodies FF camera that you may never own. Why?  Because you probably purchased the 17-55mm kit lens. If you are a crop camera photographer you probably notice at 35mm my lens gives me a normal perspective.  You don't think what the heck is this kit lens FL on a FF camera.  

You see there is a "crop factor" in reverse for the medium format guys.  However, they never seem to see the need to use it. The 645 medium format has a "crop factor", it is .62 but I bet you hardly ever heard of it or ever see people use it. That's because they don't relate back to 35mm film or FF format. Crop factor was a term created by the old 35mm film people that had to get used to the, then new, smaller digital sensors being made. It was and has been a confusing term ever since.

BTW, your iphone has a crop factor!  Do you know what it is?