Is an Ef 24mm angle as wide as an EF-S 24mm angle when mounted on a cropped frame?

[catalan77]

Hi,

I'm thinking of getting a better lens for my Canon 350D, which eventually will be replaced by the 7d.

I'm undecided between one of the following:

ef-s 15-85
ef-s 17-55
ef 24-70
ef 24-105

I've read tons of reviews but still cannot understand one thing: does an EF lens, mounted on a 7d and zoomed out at 24mm, give the same angle of view as any EF-S lens zoomed at 24mm? For instance, my EF 50mm 1.8 lens is as 'wide' as my EF-S kit lens zoomed in at 50mm (to my surprise).

If the EF-24mm angle equals the EF-S 24mm angle on a cropped frame, then I would be very inclined to getting an L lens, even though the 15/17mm angle would come in very handy - but that's another issue.

Any feedback would be greatly appreciated!

[HDNitehawk]

This is the way it should be; A 24mm is a 24mm lens regardless and there should be no difference whether it is a an L lens, EF or EF-S lens.

A FF and a crop body will have a different FOV, but that is a body to body thing not a lens thing.

Now the disclaimer, not all lenses are made the same. One may have a different FOV at the designated focal length than another, but that is just the lens manufacture playing with numbers.

[ahab1372]

Exactly, 24mm is 24mm. Both lenses, a fictional EF-S 24 and a EF 24 would project same sized images on the sensor plane. The difference is, of the EF-S lens only the center part would be usable, the corners would be very dark and not sharp. If you mount a lens designed for crop cameras on a full frame camera (some third party lenses let you do that), you will see it.
Since a crop camera uses only uses the center part, you usually never see that.
So why do EF-S lenses exist? They can be built lighter and smaller than a lens of the same focal length for full frame.

Hope that helps.
Btw where are you from?

Arnt

[ahab1372]

To your lens question:
24mm on a crop camera is not really wide (because the camera uses only the center part of the image). Some folks here use the 24-105 on crop cameras, but most prefer one of the two EF-S lenses you mentioned, depending on your shooting preferences. What to you usually shoot most?

[catalan77]

Thanks HDNitehawk and ahab1372 for your prompt feedback.

Therefore, if i understood correctly, a (EF-S) 17mm FOV on a CF (17x1.6= 27.2mm) is narrower than a 24mm (EF) FOV on a FF (24x1=24mm), right?

@HDNitehawk, regarding your disclamer, does this happen from manufacturer to manufacturer or it also happens, say, from canon to canon lenses?

@ahab1372 I'm from Malta, central mediterranean.

My shooting preferences are quite varied, from landscapes to portraits. I also like shooting in low-light environments (home, concerts, etc).. plus i enjoy achieving good bokeh.

Also, i would love to use the 7d to shoot HD footage.. And since the 7d video is not as good as the 5d, IQ has to be good

Having said that, the more portable the lens the better.. (for travelling purposes)

Maybe the EF-S 17-55 would do my case and if portability is too much of an issue i’d have to sacrifice low light action and a little bokeh to opt for the 15-85

Thanks again guys!

[Steph]

Hi,

Yes, as mentioned by ahab1372 and from my personal experience, you should find 24 really not wide enough on your APC. I have the 17-55 and I think it's an excellent lens I wish I could take with me the day I go for a full-frame. I've never tried the 15-85 which has obviously a bigger range but the constant f/2.8 + IS combo of the 17-55 does wonder indoor.

[catalan77]

Thanks Steph..

I've read very positive reviews about the 17-55.. The only thing is that the 15-85 might have better "bull's-eye focusing" - so to speak. However i stand to be corrected.

[HDNitehawk]

Yes the 17mm would have a narrower fov on a crop body than a 24mm on FF.

I have seen a few discussions about certain Canon lenses that they wouldn't have the full reach as designated by their name. None of them were the lenses you mention.

The 7d will be the better video camera, because of the deeper DOF of the crop sensor.

[FastGass]

Unless you decide to go FF in the near future (6 monthes or less) then the 17-55mm is the best lens on your list. The 15-85mm the second.

John.

[thekingb]

Hi,

Yes, as mentioned by ahab1372 and from my personal experience, you should find 24 really not wide enough on your APC. I have the 17-55 and I think it's an excellent lens I wish I could take with me the day I go for a full-frame. I've never tried the 15-85 which has obviously a bigger range but the constant f/2.8 + IS combo of the 17-55 does wonder indoor.

Just remember that the question of whether 24mm is wide enough on a crop body is a combination of personal preference and what you tend to shoot. For me, back when I had the Tamron 17-50 on my 7D, I rarely used the 17-23mm range. I now use a 24-105L on my 7D, love it, and really appreciate the extra length (and weather sealing). The 17-55 is a great lens. If that focal range plus the constant f/2.8 are important, by all means you should get it. If you don't need f/2.8, the 15-85 is also a great choice. But if you need 55-105mm more than 15-23mm, I wouldn't hesitate to get the 24-105L.