17-40L on a 1.6 sensor...

Kryptix

Kryptix

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I always struggle to get my head around this.

What would the equivalent zoom range on a EF-S lens be? How can I work it out for myself?

I'd like to know what the 24-105L would be too, or doesn't it work like that?

Basically, can I look through my EF-S 18-55mm IS and zoom into a certain distance to get it to look like the 24mm end on the 24-205L?
 
It doesn't matter if its EF-S or EF the focal length is still the same.

17-40 on a 50D is equivalent to 27-64 on say a 5D
24-105 on a 50D is equivalent to 38-168 on say a 5D

Conversly, putting a 24-105 on a 5D would be equivalent to you using a 15-66 on your 50D
 
17-40 approx 11-25

Oh, I did it the other way round... ie: to get the equiv of 17-40 on a crop you would need a 11-25
 
17-40 on a 1.6x will be almost the same as your 18-55! It'll just lack a little bit of reach at the longer end. EF-S just means that they will only work on 1.6x crop sensors, the focal range is still the same!
 
So if I put my 18-55mm lens on and zoomed to 24mm, then put the 24-105mm on and stayed at 24mm it'd look exactly the same?
 
Wouldn't the 17-40L be similar to the 18-55mm but be a lot better quality?
 
Kryptix said:
I always struggle to get my head around this.

What would the equivalent zoom range on a EF-S lens be? How can I work it out for myself?

I'd like to know what the 24-105L would be too, or doesn't it work like that?

Basically, can I look through my EF-S 18-55mm IS and zoom into a certain distance to get it to look like the 24mm end on the 24-205L?
Click to expand...

EF-S lenses only work on crop sensors, 400D, 450D, 40D 50D etc
EF lenses work on crop sensors and full frame 5D etc

If you're using a lens on a crop Sensor i.e your 50D just times the focal length by 1.6
 
jonnypb said:
If you're using a lens on a crop Sensor i.e your 50D just times the focal length by 1.6
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That's exactly what I wanted to know.

So that means the 24-105L is actually 38-168mm on a crop sensor? :cautious:

Surely not?
 
Kryptix said:
That's exactly what I wanted to know.

So that means the 24-105L is actually 38-168mm on a crop sensor? :cautious:

Surely not?
Click to expand...

It's not per se, what is happening is you are loosing some of the field of view that you would otherwise have (say on a full frame 5D). So you effectively have a 38-168mm lens.
 
EF-S is the lens mount, nothing at all to do with the optics :)





*I think ;)
 
I just can't get my head around it. So many people have 24-105L on their 1.6 crop sensor cameras as their everyday lens, but I find 18mm a bit too long at times so I have no-idea how people cope with 38mm?
 
I agree 18mm is not wide enough for me at some points (hence why i have the 10-22 also). However for some people 24 is wide enough on a crop body. I guess it is what suits your style of photogrpahy. However with your 10-20, you could probably effectively pair it with a lens that starts at 24! (24 on the 24-105 will give you the same field of view as when you set your 18-55 at 24, at least all the time they are on a crop body!) Hope that helps a little bit!

Matt
 
Kryptix - I think you're under the impression that 18mm on an EFS lens is different from 18mm on an EF lens, it's not. Your 18-55mm EFS lens is effectively 28-88mm due to the crop factor.

Focal length doesn't change because of sensor size, but as stated above, the field of view does due to cropping.
 
Ah OK, I see... So 24mm on my 18-55mm is exactly the same as 24mm on the 25-105mm?
 
an EFS 18mm is the same as an EF 18. Its just a different fitment that allows a slightly different lens design. Focal length is the same.

Field of view however changes depending on the crop ratio of the sensor. At the moment there are at least 5 different sensor sizes - Olympus 4/3rds (x2.0), Nikon x1.5, Canon APS-C x1.6, Canon APS-H x1.3 and full frame.

I use a 24-105L on my 50D as my everyday lens. I have wider options and longer options but for most of the time the 24-105 does the job.
 
Kryptix said:
I just can't get my head around it. So many people have 24-105L on their 1.6 crop sensor cameras as their everyday lens, but I find 18mm a bit too long at times so I have no-idea how people cope with 38mm?
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I think you've got it :)

And that is a very good point re the 24-105L. Which is why Canon have given us the wonderful EF-S 17-55 2.8. That is the equivalent of 27-88mm on full frame, which is pretty much perfect walkabout range, and it is a full stop faster throughout at f/2.8 than the 24-105L. It is at least as sharp, but not as robustly built as the tank-like L lenses.

There are numerous benefits to EF-S lenses over EF if you're shooting crop in the shorter focal length range. But over about 50-60mm focal length (related to the back-focus - the distance from the lens mount to the sensor) the benefits become minimal, which is why Canon don't make EF-S lenses longer than this.

Up to that point however, there are more downsides to using EF lenses than benefits. Basically, you are paying for a lens that has full frame coverage that you can never use.

Edit: just another point on choosing lenses - check at what focal lengths you actually shoot most stuff. I find that around 20mm is quite common for me, so this is where I want most over-lap on focal length. If I was to pair my 10-22 with a 24-105, I would be forever changing lenses, but with a 17-55 I can often use either without needing to swap. I think this is a big advantage.
 
But if they look the same through the 50D all the way from 24mm to 58mm and I can afford the 24-105L, is there any reason you can think of not buying it bar it being slower at f/4?

I'm sick of buying and selling so I'd sooner buy lenses that I can keep for years to come rather than upgrading to FF next year and having to sell everything again. I would have gone straight for a 1D3 this time but I figured I'd save myself some pennies and stay with the 50D. It's more fun going up through the ranks, I think.
 
Kryptix said:
But if they look the same through the 50D all the way from 24mm to 58mm and I can afford the 24-105L, is there any reason you can think of not buying it bar it being slower at f/4?

I'm sick of buying and selling so I'd sooner buy lenses that I can keep for years to come rather than upgrading to FF next year and having to sell everything again. I would have gone straight for a 1D3 this time but I figured I'd save myself some pennies and stay with the 50D. It's more fun going up through the ranks, I think.
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You mean 88mm?

It's more a question of range than cost. If the range of the 24-105L suits you better, then of course go for that. But rememebr that is you do change format at some stage, then the field of view of all your lenses will change, by a factor of 1.6x wider if you go for full frame, or 1.3x if you opt for a 1D3 (which also does not accept EF-S lenses).

Basically, if you seriously intend to change format soon, then don't buy EF-S lenses. But if you don't, then EF-S will generally give you a more 'usable' lens than an equivalent EF.

For what it's worth, I think we will see crop format close the gap even further to full frame than we already have. I am working on that assumption and therefore sticking with crop, but that is just future speculation. If you need to make big decisions here and now, it is a real dilemma with no easy answer, other than to throw money at it.
 
the IQ, AF speed, USM motor etc... would be a start from the 24-105 over your kit lens. If you can afford it get the L glass :).

I have just splashed out on my 2nd piece of L :D
 
17-40L on a 1.6 crop sensor makes for a good combination!!!!
 
Check out the link, hopefully it will explain it abit better

http://www.cambridgeincolour.com/tutorials/digital-camera-sensor-size.htm

cambridge in colour

The focal length multiplier (canon 1.6x etc) relates the focal length of a lens used on a smaller format to a 35 mm lens producing an equivalent angle of view, and is equal to the crop factor. This means that a 50 mm lens used on a sensor with a 1.6X crop factor would produce the same field of view as a 1.6 x 50 = 80 mm lens on a 35 mm full frame sensor.

The lens focal length does not change just because a lens is used on a different sized sensor-- just its angle of view. A 50 mm lens is always a 50 mm lens, regardless of the sensor type. At the same time, "crop factor" may not be appropriate to describe very small sensors because the image is not necessarily cropped out (when using lenses designed for that sensor).
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pete.rush said:
or the EF-S 17-55mm f2.8
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This

I always found that the 40mm end of a 17-40 was just not quite enough and the 17mm was not quite wide enough. a standard zoom is going to be a compromise - but compromising at both ends?

IMO the 17-40L is a perfect wide angle for the full frame crew.
 
As people have said the focal length doesn't change at all, 24mm is 24mm and will always be 24mm. But the field of view does indeed change.

But, and this is the really important bit... unless you're used to shooting (say) full frame 35mm, and are used to thinking in terms of what a particular FL will give you (on that format) then it really doesn't mean a thing! There's lots of people who have never ever used 35mm FF, or medium or large format cameras and maybe never will, it doesn't matter at all, and to be fair there's no reason at all that it should do.

Just look through the viewfinder, zoom or change lenses until you get the FOV that you want and use that.
 
nowler said:
17-40L on a 1.6 crop sensor makes for a good combination!!!!
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pete.rush said:
or the EF 16-35mm f2.8
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Why?

Compared to both those two lenses, the EF-S 17-55 2.8 has much more range, equals the better maximum aperture, and has IS. Optically it is a match for either.

Surely it is the obvious choice?
 
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