Beginner Focal length/hyperfocal questions

S

ScottT

Messages
146
Name
Scott
Edit My Images
Yes
I understand that if I fit a 10mm EF lens to my APS-C body it will give a focal length equivalent to a 16mm lens on a full frame body.
But is this the same when i use a EF-S lens?
Would a 10mm EF-S lens act as a 10mm lens or act like a 16mm? I'm a bit confused.

If i'm trying to calculate the hyperfocal distance do I base it on my lens focal length as 10mm or 16mm, or is it 10mm with an EF-S lens and 16mm with a full frame 10mm lens.
I'm fairly new to all this I hope what i'm asking make sense.
 
A 10mm lens will only ever be a 10mm lens so there will be no difference whether it is EF or EF-S. If using an online calculator then they have a field for the crop factor and you enter the actual focal length i.e 10mm.
 
The focal length quoted on the lens is the same for an EF or EF-S lens - you need to apply the 1.6x 'crop factor' to either to determine the focal length you would need on a Full Frame camera to get the equivalent field of view (and this also applies to FF and APS-C lenses for other brands, though Sony and Nikon have a 1.5x crop, rather than 1.6)
 
ScottT said:
If i'm trying to calculate the hyperfocal distance do I base it on my lens focal length as 10mm or 16mm, or is it 10mm with an EF-S lens and 16mm with a full frame 10mm lens.
Click to expand...
The hyperfocal distance is a function of...
  1. the distance at which the lens is focussed (AKA the point of focus)
  2. the aperture set on the lens (the actual aperture at which the image is exposed)
  3. the user's tolerance for unsharpness
The first two are the same regardless of what camera any given lens is mounted on. The third is affected by the sensor size, because the smaller the sensor the greater the enlargement for any given final size. Hence the apparent hyperfocal area will be less for a full frame sensor than for a micro four thirds (half frame) sensor, depending on the viewer's opinion of what is acceptably sharp.

The foregoing is a simplification, of course but should do to be going on with.
 
Faldrax said:
The focal length quoted on the lens is the same for an EF or EF-S lens - you need to apply the 1.6x 'crop factor' to either to determine the focal length you would need on a Full Frame camera to get the equivalent field of view (and this also applies to FF and APS-C lenses for other brands, though Sony and Nikon have a 1.5x crop, rather than 1.6)
Click to expand...

That does kind of make me wonder what the point of EF-S lenses are.
 
VirtualAdept said:
That does kind of make me wonder what the point of EF-S lenses are.
Click to expand...
They are designed to only provide a smaller image circle - sufficient to cover an APS-C sensor, rather than the larger FF sensor,
This means they can be smaller and lighter, and, if they were built on a like for like basis with a FF lens could AF faster, as the individual moving lens elements woudl be smaller and lighter.
Typically though, APC-S lenses are built to a smaller budget, so they are cheaper, but lower overall quality (this is a generalisation, there are good APS-C lenses, and poor FF ones)
 
Faldrax said:
They are designed to only provide a smaller image circle - sufficient to cover an APS-C sensor, rather than the larger FF sensor,
This means they can be smaller and lighter, and, if they were built on a like for like basis with a FF lens could AF faster, as the individual moving lens elements woudl be smaller and lighter.
Typically though, APC-S lenses are built to a smaller budget, so they are cheaper, but lower overall quality (this is a generalisation, there are good APS-C lenses, and poor FF ones)
Click to expand...


Yepyep, that makes perfect sense. Thank you good sir
 
Thank you for all the replies, i have a much better idea now.
 
You must log in or register to reply here.
Back
Top