Lens for car/road tripping

[Andrew Petrie]

I have 2 lenses for my 7D, the 17-55mm, and Tokina 11-16 wide. Both great lenses in their own right when I have time to set up a shot, but in-car shooting is different.

I'm looking for a lens better suited for general video shooting with minimal focus adjustment. In short, a lens with decent zoom range and deep depth of field.

Any suggestions?

[Sam Tansey]

Depth of field is determined by the size of your cameras sensor and the aperture you choose. Wider lenses like your 11-16 will give the illusion of a deeper depth of field but it is technically the same. The lenses you already have are probably the best ones for your needs.

Id suggest using higher ISO's andand stopping down the aperture if focusing is a real struggle. + more practice.

The auto focus on panasonic gh2 is meant to be pretty good.

[John Wiley]

The two big variables in DOF are focal length and aperture; longer focal lengths and wider apertures give shallower DOF, and vice versa. So, to get the deepest DOF possible you simply need to stop down your lenses. With the 11-16mm at full wide, you only need to go down to about f/4 or f/5.6 before the entire image is in focus. With the 17-55, you'll need to stop down a little further.

Sam - DOF is not determined by the sensor size - DOF is an artifact entirely produced by the lens before the sensor is even added to the equation. Sensor size does however dictate which lenses you are able to use to achieve a certain framing - bigger sensors will allow you to use a longer focal length for a patricular shot than a smaller sensor will - assuming the distance-to-subject remains constant - and it is in this ability to use longer focal length lenses that shallower DOF is introcuced.

[Kin Lau]

For road trips, I switch to my GH1 + 14-140 for both stills and video. The AF is fast and the 14-140 is perfect for this use. I also have a 7D and T3i but the GH1 wins hands down in this situation.

[Sam Tansey]

Originally Posted by John Wiley

The two big variables in DOF are focal length and aperture; longer focal lengths and wider apertures give shallower DOF, and vice versa. So, to get the deepest DOF possible you simply need to stop down your lenses. With the 11-16mm at full wide, you only need to go down to about f/4 or f/5.6 before the entire image is in focus. With the 17-55, you'll need to stop down a little further.

Sam - DOF is not determined by the sensor size - DOF is an artifact entirely produced by the lens before the sensor is even added to the equation. Sensor size does however dictate which lenses you are able to use to achieve a certain framing - bigger sensors will allow you to use a longer focal length for a patricular shot than a smaller sensor will - assuming the distance-to-subject remains constant - and it is in this ability to use longer focal length lenses that shallower DOF is introcuced.

I understand how it all works. This debate often gets caught up in technical reality v practical reality. In a practical sense, "field of view" from camera to camera tells you far more about what you are going to see in your image than what the focal length of your lens is.

To try and make things less confusing for the OP, if you look at the standard zoom ranges on cameras with various sensor sizes.

4/3rds ie GH2 14-40
APSC ie 7D 17-55
Full frame ie 5D 28-80

These three zoom examples on their respective cameras will give you a similarly wide landscape, and a similarly narrow portrait shot. However as John Wiley has explained, DOF is determined by the focal length. So a portrait on a 5D @ 80mm will have a much smaller DOF (roughly half) compared to the portrait on the GH2 @ 40mm despite framing being identical.

Hope that clears it up.