A Question re wide angle lenses

[andrew00]

Hey,

So ever since I worked on a short film with a reknown cameraman I've been interested in wide angle lenses.

The cameraman, you see, said he used an 18mm lens almost exclusively on a recent film and loved it, and used the 18mm on this short, which looked great.

So I thought to myself, ok cool I'll have a look at a wide angle, because I do a lot of Letus Extreme shooting so that'd be sweet for me.

I even saw that there's a sale on at Jessops and they've got a Sigma 20mm f1.8 for £200, down from £300 pre-xmas, which is cool.

However looking at images of it it seems to have focus markings that go something like 0.2, 0.5, 0.8, 1, then right to infinity.

Is this how wide angle lenses work? As I was hoping to get some nice DoF etc with the Letus, as I intend to shoot people, i.e. not objects less than a foot away from me.

And yet looking at this lens it would appear one has very little focus control from 1 foot onwards.

Am I missing a trick here? The 'widest' lens I currently have isn't wide at all, it's only 50mm, but it still lets me control the focus well, but this lens seems to lack those options totally?

Cheers

[sinapps]

yes, super-wide angle lenses (like the 18mm) will give you very little dof isolation. Try the 28mm sigma 1.8 if you want a wide angle that will help isolate the subject.

[andrew00]

Ah so the 28mm is really the widest I can get with the ability to control dof/isolate the subject eh?

Thanks a lot.

[DivotDan]

It depends on a lot of factors, but you can control DOF with any lens. I think if you are looking for a very shallow DOF, then you will want the fastest lens you can find for the focal length that you like. There are many wider lenses than 28mm that do at least f/2.8.

[andrew00]

Aye that's the thing that confused me as on the short I worked on the dop used an 18mm but the shots had a nice shallow dof. Now those were Zeiss movie lenses (into the same camera) but still I thought I could achieve something similar with a 20mm f1.8.

[DivotDan]

I don't know anything about the sigma lenses, but I do know that most people that shop for 35mm lenses for adapters end up using Nikon or Ziess. I'm actually selling a Nikon 20mm f/2.8 (http://www.dvxuser.com/V6/showthread.php?t=158411) in the sell forum if it interest you at all.

[OSV]

And yet looking at this lens it would appear one has very little focus control from 1 foot onwards.

Am I missing a trick here? The 'widest' lens I currently have isn't wide at all, it's only 50mm, but it still lets me control the focus well, but this lens seems to lack those options totally?


"from 1 foot onwards" is the key here... run the math at http://www.dofmaster.com/dofjs.html and look at the dof limits for various subject distances.

the 50mm you have is a far better choice for isolating the subject from the background... in fact, with a 50mm at 1.4 on my k10d, there is barely enough dof to keep the persons face in focus.

super wide angle lenses and people do not mix well, because there is too much distortion of the facial features... it looks like a funhouse mirror.

for the aps-c sized sensor, many people believe that a 35mm lense is about as wide as you can go, and still keep the proportions realistic... save the wide angles for landscapes, interiors, and such.