Help me understand this

[Fujito]

Two years ago I took some pics of my car with a 15mm f2.8 Canon fisheye.

I had the aperture wide open at f2.8. When taking the pictures EVERYTHING was in focus, including all of the buildings miles behind my car. So the DOF was all inclusive.

Someone on another forum once said something about this, but I forget. I remember him saying that it only happens on super wide angle lenses at wide open apertures.

Can someone explain this to me? All I know is that it doesn't work on my 16-35mm f2.8.

This is the pic I'm referring to.

http://farm4.static.flickr.com/3009/5799231928_f7979286b8_b.jpg

[Fabian]

great pic, but I'm not understand what your actual question is?

[Khellen]

Maybe it has something to do with your fisheye being a prime?

[mann]

Since you are shooting with a fisheye, you will lose detail and resolution at the edges due to being compressed. So any loss of focus will be much less pronounced. On top of that since you are shooting at 15mm it will already be all but impossible to have a shallow DOF--this is probably what your friend is saying.

Also if you shoot at the right angle where your subject matches the focus plane of your lens, it is entirely possible to get much more of the image in focus that way, i.e. corners being closer.

[Fujito]

No, that's not it. And it wasn't a friend, just someone on my car forum. I can't find that post since it was over a year ago.

The idea was that on an ultra wide angle lens at a fully open aperture with a certain distance from the subject, one can get everything in focus. There was a technical term for it.

I see the same effect in other car pictures taken with lenses like the 10-20mm. Everything is in focus.

[TROLL]

There's something called hyperfocal distance... if you google that you might find some more info on it. I'm not sure if it applies to shooting wide open though.
Wide lenses do have a greater DOF than long lenses so I'm sure that contributes too. I also don't think it is 100% sharp everywhere, but yeah it isn't too OOF anywhere.

[Maxxdsix]

Sounds like the focus to infinity alot of macro lenses and stationary lenses like the nikon 35mm 1.8/f have a infinity focus option on them

[oneday]

DOF is relative to distance to focal point and aperture. Focal length does play a part, but only by magnifying the circle of confusion causing the out of focus areas to be easier to see. That said, if you were to take two pictures of the same subject while using two different lenses (a 14mm and a 200mm) both set at f2.8 and both 10ft from the focal point, the image with the 14mm lens would appear have a greater DOF than the 200mm would.

A decent DOF calculator (http://www.dofmaster.com/dofjs.html).

[jen.]

I really don't know the answer to your question, but that is a really sick shot.

where was it taken?

/unhelpful post.

[95legenddriver]

if you look closely you can see there is a difference in whats in focus. since you used such a wide lens there there will be allot in focus as apposed to a tele that will give you a greater DOF its just the nature of the lens. A tele has a sort of tunnel vision making you or the sensor see one thing.

Its kinda like putting on binoculars while looking at a landscape no matter where you are looking you need to focus to the distance you are looking but once you take them off everything appears to be in focus to the naked eye.