Crazy question (maybe)

[Cutter]

If i were to take a photo of say 8 people in a group side by side, what would be the difference in the picture if I took it with a wide angle Len's (close up) or a 400 lens zoomed in showing all 8? Oh and using the same fstop and s/s for both.

[silversnapper1]

I would imagine that there would be a good deal of distortion on the wide angle image.

[Cathus]

you'd have to stand a lot further back with the 400! A lot less would be in focus so you'd get a blurred background, the people on the ends of the line would have rounded edges the further out from the centre of the shot with the WA

[SieSmith]

As I understand it Mark, if you have the same field of view on the 2 different lenses (i.e. you can get all 8 people fitting just to the sides of the image) then you will have the same depth of field in both cases, although there are circumstances where this falls down. The wide angle will have more rear biased dof from the focal point than the tele.

You will of course have more distortion, as Steve points out, with the wide angle, but should be able to correct for this in software.

The other thing you will get with the wide angle is, of course, more of the background in the shot, so look out for things either side of the group that may become a distraction, if you were to take with this lens.

Take a look at cambridgeincolour or similar for some tutorials.

Cheers, Sie

[Cathus]

I don't think that's right with depth of field.

At f8 on a 14mm lens at 3m distance the DOF is infinite after 83cm, at f8 on a 400mm at a distance of 50m is only 7.48m

(I'm guessing the distance from the group of people). The DOF is dependent on the focal length & distance to target presuming the apertures are the same, bearing in mind both cameras will a considerable distance apart to see the same field of view

[SieSmith]

Cathus, I'm just going off what it says in the tutorials in the link I provided.
Please take a look and see if they're wrong. If they are, let them know.

It does say something in there about being at the hyperfocal distance, but in general it says dof is independent of focal length.

Cheers, Sie

[Cathus]

Sie,

I take it back, I've read that site you mentioned & it seems this is a common misconception, it's quite complicated but I found a better explanation at Luminous Landscape & a demo of the theory in action at the following link http://www.luminous-landscape.com/tutorials/dof2.shtml, though I'm struggling to fit the theory into my depth of field calculator on my iPhone!

[SieSmith]

No problem, Cathus. That's a great demo, by the way. One thing that is noticable from those images is the way the tower "looks" more blurred as it gets magnified by the shortening effect of the long lens.

This does all change though if you get at or near the hyperfocal distance of the lens.

Cheers, Sie

[riddell]

There is loads of differences. For one you may not be able to use the same shutter speed / apature combination with the lower lens, simply because the shutter speed on a longer lens needs to be shorter to avoid movement blur.

The very importantly is the difference in the look of the images, a longer lens will have a forshortening effect, and when dealing with quality lenses the background blur will be different, usually more pronouced with a longer lens.

It really is a huge difference, such a difference that I regularly use short or long lenses diliberately on the same subject to create very different looks.

Often in a fashion shoot I may use a 17mm, 100mm and 300mm on the same subject, just because each of the lenses produces such a different look and its good to give the client a choice.

Paul.
www.photographybyriddell.co.uk