DoF and a mirror

[hamlet]

Lets say you want to take a group picture in your rose garden in the evening with not a lot of lighting available. You want to shoot at an aperture of 1.4 to get as much light into your sensor. Couldn't you just put a mirror in front of the group you want to photograph and photograph their reflection? I mean the mirror will let you capture everything within the dof of 1.4 because its only a flat surface. Couldn't this trick work?

 

[480sparky]

No. The image is not ON the mirror. It would simply be further away.

 

[pgriz]

If you want to photograph what's on the surface of the mirror, then yes. If you're photographing the reflection, then no. But don't let me discourage you. Try it and see. The first problem you'll come up against is that the AF will ignore the surface, and try to focus on the object reflected in the mirror.

 

[ratssass]

...not to mention you'd need to put a stringline up to put the tip of everyones nose on..........lol

 

[hamlet]

No. The image is not ON the mirror. It would simply be further away.

But you put the mirror at the distance you would photograph. So that would cancel that out.

 

[hamlet]

If you want to photograph what's on the surface of the mirror, then yes. If you're photographing the reflection, then no. But don't let me discourage you. Try it and see. The first problem you'll come up against is that the AF will ignore the surface, and try to focus on the object reflected in the mirror.

You just manual focus on the surface of the mirror and the mirror will do the work. I will find a mirror and gather up my backyard dwarves. This idea of mine is going places.

 

[vintagesnaps]

I've taken pictures of reflections in a mirror, they aren't as sharp. (I focus manually all the time anyway.)

Go out in your rose garden sometime and do some test shots. You could use some objects to be 'stand-ins' of a sort to have something to focus the camera on. See what works and what doesn't so when you want to do a group photo you'll know how to set your camera.

Or if you want, go out and set up a mirror, prop it somehow in front of where a group might stand, take some test shots and see if it works. Or the mirror might fall and break and that will be the end of this experiment...

 

[Judobreaker]

Not going to work.

A mirror just reflects objects, it doesn't become them.
Just try standing in front of a mirror and focussing on different objects of different distances from the mirror. You'll see that the camera will need to refocus for every object... That wouldn't happen if it were all focussed on the same plane would it now?

 

[480sparky]

........You just manual focus on the surface of the mirror and the mirror will do the work. I will find a mirror and gather up my backyard dwarves. This idea of mine is going places.

Make sure you focus on the mirror, now, and not the subject's reflection!

I think you'll find you'll end up with sharp images of the dust and fingerprints on the mirror.

 

[gsgary]

A very dirty mirror at my friends forge where he makes hand beaten armoury not sure if it would work

An extra shot of something he made from a drawing of someones hand with measurements for a gentleman in Switzerland

 

[hamlet]

If windex worked for enter the dragon then it'll work for me.

 

[480sparky]

You didn't focus on the mirror. See how OOF it is?

Focus on the mirror like you said you would.

 

[hamlet]

You didn't focus on the mirror. See how OOF it is?

Focus on the mirror like you said you would.

It is very easy actually. You can even try this with autofocus. Just put the dslr on a tripod facing the thing you want to photograph. Now get an a4 paper and a small tape to tape it to the mirror, now autofocus on the paper that is taped to the mirror, lock focus and remove paper and take the shot. We've now turned an aperture 1.4 into infinite.

 

[Overread]

Television cameras often used very small film/sensor sizes. Much like how a mobile phone or bridge camera has a very deep depth of field the same is true of your average TV camera; which is why you can see more depth in the windows there than you might if you used a DSLR which has a much bigger sensor.

Also remember your eyes constantly re-focus a we look around a scene so we also get an artificial increase in what we perceive to be our depth of field.

 

[amolitor]

It won't work for reasons described, but good luck with that.

This is one of those things you need to try to see what's going on, so, you should try it.