Wide aperture - Pictures out of focus

Started Aug 3, 2014 | Discussions thread
tedolf Forum Pro • Posts: 26,892

Truthiness wrote:

tedolf wrote:

Truthiness wrote:

tedolf wrote:

this is one of the problems with larger sensored cameras. Wide open the DOF is just too shallow to do portrait work.

How can an option be a problem? No one is forcing to shoot wide open, but isn't it good to have a such option?

If you need to shoot wide open (need faster shutter speed, need to shoot at base ISO) it is a useless option.

But that is a condition which is outside the performance envelope of the smaller sensor camera.

An Olympus OM-D EM-5 can't shoot wide open at base ISO?

The big sensor can still do what the small can.

It can't.  It can't shoot a tight head and shoulders shot with an 85mm lens wide open at 10' because the DOF is less than 3".

A 4/3 sensor camera can  (45mm lens, f/1.8 focused @ ten feet DOF = 10 inches.

Look at a DOF table.

And in the case you want to take advantage of the extra full frame has, you have it.

If you stop down FF, you'll get the same image quality (for the same shutter speed)

????? how are you going to get the same image quality if you need 1/125 sec. shutter speed to freeze the bride walking down the isle but you want to use base ISO for a variety of reasons?

If you use a FF DSLR you are going to be shooting at 1/30 sec. to get the same DOF as on the 4/3 sensor.

and DOF you get from a smaller format, but if you need more speed, you can open the aperture further, to terriritory the smaller formats can not.

And once you open up the aperture your DOF shrinks and parts of your shot are going to be OOF.

Do you realize that f/2 wide open m43 or APS-C is not the same as f/2 wide open on full frame?

That is exactly my point!  DOF is greater on the 4/3 sensor at the same aperture/shutter speed combination.

f/4 on FF gets the same DOF and with the same shutter speed

No, not the same shutter speed.  You would have to change your ISO on the FF camera.

the same image quality a m43 gets on f/2.

It is not the same image quality if you use the same aperture, same ISO and slower shutter speed if the subject is moving!

But for the cases you need more speed, you still have two stops of space with the FF.

Not unless you change your ISO by two stops.


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