Not so important question concerning DOF

[Mr. Murmeli]

Hi,

Ok this just popped into my head and i got curious...

With a full frame sensor, 85mm lens roughly equals 50mm with a crop one. But I know that the bigger the sensor is, more shallow the depth of field will be with high aperture (therefore p&s won't do properly shallow DOF no matter what you do).

So my question is: What kind of difference (noticable or not etc) would i see in DOF if i took a portrait picture with a FF camera & 85mm lens @ f/2, and then the same picture with crop sensor cam & 50mm lens @ f/2 ?

 

[Big Mike]

So my question is: What kind of difference (noticable or not etc) would i see in DOF if i took a portrait picture with a FF camera & 85mm lens @ f/2, and then the same picture with crop sensor cam & 50mm lens @ f/2 ?

The difference would be quite dramatic...keeping in mind that the distance to the subject will also affect your DOF.

Firstly, the larger sensor will give you a shallower DOF.
Secondly, the longer focal length with give you a shallower DOF.
Those two things combined can give you a very shallow DOF.

 

[Big Mike]

I know a wedding photographer who shoots with a full frame body 1DsIII as well as 1.3 and 1.6 crop bodies. He likes the crop body (40D) because of the great AF but also because of the extra DOF.

For example, you are shooting two people in a dimly lit area and you want to have both of them in focus. With the full frame body, you would need to stop down to say, F5.6, to get both in focus...thus sacrificing your shutter speed.
With a crop body and the same lens, you have a deeper DOF so you might be able to get both in focus at F4 or F2.8...giving you a faster shutter speed.

Of course, ISO may be an equalizer because typically a full frame camera will give you better performance at higher ISO levels...so you get get back the lost shutter speeds without too much sacrifice.

 

[Mr. Murmeli]

Thanks for the answers!

I just thought that with those two settings i mentioned the pictures themself should cover about the same area and therefore look similar but the DOF -queestion came to my mind.

 

[gsgary]

full frame is fantastic, this is F3.5 at 300mm you don't get much DOF

 

[Dao]

I know a wedding photographer who shoots with a full frame body 1DsIII as well as 1.3 and 1.6 crop bodies. He likes the crop body (40D) because of the great AF but also because of the extra DOF.

For example, you are shooting two people in a dimly lit area and you want to have both of them in focus. With the full frame body, you would need to stop down to say, F5.6, to get both in focus...thus sacrificing your shutter speed.
With a crop body and the same lens, you have a deeper DOF so you might be able to get both in focus at F4 or F2.8...giving you a faster shutter speed.

Of course, ISO may be an equalizer because typically a full frame camera will give you better performance at higher ISO levels...so you get get back the lost shutter speeds without too much sacrifice.

Good point! Noted.