Long Telephoto lenses and increasing depth of field?

Tommi K1 wrote:

C Sean wrote:

So the question is when you zoom in close to your subject with a long telephoto lens, no matter how much you stop down, you can only get one subject in focus unless the subjects are perfectly lined up?

I haven't shot properly with Full Frame and less experience shooting with their standard 70-300/100-400 type lenses. However, I know several M43 members mention with long telephoto zooms, you don't need to stop down all the time and therefor it's easier to shoot with long telephoto lenses compared to Full Frame. So is there a long telephoto rule, if you zoom in close, you can only get one subject in focus no matter how much you stop down?

You will get same DOF regardless the focal length, when you have three factors same:

1. Same subject framing
2. Same format
3. Same F-stop

So in this case with m4/3 and example f/5.6, there is no difference do you shoot with 12mm or with 300mm, you are having the same DOF when the subject framing (magnification) is same.

The typical scenario is this, your subject is further but you want the same framing, so you use longer focal length. That will deliver you same DOF as you would get if you would use shorter focal length at the closer distance and frame the subject same size.

If you want multiple different subjects to be framed in same size, then you need to start to play around with multiple factors:

You can only get so far all the magnifications same, but never get the same perspective or background blur, but the DOF will be same.

Tommi I have a general idea where you're coming from and I'd had read an article last night regarding both long telephoto lenses and depth of field. However, if I wanted to say photograph a group of people, not only would I say use the 15mm 1.7 (depending on the size of the group) but I would also close the lens down to F5.6 or F4.0.

When it comes to long telephoto lenses, if we ignore 70-200mm and the use for landscape or portrait. The long telephoto lenses often use for either wildlife or sport and in those situation, very often you can't get close to the subjects and use a wide angle lense. I imagine you can zoom out a bit to increase the DOF and crop in later if you have spare megapixels but in general use of long telephoto lenses is because you can get close to the subject by foot.

The image below was taken in South Africa last year and I can't remember if I stopped down or not. If I remember correctly the shot was taken at 400mm at either 6.3 or 8.0 or even higher. Problem is the 100-400 at 400mm generate a thin depth of field.

The options is either to use the 100-400, drive closer and scare the birds away. The other option is to jump out of the vehicle, walk up to them and scare the birds or at the sometime get killed by the bleeding and peed off cape buffalo close by.