[Hidrieus]

Let me put a concern of mine: if a 36x24 sensor can mimic the results of a 24x16 sensor with more benefits. Suppose I have a 50mm lens on my K5. I want to shoot at f/2.8 and 1/200sec ISO100 for a portrait. I personally do not like on my K5 24x16 sensor too sallow depth of field for portraits. I want both eyes in focus, if the ear and the nose are in focus even better. So I do not go larger than f/1.8 in my 50mm. A f/1.4 50mm lens would be useless to me, I have tried them in other APS-C cameras and found the depth of field annoyingly shallow and the bokeh is just an undistinguishable mesh. So to replicate the before mentioned set with a 36x24 sensor I would need a pricier 75mm lens, probably available will only be a 80mm. Time kept at 1/200sec. If I set aperture at f/2.8 I would not have the depth of field I like, it would be shallower. So I will need to step down lets say one stop. But then I could not keep the ISO at 100 but I would need to step up at ISO200. Then the benefit of the 36x24 sensor having one stop more benefit in sensitivity is evaporated. Dynamic range of ISO200 of the 36x24 sensor may be in comparison with ISO100 of the 24x16 sensor.
Am I wrong? What do you think?

[swanlefitte]

How did you happen upon 200 f/2.8 light? Was that by luck or was it set or found? I mean in your example is there another reason not to go higher than shutter 200?

[Madaboutpix]

Er, why don't you just try medium apertures - in the range between, say, F3.5 to F8 - of your 50-mil lens on your K-5 till you get the desired combination of DOF and bokeh? In that range, a 50-mil standard will also deliver the best overall sharpness it's capable of.

[pschlute]

So to replicate the before mentioned set with a 36x24 sensor I would need a pricier 75mm lens

Nope. just crop the picture.

If I set aperture at f/2.8 I would not have the depth of field I like, it would be shallower.

If you use the same lens 50mm on a FF camera, same distance to subject, and same aperture, and crop the FF image to a aps-c perspective you have the same DOF.

[Dartmoor Dave]

I'm just filled with happiness to see a thread about portraiture where someone wants more depth of field rather than less.

[swanlefitte]

Nope. just crop the picture.


.

But that eliminates the benefits.

[pschlute]

I'm just filled with happiness to see a thread about portraiture where someone wants more depth of field rather than less.

Agreed...... I rarely use wider than f8 or f11.

But then my portrait subjects do have long noses !!



---------- Post added 10-12-19 at 08:42 PM ----------

But that eliminates the benefits.

In what way ?

[Madaboutpix]

I'm just filled with happiness to see a thread about portraiture where someone wants more depth of field rather than less.

That's indeed a remarkable event. Reminds me of a classic eye-opening article: The Online Photographer: In Defense of Depth

[swanlefitte]

In what way ?

The extra or bigger pixels are gone.

[StiffLegged]

I think the OP may have a bad case of Jarhead fever — shooting at f/2.8 being a classic symptom. I suggest lying down in a darkened room for a while and getting a good haircut, lest the 'fro get out of control.

[pschlute]

The extra or bigger pixels are gone.

Well then the OP should either buy an 85mm lens or use a 50mm lens and move closer to the subject. Whether he chooses my option or either of the other options, he wont notice the slight bit of difference. Hell I have done a portrait shoot at 800 by mistake instead of 100 on the K1. Did not need to re shoot.

[kiwi_jono]

Exposure is the same between APS-C and FF and, assuming well calibrated sensors, ISO 100 f2.8 1/125 should give same exposure on both.

For the same focal length (same lens), same aperture and same distance from subject, depth of field is the same between APS-C and FF. However the lens will have a wider field of view on FF and therefore to fill the frame with the same subject you will either need get closer to your subject (narrowing depth of field) or use a longer focal length (which will also narrow the depth of field if the same aperture is used).
Consequently when shooting a scene where I want to a deep field of view on my K-1, I have found I typically end up stopping down a bit more than I did my K-5.

[normhead]

Let me put a concern of mine: if a 36x24 sensor can mimic the results of a 24x16 sensor with more benefits. Suppose I have a 50mm lens on my K5. I want to shoot at f/2.8 and 1/200sec ISO100 for a portrait. I personally do not like on my K5 24x16 sensor too sallow depth of field for portraits. I want both eyes in focus, if the ear and the nose are in focus even better. So I do not go larger than f/1.8 in my 50mm. A f/1.4 50mm lens would be useless to me, I have tried them in other APS-C cameras and found the depth of field annoyingly shallow and the bokeh is just an undistinguishable mesh. So to replicate the before mentioned set with a 36x24 sensor I would need a pricier 75mm lens, probably available will only be a 80mm. Time kept at 1/200sec. If I set aperture at f/2.8 I would not have the depth of field I like, it would be shallower. So I will need to step down lets say one stop. But then I could not keep the ISO at 100 but I would need to step up at ISO200. Then the benefit of the 36x24 sensor having one stop more benefit in sensitivity is evaporated. Dynamic range of ISO200 of the 36x24 sensor may be in comparison with ISO100 of the 24x16 sensor.
Am I wrong? What do you think?

You're thinking too much. Take some pictures at different apertures, select the best. Find out where you like each lens individually. And stop being so critical about what shutter and ƒ-stop to use. It looks like me like you've set restrictive parameters that are interfering with your ability to get the image you want. For a portrait, there's no reason to set the aperture at ƒ2.8, there's no reason to set the speed at 1/200. All you're doing here is causing yourself grief.

[pschlute]

I generally find that it is best to concentrate on what the camera and lens in my hand can produce in relation to DOF, rather than have a philosophical debate about what other format/lens may or may not equal the same thing.

[swanlefitte]

. Whether he chooses my option or either of the other options, he wont notice the slight bit of difference.

My understanding is OP is trying to understand why one would benefit from FF if you don't want shallow dof. The scenario illustrated pits the lost ISO vs the benefits of a large sensor.