Fast lenses, depth of field, and Photoshop CS6

[Alan]

As I understand it, the new CS6 will have a very intriguing tool. It will be able to create depth of field, and do it simply.

This begs the question: who needs an expensive, fast lens?

One might say that "it's not the same as what a lens can do." Perhaps? Perhaps, not.

For example, rather than buy the 70-200 2.8 II IS, one might be better off with the 70-200 f/4 IS. Half the price, and still high IQ.

Plus, the tool in CS6 will allow the user to decide where to place the depth of field.

However, it's surely a tool that will improve as time goes on, and then buying that expensive (and, heavy) piece of glass might be a thing of the past.

[Sean Setters]

Depth-of-field is not the only advantage of a fast lens. A lens with a maximum aperture of f/2.8 lets in twice as much light than a lens with a maximum aperture of f/4. That could mean the difference between a motion bluring 1/60 sec or a crisp 1/120 sec at the same acceptable ISO.

[M_Six]

And I'll be amazed if CS6 can match the buttery bokeh of a 135mm F2L. I've been surprised at Photoshop before, though.

[Alan]

Depth-of-field is not the only advantage of a fast lens. A lens with a maximum aperture of f/2.8 lets in twice as much light than a lens with a maximum aperture of f/4. That could mean the difference between a motion bluring 1/60 sec or a crisp 1/120 sec at the same acceptable ISO.

True. But, those occasions are much more limited, and probably more often than not, it's the depth of field that will be preferred (portraiture is a good example).

Plus, with newer, low noise, high ISO cameras (plus, greatly improved noise reduction software), the need for the heavier, fast lens could wane.

Certainly, the cost could be a significant deterring factor.

[Alan]

And I'll be amazed if CS6 can match the buttery bokeh of a 135mm F2L. I've been surprised at Photoshop before, though.

Even if it doesn't, it won't stop the next version from imitating it more closely.

[HDNitehawk]

There is no substitute for getting it right in the camera to start with, there are only repairs you can do to the pictures later. I can't see how it would be a good substitute if you have to individual touch each of your photo's to get the DOF and Bokeh you want, when with a turn of a dial on your camera you can set it instantly.

If you couldn't afford a fast lens I see how a person might use this, but it still costs you. You will end up spending your time with additional processing to save the cost of the faster lens.

+1 for Sean's points. If it were just about DOF I wouldn't own the 70-200mm F/2.8L II, I would just go for the F/4 version and carry a lighter lens. It is the Wide open F/2.8 and it's ability to perform in lower light that makes me choose the F/2.8 version.

[Alan]

There is no substitute for getting it right in the camera to start with, there are only repairs you can do to the pictures later. I can't see how it would be a good substitute if you have to individual touch each of your photo's to get the DOF and Bokeh you want, when with a turn of a dial on your camera you can set it instantly.

If you couldn't afford a fast lens I see how a person might use this, but it still costs you. You will end up spending your time with additional processing to save the cost of the faster lens.

+1 for Sean's points. If it were just about DOF I wouldn't own the 70-200mm F/2.8L II, I would just go for the F/4 version and carry a lighter lens. It is the Wide open F/2.8 and it's ability to perform in lower light that makes me choose the F/2.8 version.

As for the first point, it's called creativity, and gives one an option that might not have existed in the situation at the time.

As for the second point, each successive program improvement makes processing easier. Besides, we all spend time tweaking images, whether globally in LR, or with actions, in PS.

Sean's point is well taken, but as time goes on, this may not be as an important factor, in light of costs (which will increase with future releases of lenses). We are so used to expecting bokeh and depth of field, and we are willing to pay for it, but if the same can be achieved with manipulation of the data (which, after all, is what we all do with every image we take, and don't take perfect pictures every time), then why not?

Maybe we'll feel upset when we realize that the $12,000 f/2.8 wasn't necessary after all, since a simple Photoshop action can give the same result?

[HDNitehawk]

It is the Garbage in Garbage out saying that applies. The better data you start with the better finished product you will be achieve. You can start with a picture that needs more work, but the product will be better from a picture that already has the most elements already in it.

I am not so impressed with Adobe that I believe were close to the point you are talking about. Maybe some time off in the distant future.

[Alan]

It is the Garbage in Garbage out saying that applies. The better data you start with the better finished product you will be achieve. You can start with a picture that needs more work, but the product will be better from a picture that already has the most elements already in it.

I am not so impressed with Adobe that I believe were close to the point you are talking about. Maybe some time off in the distant future.

That's a bit harsh, don't you think?

And, how did you do your macro photos? Was it "get it right in the camera" or did you do a photo stack with Photoshop?

[Daniel Browning]

This begs the question: who needs an expensive, fast lens?

Anyone who is picky enough to use a fast lens for thin DoF will be way too picky to switch to software-based thin DoF. It's like the difference between shooting real infrared and simulating it in Photoshop. Sure, the simulation might be good enough for some people, but certainly not for anyone who went to expense and effort of shooting infrared.

One might say that "it's not the same as what a lens can do." Perhaps? Perhaps, not.

No "perhaps" about it. Physically impossible. But of course, for many purposes it will be good enough. I'm sure there are already many good plugins (or standalone programs) that are superior to this new Photoshop feature for simulating thin DOF [edit: I'm guessing this because Photoshop is not really the best at anything that has a plugin or standalone alternative -- Photoshop is more of a jack of all trades]. But this one will definitely be easier to install, considering that it comes out of the box. And even without any plugins, I've simulated thin DOF with just a masked layer and gaussian blur (though I'm sure this will look more realistic than that).