Razor thin depth of field

Is the depth of field of the 200mm @ f2.0 wider than the 50mm @ f1.4 or 85mm @ f1.2? I am not referring to background blur but rather subject blur. For example, many complain how hard it is to get both eyeballs in focus with the 50mm @ f1.4 or the 85mm @ f1.2. Will I have less of a problem with the 200mm @ f2.0? Assuming the subject is sized the samed inside the frame, of course. I want a lens that will blur the background the most but at the same time get the whole face in sharp focus. Which is my best option?

http://www.dofmaster.c​om/dofjs.html

Lots of variables. Generally a longer lens will give less DOF but subject distance is a key variable.

For the same framing and aperture, you should get DoF that's very, very similar regardless of focal length (though you'll get more bg blur the longer the FL).

texshooter wrote in post #17350554
Is the depth of field of the 200mm @ f2.0 wider than the 50mm @ f1.4 or 85mm @ f1.2? I am not referring to background blur but rather subject blur. For example, many complain how hard it is to get both eyeballs in focus with the 50mm @ f1.4 or the 85mm @ f1.2. Will I have less of a problem with the 200mm @ f2.0? Assuming the subject is sized the samed inside the frame, of course. I want a lens that will blur the background the most but at the same time get the whole face in sharp focus. Which is my best option?

For the same framing and same sensor size, only aperture affects DOF.

But the focal length affects perspective and how the background looks.

This is all just approximate, though. Lens design (size of exit pupil) also affects DOF, but is usually ignored.

So I gather from this, if I'm shooting at 50mm f1.4 and am having difficulty keeping both eyeballs in focus, then what I should do is switch to a 100mm f2.0. The one stop closed down aperture will give me more depth of field (both eyeballs in focus) at the same time the 2x in focal length will give more (or at least preserve) the background blur.
Lesson learned: close down the aperture and use a longer lens.

texshooter wrote in post #17350594
So I gather from this, if I'm shooting at 50mm f1.4 and am having difficulty keeping both eyeballs in focus, then what I should do is switch to a 100mm f2.0. The one stop closed down aperture will give me more depth of field (both eyeballs in focus) at the same time the 2x in focal length will give more (or at least preserve) the background blur.
Lesson learned: close down the aperture and use a longer lens.

Keep in mind that changing focal length to maintain the same framing will change the perspective of a photo. Generally a longer lens and therefore greater distance from the subject often is more flattering but know that it does change the image. See below. http://stepheneastwood​.com …ials_Lens_Persp​ective.htm

Yes, essentially. DOF is strictly a function of aperture and subject framing. As an example if you had a series of f/2.8 lenses and used them all at f/2.8 you would get the exact same DOF at:

25mm and 5 feet to the subject
50mm and 10 feet to the subject
100mm and 20 feet to the subject.

And on and on. This is handy to know, as a waist up portrait (for example) will have the same DOF at f/2.8 no matter if you shoot it close with a wide lens or far away with a long lens. Understanding this makes a lot more sense than the hash of data than you get working with focal lengths, distances and apertures in DOF calculators.

Note that then for any fixed DOF, the longer focal length you use (meaning a longer focal length from a greater distance) the greater the background blur you will get. So 200mm and f/2 from 40 feet will give much more blur (but the same DOF) as 100mm and f/2 from 20 feet.

everybody drools for the 85mm f1.2 because of the bohke. but what point is there of having a nice bohke if you can't keep the face in focus. sounds like for head shots a 135mm f2 would be a better choice over the 85mm 1.2. And a 100mm 2.0 ( or 2.8 macro) a better choice over the 50mm f1.2. For best portraits it's the length, not the girth, that really matters. As so it seems.

You are presuming headshots. Back up enough to frame half body or more and 1.2 can give a nice slice of DOF sufficient for portraits.

texshooter wrote in post #17350554
Assuming the subject is sized the samed inside the frame, of course. I want a lens that will blur the background the most but at the same time get the whole face in sharp focus. Which is my best option?

Hi Texshooter, I asked myself the same question about 3 years ago. Please firstly note that this my own personal view based on experiences with lenses I own and have owned.

The 200mm f/2.0 for portraiture is my favourite, this is a magical lens just rent one to be convinced. What you will love about this lens is its Sharpness and Depth of field. The 200mm works as a portrait lens utilizing the telephoto compression effect. The background bokeh is rendered beautifully thanks to a fast aperture. This lens excels outside because the benefits of a narrower angle of view is that its much easier to find a pleasing backdrop for your shot you only require a couple feet of pleasing background, meaning that you can get great shots just about anywhere. I have done a review on my lens which you can read in this Forum.

I still own and love the 85L II f/1.2 and yes it can take practice to nailing the focus at f1.2 and for me it is more suited to the studio/inside shots.

I would say in third place for me was the 135 f/2.0, again super sharp and produces great bokeh. I sold mine to help finance the 200.

I currently also own the 50 f/1.4 which is great for what it cost. The 1.2 L version having borrowed a few at my Camera club I never found them to be as sharp as I wanted and was disappointed and decided not to purchase one (Waiting for a MK2 version).

Referring back to your post for your requirements I would say Stick with a fast Prime.

I still more so use the 24-70 & 70-200 telephoto's for their focal range versatility but for portraits it's a prime every time.

Yes, and no. Yes from the standpoint that a longer lens will allow you to get a good background blur while also having good (more) DOF on the subject. The effect of this is too make the entire subject sharp, which pops them out from the blurry background.

What I see too much of (IMO) are shots where a shorter focal length was used and the subject appears to be melting into the background, because they are only partially within the DOF. I think that looks lousy. I shot a quick example of this effect a couple years ago, posted below. Here I shot the same framing using a 50mm/1.2 lens (first picture) and a 200mm/2.8 lens for the second shot. The faster aperture of the short lens achieves about the same amount of blur, but this comes at the expense of too little DOF. The subject stands out much better with the longer lens and greater DOF.

But that does not mean shorter, very fast lenses are not useful for portraits. It means they are useful when you want to take a rather loosely framed shot, like a full body portrait shot with the camera horizontal. If you do that with a 200mm or 300mm lens, you will be way back. If you shoot it with a slower zoom like a 24-70 from a reasonable distance, the background won't be very blurry. So this (a loosely framed, full body portrait) is where the 50/1.2 or 85/1.2 are quite useful.

JeffreyG wrote in post #17351231
What I see too much of (IMO) are shots where a shorter focal length was used and the subject appears to be melting into the background, because they are only partially within the DOF. I think that looks lousy. I shot a quick example of this effect a couple years ago, posted below. Here I shot the same framing using a 50mm/1.2 lens (first picture) and a 200mm/2.8 lens for the second shot. The faster aperture of the short lens achieves about the same amount of blur, but this comes at the expense of too little DOF. The subject stands out much better with the longer lens and greater DOF.

I actually like the 50mm shot more. I understand your point about the subject melting into the background though, and I mostly agree (like your comment on my other photo in the zoom vs prime thread) but for this one, I actually think the 50mm looks better. IMO, the 200mm makes the background look almost artificial, like it's a studio backdrop. The 50mm shot looks livelier and more 3-dimensional. Also, my attention is instantly drawn to the in-focus face, and not the stitching on the shirt that doesn't matter. But, I suppose this is just aesthetic preferences.

JeffryG, your examples drive home my point about how f1.4 can be more a curse than a blessing. But I think your second shot could have been achieved with a 135mm @ f2.0. In fact, almost all the shots that I've looked at inside the Canon 200m f2.0 Lens Sample thread could have been achieved with "close enough" results with a 135mm lens. So why spend $6K for "slightly" better when only "WOW" better can justify the price.

PCcousins, I'm sure you made the right choice to buy the 200mm f2.0, and selling your 135mm to help finance it. But for me, I can't justify the cost. So I asked myself this question:

"What can the 200mm f2.0 do that the 135mm f2.0 can't do with "good enough" quality. I have concluded that only the 200mm f2.0 (or longer) can produce long shots like this one by OP Smorter (great shot!)
https://photography-on-the.net …read.php?t=1350​570&page=3

smorter wrote in post #16565470
Ok tried Brenzier - what do you are reckon?

The only other way to achieve this look is with the Brenizer method. But who has time for that. Unless.... I have an idea....

What if I took a double exposure. One for the model and one for the background both with 135mm @ f2.0 and both on a tripod. The background shot would be taken with the lens deliberately de-focused. This will enhance the blur effect. Then in Photoshop I separate the model and paste it onto the extra-blured background. Whalla! 200mm f2.0 results with a 135mm f2.0 lens And because the scene is a full body shot, the subject digital separation need not be perfect because no one will notice.

In short: Use the 200mm f2.0 for full-body shots or long shots when you want the Brenizer look. And for mid-body and headshots, use a 135mm f2.0. Forget the 85mm 1.2.

The 135L is fine, and you are correct that it will get you most of the way to the look of the 200/2 for a fraction of the cost. That's typical of photography gear though, isn't it? That last little bit (if you really want it) costs a ton.

You also mention the 135L for headshots, but if you are really talking about as tight a shot as I'm thinking, longer would be better. But since you should probably shoot a headshot at f/8 to f/11, you sure as heck do not need the 200/2 for that. In fact, just about any lens that get's out to 200mm (or even longer) would be just fine. Any of the 70-200 zooms, the 70-300, the 100-400, the 200/2.8 II etc. etc. The 135L with a 1.4X TC is very good for headshots as well.

JeffreyG wrote in post #17352795
. But since you should probably shoot a headshot at f/8 to f/11, you sure as heck do not need the 200/2 for that. In fact, just about any lens that get's out to 200mm (or even longer) would be just fine. Any of the 70-200 zooms, the 70-300, the 100-400, the 200/2.8 II etc. etc. The 135L with a 1.4X TC is very good for headshots as well.

Are you recommending a 200mm 2.8 lens for headshots over the 135mm f2.0 because of the razor thin DOF problem or because of facial compression?