Update/getting your advice on the perfect portrait setup for my M50

[bigbrother]

So this has been interesting. I'm somewhere above beginner, I'd say, and for my fashion/portraiture work was looking to home in on my perfect solution.

I began with the expected kit lens and 50mm f1.8 with Canon adapter. Absolutely fell in love with the nifty and really, almost anytime I diverge from 50 at 1.8, regret it. It's just a perfect set up for 95% of the shots I take.

Well, almost perfect :). I didn't know about the sensor scaling aspect before purchasing and so the zoom-in with the 50 has been hampering me sometimes. Really, besides that it's been awesome.

Anyway, my attention was directed to the native 32mm f1.4 and it looked really impressive, especially given Canon designed it to scale to the equivalent of about 50mm.

Now, I'm just starting off and can't blow $300 on a speculative lens, so I started looking at rental places around me. As I somewhat expected, they don't stock $300 lenses :). But, last night I saw an EF 35mm f1.4 that many places carry and thought, "oh, THIS is going to be cool!" I confirmed with Canon support that it would be more or less the same as the native 32 (though I was of course expecting higher overall quality) and excitedly rented one nearby for $30 this morning for today's shoot. Wow what a beast, physically-speaking.

I take it to the shoot and no joke, 3 or 4 shots in and I'm RACING to swap my 50 back on there. The shots from the 35 were looking awful by comparison. For starters, the sharpness/color/overall quality were no better, but critically, the perspective change made the subject look awful. I didn't expect such a dramatic change going just from 50 to 35 (especially since Canon picked this length for their M portrait lens), but there it was!

So anyway, I decided 50 is much, much more my taste for these shots.

I happened to come across the Speed Booster last night when looking at random videos along these lines, and I think (?) that's the right solution for me. I get to keep 50mm perspective but get to undo the scaling, more or less.

But I am, alas, barely above beginner when it comes to such things. Should I consider anything else given all the above? I'm zoomed in too much as is but love the 50 perspective. I saw that the Speed Booster degrades image quality more than the Canon adapter so am a little hesitant on that front.

Anyway thanks for reading along and would love to get your thoughts!

[MikeSowsun]

On a full frame camera, with a 24mm x 36mm sensor, the classic portrait lens has long been either 85mm or 135mm.

On your crop sensor M50, that would translate to 50mm or 85mm. You were wrong to assume 35mm would be a good portrait lens. (maybe if you are doing full body shots) 

There is a rule of thumb that any kind of portrait should be at least 10' away from the subject in order to avoid perspective distortion which exaggerates facial features on your subject. Perspective distortion has nothing to do with the lens or it's focal length, and everything to do with the distance from the subject. 

A speed booster is not your answer either. Adding a speed booster to your 50mm lens will just make it act just like a 35mm lens, and you will have the same disappointment. 

[bigbrother]

Wait, this is quite confusing then.

I thought every time I hear about scale factors/cropping/sensor size phenomena, it's always referring to a scaling in image space, isn't it? Optically, there is no change in perspective or distortion correct? When Canon touts that their EF M 32 lens behaves like a 51 on the M series, it's just the image size at a given distance, right? A true 50mm at the same distance would create a different image due to its particular perspective yes?

And if I were to get something like a speed booster, when it's changing crop factors, I thought that's it, it's all just image cropping. The perspective to expect is exactly what's printed on the lens, I thought.

I ask for obvious reasons but basically I want to know A) how things are technically working, B) that my recent experience tells me that in fact anything shorter than 50 is a no-go for what I'm trying to achieve (on any sensor!), C) that what I'm achieving is in fact the result of a 50mm's perspective and not an 80-85mm (which would be the case if I'm wrong and the scaling is actually optically causing a perspective change to a different length), etc. etc. etc.

You get the point.

Thanks!

[MikeSowsun]

As I said before,  "Perspective distortion has nothing to do with the lens or it's focal length, and everything to do with the distance from the subject."

Scaling, Angle of view, focal length, crop factor, aperture, etc, all have nothing to do with perspective distortion. If you shove a camera up to the nose of your subject, that nose is going to look HUGE and disproportionate. 

Stand back 10 feet and take the picture and it will look just fine.  You can use whatever lens and camera combination you want, to get the framing you want, but you need to stay back. 

It sounds like you find 50mm on your M50 to be a little too tight for the portrait framing you want to achieve. Just move back a little and 50mm will be fine.  If you can't move back, your room is too small, and there is nothing you can do to fix it. It is simple physics. 

[bigbrother]

"Perspective distortion has nothing to do with the lens or it's focal length, and everything to do with the distance from the subject."

Then I'm missing something basic here (or perhaps your answer is a tad pedantic? :)) With your subject occupying the same area in your frame, you're going to experience massive differences in perspective/distortion, as you know:

https://clicklovegrow.com/wp-content/new_folder/2014/11/zoom-vs-out.jpg

Perhaps I didn't use the exact right terminology above but I feel you know what I'm trying to achieve. All I'm trying to say is that at 50mm, the subject occupying the same space is proportioned very well; with the 32 she wasn't at all. 

Ergo, I know that at that width/lens length (or shorter) I'm not going to get what I want at portrait framings, regardless of my distance to the subject!

Now what I'm trying to understand is if crop/scale factors (like EF on an M body or speed booster on the EF) in any way change this warping/perspective/distortion or if it's just, in image-space, a scaling/cropping.

If it's just that, I can then use a speed booster to *not* have to get 10'-20' away from my subject for basic shots, which is in some situations inconvenient and in others downright impossible.

[ebiggs1]

"Perspective distortion has nothing to do with the lens or it's focal length, and everything to do with the distance from the subject."

This statement while true is not clear as it might be.  Consider this, if you stand 10 feet from a subject and take a shot now move back 100 feet, same lens, the perspective changes but the lens did not.  The AOV stayed the same. Can't change. As you distance yourself form a subject you have to add the angle as the distance between its arc widens.

[bigbrother]

What's funny is I was about to come back here to write something like this, due to a realization I think I had just now while responding to a similar thread on another forum.

So I think it goes like this, simple example:

Say I have a perfect head and shoulders shot in my frame. Setup is a 50mm, with adapter, on my M50.

I change the adapter to a speed booster. Now instead of standing 10' away to get this ideal framing, I only need to stand 6' away. But due to getting closer the effective distortion has changed.

This leads me to wonder if deep zoom from a far distance is some ideal for portraiture... but that certainly can't be the case because I'm sure you can flatten things too much, plus you never see photographers taking portraits from 50' away :).

[bigbrother]

Ok, ebiggs, I know I'm double answering before a response :), but I think I get what you mean now!

The constant (that is, the thing to shoor for) is AOV, plain and simple. So the chart you posted is much more authoritative/important than any sort of length numbers. All one needs to know is the ideal AOV for the objective and then work backwards to know the right lens/equipment combo.

I'm curious now where you got the 20-28 deg. AOV for portrait number. Seems to fit what I like as well. Is this from personal experience, a guide, or some long-held knowledge you have from God-knows-where/how-far-back?:).

Thanks!

[MikeSowsun]

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@bigbrother wrote:

What's funny is I was about to come back here to write something like this, due to a realization I think I had just now while responding to a similar thread on another forum.

So I think it goes like this, simple example:

Say I have a perfect head and shoulders shot in my frame. Setup is a 50mm, with adapter, on my M50.

I change the adapter to a speed booster. Now instead of standing 10' away to get this ideal framing, I only need to stand 6' away. But due to getting closer the effective distortion has changed.

This leads me to wonder if deep zoom from a far distance is some ideal for portraiture... but that certainly can't be the case because I'm sure you can flatten things too much, plus you never see photographers taking portraits from 50' away :).

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Yes, 50' is too much, but 15-20 feet with a long lens can work. It will not flatten too much, but it is difficult to communicate with your subject if you are too far away.  The EF 70-200mm f/2.8 is a VERY popular portrait lens for a reason. 

[ebiggs1]

Let's start from the beginning. It doesn't help to just tell a person what to use or is best.  You must understand why it is the way it is.

First a lens is a lens is a lens. It can not change once it is manufactured. No matter what camera you use it on.  There is no scaling, no crop factor or "sensor size phenomena". The only reason these terms exists is if someone wants to compare a given lens to different camera formats. Otherwise it is useless.

What you need to understans is AOV or angle of view. A AOV char is helpful.

It is generally thought that a lens that gives a AOV in the 20 degree to 28 degree is best for portraits. Again lenses do not change their FL or their aperture or anything just because you use it on a crop sensor camera.  And, nothing is cropped or scaled or anything. You get exactly what you see in the view finder. As you can read from the AOV chart a 55mm to 60mm lens would be ideal.