Better lense 35mm 1.4l versus 50mm 1.2l?

I am currently looking at either a 50mm 1.2 lense or a 35mm 1.4l to shoot fashion portraits/head and shoulders. While i understand that they are both different focal lengths, and that the 50mm will give less distortion, i never had that problem with the sigma 35mm which alot of my work has been shot with (until big focus issues)

What this comes down to which is which is a sharper lense (i know how to shoot so the photographer isn't an issue) and secondly more reliable when it comes to focusing. The 50mm seems to be quite mixed unfortunately, where not so much with the 35mm?

An 85mm takes me to far away

Any opinions would be great. Thanks

The 50/1.2 suffers from focus shift by-design, so the photographer is not an issue but the lens might be.
The 35/1.4 is a nice reliable prime. If the Sigma 35 worked for you, then get the 35L.

I ended up selling my sigma as it was very unreliable when it came to focus and consistently calibrating. I have heard better things about the 35 so far. Thx CheshireCat

The 50 F1.2 L is often criticized for its softness that is also by many liked when coupled with the dreamy unique look of a f/1.2 aperture. The 35L has been widely used by many photographers with great results, it is sharper than the 50 1.2L but still its sharpness is noticeably lower than the new 35L ii.
By the way Sigma produces sharper 35/50 - but with less reliable AF - if you are interested in 3rd party lenses.

I suggest you to decide exclusively based on which FL you want as opposed to which lens best performs. 35 and 50 are close but two different animals and generally suit alternative styles.

Unfortunately sigma are just to hit and miss to consider. Yes i noticed the sharpness want all that great on the 35 either. the ii is a bit out of price range

CheshireCat wrote in post #18290313
The 50/1.2 suffers from focus shift by-design, so the photographer is not an issue but the lens might be.
The 35/1.4 is a nice reliable prime. If the Sigma 35 worked for you, then get the 35L.

I own both so let me expand a bit on CheshireCat's comment.

If you don't mind manual focusing the 50 L f/1.2, you can minimize (or even eliminate) the focus shift issues. Focus shift is very evident at five feet and closer when shooting between f/1.4 and f/4. I use live view (10x) to focus; obviously a PITA but I can get very sharp images. Strangely, I don't seem to experience focus shift at f/1.2.

I'd suggest keeping life really simple and go with the 35 L f/1.4. I haven't experienced any noticeable focus shift issues with the 35 L.

Elton Balch wrote in post #18292094
Strangely, I don't seem to experience focus shift at f/1.2.

Why is that strange? Autofocus at f/1.2, expose at f/1.2, no shift. The shift occurs when you focus wide open and then expose at an aperture that is narrower... but not narrow enough for the extra DOF exceed the magnitude of the shift. Which, apparently, is f/4 or so for this lens.

LonelyBoy wrote in post #18292107
Why is that strange? Autofocus at f/1.2, expose at f/1.2, no shift. The shift occurs when you focus wide open and then expose at an aperture that is narrower... but not narrow enough for the extra DOF exceed the magnitude of the shift. Which, apparently, is f/4 or so for this lens.

Correct. However, the narrower aperture also depends on sensor pixel density.

CheshireCat wrote in post #18292212
Correct. However, the narrower aperture also depends on sensor pixel density.

How? Resolution is not, and never has been a variable in Depth of Field calculations. Generally, given how DoF calculations are shown, once you have agreed on the viewing conditions, i.e. visual acuity and viewing distance, all you need to know on the camera side is lens focal length, f/number, and focus distance. Then finally, you need to know the final output magnification. The knowledge of these variables will allow you to derive the values that you need to use any of the usual DoF calculators. There is no mention of resolution at all.

Of course where you have a digital image, if you chose to do the DoF calculation based on using an output device with a fixed output resolution, then changing the sensor resolution will naturally change the output magnification. It is the change in output magnification that causes the perceived change in DoF.

Of course there is one assumption that is always made when considering DoF, and that usually gets ignored, because generally it is one that is always satisfied. The assumption is that the resolution of the camera lens and sensor system is adequate. Again this resolution requirement is the same for both analogue and digital sensors, since grain size affects analogue sensors (film) identically to sensel resolution in digital sensors. Generally since the introduction of the 10D I would say that Canon's digital sensors have had more than adequate resolution. I would go further and say that they have had much better resolution than any 35mm film that I have ever used.

Alan

LonelyBoy wrote in post #18292107
Why is that strange? Autofocus at f/1.2, expose at f/1.2, no shift. The shift occurs when you focus wide open and then expose at an aperture that is narrower... but not narrow enough for the extra DOF exceed the magnitude of the shift. Which, apparently, is f/4 or so for this lens.

I'm describing my experience but not the science behind it. I'm still puzzled though; I set the aperture prior to shooting so I assume when I set the aperture at f/2 for example I'm focusing at f/2 and not wide open. I get focus shift at the f/2 setting when I'm close to the subject. When I set aperture at f/1.2 there appears to be no focus shift. All of this test shooting is done with a tripod of course since DOF is extremely narrow and doesn't minimize focus shift until about f/4 as you point out. I'm probably out of my depth (of field) here.

Elton Balch wrote in post #18292395
I'm describing my experience but not the science behind it. I'm still puzzled though; I set the aperture prior to shooting so I assume when I set the aperture at f/2 for example I'm focusing at f/2 and not wide open. I get focus shift at the f/2 setting when I'm close to the subject. When I set aperture at f/1.2 there appears to be no focus shift. All of this test shooting is done with a tripod of course since DOF is extremely narrow and doesn't minimize focus shift until about f/4 as you point out. I'm probably out of my depth (of field) here.

No matter what you set the aperture to, the aperture blades stay wide open (to facilitate AF and brighten the viewfinder) until you trigger the shutter. Think about it - if you set the aperture to (for an extreme example) f/22, the viewfinder stays as bright as it is when the lens is wide open, and AF continues to work even though none of the points work with an aperture slower than f/8.

This is also what the DOF preview button is for: it closes the aperture blades to the selected f-stop. Try it with, say, f/8 and watch the viewfinder darken. After that you should understand what's going on.

LonelyBoy wrote in post #18292516
No matter what you set the aperture to, the aperture blades stay wide open (to facilitate AF and brighten the viewfinder) until you trigger the shutter. Think about it - if you set the aperture to (for an extreme example) f/22, the viewfinder stays as bright as it is when the lens is wide open, and AF continues to work even though none of the points work with an aperture slower than f/8.

This is also what the DOF preview button is for: it closes the aperture blades to the selected f-stop. Try it with, say, f/8 and watch the viewfinder darken. After that you should understand what's going on.

I should be clearer--I understand what happens when I press the shutter and I'm very familiar with the DOF function. I'm simply saying the lens doesn't seem to focus shift at f/1.2 and was just wondering why. When I set the aperture to f/2 I understand the lens is wide open but when I press the shutter the camera and lens have their digital conversation and the lens focuses accordingly. When I use manual focus in live view with 10x magnification with a tripod I get great results. I have 7 primes and all function as expected at various apertures with autofocus except this one. I'm guessing (and I'll readily admit I don't know) it may have to do with the fixed front element design but those with more knowledge of lens design should weigh in on this.

Elton Balch wrote in post #18292547
I should be clearer--I understand what happens when I press the shutter and I'm very familiar with the DOF function. I'm simply saying the lens doesn't seem to focus shift at f/1.2 and was just wondering why. When I set the aperture to f/2 I understand the lens is wide open but when I press the shutter the camera and lens have their digital conversation and the lens focuses accordingly. When I use manual focus in live view with 10x magnification with a tripod I get great results. I have 7 primes and all function as expected at various apertures with autofocus except this one. I'm guessing (and I'll readily admit I don't know) it may have to do with the fixed front element design but those with more knowledge of lens design should weigh in on this.

Because like the other poster mentioned, at 1.2 aperture isn't engaged. Focus shift happens when the aperture is engaged. You can test this via tripod and close focus(most evident). Simply changing aperture will change focus.

Elton Balch wrote in post #18292547
I should be clearer--I understand what happens when I press the shutter and I'm very familiar with the DOF function. I'm simply saying the lens doesn't seem to focus shift at f/1.2 and was just wondering why.

These two sentences seem at odds. Focus shift happens because the lens's focus distance at f/1.2 (where AF occurs) is different from it's focus distance when stopped down (without adjusting the focus ring). When you shoot at f/2, the camera AFs at f/1.2, then exposes at f/2, and the lens shifts its focus. When you shoot at f/1.2, you are both AFing at f/1.2 and exposing at f/1.2, so the focus distance is the same and focus shift cannot, by definition, occur. You can only get focus shift when the lens is stopped down.

Charlie wrote in post #18292658
Because like the other poster mentioned, at 1.2 aperture isn't engaged. Focus shift happens when the aperture is engaged. You can test this via tripod and close focus(most evident). Simply changing aperture will change focus.

LonelyBoy wrote in post #18292694
These two sentences seem at odds. Focus shift happens because the lens's focus distance at f/1.2 (where AF occurs) is different from it's focus distance when stopped down (without adjusting the focus ring). When you shoot at f/2, the camera AFs at f/1.2, then exposes at f/2, and the lens shifts its focus. When you shoot at f/1.2, you are both AFing at f/1.2 and exposing at f/1.2, so the focus distance is the same and focus shift cannot, by definition, occur. You can only get focus shift when the lens is stopped down.

Well, clearly, I'm no threat to "Bill Nye, the science guy"!!!

Here's an article which explained it in simple terms with a couple of visuals:

https://photographylif​e.com/what-is-focus-shift/