Canon 50mm f1.8

bensherman2

bensherman2

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Matt
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Hi all

I have a first gen 50mm f1.8 lens and it gives great results but it doesn't half hunt for focus when I'm trying to shoot my black Labrador.
Has anyone got the 50mm f1.4 and can tell me if it is any better at grabbing focus in either dark situations or trying to shoot a black animal. I don't really want to spend a grand on the 50mm f1.2. Any recommendations?

Cheers

Matt
 
The 50mm f1.4 is better but the newer 50mm f1.8 STM is your best bet.
 
Whilst the 1.8 STM is the better of those lenses I'm not sure it's an answer to your problem, a black dog in poor light offers virtually no contrast, what's the focus system supposed to lock onto?
 
Hi Phil

That was what I wondered, am I asking the impossible? Just thought that the extra little bit of light going in on the f1.4 may be enough to help the focus. My f1.8
hunts something terrible, although if I switch to manual focus I can easily get focus.
 
bensherman2 said:
Hi Phil

That was what I wondered, am I asking the impossible? Just thought that the extra little bit of light going in on the f1.4 may be enough to help the focus. My f1.8
hunts something terrible, although if I switch to manual focus I can easily get focus.
Click to expand...
IIRC Most DSLRs focus at around f2 so we don't see any advantage in focussing from 1.8 on.

The old 1.8 focus motor was awful though, and the USM in the 1.4 isn't much better (not a true USM) my opinion is that the STM is much better, but I've never tested it in those circumstances.
 
I'm using a 1D mark IV. Did think about using flash to help with the focus, but then was wondering how to get it not to fire.
 
Phil V said:
IIRC Most DSLRs focus at around f2 so we don't see any advantage in focussing from 1.8 on.
Click to expand...
Geek alert:

All lenses(screens) have a "FL" and a "diameter," which means they all have an aperture/max aperture.

The camera focus screen (viewfinder) has an aperture of approx f/2, this limits how shallow of a DOF you can preview. The PDAF module has lenses with an aperture of approx f/28*, this limits the amount of light and depth of focus at the AF sensor. The AF module lenses fit w/in (view) an aperture area of approx f/7 (for f/5.6 AF capable sensors).

The AF sensor gets light equivalent to ~ f/28* unless the lens' max aperture is less than ~ f/7 (or it's mechanically stopped down) at which point they begin to be vignetted... i.e. "fast" lenses do not transmit more light to the AF module and thereby improve AF. What they do is allow additional AF points to see additional areas of the entrance pupil *if* the module has f/2.8 sensor lines (increased sampling, i.e. 1Dx/D4/etc).
There is probably some SNR advantage if the light is stronger prior to being restricted by the AF module, much like how you can get a high IQ image when stopped down in good light and crap IQ wide open in bad light (but that is more a function of the light/scene itself rather than aperture per-se).


*cameras since the D700 may have faster aperture AF modules... they're improving the low light focus capabilities somehow, and at least some focus points (sensor lines) fall within the f/8 aperture area for f/8 AF capable bodies.
 
Last edited:
bensherman2 said:
Hi all

I have a first gen 50mm f1.8 lens and it gives great results but it doesn't half hunt for focus when I'm trying to shoot my black Labrador.
Has anyone got the 50mm f1.4 and can tell me if it is any better at grabbing focus in either dark situations or trying to shoot a black animal. I don't really want to spend a grand on the 50mm f1.2. Any recommendations?

Cheers

Matt
Click to expand...
The 1.4 has USM AF drive, so it should be faster and possibly more accurate/consistent. But I don't think that is likely to help with your issue.
 
sk66 said:
The 1.4 has USM AF drive, so it should be faster and possibly more accurate/consistent. But I don't think that is likely to help with your issue.
Click to expand...

Cheers for the replies, like Phil said I suppose it's the old black cat in a coal shed - I'm asking the almost impossible.
I suppose I was questioning the nifty fifty as I didn't spend a lot on it and my other lenses are L's and they seem to lock focus a lot quicker/consistently.
 
sk66 said:
The 1.4 has USM AF drive, so it should be faster and possibly more accurate/consistent. But I don't think that is likely to help with your issue.
Click to expand...
It's not a 'proper' USM lens, I do recall reading a lot about this years ago, but the details are lost on me. There were a handful of lenses labelled USM that had a variant of USM motor that didn't have all the features of true USM. The STM motor in the new 1.8 is definitely as quick as USM and quieter, just can't guarantee it's accuracy being better.
 
bensherman2 said:
Cheers for the replies, like Phil said I suppose it's the old black cat in a coal shed - I'm asking the almost impossible.
I suppose I was questioning the nifty fifty as I didn't spend a lot on it and my other lenses are L's and they seem to lock focus a lot quicker/consistently.
Click to expand...

I think we might have missed a trick here...
I suppose if I was buying a 50mm to use with a 1d and a bunch of L lenses, I'd get the Sigma 50mm 1.4 Art, a much better lens than the Canons (arguably all of them including the L)
 
I've had the Mk1 1.8, the 1.8 STM and the 1.4 - The STM definitely focused best out of all of them, and was quite noticeably sharper than all of them as well. But yes, trying to acquire focus on a black animal in low light is never going to be easy - a flash with focus assist works well, although if it's one with a flashy laser assist grid thing it tends to then result in movement of the subject if they're feline. :D
 
bensherman2 said:
Hi all

I have a first gen 50mm f1.8 lens and it gives great results but it doesn't half hunt for focus when I'm trying to shoot my black Labrador.
Has anyone got the 50mm f1.4 and can tell me if it is any better at grabbing focus in either dark situations or trying to shoot a black animal. I don't really want to spend a grand on the 50mm f1.2. Any recommendations?

Cheers

Matt
Click to expand...
Look at he 50mm f/1.8 STM. Much faster and more accurate AF (and silent too!).
 
Thanks for the replies, my only concern with the STM is build quality. My f1.8 is all plastic and compared to the rest of my lenses it's seems "cheap" which in price it is although I can't argue with how sharp just the hunting for focus.
 
bensherman2 said:
Thanks for the replies, my only concern with the STM is build quality. My f1.8 is all plastic and compared to the rest of my lenses it's seems "cheap" which in price it is although I can't argue with how sharp just the hunting for focus.
Click to expand...
The build quality is top notch, very solid with a nice metal mount and operates silently. Its another area of vast improvement from the mk2.
 
bensherman2 said:
Thanks for the replies, my only concern with the STM is build quality. My f1.8 is all plastic and compared to the rest of my lenses it's seems "cheap" which in price it is although I can't argue with how sharp just the hunting for focus.
Click to expand...

Honestly, if you're concerned about build quality, it's worth staying away from the 1.4 USM - it doesn't exactly have a reputation for solidity, mine broke falling six inches on to a carpet. :eek:

1.8 STM is definitely leagues more solid feeling than the previous 1.8's, and although they're still very plastic-y, it's much nicer feeling plastic - I'd still not treat one roughly, but I'd trust one a lot more than a 1.4.
 
bensherman2 said:
Hi Phil

That was what I wondered, am I asking the impossible? Just thought that the extra little bit of light going in on the f1.4 may be enough to help the focus. My f1.8
hunts something terrible, although if I switch to manual focus I can easily get focus.
Click to expand...

Have you thought about using a wireless trigger to put out a AF target? Might be a cheaper option and less hassle than having to use a flash. Ive used my Godox and Youngnuo triggers like this and they seem to work well.
 
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