50 f1.4 or 85 f1.8

Cason · October 22, 2006

I'm sorry for yet another lens "which lens to get" thread. I've read the reviews; however, I value the discussions on DGRIN when it comes to advice from those that actually have the lenses.

I find myself taking more and more portraits. For my Rebel XT, I have the 50 f1.8. I knew when I bought this lens that it would hunt in low light. However, for $80, I couldn't pass it up. When it decides to focus, it is dead on and sharp.

I have some extra money to buy another lens. I've played around with the 85 1.8 and love it; however, I lose so much room with it in certain areas I shoot.

As far as speed and able to focus the first time, is the 50 f1.4 comparable to the 85 f1.8? I'm really thinking about getting the 50 f1.4; however, I'm hesitant to be redundant in my focal lengths.

Also, for those that have the 50 f1.8 and 50 f1.4 do you ever pull the f1.8 out?

Andy · October 22, 2006

RTP wrote:

I'm sorry for yet another lens "which lens to get" thread. I've read the reviews; however, I value the discussions on DGRIN when it comes to advice from those that actually have the lenses.

This was discussed just about a week ago, here's another thread:
http://www.dgrin.com/showthread.php?p=403049

Sounds like you could really use another FL, so my recommendation would be the 85 f/1.8 - it's such a great lens. And the longer, the better, for portraits IMO. 85mm on a 1.6 body is a great FL for portraits.

Cason · October 22, 2006

Not sure how I missed that thread.

Is the 50 f1.4 fast like the 85mm 1.8?

Cason · October 23, 2006

I've read some reviews stating that the 50\1.4 is not that much faster than 50\1.8.

Is that true? I would have thought otherwise because of the USM.

ziggy53 · October 24, 2006

RTP wrote:

I've read some reviews stating that the 50\1.4 is not that much faster than 50\1.8.

Is that true? I would have thought otherwise because of the USM.

USM is simply a motor type. It does not imply any particular attributes as far as speed, although the Marketing Department of Canon would have you thinking otherwise.

Focus speed is dependant upon:

Mass of the elements to be moved.
Distance the elements have to move.
Torque and speed of the motor used.
Gearing ratio of the focussing threads (and motor coupling if applicable).
Drag of moving parts.
Communication speed of the interface between camera and lens.
Processing speed of autofocus circuits.
Type of autofocus technology employed.
Effective aperture of lens.
Contrast of lens.
Resolution of lens.
Subject contrast.
Edge acutance of subject.
Edge orientation of subject.
Number of focus points selected.

Probably a half-dozen other factors I've forgotten or neglected.

USM usually "does" mean quiet operation with almost no vibration, because that is a feature of the technology, but that's really about it. The fact that "ring" USM is usually custom designed for the shape of the lens barrel probably contributes to the cost of the motor, as does the "economies of scale", so that ring USM is usually reserved for the very best of Canon's lenses, where the extra costs of the focus motor are more easily absorbed into the total cost of the lens.

All that said, I have also read that the Canon 50mm, f1.4 is no speed demon. The (realtively) slow speed is blamed on the age of the lens design (1993) and partly on the mass of the moving elements, and partly because the lens was never marketed for applications requiring much speed.

I am very curious what reviewers will say about the 50mm, f1.2L vs f1.4 focus speed difference and also focus accuracy and any front or back focus problems.

ziggy53

mercphoto · October 24, 2006

RTP wrote:

I've read some reviews stating that the 50\1.4 is not that much faster than 50\1.8.

Is that true? I would have thought otherwise because of the USM.

I don't know if it is faster than the 1.8 or not. But I do know the 50/1.4 is a very slow focusing animal. Its painful at times. Worse is how mine likes to hunt a lot in low light. I would think that with a really wide 1.4 aperture that it would at least not hunt, but it does. I can understand slow, I can't understand hunt. I keep it, however, because the results of that lens are stunning.

TristanP · October 24, 2006

mercphoto wrote:

I don't know if it is faster than the 1.8 or not. But I do know the 50/1.4 is a very slow focusing animal. Its painful at times. Worse is how mine likes to hunt a lot in low light. I would think that with a really wide 1.4 aperture that it would at least not hunt, but it does. I can understand slow, I can't understand hunt. I keep it, however, because the results of that lens are stunning.

I'll second all of that.

Ziggy obviously has the answers here. Just to add - there are two types of Canon USM: micro and ring. FTM focusing is typically only available on the ring-equipped versions. Micro is usually the slower of the two. The 50/1.4 is unique in that it has micro USM and FTM focusing.

Cason · October 25, 2006

Thank you for the feedback.

Looks like I will go with the 85mm 1.8. and stick it out with the 50 1.8 since the 50 1.4 is not that much faster.

handlebar · October 25, 2006

I'll throw a last thing in the 1.4 has a metal mount and the 1.8 is plastic. so you may want to consider how much changing of the lens you will do because that will wear on the plastic faster.

claudermilk · October 26, 2006

Unless of course you find a used Mk I like I did--metal mount, nicer focus ring, focus scale (such as it is). Price splits the difference between a 1.8 Mk II and a 1.4.

I've been pondering eventually moving to a 1.4, but it sounds like I'm just as well off sticking with my 1.8 Mk I.

handlebar · October 27, 2006

Very true and there was one available at keh.com last night for around $180 I believe. If i did it over I would probably pump 200 towards another lens and buy the mark I.

claudermilk · October 27, 2006

$180 is high. I just checked KEH, they have 2 EX lenses, $159 & w/ caps $165--still a bit high but reasonable.

Keep an eye on the FM B&S forum, they show up there pretty regularly for $140-$150.

50 f1.4 or 85 f1.8

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