p.24 #1 · Sigma 35mm f/1.4 DG HSM first impressions
Yakim Peled wrote:
Joining late to the party. Has anyone comented about AF accuracy? I still remember selling my Sigma 50/1.4 a few years ago just because of this.
Happy shooting,
Yakim.
From the darkside,
my copy needed -18 to get it right. It is now tack sharp. Great clarity and pop. Build quality is amazing. AF is quick and consistent, It hasn't gone hunting for me.
p.24 #2 · Sigma 35mm f/1.4 DG HSM first impressions
jojomon11 wrote:
Mine was sharp right out of the box with zero MA on my 5d mk3, if this trend continues I wouldn't hesitate to purchase sigma's next 'A' series lens, hopefully it will be a 50
Phil
Same here on my 5d III. I think my next 50, though, will be the Zeiss f2; I might even see if I can sell my 50 1.2L to fund it.
p.24 #4 · Sigma 35mm f/1.4 DG HSM first impressions
Well, looks like I spoke too soon regarding the AF of my new Sigma 35. Took it out for a spin this morning and it's front-focusing consistently and badly:
I'm going to MA the lens with Reikan FoCal now and see what happens.
However, I should point out that I'm beginning to suspect that the AF is off in my 5D3, not this lens. Why? Because I've had AF issues with so many lenses. At first I thought the issues were with the lenses, especially because two of them were Sigmas (50/1.4 and 85/1.4). But I recently bought a Canon 24-70 II and it doesn't seem to be nailing focus either. After Christmas I'm going to send my camera in to Canon for service since it's still under warranty.
p.24 #5 · Sigma 35mm f/1.4 DG HSM first impressions
Okay, now I'm really confused. I just MA'd the Sigma 35 with FoCal. Not only did it come back with a tiny adjustment (-1), it was the fastest calibration I've ever done. It only took 5 readings: -20, -10, 0, 10, 20 and -1. Then I did a focus consistency test with 10 shots and got a 98.7% CoF.
Could a 1 point difference in AFMA explain the front-focusing in the pictures above? I was under the impression that these are very minor adjustments, accounting for only a few millimeters, if that.
And how is it possible that the lens would front-focus so consistently in real-world shooting, but score so well in a focus test? If the problem is with the camera, as I suspected, then how could the lens do well in a test?
I had the 35L before this (which I'm now regretting I sold), and strangely it was the one lens I didn't have AF issues with.
p.24 #6 · Sigma 35mm f/1.4 DG HSM first impressions
The only aspect of this that I would feel competent to comment on is that the amount by which the focus is off in those samples is more than the difference one adjustment point would make. And, to counter front focusing, you'd apply a positive value, not a negative one; negative adjustments move the plane of focus closer to the camera.
p.24 #7 · Sigma 35mm f/1.4 DG HSM first impressions
Ernie Aubert wrote:
The only aspect of this that I would feel competent to comment on is that the amount by which the focus is off in those samples is more than the difference one adjustment point would make. And, to counter front focusing, you'd apply a positive value, not a negative one; negative adjustments move the plane of focus closer to the camera.
That's exactly what I thought re: how far off the focus is. And yes, a -1 would theoretically make it worse.
The operative question, then, is whether there's any way of explaining how a lens could front-focus so consistently in real-world use (I have at least 7 other pictures from the same shoot demonstrating this) but pretty much nail the FoCal test?
p.24 #8 · Sigma 35mm f/1.4 DG HSM first impressions
On the face of it, that would incline me to try making adjustments without reference to the software and see what I could achieve. I've never used that software, but I have successfully adjusted the AF on multiple lenses. I'd say, if you can get good results without the software's assistance, then all is well and there's some issue with your implementation of the software.
p.24 #9 · Sigma 35mm f/1.4 DG HSM first impressions
badlydrawnboy wrote:
Okay, now I'm really confused. I just MA'd the Sigma 35 with FoCal. Not only did it come back with a tiny adjustment (-1), it was the fastest calibration I've ever done. It only took 5 readings: -20, -10, 0, 10, 20 and -1. Then I did a focus consistency test with 10 shots and got a 98.7% CoF.
Could a 1 point difference in AFMA explain the front-focusing in the pictures above? I was under the impression that these are very minor adjustments, accounting for only a few millimeters, if that.
And how is it possible that the lens would front-focus so consistently in real-world shooting, but score so well in a focus test? If the problem is with the camera, as I suspected, then how could the lens do well in a test?
I had the 35L before this (which I'm now regretting I sold), and strangely it was the one lens I didn't have AF issues with.
I think the first step should be to use the lens after this calibration and see if it is accurate now or not. Without that you will get lots of random guesses
p.24 #10 · Sigma 35mm f/1.4 DG HSM first impressions
Did you try powering down the camera, restarting focal, and seeing if it gives you the same result? I have had an odd result a time or two with Focal and a 5d2 when calibrating. From what I have watched of Focal during the calibration process, the increments you describe are too short to possibly be accurate.
p.24 #11 · Sigma 35mm f/1.4 DG HSM first impressions
It's still front-focusing badly. I'm going to start another thread so I don't hijack this one – especially since the problem may be with my camera, rather than the Sigma 35/1.4.
p.24 #15 · Sigma 35mm f/1.4 DG HSM first impressions
badlydrawnboy wrote:
It's still front-focusing badly. I'm going to start another thread so I don't hijack this one – especially since the problem may be with my camera, rather than the Sigma 35/1.4.
Did you use the same AF distance in FoCal and your shots above?
Next, set lens at f/1.4, mount camera and lens on tripod, point at contrasting test subject at your favorite AF distance, carry out a series of half-presses and watch the distance scale. Does it wander all over? If it does, problem most likely lies in Sigma lens since 5D3 is very consistent with Canon lenses.
Last thing to try: ignore FoCal's recommendation, dial in your own adjustment, e.g. +10, and take several shots at the usual AF distance for consistency, adjust your correction if necessary and repeat. Once it's OK, try on your intended subject.
p.24 #16 · Sigma 35mm f/1.4 DG HSM first impressions
thw2 wrote:
Did you use the same AF distance in FoCal and your shots above?
Next, set lens at f/1.4, mount camera and lens on tripod, point at contrasting test subject at your favorite AF distance, carry out a series of half-presses and watch the distance scale. Does it wander all over? If it does, problem most likely lies in Sigma lens since 5D3 is very consistent with Canon lenses.
Last thing to try: ignore FoCal's recommendation, dial in your own adjustment, e.g. +10, and take several shots at the usual AF distance for consistency, adjust your correction if necessary and repeat. Once it's OK, try on your intended subject.
No. The recommended distance from the target for microadjustment is 50x the focal length of the lens, which comes out to about 69 inches (close to 6 feet). The "real world" shots I took were closer to 4 feet.
I'll try what you suggest next. I will also try shooting with my Canon 24-70 II today to see if it has AF issues.
FWIW, Reikan responded to my email about this and said that it is possible for a lens or camera to perform well in an AF test with a static target, but not in real world shooting.
p.24 #19 · Sigma 35mm f/1.4 DG HSM first impressions
badlydrawnboy wrote:
It's still front-focusing badly. I'm going to start another thread so I don't hijack this one – especially since the problem may be with my camera, rather than the Sigma 35/1.4.
All of those images appeard focused on nearer objects; the operative question is which AF mode and point(s) were used for AF. In DPP you can show the actual AF point used; you may find that it is not the fault of the lens
