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Old 11th June 2010
SoundRich SoundRich is offline
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Sigma 150mm F/2.8 Macro AF performance - is something wrong?

I've been using my Sigma 150 F2.8 macro for a fair while now, but I've become concerned about its AF performance. I know that it is a macro lens and therefore will be slower focusing than other lenses, but the performance of the lens in non-macro situations is getting to be a bit tiresome.

I wonder if anyone who has a copy of the lens could compare the performance they see to the performance that I am experiencing .
I've been using the lens on my E-400 and E-600 in light varying from ~EV 6 (1/8s, f/2.8 iso 100) to ~EV 14 (1/2000s, f2.8, iso 100) at distances greater than 50 times the focal length. The AF performance does not vary at all under the different lighting conditions. The AF targets have all been good targets, and centre point only was used on both cameras.

I have found that, unless the image is already nearly in focus, the camera/lens combo will often be unable to bring the image into focus *at all* and will give up. The rate of giving up does seem to be related to the light intensity, with more give ups in lower light. The strongest indicator of a give up though is how out of focus the image is. Other lens in my possession, including an Oly 35mm f/3.5 macro do not give up anywhere near as readily, even when the AF target is appears to be initially substantially more out of focus than is the case with the sigma lens.

In addition, the lens appears to have a real aversion to focusing quickly. Despite the use of the focus limiters, numerous lens resets and moving from AF to MF and back again, I am unable to make the lens make focus adjustments at anything but a positively glacial speed. The lens makes a ticking sound as it is focusing, as if it is constantly using the smallest focus steps available to it to adjust the focus. It is almost as if the lens were focusing using a contrast based focusing system! Is this behaviour normal? I would hate to think so as it would render the lens total unusable in non-still life uses (and therefore hardly fit-for-purpose, do I smell a refund).

Given the cost of sending the lens in for service, and the fee if there is nothing wrong, I'd like to see if other users of this lens see similar performance, or if something is likely to be wrong with my lens.
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Old 11th June 2010
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Re: Sigma 150mm F/2.8 Macro AF performance - is something wrong?

A long shot, maybe, but it may be worth checking that there is no dirt or dust obstructing the AF sensor under the mirror (either on the mirror itself or on the sensor below the mirror, which is fed by semi-silvered areas on the mirror).

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Old 11th June 2010
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Re: Sigma 150mm F/2.8 Macro AF performance - is something wrong?

Done that several times, to no effect. In addition other lenses focus just fine.

To give an idea of how slow the lens is at focusing, it is not unusual for it to take up to a minute to get to correct focus from a slightly out of focus image.

Surely no lens should be *that* slow!
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Old 14th August 2011
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Re: Sigma 150mm F/2.8 Macro AF performance - is something wrong?

this lense works great on my e300 but my e30 even with the focus adjustment does not get sharp images in AF only in MF. but the kit 14-45? lense my e30 pics are always dark but my e300 pics are impresive
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Old 14th August 2011
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Re: Sigma 150mm F/2.8 Macro AF performance - is something wrong?

I have a Sigma 105 and while it's not the same lens, I have some thoughts. First, on the 105 there are two things you need to do to set the camera to AF (besides setting AF in the camera). There's an AF/MF switch on the barrel side. It's small and must be firmly set to AF. Then somewhere on the inside of the focus ring you'll see either an MF or AF with a small line. Push the focus ring either in or out until the AF shows. It's not a lock but there's a firm indication when you get to the end of barrel travel.

Finally, I'm pretty sure the lens has a Limit switch, probably near the AF/MF switch. This needs to (must) be set to Limit unless you're shooting macro (in which case it won't close focus at all). The limit switch prevents the AF from trying to focus too close. Close in is generally the slowest and hardest point for AF. I dearly wish the ZD 50 macro had such a switch.
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Old 15th August 2011
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Re: Sigma 150mm F/2.8 Macro AF performance - is something wrong?

i have all the basic stuff it will a few feet past. even after i have used up all the internal focus adjustment
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Old 16th August 2011
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Re: Sigma 150mm F/2.8 Macro AF performance - is something wrong?

This is a lovely lens, but it can sometimes take a bit for it to find focus in some situations. As it does not have the push/pull engagement of the Sigma 105, it has full time manual control over the focus. This should not be done while the focus motor is driving, that is, it's fine to manually adjust focus to get close before pressing the shutter button & quite often that can be the quick & reliable way of achieving focus. If you are hand holding it for macro use, you are likely to be moving slightly as the lens steps it's way through its very fine focus steps (this can quickly drive through the whole range but slows down to fine steps for final adjustment) until it is locked on, but the movement in holding it (especially as we get older) can keep the focus adjustment chasing your movements which can be a little frustraing at times. This can also happen in telephoto use too.

In answer to your question, " The lens makes a ticking sound as it is focusing, as if it is constantly using the smallest focus steps available to it to adjust the focus. It is almost as if the lens were focusing using a contrast based focusing system! Is this behaviour normal?" Yes, & maybe your movements might be your problem here. Have you tried a monopod when using this lens? Remember, as we grow older, some of us become less steady & other means of preventing shake & movement needs to be considered (I speak from experience here ). As this is a macro lens, while it will take telephoto shots, any movement in them (or the photographer) makes it difficult for focus lock.

I hope that helps.
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Old 16th August 2011
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Re: Sigma 150mm F/2.8 Macro AF performance - is something wrong?

the problem occurs when on a tripod and hand hold. it always focus's 2 -3 feet behind the subject.
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