Sigma 500 4.5 problem- reprise

[momji1971]

Well, 500mm 4.5 in for repair at a local camera shop. This chap knows some of the engineers at Sigma.

Found out why Sigma wanted my camera to go in with the lens. They shoot a test image with the combi and send it to Japan. There, they make a custom chip for the combi and send it back to the UK for a refit!

I've mentioned I update camera bodies every three years. With a custom chip inside, would I have to have the lens rechipped every time? Waiting for an answer. Will let you know.

If the answer is yes, think I'm gonna mention to Sigma UK that under the sales of goods act, it is reasonable to expect a lens to last longer than 12 months and fit other bodies. Thereby, this lens was not fit for the purpose it was sold for. We'll see what comes about. Who know's, Sigma might suprise me and get this lens working as it should!

regards.
Stu.

[RichBrew]

Originally Posted by momji1971

Found out why Sigma wanted my camera to go in with the lens. They shoot a test image with the combi and send it to Japan. There, they make a custom chip for the combi and send it back to the UK for a refit!

That sounds rather unlikely. How well do you know the "chap" in the shop?

I once had a Sigma lens that would give unpredictable exposures on a digital body, so I sent it to Sigma UK for it to be re-chipped at a cost of five quid. It performed as it should from there on. At no time did they need the camera to make the upgrade, although I did specify what camera I was using it on.
Making a one-of custom chip for a camera/lens combination would be prohibitively expensive, and sounds implausible, especially the 'send it back to Japan' part. Sigma must be able to calibrate a lens at their repair facility without the need for your specific camera.
I smell something fishy.

RichBrew

[momji1971]

Thats kind of along the lines I was thinking. Oh, I did mean they send the test file to Japan.

Anyways, will keep you upto date with the sorry saga!

Thanks for the reply.

[RichBrew]

Originally Posted by momji1971

... Oh, I did mean they send the test file to Japan.

Ah, a slight misunderstanding, here.

However, I still don't see why Sigma need the body to calibrate a lens to focus correctly. A lens should be able to be used on any body with the same mount, without the need to sort out focus problems every time you change models.
Sigma UK should be able to adjust a lens that they built so that if will focus light at the focal plane.
I still believe you have an issue with quality control on their part, and they should either resolve the problem so that the lens performs to specification, or replace it with one that does.
If I spent that sort of money on a prime lens that I couldn't shoot wide open I would want to know why.

RichBrew

[DrNickBurton]

Originally Posted by RichBrew

Ah, a slight misunderstanding, here.

However, I still don't see why Sigma need the body to calibrate a lens to focus correctly. A lens should be able to be used on any body with the same mount, without the need to sort out focus problems every time you change models.

RichBrew

I think the reason for this is that focusing errors can arise from:

(i) manufacturing variations in the lens
(ii) manufacturing variations in the camera body
(iii) more typically a combination of (i) and (ii).

Due these variations, each combination of lens + body is unique, and it is the combination of lens + body upon which the calibration needs to be based. It's not possible in principle to calibrate the lens without having the body present, as otherwise you are essentially guessing where the focal plane should be, and cannot take (ii) into account.

I've heard of people sending their cameras in like this before, although I've not had to do it myself. The chip thing is new to me though, and it's interesting to hear that that is what they do. I guess they program in some kind of focusing offset to compensate for the misalignments.

[momji1971]

Nick, I understand what you're saying. However, these minute variations are why canon and nikon have put focus adjust on their dslr's. It's much more than that.

I have just purchased a nikon 50mm 1.8, cost £100. This is sharper wide open than the £2,000 (now £3,700!) Sigma!

As a quick reminder. At 4.5 is useless or less! at 6.3/7.1 its amazingly sharp, most of my bird shots on here have been with this lens. There is a problem with the optics/focusing of the lens and Sigma admit it is way worse than it should be and that increasing the depth of field is 'masking' the problem.

It's been like this from new, I just didn't realise it until, for creative reasons/shutter speed I recently investigated. My 1 year warranty is up by two months

Like I said, should find out more tomorrow.

regards.
Stu.

[DrNickBurton]

Hey, I'm not defending Sigma - I'd be just as annoyed if this happened to me. I'm just saying it's not suprising they need your camera to get the correction right. I hope it works out, I'm sure it will be fine.

Originally Posted by momji1971

Nick, I understand what you're saying. However, these minute variations are why canon and nikon have put focus adjust on their dslr's. It's much more than that.

I have just purchased a nikon 50mm 1.8, cost £100. This is sharper wide open than the £2,000 (now £3,700!) Sigma!

As a quick reminder. At 4.5 is useless or less! at 6.3/7.1 its amazingly sharp, most of my bird shots on here have been with this lens. There is a problem with the optics/focusing of the lens and Sigma admit it is way worse than it should be and that increasing the depth of field is 'masking' the problem.

It's been like this from new, I just didn't realise it until, for creative reasons/shutter speed I recently investigated. My 1 year warranty is up by two months

Like I said, should find out more tomorrow.

regards.
Stu.

[RichBrew]

Hi, Dr Nick,

I have a 300mm f/2.8 AF-S Nikkor that produces superb images wide open on an F5, a D200 and D300 without any calibration to a specific body whatsoever (I also have the 300mm f/4 AF-S variant that performs equally well at full aperture with these cameras). The former is designed to be used at maximum aperture, and I freely swap it between the aforementioned bodies with no depth of focus issues. In other words, the lens is working within tolerance: It sounds like Stu's 500mm Sigma lens isn't.
I would find it unacceptable to have to send a new camera body to a third party lens manufacturer every time I upgraded to a different model.

Ultimately, it brings me back to Sigma's quality control with lenses - even from their professional range. It's just not that good.

RichBrew

[DrNickBurton]

Again, I'm not saying that the situation is a good one. It's clearly not.
I am merely providing a potential explanation as to why Sigma want the body. A google search for "Sigma lens calibration" will quickly reveal that sending the body in along with the lens is a common procedure, and there is an article at lens rentals dot com which expalins why.

By the way, I don't work for Sigma or anything

Originally Posted by RichBrew

Hi, Dr Nick,

I have a 300mm f/2.8 AF-S Nikkor that produces superb images wide open on an F5, a D200 and D300 without any calibration to a specific body whatsoever (I also have the 300mm f/4 AF-S variant that performs equally well at full aperture with these cameras). The former is designed to be used at maximum aperture, and I freely swap it between the aforementioned bodies with no depth of focus issues. In other words, the lens is working within tolerance: It sounds like Stu's 500mm Sigma lens isn't.
I would find it unacceptable to have to send a new camera body to a third party lens manufacturer every time I upgraded to a different model.

Ultimately, it brings me back to Sigma's quality control with lenses - even from their professional range. It's just not that good.

RichBrew

[momji1971]

You sure Nick?