Sigma Micro focus adjustment question

[cuthbert]

just a quick one, i've just got my Sigma 85 1.4 lens. i've added +9 micro adjustment and it's razor sharp wide open, but another forum member's (see Joe's post) was perfect out of the box. http://www.talkphotography.co.uk/forums/showthread.php?t=278989&page=2.

would i gain anything by sending it to Sigma to get it recalibrated? I'd probably rather that then send it back to where i purchased it as there is no guarantee the replacement would be any better.

and is +9 MA on the high side or not? I can certainly live with it if it's just one of those things, but of the two sigma lenses I've had, both needed the same MA value. My other (Canon) lenses are fine.

My (limited) testing seems to suggest that the +9 micro adjustment is consistent at a variety of distances and apertures and i'm extremely pleased with the performance of the lens so far.

What would you do?

 

[LongLensPhotography]

It is easier with a prime. A zoom would probably have to go to service.

I think you may want to ask if the lens can focus accurately at minimum focus distance, infinity and anywhere in between. If, yes, then probably it is OK (unless you intend to ever sell it or use on an older body). If no, it really has to go back.

 

[cuthbert]

thanks daugirdas.

as far as i can tell, it does focus consistently at varying distances. hopefully we'll get some dry weather at the weekend and i can 100% check.

i've emailed Sigma in general terms to see what they say - there are a few threads and posts elsewhere on the net which seems to suggest that some people's lens/body combination needs varying amounts of MA so i'm not overly worried about it. as long as it's consistent, that's all that matters to me, and it certainly seems to be that way.

 

[StewartR]

would i gain anything by sending it to Sigma to get it recalibrated?

No.

The whole point of micro adjustment is that lenses and bodies have a certain (small) amount of manufacturing variation, and they can be within the target manufacturing tolerances but not quite perfect together. So you can do the micro adjustments to calibrate specific lenses with specific bodies.

If you can adjust the lens to get optimal results then by definition there's nothing wrong with it.

 

[cuthbert]

Thanks for that Stewart.

In your view is +9 MA about average/nothing to be worried about/a bit high?

do you see this sort of value crop up a bit with the lenses you deal with?

 

[StewartR]

In your view is +9 MA about average/nothing to be worried about/a bit high?

I have no specialist knowledge here, but I would say there are plenty of things in life to worry about without seeking to add to the list unnecessarly. I'm just taking the simple view that, if you CAN set it up so that the lens works perfectly, then there's nothing wrong with it.

 

[cuthbert]

fwiw, Sigma emailed me back and said the same thing. if i do have any problems I can always send it in at a later date. just waiting for it to stop raining now!

thanks again everyone.