Photographers have been warned of a potential 'autofocus defect' affecting some Sigma telezoom lenses.

Photographers have been warned of a potential ‘autofocus defect’ affecting some Sigma telezoom lenses.

The problem affects some APO 50-500mm f/4.5-6.3 DG OS HSM, APO 120-400mm f/4.5-5.6 DG OS HSM and APO 150-500mm f/5-6.3 DG OS HSM zooms.

Sigma has pledged to rectify the fault, free of charge.

The affected serial numbers are listed in the firm’s statement below.

‘This is a limited problem that will not occur in any lenses other than those specifically listed…,’ says Sigma.

Sigma 120-400mm lensSigma statement, as supplied by Sigma UK at 9.00am on 16 June 2010:

Auto focusing issue affects limited number of Sigma telezoom lenses

After thorough investigation, we have ascertained that some APO 50-500mm F4.5-6.3 DG OS HSM, APO 120-400mm F4.5-5.6 DG OS HSM and APO 150-500mm F5-6.3 DG OS HSM lenses, produced recently, may have a potential autofocus defect.

This issue could possibly occur in some lenses within the following range of serial numbers:

APO 50-500mm F4.5-6.3 DG OS HSM: Serial Numbers between 10633051 and 10972000

APO 120-400mm F4.5-5.6 DG OS HSM: Serial Numbers between 10574001 and 10972000

APO 150-500mm F5-6.3 DG OS HSM: Serial Numbers between 10674301 and 10972000

This is a limited problem that will not occur in any lenses other than those specifically listed above.

To overcome this issue, we will be offering our customers an inspection and where applicable, a modification service, free of charge. In the case of any autofocus problem becoming apparent on inspection, we will rectify the situation and make every effort to minimise delay and inconvenience.

If you are the owner of one of the above three focal lengths but your serial number is different to those specified above, then you need take no further action. If however you are in possession of one of the lenses with a serial number mentioned above, please contact us on our special helpline 01707 376 795 and we will arrange to collect your lens at no cost to yourself. In the unlikely event that the inspection uncovers a potential problem, your lens will be modified and returned to you absolutely free of charge with the minimum of delay.

We deeply apologise if any inconvenience has been caused to our customers.

For further information, please visit www.sigma-imaging-uk.com/returns, call our helpline on 01707 376 795 or email us at support@sigma-imaging-uk.com.