Inacurate Auto focus

[Cathus]

Originally Posted by OldBoy

All lenses have international warranty, so it makes no difference where you brought it. )

with a caveat, I know Sigma won't repair a lens imported from abroad unless you are able to produce proof that you paid VAT & import duty & purchased it through legal channels as this happened to someone I know.

I don't know if other lens manufacturers have the same policy

[wadooz]

Originally Posted by chris-p

Of the 70-300mm lenses, the Tamron is miles ahead of the Sigma. It'll be a bit more expensive but it's one of the best 70-300mm lenses on the market at the moment (barring the Canon L or DO models)

Thanks Chris, that just about clinches it. My daughter is in the US at the moment and the exchange rate is really good now. I might ask her to check out prices there. I'm sure she'd be happy to use my new lens on her Canon 550D.
I'll still enquire about a free repair though, it'll make it a bit more saleable later.
Thanks for the advice everyone.

PS. Cathus I may have the same trouble as your friend, we don't have VAT here but our GST is the equivalent. I'll let you know what Canon have to say. I didn't pay GST or import duty so we'll see.

[wadooz]

I rang Canons head office in Sydney. They said they would honour internet purchases provided they were accompanied by a proper receipt. They put me onto our local repairer in Adelaide who said it was $30 up front to look at it but wouldn't say how much it would cost to tweak it back into perfect focus. Said it depended what was wrong with it. I don't think the receipt I got with it would be any good anyhow.
I don't think I'll bother pushing any further, the lens is quite usable and the images are very good if I stop down a tad. I think I wrote earlier that I got decent focus if I stopped down a couple of stops; what I should have said was it was OK if I stopped down a couple of notches. Sorry, my inexperience shining through again. Maybe I'm expecting too much from a kit lens at the long end with a shallow depth of field.
Thanks for everyone's advice and comments. It's great to be able to bounce ideas off people with far more experience. This website rock!

[chris-p]

I don't think you're expecting too much from a cheaper lens. It's not that cheap and it should work. It seems like a lot just to look at it.

Also, if it's a couple of clicks rather than a couple of stops then it's not so bad - it's probably only 2/3 of a stop (assuming your camera is adjusting in 1/3 of a stop).

[wadooz]

That's why I'm not going to push any further, it's not two full stops so I'm not losing much really. I agree it's not that cheap but the error must be quite small if it can be negated with just a minor loss of aperture. They may even say it's within acceptable tolerances and charge me $100 dollars for the investigation. I'll just keep using it until I've made a final decision on the upgrade.
Speaking of which..... I've been reading up on various online forums about the Tamron 70-300 and a few people have had focusing issues with that too. If I buy it from US, Canada, or Hong Kong it'll save me $200-$300 but what will the warranty be worth? Tamron Australia are offering an introductory 5 year warranty on the Tamron 18-270mm F/3.5-6.3 Di II VC PZD but it'll cost me a fair bit more. Our local stockist is selling 'em at $700 as opposed to $500 for a Tamron 70-300 from overseas.
Gee life's complicated eh!

[chris-p]

I think you have to be a little cautious of internet comments - people are only likely to go and say something about a lens (or anything, really) if it's negative.
Look through this forum and find how many threads are started with "I got this, it's great" and compare that to the number of "is this broken" or "this is rubbish" threads there are... Just take everything with a pinch of salt.

My other half has the Tamron 70-300mm VC on an EOS 60D and it's never put a foot wrong. Now add the pinch of salt. It might. Who knows? It hasn't yet and shows no signs of it either. But these things, especially cheaper lenses like these, are produced on production lines within a tolerance range - some will be better than others.

As for warranties - most lenses have international ones, not region or continent specific ones like camera bodies have. In theory, at least, a US sourced lens should be just as "warrantied" as a locally sourced one. I don't know what the import regulations are like in Australia, so they would be worth checking. If you're likely to get stung for a load of import duty that negates the sale price savings, it's not worth it. However, a couple of hundred dollars different could easily be worth it.
My advice would be to check if you're likely to get extra charges and buy from a reputable dealer, someone like B&H in the US are a good starting point. Check their T&C for international shipping and you should be fine.

[wadooz]

Thanks again Chris, I know what you mean about people only bothering to write if there's a problem. I'll bear that in mind. If my daughter manages to find a Tamron 70-300mm VC while in US I'll get her to ask about international warrantys before committing to buy.
Cheers.

[rbarry]

Hi Wadooz,

Front and back focus issues can vary by degree. Your lens may be within the manufacturers tolerances as may be your camera body. If your camera body is erring on a slight back focus issue and you purchase a lens that has the same discrepancy, then the problem is doubled. If you purchased a lens that had a slight front focus issue, but within tolerance, then your camera body and lens would be a good match. This is why the facility to fine tune a body to a lens in later more expensive models has been developed. I suspect this facility will filter down to lower end camera body models soon, as complaints about front/back focus issues cannot be doing the camera body and lens manufacturers any good.

Obviously there are many instances where front/back focus problems are beyond tolerances and should be returned for correction. Have you tried the same tests on other lenses you own? You could find a new purchase may improve or exacerbate the problem!

This is just my opinion from reading material here and elsewhere and talking with people.

All the best,

Rick.

[donoreo]

Originally Posted by wadooz

Thanks again Chris, I know what you mean about people only bothering to write if there's a problem. I'll bear that in mind. If my daughter manages to find a Tamron 70-300mm VC while in US I'll get her to ask about international warrantys before committing to buy.
Cheers.

I think you would be better to ask at home about the international warranty. If she is buying from a store in the US, they may not actually know that answer. Without sounding like I am bashing Americans but they do tend to be rather "self-focused" and so they may never have bothered to check on international warranties. However, you did not say where she was in the US, so that could make a difference. If she was in New York and visited the awesome B&H SuperStore then they would know. Someplace like Las Vegas stores would probably know as well.

[wadooz]

Originally Posted by rbarry

Hi Wadooz,

Front and back focus issues can vary by degree. Your lens may be within the manufacturers tolerances as may be your camera body. If your camera body is erring on a slight back focus issue and you purchase a lens that has the same discrepancy, then the problem is doubled. If you purchased a lens that had a slight front focus issue, but within tolerance, then your camera body and lens would be a good match.


Rick.

Hi Rick, now there's something I hadn't considered. I've just done the focus test again and my 18-55 kit lens seems pretty accurate but as you say it may have the reverse error and cancel any possible camera error out. Pity my daughter is away or I could borrow her two kit lenses to compare. I'll have to wait until Monday to ask a mate from work to borrow his.

Does anybody know what's involved in recalibrating kit lenses. I'm a maintenance fitter and always find it hard to resist stripping things down to see how they work. It's a big gamble though with no drawings to work from. Mr. Google might help.