Opinions of the Tamron SP 28-70 2.8 XR Di?

I bought it mainly as a studio lens for my 20D and I love it. Tack sharp to about f/4 and pretty decent even at f/2.8. I own about a dozen primes and it's the first zoom I've even used that I thought could hold its own in a case full of primes.

I have heard that at that price Tamron can't afford great QC so they have huge sample-to-sample variation and more than a few lemons. My suggestion is to buy it from a place with a good return policy, take it home and test it VERY thoroughly, and if it's not great, return it.

\you don't get great QC,

> I have heard that at that price Tamron can't afford great QC...

That is one of the great myths about quality. Quality programs SAVE money, they don't cost money.

Why do you think a $14k Toyota is more reliable (or repeatable, if you prefer) than a $70k Mercedes?

QC only saves money if you have to repair or replace the item.

If all items work, but some work slightly better than others and most users can't tell the difference anyway, QC cost money.

It's only an assumption based on anecdotal "evidence" that QC is lax anyway. I'm not inclined to believe much of what I read about problems with lenses and cameras since very often it's user error and inexperience rather than an actual equipment problem.

> QC only saves money if you have to repair or replace the item.

No. QC eliminates non-value-added tasks like inspection, testing, scrap, and rework. The cost of manufacture goes down, and the cost of warrantee repair/replacement goes down as well. You get better products and lower cost. The literature is clear on this point.

In 1994 I walked into a VW dealer to look over the lineup. They had just started to recover from a horrible sales slump in the US, and were touting their new and improved lineup. I asked the salesman "so, what makes these new models more reliable than the older ones?" He replied "We've added 100 'quality inspection points' as the car is made so we make sure it's good." I walked out and never went back. Inspections don't add quality to an item, they add cost.

VW didn't get it, and from what I read most of the German automakers still don't get it. The Japanese took Deming's message to heart and enjoyed 40 years of worldwide manufacturing dominance.

> It's only an assumption based on anecdotal "evidence" that QC is lax anyway.

On that we agree.

If we want a seminar by the W. Edwards Deming Institute we can invite them to do a webinar here on Photo.net.

The bottom line is that reports of bad samples and the need to return the lens are far more common with the Tamron 28-75 than they are with, say, the Canon 24-70, which is a common alternative. For whatever reason, the Tamron lens has developed a rep for inconsistent quality. This despite the fact that the Canon lens is a much more expensive lens, often bought by more serious or demanding photographers, so we might expect them to be less tolerant of poor performance.

As I said, I love my Tamron, but I would never buy one anyplace where it couldn't be quickly and easily returned for exchange.

> The bottom line is that reports of bad samples...

Actually, that's not the bottom line. "Anecdotal evidence" is a contradiction in terms. Anecdotes are nothing more than stories, usually tainted with personal bias and hidden agendas. I'm not saying *you* have an agenda, but you can't draw sweeping conclusions like that without using statistical data. Statistics provide the bottom line.

Do the photo community a service and find data to back up your assertion that this Tamron lens suffers from high sample variation. Until then, people like Denis are well advised to ignore hearsay.

Until then, people like Denis are well advised to ignore hearsay.

EVERYTHING on these forums is hearsay!

There aren't any statistics on ANY of the things we discuss! Purple fringing? Which fine-art inkjet papers flake the most? Third-party ink clogs? Long-term reliability of D70' -vs- D2X's? Number of coasters for different brands of DVD-R's or CD-RW's? Capacitor life on studio strobes? How many trips through the x-ray machine you can take with your film? Even the relative sharpness of different lenses is hearsay because right now there is NO PLACE that does comprehensive, detailed lens testing of a wide selection of current lenses in a statistically-meaningful way (i.e., where they test more than a single sample)

Go ahead - just TRY to compute some statistics on how many topics we discuss here that aren't hearsay. If you don't like hearsay, you shouldn't be in a photography discussion forum

So far I'm the ONLY person who's even answered this guy's question.

If I were you, Denis, I would not ignore Peter's advice. I purchased a Tamron 28-75 and found it to be blurry at large apertures and in the 50mm zoom range. I exchanged it, and my second copy is quite good. Therefore, I too recommend that you buy the Tamron where you will be able to exchange it if needed. I would not bother spending too much time trying to decipher whether my experience constitutes anecdotal evidence, hearsay (I'm not in court, so it must be), statistical evidence, biased rantings of an agenda-driven neophyte, or what have you.

Put yourself in Tamron's shoes for a moment. How would you like it if you worked hard, put out a quality product, received good reviews, and then had people bad-mouth it in public based on nothing more than gossip?

*If* it's true that Tamron has a higher return rate than the Canon offering, there's any number of possible explanations other than lower quality. Maybe Tamron simply sells more lenses, and for equal quality would have more returns due to higher sales volume. Maybe cost-conscious buyers examine their purchases *more* than someone who simply buys brand name items--and there are plenty of brand bigots who buy only Canon for that reason. Sweeping generalizations aren't helpful.

It's true, you're the only one who commented on the lens itself, but then you followed it up with an unproven dig at Tamron's QC. Let products stand on their merits, and keep rumour out of it.