Are Tamron ripping us off?

I bought the Tamron 28-300 VC thinking it would make a good general travel lens for out and about. But on testing I found this...

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No explination but it does raise some questions.

With any zoom that covers a long range, the 300mm they advertise will only be for subjects that are slightly further away. I've seen many people ask the same question about this lens.

There is allot of monkey busines going on with various makers. The Sigma 50-500 is more like 50-460

Maybe they are claiming 300mm with a crop body!?!?!? 188 x 1.6= 300.8mm??.? (I know that sounds stupid but? )

Who knows....Everyones out to cut corners it seems...

Neilyb: Try shooting a DISTANT object and you'll see you are not losing the zoom ability. Hyperzoom lenses never reach the end of the telephoto range at close distances (~ < 10 metres or so).

thw wrote in post #4870088
Neilyb: Try shooting a DISTANT object and you'll see you are not losing the zoom ability. Hyperzoom lenses never reach the end of the telephoto range at close distances (~ < 10 metres or so).

But comparing the two shots above, something is crazy there!

thw wrote in post #4870088
Neilyb: Try shooting a DISTANT object and you'll see you are not losing the zoom ability. Hyperzoom lenses never reach the end of the telephoto range at close distances (~ < 10 metres or so).

I don't entirely follow, focal length is focal length, unless you mean that the barrel extends enough as you focus towards infinity that the difference between minimum focusing distance and infinity is 50 odd millimetres.

That could be your explanation.

There's always a bit of fudging, especially at the long end of super zooms.

There's even differences at the wide end of wide-angle lenses, and with aperture too.

The Tamron 17-50's 17mm is pretty close to 17mm (17.36) with a real aperture range of f/2.74 - 2.93. The canon 17-55 is closer to 18mm than 17mm (17.69 or so) with a real aperture of 2.92-2.93. And the Sigma 18-50 is at 18.8, with a real aperture of f/2.99-3.03.

I'm not defending Tamron in any regard, but 17mm on the Tamron 17-50 is wider than the Canon 17-55.

Does that mean Canon's jipping us?

I think it's just like shoe sizes that vary from one manufacturer to another.

That being said the 50mm end of Tamron is shorter than the nifty.

Perhaps Tamron is wider overall.

Edit: Drat! Jman13 beat me to it.

Well since the 28-300 is on its way back i can't test it again I just thought that 2 lenses of 300mm at the same place taking the same shot should be closer than that.

Sorta of like how big is a 2X4? Not 2" by 4". MM/aperaturers of lenses are nominal I believe. Some brands are more accurate in their descriptions than others. Besides, how many people do you think ever notice the difference?

There may be a focus contribution.

Maybe focusing close also reduces the focal length due to some funky interaction of the internal lens elements?

??

The Canon 70-300mm DO lens isn't "quite" 300mm either.

What's the EXIF info say for focal length? I've heard this happening on other lenses and there was an explanation that offhand I don't recall. What thw said about near and distant objects sort rings a bell in my memory.