Tamron 17-50mm f/2.8

mdw wrote in post #6153239
THANK GOD!!

Nah, no kiddin', I have read that this lens can produce some vignette on some occasions. Any experiences?

i have only had it for about 6 hours, and ive taken 60 or so pictures, and havent seen a bit. i have researched it for a few months and the only cases of vignette i saw were from a full-frame camera. i can sing nothing but praises about this lens, it is extremely sharp. way sharper than i even anticipated. and the constant 2.8 aperture makes it comparable to the canon 17-55 IS lens. best $400 i ever spent!!

Can someone explain me how the constant 2.8 aperture works? I know its good but don't really understand how it works...:o

[QUOTE=mdw;6153000]I don't get this, what do you mean?!


Regarding my statement that the Tamron 17-50 takes extra TLC to achieve its potential and exceed the performance of the 18-55 IS Kit lens, perhaps you never tired a really hot pair of racing skis and found out how much more effort they took than shorties.

What I noticed is that the programmed exposure mode on the Xsi tends to be optimized for the kit lens. With it any dumb bunny will do OK. The P mode coupled with auto ISO tends to result in lower shutter speeds in low light than would be optimum. Also the wide aperture has less DOF, so more attention to focusing is necessary.

None of this is earthshaking, and its really photography 101, IMO. Most who participate in this forum do not use the P mode (or worse yet the dreded green box) anyway, and many use the central focus sensor and reframe. I think I just got lazy with the kit lens.

My advice is if you are really lazy, or completely new to photography, keep your kit lens until you get the hang of things. For the rest of us, the 17-50 is a nice upgrade.

mdw wrote in post #6153386
Can someone explain me how the constant 2.8 aperture works? I know its good but don't really understand how it works...:o

a lens in the lower budget or i.e. kit lens have a maximum aperture varying depending at what end of the focal length you are at
for exemple, my 17-85mm has a max aperture of f/4 at 17mm but max aperture of f/5.6 at 85mm
instead, the Tamron 17-50 here, has a wider aperture of f/2.8 and the max aperture at all focal length is f/2.8
hope it answer your question...

leadweight wrote in post #6154163
...
What I noticed is that the programmed exposure mode on the Xsi tends to be optimized for the kit lens. With it any dumb bunny will do OK. The P mode coupled with auto ISO tends to result in lower shutter speeds in low light than would be optimum. Also the wide aperture has less DOF, so more attention to focusing is necessary.

None of this is earthshaking, and its really photography 101, IMO. Most who participate in this forum do not use the P mode (or worse yet the dreded green box) anyway, and many use the central focus sensor and reframe. I think I just got lazy with the kit lens.
...

Thanks! Now I get what you meant! To a certain extend I think you will experience this stuff with every new lens you'll buy. The Canon 100mm f/2.8 I bought 'forces' you to take pictures differently than before as well. One the one side because it has more capabilities that way, on the other just because it is necessary!

Fortunately, most of the time I'm shooting manual. Depending on the lens and subject I also focus manually. So, I'm not too worried about your comment any more! It's good to read these experiences and findings from others with the same lens!

Daniel2000 wrote in post #6154252
hope it answer your question...

Yes and no...
What I meant was how it works internally. What makes the lens to have a f/2.8 over the whole range? Quality of the glass, different size, more glass etc....

now there you got me, I think it's definitely the way it's built over the quality (Of course they normally have good glass in that kind of lenses)
I would guess its where they placed the diaphragm in the lens that make it to keep the same aperture
but hey, I never opened a lens to check
and we are going off subject

My guess is it has to do with the size of the glass, especially the rear element.

I got mine today and all I can say is WOW! What a great lens!!!!

So to everyone debating between this and the Sigma 24-60mm f/2.8, I did a comparison test here. Fairly thorough with lots of images and video/audio...

https://photography-on-the.net …php?p=6157506#p​ost6157506

This lens has to be the best value for money. The colors, sharpness, build, hood are superb. Makes a great walk around lens. If I have to crib on something, then it has to be the not-so-good bokeh rendition. Pretty harsh I should say. Or maybe, the 85 1.8 has upped the expectations. But yeah, for $400 it is already too much value

Well I got this lens and mine is nice and sharp and spot-on focus. It pretty weird going from 28mm to 17mm on a crop body. 17mm seems so wide!

Anyways, I have a couple samples below wide-open at 50mm untouched 100% crops. I will have a good test tomorrow at a neighbor's kids birthday party.

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Yeah- I was super impressed by this lens.

However, I say the Sigma 24-60mm f/2.8 is still a better bang for the buck. (If you can deal with a 24mm on the wide end....) I will be keeping them both and using the 17-50 for the 17-30mm range, and the 24-60mm for the 30-60...

Here are a couple starscapes I did with this lens.

#1: ISO3200, 30s, f2.8, 17mm

#2: ISO3200, 20s, f2.8, 17mm

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Wow, is it true our sky has so many stars if it isn't blocked by the atmosphere (and pollution)?

Great pics btw.

Got an aerial shot the other day:

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Great sky shots! This is why I like being in the country. Amazes city people when they find out how many stars you can actually see!