Tamron 17-50 or Sigma 17-70 ???

[skuliaxe]

I just can't make up my mind between these two lenses.
I'm looking for a walkround lens for my Canon XTi. (won't be switcging lenses).

The Tamron 17-50 is getting better scores in the Photozone review, and is said to be sharper (plus has f/2.8 all the way).
Tamron review (http://www.photozone.de/8Reviews/lenses/tamron_1750_28/index.htm)
Sigma review (http://www.photozone.de/8Reviews/lenses/sigma_1770_2845/index.htm)

Then again, the Sigma has a wider zoom range, better build and comparing the sharpness of the two lenses in this comparison test (http://www.pbase.com/alexis/compare) I would say that the Sigma is noticably sharper!

Price of the two is similar (Sigma a little cheaper).
What's your opinion?

[The_Camera_Poser]

There was an identical thread to yours a few weeks ago- try searching for "17-70 17-50"

:-)

[Samgoit]

here you go:
http://photography-on-the.net/forum/showthread.php?t=297224&highlight=sigma+tamron

[skuliaxe]

here you go:
http://photography-on-the.net/forum/showthread.php?t=297224&highlight=sigma+tamron

Yeah, I had already read that thread but there is no conclusion. It's more or less 50/50.

Guess I can't go wrong with either ;)
Main thing that is bugging me is that people say that the Tamron is sharper (and it scores higher in reviews) but judging from these comparison photos (http://www.pbase.com/alexis/compare) and other photos (http://photography-on-the.net/forum/showthread.php?t=186589) the Sigma seems sharper to me and takes beautiful images.

I'm somewhat leaning towards the Sigma again... :rolleyes: (this back and forth won't stopp till I just flipp a coin I guess).

[Jman13]

Both are excellent. Go with the Sigma if you need extra range, and don't care about variable aperture. Go with the Tamron if you want constant f/2.8. I definitely wanted a fast zoom, so I went for the Tamron and haven't been disappointed.

[sebr]

I got the Tamron 17-50 a couple of days ago. So far I am happy with it, but I need to use it some more to really find out how happy I am :D

I chose the Tamron over other lenses in similar focal ranges because:
- it has a constant f/2.8 aperture;
- I asked POTN and everybody is just so positive about it (http://photography-on-the.net/forum/showthread.php?t=306192);
- It got very good reviews (see for instance www.the-digital-picture.com (http://www.the-digital-picture.com))
- it is rather inexpensive.

Sebastien

[DerekI]

Yeah, I had already read that thread but there is no conclusion. It's more or less 50/50.

Guess I can't go wrong with either ;)
Main thing that is bugging me is that people say that the Tamron is sharper (and it scores higher in reviews) but judging from these comparison photos (http://www.pbase.com/alexis/compare) and other photos (http://photography-on-the.net/forum/showthread.php?t=186589) the Sigma seems sharper to me and takes beautiful images.

I'm somewhat leaning towards the Sigma again... :rolleyes: (this back and forth won't stopp till I just flipp a coin I guess).

the Tamron is much sharper with better color reproduction and tonality.

the Sigma AF is not so good , I tried it for a couple days but returned it and bought the Tamron 17-50 and Canon 17-85IS both are good lenses for my use , mostly in door , static stuff like art paints , flowers and statues.
so , I think the Tamron is much safer choice .........


That said ,an ultimate , general purpose lens for an EF-S mount body if you dont mind spending a grand for an EF-S lens is the Canon EF-S17-55IS .

This lens was amazing ,truly fast and accurate AF and incredibly effective IS with the best IQ ever seen but for me it is kind of ridiculous to pay a grand for an EF-S , I 'd rather have a couple of good lenses than a great lens ....

I personally like the 24-105L but it is not available right now(all sold out) here where I am at now..........

It is important that before making any serious decision to buy any lens , you should question yourself if you 'll ever buy a full frame. The answer here will help you decide what lens to choose really........ I wont buy any more EF-S and DC or DI2 lenses..... Maybe for your a wide angle ,general walk-around lens , you should also consider the 17-40L , which can be mounted on a FF and not so badly vignetting though, it is expensive (still cheaper than the 17-55IS) and super heavy(this weight is more of serious problem for me).

But this 17-40L is so cool that the lens does not extend itself at all and it looks nice and durable ..........

Any way , good luck to you , I dont think you 'll dislike this Tamron any way unless you get a bad bad copy (do not worry about getting a bad copy cause it is already in production line for about 8 months in the US , this means the QC now is quite good or of very high standard).

Mine focuses perfectly fine.
:rolleyes:

[Pasukun]

I will take 17-50 anyday. Just because it has a constant aperture.
A variable aperture is a pain in the butt in the manual mode (which is my favorite).. because you got one more thing to worry about to get a proper exposure. And in my humble opinion.. photography is already tough enough as it is.
With constant aperture, I am more certain about the exposure and ready to shoot at any moment as I zoom in and out.

[The_Camera_Poser]

I have been having this same debate myself- and I've decided (more or less) to go with the Tamron, for a couple of reasons:

1) I want a macro lens, but what I've seen the Sigma do in macro isn't really all that great, and I'd be better getting an extension tube or holding out for a 100 F/2.8

2) Because my main walk-around lens is a Canon 24-105L F/4, I'd like something to take wider angle pics at lower light than the 24-105L on my second body. Whilst both lenses do wider, the Sigma has a variable aperature which can be lower at wide angle than the 24-105L, but the IQ is pretty poor, and the Tamron is fixed at F/2.8 and has very good IQ at those focal lengths, wide open or otherwise

3) When you see these two lenses discussed, the Sigma is inevitably discussed as a rpelacement kit lens, or compared to other consumer grade lenses such as the Canon 17-85 IS, whereas the Tamron would appear to be being compared, occassionally favourably, with professional lenses such as the 17-40L and the 16-35L. To me this means Tamron has produced a professional grade lens, whereas the Sigma is a very good consumer grade lens.

Something I'm coming ot realize though is that as long as you stay away from the non-APO Sigma 70-300 (I HATE that bloody lens LOL) then you can get awesome pics with any lens. I guess the end question should boil down to:

1) Can I afford the Tamron?
2) Do I need/want Macro, and if I do am I able to buy a real macro lens or a set of tubes in the near future?
3) Do I want exceptional IQ or versatility?

Hope this helps!

[Nick_C]

Take a look here:

http://www.pbase.com/lightrules/image/77501288/original

Ive tried Tamron before but they never quite have the build quality, I dont know what it is but they are plastic fantastic, where as even the cheapest Sigma has a similar EX finish to it.

I wouldnt put much score to what others compare it to, yes they compare a Sigma 17-70 to a kit lens but I have no idea why as its leagues better than a kit lens.

Tamron 17-50 Pro's = constant aperture, / Cons = only 50mm, worse macro 1:4

Sigma 17-70 Pro's = Better range, much better macro, quieter & slightly faster AF / Cons = not constant aperture

I didnt mention poorer IQ as from the shots ive seen there isnt anything in it between the 2 lenses, they are both on par with each other.

I guess that makes me sound biased towards Sigma, but then I guess its personal preference, on my recent test of 55-200's the Tamron didnt score too highly against the Sigma, the 17-50 is in another price range & is better but I personally wouldnt want to lose the 70mm end & more important to me is the macro, I love to be able to focus as close as touching the subject on the front UV IF I need to get that close, ive had some great results from the macro of this lens, I even compared the results to a 50mm F2.8 EX Macro lens, the IQ was the same at 1:2.


Nick :-)

[purelithium]

They are very close in my books, BUT if I had to make my decision again, I would go for the Tamron. Simply because I could use a faster lens more than longer reach.

[Nick_C]

They are very close in my books, BUT if I had to make my decision again, I would go for the Tamron. Simply because I could use a faster lens more than longer reach.

I see you have the 50mm F1.8, I would use your 17-70 for general stuff, when the light is going I use my 17-70 @ 17mm F2.8 ISO1600 with good results, but being as you have the 50mm F1.8 you could use that at 50mm F2.8 & get better results than the Tamron, although it does require a lens change.

I thought about this the other day, what if I could do it over again, would I buy anything different, but you know what I couldnt think of anything more versatile.

The Tamron 17-50 is nice & all but there is something about it that isnt pushing all the right buttons with me.

I think my ideal isnt the 17-50 or the 17-70, it would be the 18-200OS, but & its a bit BUT!!! only if it had the same image clarity of the 17-50 or 17-70 which I doubt that very much.

Nick :-)

[purelithium]

The constant/fast aperture doesn't really have anything to do with low-light situations. But I would like a constant aperture so I don't have to adjust my exposure when I change my FL. I also would maybe like using multiple FL's in a low-light situation... I don't know, maybe I'm crazy haha!

[Nick_C]

The constant/fast aperture doesn't really have anything to do with low-light situations. But I would like a constant aperture so I don't have to adjust my exposure when I change my FL. I also would maybe like using multiple FL's in a low-light situation... I don't know, maybe I'm crazy haha!

Ah ok, I thought you meant you would have liked the constant aperture because of low light, IE/ 50mm F2.8 isntead of the 17-70's F4.0 I think it is.

I can see the benefits of a constant aperture but if I was going to upgrade from my 17-70 I would really want something more.

One day we will be able to get a decent quality 10-500mm F1.8 IS, but im not holding my breath for that yet ;)

One thing I have learnt by doing all these tests with my 17-70 & 55-200 is that its all well & good to do tests, otherwise you dont really KNOW your lens properly, its weak & good points, but I find when I forget all about the techy side of things & shoot with my 17-70 (& my new 55-200 cheapy) I get back to the computer & sure some shots could have been focussed better but most really give that "wow thats sharp" feeling, the poorly focussed ones is really down to AF accuracy which isnt stunning on either lens, if anything judging from the lightrules recent tests the Tamron is even worse at 17mm.

Nick :-)

[purelithium]

I can see the benefits of a constant aperture but if I was going to upgrade from my 17-70 I would really want something more.

I completely understand, I meant that If I had to make the choice again knowing what I know now, I would choose the Tamron. BUT I'll probably switch to a two-lens system when I "upgrade" the 17-70. I will probably get some variant of a 24-70 or 24-105 and get a dedicated UWA like the sigma 12-24 for those times I need the wide end.

That won't be for a while, as I'm very pleased with the performance of all my lenses right now, and am probably not going to be able to shoot quite as much as I'd like to in the coming year or so. Stupid work *laugh*

[LightRules]

the poorly focussed ones is really down to AF accuracy which isnt stunning on either lens, if anything judging from the lightrules recent tests the Tamron is even worse at 17mm

What I'm finding more and more is that the 17mm AF accuracy really depends on subject distance. I'm consistently getting a high rate of in-focus shots for closer subjects (e.g., 1-8 feet away), but once it starts going beyond that, my keeper-rate dips very quickly. Most distant shots are clearly front-focused. So a lot of it realizing where it's good and where it's not at this point, prior to any Tamron service calibration.

[liza]

I was going to purchase the 17-50 for the constant f/2.8 aperture, but saved my money a bit longer and purchased the 17-55 IS. I highly recommend it. :)

[Pasukun]

I was going to purchase the 17-50 for the constant f/2.8 aperture, but saved my money a bit longer and purchased the 17-55 IS. I highly recommend it. :)

Good call.
I am about to replace my Tammy 17-50 with 17-55 IS as well.
I have a 35L for a low light situation which works great, but @ f/1.4.. the DOF is too shallow and shallow DOF is not always prefered. Sometimes you need as much DOF as f/4+ and that is when 17-55 IS will truely shine.
For a shutter speed demending shots, I will use 35L (moving subject).
And for a deeper DOF demending shots, I will use 17-55 IS (museum for example).

[Marsellus_Wallace]

If there's any difference between the two in either sharpness or build quality, it's in the beholders' eye, and minimal anyway.

The sigma is not a real macro lens, it just focuses a little closer.

The sigma's advantages are price and convenience.
The tamron's advantage is clearly speed/aperture/shallow DOF.

If you have problems saving up for the tamron, get the sigma and never look back. It's great. If you want constant F/2.8, get the tamron.

BTW with constant F/2.8 your exposure of course still changes if you zoom from 17 to 50 mm or the other way round.

[purelithium]

BTW with constant F/2.8 your exposure of course still changes if you zoom from 17 to 50 mm or the other way round.

Not if you want the same subject properly exposed.

[timbop]

The point that hasn't been discussed is that the XTi has the extra sensitive cross sensor that is engaged when an f/2.8 lens is mounted. That sensor will only be active at the extreme wide angle of the 17-70, whereas it is active for the entire range of the tammy.

[Nick_C]

The sigma is not a real macro lens, it just focuses a little closer.



Your right it isnt a true macro in that it can do 1:1, but its not a feature that is in anyway just put on the lens as a marketing thing, I put it up against a true macro & set the macro lens to 1:2 the same as the Sigma, there wasnt much in it, the macro lens had slightly better border sharpness but nothing that would come across in a final print.

So I sent the macro lens back, I condider the macro side of the 17-70 to be every bit as good as a true macro lens, just that it cant do 1:1, but 1:2 is close enough unless you want to do bug shots, but then even 1:1 isnt good enough for that.

Its the most understated feature of the 17-70.

Nick :-)

[Nick_C]

The point that hasn't been discussed is that the XTi has the extra sensitive cross sensor that is engaged when an f/2.8 lens is mounted. That sensor will only be active at the extreme wide angle of the 17-70, whereas it is active for the entire range of the tammy.

I heard the extra cross is for lenses wider than F2.8, IE/ 30mm F1.4, going from my own tests & having it confirmed by the recent Lightrules tests on the Tamron I find that focus is better at the longer end of the lens anyway, its at 17mm with distant objects where it can not lock properly, it will lock on but its either front or back focussed or just plain OOF, the Tamron doesnt appear to have improved upon this problem either.

I find on long distant shots at 17mm its best to zoom in to focus, then back out & take the shot without refocussing, best to use * as focus.

Without it sounding nasty its made me happy to see the Tamron has the same problems as the 17-70, it shows that they are basically identical lenses with identical problems, its now just about features & what you want for your money, constant aperure? or longer focal length with 1:2 macro, your choice.

Nick :-)

[Nick_C]

I have been having this same debate myself- and I've decided (more or less) to go with the Tamron, for a couple of reasons:

3) When you see these two lenses discussed, the Sigma is inevitably discussed as a rpelacement kit lens, or compared to other consumer grade lenses such as the Canon 17-85 IS, whereas the Tamron would appear to be being compared, occassionally favourably, with professional lenses such as the 17-40L and the 16-35L. To me this means Tamron has produced a professional grade lens, whereas the Sigma is a very good consumer grade lens.

The Tamron has also won an award, the "Best Product - Consumer Lens"

http://www.popphoto.com/photonews/2850/tamron-sp-af17-50mm-lens-wins-eisa-award.html

Like I said, forget about what "they" compare them too, both lenses have their good & bad points, no one lens is perfect.



Nick ;-)

[DerekI]

Then , you should try the 18-50 EX macro .

Since this is an almost macro kind of lens , you may not need a dedicated macro lens separately, and so save alot ................

This one 's got the best part of the 17-70 nortably the close-up feature and the constant F2.8 of the 17-50, I do not like the old version of this non-macro 18-50EX but I think I 'll give it a try and if I like it , I will sell the Tamron with EF-S60 .......

As I beleive the fewer lens I have with me, the better or more active I can be to take better photos when I am out of my room , and I would like to save a bit of space , this Sigma seems to be a great lens for me... I love flowers and art museum shots.

According to most of reviews (they are written in Japanese unfortunately) , the Sigma EX macro is a superb lens with better center res than that of the Tamron and I will at least give it a try ...

As for the 17-70 , it is sharp at the widest end of it , but as you zoom in , it gradurally becomes softer and softer , it is the opposite characteristic to that of the EF-S17-85IS, which becomes sharper and sharper as you zoom in .
Also , it is important to mention the Sigma 17-70 has a bit grey cast and that makes color tonality of the lens unnatural.


Any way , my conclusion is the best walk around lens for an APS-C camera is not yet to be released and so I go with 2 lenses ,,,, the Tamron 17-50 and Canon 17-85IS but I may replace the Tammy with the New Sigma 1850EX macro ............. I also have some primes including broken Sigmas.

Well , there is always the super expensive Canon EF-S17-55IS but that is not a perfect lens either , according to many reviews and my own shooting experience with it for 2 days comparing it with my 17-85IS and 17-50 Tamron , I think it is more prone to flare and ghosting and more severely vignetting than my 17-85IS .
Although the 17-55IS is a bit shaper lens than my Canon 17-85IS ,I like the 17-85IS better with its (I think )more beautiful color and better close-up feature.

So I think having 2 general walk around lesnes and bring a one more suited for what you 'll do in at a time is better than having one most expensive EF-S lens. Plus, the 17-55IS is big and heavy and more importantly EF-S only and costs you a grand.

If I were to ever spend a grand for a lens , I would get a 17-40L or 24-105L...

To be honest , I really love my 17-85IS and that is the one I will use for most of my shots............Unless I need to shoot indoor actions , I do not need any other lens , this can do close-up at 85mm with 1:5, this can do landscaps , this can shoot in door museum arts or group shots.

I think most of time I've mounted this lens on my xti as I recall , and other times like travelling or shooting a dog runing around my house I reach for my old Sigma 18-200 or 70-300. I thought I'd get rid of them but I realized they are good for some travel shots so kept them , instead I will probably get rid of the EF-S60( ,which is probably the sharpest and nicest lens of mine but useless focal length for my needs )and 30mm EX (,which was a sharp lens but broken in 5 days or 6 days without abuse) if the sigma 18-50EX macro is as good as those Japanese review said or at least as good as my local dealor raves about it.

PS. , I will test this Sigma , maybe very unscientific ways . I would love to compare it with my Canon lenses (EF-S17-85IS , EF50mm F1.8 and EF 85mm F1.8 . If I can , I will rent some others too.

[tmonatr]

I can't speak for the Tamron, but I have the Sigma 17-70 and I don't know how the Tamron could be much sharper than the Sigma. It does have the constant aperature, but certainly couldn't be much, if any better on IQ. (at least my lens is that good)

[DerekI]

http://www.flickr.com/photos/sushanta/388126259/

This is the link to some samples of the Sigma 18-50EX macro new version.

[Dylanlewis2000]

I found the sigma very slow to focus when i tried it in a shop, maybe it was just my version but it put me off a bit

[DerekI]

http://www.flickr.com/photos/rowenaphotography/449246494/

http://www.flickr.com/photos/mattbrowne/458970524/http://www.flickr.com/photos/jpspider/467378597/

More smaples of the Sigma EX macro.

[DerekI]

I found the sigma very slow to focus when i tried it in a shop, maybe it was just my version but it put me off a bit

you are talking about the 17-70?

Yeah that one is annoyingly slow.

[purelithium]

you are talking about the 17-70?

Yeah that one is annoyingly slow.

???

I've found it on par or even slightly faster than any Canon micro-USM lenses I've tried. How is that slow?

[DerekI]

???

I've found it on par or even slightly faster than any Canon micro-USM lenses I've tried. How is that slow?

Shoot in a low light or moving people , you will see the difference and probably shocked the result.

I thought it was ok until I shot artistic paints at my students ' room(the room was so dark).

[purelithium]

Well I haven't noticed any problem tracking dogs running full sprint...

Also, yes It doesn't do well at focusing when there is either low contrast or low light, that's where an AF-assist beam helps, like the one from my 430EX, even if I don't use the flash. But the low-light/contrast focusing has nothing to do with speed.

I still stand by my previous comment.

Curious, how long did you use the lens for?

[DerekI]

Well I haven't noticed any problem tracking dogs running full sprint...

Also, yes It doesn't do well at focusing when there is either low contrast or low light, that's where an AF-assist beam helps, like the one from my 430EX, even if I don't use the flash. But the low-light/contrast focusing has nothing to do with speed.

I still stand by my previous comment.

Curious, how long did you use the lens for?

The Low Light contrast focsing has alot to do with the actual AF speed in real life cause those non-usm lenses tend to hunt a lot and so it is slower or seem slower.

But now I realize that the Tamron is not much better than the Sigma as I thought and mybe my test copy was a lemon...:oops:

Actually , the Sigma 10-20 and 18-50 EX macro are quite fast in term of low light focus but not sure in real life use , they are still as fast as they smeemed to be at a camera shop.

The camera shop was not so well lit either so , maybe they are good , hope so.

If the 18-50EX macro is as fast as it seemed at the shop , I will get it in heat beat since I love to have a fast, general pupose lens with close-up feature.

[Nick_C]

Then , you should try the 18-50 EX macro .

Since this is an almost macro kind of lens , you may not need a dedicated macro lens separately, and so save alot ................

This one 's got the best part of the 17-70 nortably the close-up feature and the constant F2.8 of the 17-50, I do not like the old version of this non-macro 18-50EX but I think I 'll give it a try and if I like it , I will sell the Tamron with EF-S60 .......

As I beleive the fewer lens I have with me, the better or more active I can be to take better photos when I am out of my room , and I would like to save a bit of space , this Sigma seems to be a great lens for me... I love flowers and art museum shots.

According to most of reviews (they are written in Japanese unfortunately) , the Sigma EX macro is a superb lens with better center res than that of the Tamron and I will at least give it a try ...

As for the 17-70 , it is sharp at the widest end of it , but as you zoom in , it gradurally becomes softer and softer , it is the opposite characteristic to that of the EF-S17-85IS, which becomes sharper and sharper as you zoom in .
Also , it is important to mention the Sigma 17-70 has a bit grey cast and that makes color tonality of the lens unnatural.


Any way , my conclusion is the best walk around lens for an APS-C camera is not yet to be released and so I go with 2 lenses ,,,, the Tamron 17-50 and Canon 17-85IS but I may replace the Tammy with the New Sigma 1850EX macro ............. I also have some primes including broken Sigmas.

Well , there is always the super expensive Canon EF-S17-55IS but that is not a perfect lens either , according to many reviews and my own shooting experience with it for 2 days comparing it with my 17-85IS and 17-50 Tamron , I think it is more prone to flare and ghosting and more severely vignetting than my 17-85IS .
Although the 17-55IS is a bit shaper lens than my Canon 17-85IS ,I like the 17-85IS better with its (I think )more beautiful color and better close-up feature.

So I think having 2 general walk around lesnes and bring a one more suited for what you 'll do in at a time is better than having one most expensive EF-S lens. Plus, the 17-55IS is big and heavy and more importantly EF-S only and costs you a grand.

If I were to ever spend a grand for a lens , I would get a 17-40L or 24-105L...

To be honest , I really love my 17-85IS and that is the one I will use for most of my shots............Unless I need to shoot indoor actions , I do not need any other lens , this can do close-up at 85mm with 1:5, this can do landscaps , this can shoot in door museum arts or group shots.

I think most of time I've mounted this lens on my xti as I recall , and other times like travelling or shooting a dog runing around my house I reach for my old Sigma 18-200 or 70-300. I thought I'd get rid of them but I realized they are good for some travel shots so kept them , instead I will probably get rid of the EF-S60( ,which is probably the sharpest and nicest lens of mine but useless focal length for my needs )and 30mm EX (,which was a sharp lens but broken in 5 days or 6 days without abuse) if the sigma 18-50EX macro is as good as those Japanese review said or at least as good as my local dealor raves about it.

PS. , I will test this Sigma , maybe very unscientific ways . I would love to compare it with my Canon lenses (EF-S17-85IS , EF50mm F1.8 and EF 85mm F1.8 . If I can , I will rent some others too.

The 18-50EX can only acheive 1:3 where as the 17-70 is 1:2, also this might come across as me defending my 17-70 which im not, if I had a problem I would say but ive never seen anything like what you describe, grey casts & getting softer at the long end, I shoot panos at 50mm & the sharpness is actually a little too sharp sometimes, I do all my macro work at 70mm & again the sharpness is really sharp.

I can only guess you must have had a poor copy as there are poor copies going around.

Nick :-)

[Nick_C]

Well I haven't noticed any problem tracking dogs running full sprint...

Also, yes It doesn't do well at focusing when there is either low contrast or low light, that's where an AF-assist beam helps, like the one from my 430EX, even if I don't use the flash. But the low-light/contrast focusing has nothing to do with speed.

I still stand by my previous comment.

Curious, how long did you use the lens for?

Same here, I find it quite fast, all the reviews online mention the fast speed as well, from what ive read on here its quite amusing, its like "are we talking about the same lens here, the 17-70?" as ive read grey casts, soft at the long end, poor AF speed, hunting, wow it sounds like a really poor lens if you read this, ive used my 17-70 in no light at all with my 500DG Super & using the assist beam I never had any hunting or anything, really locks on fast everytime, of course if you point at something like a solid white board you will get problems but thats the same with any lens.

Nick :-)

[webcrawlur]

Here's a link to the new 18-50 from Sigma.

http://www.bhphotovideo.com/bnh/controller/home?O=WishList.jsp&A=details&Q=&sku=463428&is=REG

[DerekI]

The 18-50EX can only acheive 1:3 where as the 17-70 is 1:2, also this might come across as me defending my 17-70 which im not, if I had a problem I would say but ive never seen anything like what you describe, grey casts & getting softer at the long end, I shoot panos at 50mm & the sharpness is actually a little too sharp sometimes, I do all my macro work at 70mm & again the sharpness is really sharp.

I can only guess you must have had a poor copy as there are poor copies going around.

Nick :-)

Ok , I will try it again in a few days , will re-rent the lens since it is free.

I hope your right , Nikc . thanks and hope my tried copy was a really bad copy like you siad.
Take care.


PS. the Sigma 18-50EX macro requires a 72mm filter, so I can not buy one ... I like to share a 67 mm filter for all my lenses , but I will try it at a shop and shoot some old cameras displyed there such as Leica M6 and Nikon FM2.

All the ebst for all .

[Marsellus_Wallace]

Not if you want the same subject properly exposed.

If you walk, so that your composition stays the same, your exposure stays the same.
If you zoom in or out and keep standing on the same spot, your exposure changes.

[purelithium]

If you walk, so that your composition stays the same, your exposure stays the same.
If you zoom in or out and keep standing on the same spot, your exposure changes.

Focal length has nothing do do with exposure. If you are zoomed in to 50mm and set your exposure for say someone's face. You keep the same aperture, shutter speed, and ISO. You then zoom out, to say 18 or so. Your exposure is correct for that person's face. Your exposure is correct for what you WANT properly exposed, providing the light level has stayed relatively the same..

If you're using evaluative metering, or center weighted metering, sure the light meter will say your exposure should change, but it doesn't have to.

The light meter is not the almighty. You are. The Light meter is easily tricked and will not always give you the exposure you want. You need to learn when to trust it and when not to trust it.

That is what I meant by my previous comment: "Not if you want the same subject properly exposed.

[bowlesbe]

Which of the two lenses has nicer bokeh?

[gef]

DerekI's experience with the Sigma 17-70 lens is nothing like mine! I find the auto focus fast and bang on most of the time. A grey cast? I find my a bit warm myself (if anything), and sometimes adjust my white balance in PP to compensate for it. I recently picked up my Canon 580EX and the assist beam is amazing for low light auto focus. If I knew how much this helps I would have picked up a external flash much sooner! For DOF I have my eye on a Sigma 30mm 1.4! I'm with Nick_C, it seems like a totally different lens than what I've experienced with mine...

[DerekI]

DerekI's experience with the Sigma 17-70 lens is nothing like mine! I find the auto focus fast and bang on most of the time. A grey cast? I find my a bit warm myself (if anything), and sometimes adjust my white balance in PP to compensate for it. I recently picked up my Canon 580EX and the assist beam is amazing for low light auto focus. If I knew how much this helps I would have picked up a external flash much sooner! For DOF I have my eye on a Sigma 30mm 1.4! I'm with Nick_C, it seems like a totally different lens than what I've experienced with mine...

As I siad , I tried another copyof the lens this morning at a local shop and asked to take it out with me but they did not allow me to do it this time .

But I noticed the new copy was quite good , and I guessed it was improved or the Sigma QC of this lens now is better because it 's been in the Sigma production line for more than 4 months in Asia.

Last time , I rented it was when it was just first out here .

So I think now like the Tamron , the Sigma QC of the lens is ok or good , maybe hard to get a lemon .

Best regards.

[gef]

Ok, last I read you were going to try a second copy out. Glad to hear the second time out was better....

[Nick_C]

Its always best to avoid buying things when they first come out, whether it be Sigma,Tamron or Canon im sure these companies use us as quality control, there really isnt any testing or quality control like there was in the old days, they have to shift too much stock out the door now.

Nick :-)