EF lens on crop body. Am I thinking odd?

ok, now that I understand that the assumption may hold good. The second part.
Will it hold good for Tamron lenses. Canon classifies EF and EFs and hence all the marketing and explanation on larger surface, vignetting etc but Tamron has a no such category. Do they make lenses focused on FF? Is the 28-75 made for FF or did they ever market 28-75 as FF lens?

Pupu wrote in post #14545744
ok, now that I understand that the assumption may hold good. The second part.
Will it hold good for Tamron lenses. Canon classifies EF and EFs and hence all the marketing and explanation on larger surface, vignetting etc but Tamron has a no such category.

Yes, they do. If you go to their website you will see that they have:

• Di lenses. Lenses for full-sized digital, APS-C digital, and film cameras. These lenses are designed to work with image sensors that are the same size as 35mm film (36mm x 24mm), and they are easily used on smaller APS-C cameras as well. These lenses offer plenty of performance and versatility for any photographer with different cameras.
  
• Di II lenses. These lenses are compact, light and designed specifically for the most common digital SLR cameras - cameras with APS-C size (approx. 23.3 x 15.5mm) image sensors.

krb wrote in post #14545784
Yes, they do. If you go to their website you will see that they have:

• Di lenses. Lenses for full-sized digital, APS-C digital, and film cameras.
  
• Di II lenses. These lenses are compact, light and designed specifically for the most common digital SLR cameras - cameras with APS-C size (approx. 23.3 x 15.5mm) image sensors.

Di == EF. Di II == EF-S.

Oh Yes I completely missed that. Thank you for correcting me!

So now the choice seems fairly easy. 28-75mm it is Additional 40mm coverage will help a lot.

Thank you guys. I really appreciate your help!

Pupu wrote in post #14545645
hold on guys. What focal length I need is a different issue. I do understand the limitations of 28mm instead of 17mm on a crop body. But my question is purely focused on sharp image (rather image with greater sharp area) as a result of using a EF focused lens (not sure if Tamron makes its lenses keeping FF/Crop in mind). If canon EF and EFs is to be compared for that matter.

again > "Is it a fair assumption that the combination would deliver 'bigger sharper area' (for lack of word) as compared to EFs lens?"

In theory, yes. In practice, not necessarily (unless you compare the same lens), because lenses have their own characteristics, thus a lens designed for crop may be sharp throughout the frame whereas a lens for FF may have weak edges. Its best to just look for reviews of the specific lenses you're interested in and see for yourself rather than attempt to make generalisations.

And yes, you can compare EF and EF-S, for example the canon 55-250 vs 70-300 or 17-40 vs 17-55.

One thing to keep in mind, kind of as an aside, is that many lenses designed for crop sensors, *other than Canon EF-S lenses* will still fit and work on full frame cameras, just with some (or more than "some" in some cases) vignetting. For example, my Tokina 11-16, while designed for crops, will not vignette on my 35mm film body until I get to about 14mm or below, so I have a usable UWA if needed (16mm on a ff is really wide!).

If you're going to be cropping the edges any way, that may get you through in a pinch.

Sirrith & Archer Thanks a lot. All these really help a newbie (like me) to learn. Appreciate it!

Pupu wrote in post #14545838
So now the choice seems fairly easy. 28-75mm it is Additional 40mm coverage will help a lot.

Hold on, where are you getting an additional 40mm from?

And if this is your first lens, I'll give my 2 cents: 28mm is not wide enough for most people on crop as a general purpose/single lens solution.

Pupu wrote in post #14545645
again > "Is it a fair assumption that the combination would deliver 'bigger sharper area' (for lack of word) as compared to EFs lens?"

Not necessarily. There are some truly great EF-S lenses which can challenge any "L" lens for image quality. The 17-55 f2.8 is one of those. 10-22 f3.5-f4.5 is another which is highly respected. The 60mm macro is one of Canon's sharpest lenses - great macro, but excellent for any short telephoto subject - it shines for portraiture.

Pupu wrote in post #14544472
Any particular reason you say this?

ceegee wrote in post #14544545
Can I ask why you say this?

Sure, I've tried both. The 17-50 was sharper and had less CA. Not saying the 28-75 is a bad lens just pointing out that buying a lens designed for FF and expecting it to be better then one designed for a crop just because the lens is a "FF lens" is not always true.

Pupu wrote in post #14545645
hold on guys. What focal length I need is a different issue

focal length should be your main deciding issue...not some factor that you ignore...honestly i doubt you'd be able to notice much of a difference between the two lenses...so go with which one works for you best...most crop users would go for the 17-50mm...

Sirrith: 17-50 f2.8 on crop ~ 27.2-80mm on crop, FF equivalent
28-75 f2.8 on crop ~ 44.8-120mm on crop, FF equivalent.
So long end difference is additional 40mm (compromised on wide view), when compared to 17-50 f2.8, unless I'm gooing wrong.

I rarely shoot wide. When I feel the need, I will get 11-16mm. What I'm about to purchase will be my first lens, of the 3 lens package. Other lenses I'm looking are 70-200 f2.8/f4 or 70-300 VC and a really wide lens. So as you can see, I'm trying to build a specific package.

EF-S 17-50 f2.8 USM is 2.5 times the price of tamron /sigma version and only $100 less than the EF version. In short it better be good in quality (Prices as applicable in India). I have not used any of these lenses so clearly I cannot comment on the subjective preferences of these, but objectively do they justify.

Hey anyone of you have pictures of 17-50mm and 28-75mm tried on 400D / 450D / 500D /550D, preferably on same subject? Is there any website when I can see this test?

Pupu wrote in post #14549125
Sirrith: 17-50 f2.8 on crop ~ 27.2-80mm on crop, FF equivalent
28-75 f2.8 on crop ~ 44.8-120mm on crop, FF equivalent.
So long end difference is additional 40mm (compromised on wide view), when compared to 17-50 f2.8, unless I'm gooing wrong.

You're going wrong. The 17-50 is 17-50 and the 28-75 is 28-75. There's a 25mm difference only. Focal length doesn't change with sensor size, only effective FOV.

You say this is your first lens, but you rarely shoot wide? What are you basing your usage on? What subjects do you normally shoot?

Sirrith, I think the issue is with the confusion of the 1.6 crop. Most here will say a 100mm gives you the focal length equal to a 160mm lens and so on. To be honest this confuses me as well. I obviously know that a 100mm lens will still be a 100mm lens no matter what camera you put it on. However, knowing that I will not capture as much "picture" as a FF, I have to be further away to get the same shot.

mikeinctown wrote in post #14549293
Sirrith, I think the issue is with the confusion of the 1.6 crop. Most here will say a 100mm gives you the focal length equal to a 160mm lens and so on. To be honest this confuses me as well. I obviously know that a 100mm lens will still be a 100mm lens no matter what camera you put it on. However, knowing that I will not capture as much "picture" as a FF, I have to be further away to get the same shot.

Why do you need to know what picture you'll capture on FF? Do you use both FF and crop? If not, then forget about crop factor, just know what FOV your lens will give you on your camera, no need to confuse yourself with the FOV it will give on another camera which you aren't using because that is just irrelevant.

ill pull this back on track for you..

i too have a 550d


- Canon 50mm f1.8
I bought this... well put on my xmas list and wife got it for me.. i love it.. feels light and cheap.. plastic..but hey 1.8..
I may or may not go to the 1.4 version... but for now i dont hesitate to use this guy....

- Tamron 17-50 f2.8
I borrowed this from my neighbor.. I did not like one thing about it.. i used it for indoor pics, outdoor hockey both in low light... and it was noisy.. noisy as in loud... in addition it was hunting in low light..
i was going to get one of these but after using his.. i just cant do it..

- Tamron 28-75 f2.8 or Sigma version for 550D.
i have not used this so sorry i cant help there...