# Thread: Difference between 18-55mm and 17-50mm

1. ## Difference between 18-55mm and 17-50mm

Hi all,

I'm super new to DSLR, aiming to buy Canon 550D soon. As I know Kit I is with 18-55mm lens.
But having reading some posts in the forum, I noticed there are so many other kind of lens out there with different specs like, 17-50mm, etc.

So can I say that 17-50mm is able to shoot a wider angle at 17mm compare to 18mm. But cant zoom as far as 55mm. ?

Also, 18-55mm for example, 55mm is like equilvalent to how many times zoom as in a Compact Digital Camera?.

Thanks.
Iven

2. ## Re: Difference between 18-55mm and 17-50mm

Well, this is simple maths lol.

Smaller number = wider angle

Bigger number = larger magnification

For zoom, just take the biggest focal length divide by smallest, so for ur example it'll be 55 divided by 18 = 3x

However do note that dslr users don talk about focal length in zooms.

3. ## Re: Difference between 18-55mm and 17-50mm

for your question "18-55mm for example, 55mm is like equilvalent to how many times zoom as in a Compact Digital Camera?", 55/18 = 3x zoom
but you got it all wrong, 55mm is only the focal length, not times of zoom.

between 17mm and 18mm, i feel that the difference is very minute. but of course the IQ is better than 18-55mm. dont forget that 550d is a cropped body with factor of 1.6x, ie 17x1.6=27.2mm and 18x1.6=28.8mm

4. ## Re: Difference between 18-55mm and 17-50mm

The focal length differences are minute, but if the two lenses that you are comparing are the 18-55 f3.5-5.6 and the 17-50 f2.8, then the largest difference is the aperture at 50mm. That's f5.6 vs f2.8, a total of around 2 stops difference, thus performing far better in low-light situations.

Regards,
gibss.

5. ## Re: Difference between 18-55mm and 17-50mm

Originally Posted by Ivshootphoto
Hi all,

So can I say that 17-50mm is able to shoot a wider angle at 17mm compare to 18mm. But cant zoom as far as 55mm. ?

Also, 18-55mm for example, 55mm is like equilvalent to how many times zoom as in a Compact Digital Camera?.

Thanks.
Iven
To calculate zoom level, you simply divide the longer focal length by the shorter one. Thus it doesn't mean that a 18-55mm (3X) can reach further than say a 70-200mm (2.8X)

Anyways, 17-50 has constant aperture across its entire zoom range, compared to 18-55 which is variable. IQ is also much better as well.

6. ## Re: Difference between 18-55mm and 17-50mm

To shoot 1mm wider & 5mm longer is not much of a difference. The difference between the two lenses you mentioned is a kit lens & a third party lens.
For the kit lens, the widest aperture is f3.5 at the wide end & f5.6 at the far end if you zoom out. Whereas, the 17-50mm gives you a constant aperture of f2.8 throughout

7. ## Re: Difference between 18-55mm and 17-50mm

Welcome to CS

8. ## Re: Difference between 18-55mm and 17-50mm

hi all. i believe the price difference is like 'Heaven' and 'Hell' right?

9. ## Re: Difference between 18-55mm and 17-50mm

Originally Posted by gibss
The focal length differences are minute, but if the two lenses that you are comparing are the 18-55 f3.5-5.6 and the 17-50 f2.8, then the largest difference is the aperture at 50mm. That's f5.6 vs f2.8, a total of around 2 stops difference, thus performing far better in low-light situations.

Regards,
gibss.
TS, i think gibss explanation is the best, the 17-50 has an aperture of f2.8, therefore it works well in low light (with zoom), unlike the 18-55. 'Zoom'-wise, 17 to 50mm or 18 to 55mm is actually up to your preference though. Main reason ppl get the 17-50 is because of its low light capability. Thats my 2-newbie-cents worth, cheers!

PS. the 17-50 is also more ex than the 18-55

10. ## Re: Difference between 18-55mm and 17-50mm

Is there a Canon 17-50mm?

I only know there are EF-S17-55mm f/2.8 IS USM and EF17-40mm f/4L USM.

11. ## Re: Difference between 18-55mm and 17-50mm

Originally Posted by krazyman
Is there a Canon 17-50mm?

I only know there are EF-S17-55mm f/2.8 IS USM and EF17-40mm f/4L USM.
Errr i think we made an error,its 17-55mm, Nikkor has that lens also ;

12. ## Re: Difference between 18-55mm and 17-50mm

Originally Posted by krazyman
Is there a Canon 17-50mm?
I only know there are EF-S17-55mm f/2.8 IS USM and EF17-40mm f/4L USM.
Tamron 17-50 f/2.8 with Canon mount.

13. ## Re: Difference between 18-55mm and 17-50mm

Originally Posted by Octarine
Tamron 17-50 f/2.8 with Canon mount.
I'm using Canon 17-55mm IS USM..Excellent lens!

14. ## Re: Difference between 18-55mm and 17-50mm

Is there a large difference in image quality between the 18-55mm IS and the tamron 17-50mm non VC? Or in other words, is it better to not get the kit lens and jump straight to the tamron for better IQ? Thanks! (:

15. ## Re: Difference between 18-55mm and 17-50mm

Originally Posted by summerbirds
Is there a large difference in image quality between the 18-55mm IS and the tamron 17-50mm non VC? Or in other words, is it better to not get the kit lens and jump straight to the tamron for better IQ? Thanks! (:
if you have the budget, then just get the tamron.

16. ## Re: Difference between 18-55mm and 17-50mm

Originally Posted by summerbirds
Is there a large difference in image quality between the 18-55mm IS and the tamron 17-50mm non VC? Or in other words, is it better to not get the kit lens and jump straight to the tamron for better IQ? Thanks! (:
Sure, try shooting at 50mm f/4 and compare the quality .. oops.. kit lens can't do that
Basically: the Tamron is sharper and is a f/2.8 lens, usable already at f/2.8 for sharp pictures. The kit lens always needs some step-down (at least 1 stop) which gives you f/8 at 50mm. Using f/8 is not really helpful for subject isolation (shallow depth of field) and it requires higher ISO or more light.
Personally, the weight of the Tamron balances the camera much better than the kit lens.

17. ## Re: Difference between 18-55mm and 17-50mm

Originally Posted by Octarine
Sure, try shooting at 50mm f/4 and compare the quality .. oops.. kit lens can't do that
Basically: the Tamron is sharper and is a f/2.8 lens, usable already at f/2.8 for sharp pictures. The kit lens always needs some step-down (at least 1 stop) which gives you f/8 at 50mm. Using f/8 is not really helpful for subject isolation (shallow depth of field) and it requires higher ISO or more light.
Personally, the weight of the Tamron balances the camera much better than the kit lens.