Question about lenses...

[Shimmishim]

So I've been doing a lot of reading up on cameras and lenses...

I think I've got a camera picked out (either the XTi or 30D) and a starter lens (Tamron 17-50 f/2.8 ....)

So I've been looking at the "post your current photo gear" thread and see that there are certain lenses that seem to overlap a lot of users... with that mind...

what makes one lens better than another lens?

I understand that all lenses have their strengths and weaknesses but certain ones appear to cost more for lenses that have comparable focal lengths.

I also understand that some lenses come with IS and USM which I assume will make them more expensive... but what is the advantage of a $1,000 lens vs. a $500 lens with similar "specs"?

okay maybe that's more than A question but you get the idea!

thanks!

 

[fatkorean]

When you get to each companies top of the line lenses, I think that you will get close to the same image quality.

With Canon L lenses, you are getting weather sealing (with lens filter), better build, faster and quieter AF when you buy the canon L lenses.

Now are they worth 2-3x more than their counterpart? That part is very debatable. I think it boils down to what you feel comfortable buying in terms of cost and name recognition. Do you want to buy an Acura RL or a BMW 7 series?

-fk

 

[fuzzybabybunny]

1. Optical Quality:

This can be a defining factor. Based on reviews, optical quality will obviously make one lens better than another. For example, the Sigma 18-50mm f/2.8 arguably has worse optical quality than the Tamron 17-50mm f/2.8, hence the latter's popularity.

general rules of thumb:

a. the wider the zoom range, the lesser the optical quality
b. lenses in each manufacturer's "pro" line will generally have higher optical quality than lenses in their consumer line. "Pro" lines are Canon - L, Sigma - EX, Tamron - SP, Tokina - AT-X Pro. There are definitely exceptions to this. For example, the Tamron 17-50mm is excellent but is not designated with an SP. Canon's prime lenses are all excellent but they are not designated with an L.
c. higher quality optical elements. More expensive lenses will often have things like LD/AD/ELD/SLD/ULD glass elements to improve optical performance.
d. "Digital" coatings. Extra coatings on the inside of the lenses to prevent internal reflections as a result of light reflecting off of the shiny sensor. Sigma - DG. It is debatable whether these coatings actually do anything.

2. AF speed and noise. Canon's USM is the fastest. Ring USM is faster and quieter than Micro USM. Sigma has their own version, HSM. In my experience it is not on par with Ring USM although it is still very quick and quiet. Tamron and Tokina do not have USM-type motors, so their AF is slower compared to competitors and pretty loud, although they can still be quick enough for most situations. The AF noise on the Tamron 17-50mm can be very distracting in quiet environs.

3. Maximum aperture: lenses with large apertures will be more expensive than lenses of similar focal length but with smaller apertures.

4. Branding. Canon will always have a price premium over third parties just because it's Canon. Plus a lot of people like the white color.

5. Weathersealing. NOT ALL L lenses have weathersealing. Only a select number do. None of the third parties offer weathersealing in their lenses.

6. Function and feel. Canon L lenses are all very smooth and refined, and are great to shoot with. Sigma lenses are a little less smooth but feel really beefy. Tamron lenses are plasticy and not as smooth as Sigma but just because it's plastic doesn't necessarily mean it's going to commit suicide on you. If the optics are great and the price is right and the specs are right you may be willing to make this trade-off.

7. Resale value: higher quality and more popular lenses will retain their monetary value better than lenses that are not as popular or of high quality. They will also be easier to sell AND buy on the used markets. L lenses hold their value very well.

 

[montanafan]

If I understand your question correctly you're asking why do lenses of the same focal length vary so much in price. It depends on the:

1) Aperture
2) Type of glass
3) Is the widest aperture consistent throughout the focal range
4) IS
5) USM
6) Brand

What you plan to shoot determines which features are worth the cost to you.

I shoot a lot of sports indoor and in low light outdoors so 1, 3, and 5 are especially valuable to me. I mainly buy lenses with apertures of 2.8 and 1.8. For outdoor sports in daylight I go for length and can get away with a smaller aperture. Fast focusing is important as well, but IS doesn't matter at all. Canon L glass would be nice, but isn't worth the extra cost to me. As far as brands go, I prefer Canon and Sigma, but that's just me. On the other hand, some people shoot sports with a flash, so aperture isn't as important to them, but I don't like the look of sports photos taken with a flash so I need the widest aperture I can afford.

Edit: Oh yeah, and what Fuzzy said.

 

[Shimmishim]

ahh, thanks guys. that makes a lot of sense.

i understand that a lens that's capable of an aperture of 2.8 across its entire focal length will cost more than say a lens that has a smaller aperture that varies across its focal length

for example:
50-200mm with f/2.8 will cost more than say a lens that is 50-200mm with a f/3 to 5.5 (these are just made up numbers) assuming all other features (USM, IS, build material, glass quality, etc...) are the same... is this a correct assumption or am I over simplifying this?



and FBB thanks for the detailed explanation (and others as well).

some more questions...

is it good to have lenses that overlap focal lengths or is it better to have lenses that don't overlap?

what sort of lenses are more fitting for outdoor shooting vs. indoor shooting with and w/o a flash?

sorry for all these questions but there just appears to be a butt-load of lenses out there and I just want to be sure i have a correct understanding before I spend $500-$1000+ on a lens!

thanks again

 

[OdiN]

Yeah lenses with a fixed aperture across the entire range are more costly to produce, hence more expensive.

It's too bad Canon doesn't make a 10-400mm f/1.2L DO

 

[corkyg]

Originally posted by: OdiN
It's too bad Canon doesn't make a 10-400mm f/1.2L DO

Awesome! Can you imagine the diameter of the objective glass? That sucker would weigh close to 5+ lbs.

 

[Zenmervolt]

Originally posted by: corkyg

Originally posted by: OdiN
It's too bad Canon doesn't make a 10-400mm f/1.2L DO

Awesome! Can you imagine the diameter of the objective glass? That sucker would weigh close to 5+ lbs.

Diameter of the objective would have to be at least 333 1/3 mm. (400/1.2=333.3333)

For my 70-200 f/2.8 the filter threads are 77mm. Calculations show a minimum objective size of just over 71mm, so it looks like there's a safety margin of about 8%.

A 400mm f/1.2 would then probably have 360mm diameter filter threads. I would bet on a good deal more than 5 pounds.

ZV

 

[Shimmishim]

all right...

this is all coming together.

lenses that have single focal lengths appear to have very low apertures (1.4, 2.4).

what is the advantage of having a single focal length lens with low aperture?

also... i've narrowed it down to these two lenses

Tamron 17-50mm f/2.8 XR Di-II LD Aspherical [IF] SP
Tamron 28-75mm F/2.8 SP AF Macro XR Di LD-IF

which would you pick and why? anyone have experience with both of these? thanks

 

[fuzzybabybunny]

Originally posted by: Shimmishim
all right...

this is all coming together.

lenses that have single focal lengths appear to have very low apertures (1.4, 2.4).

what is the advantage of having a single focal length lens with low aperture?

also... i've narrowed it down to these two lenses

Tamron 17-50mm f/2.8 XR Di-II LD Aspherical [IF] SP
Tamron 28-75mm F/2.8 SP AF Macro XR Di LD-IF

which would you pick and why? anyone have experience with both of these? thanks

Single focal length lenses, more commonly known as "primes," are known for their razor sharpness and brightness. Because they're not as optically complex as zooms, they can be uncompromisingly sharp. Note that some high quality zooms can approach the sharpness of primes.

The lower the aperture number, the "brighter" a lens is, meaning it can take in more light than a lens with a higher aperture number.

1. Sharpness
2. Low weight (usually)
3. Brightness (better for situations with low light)
4. Shallow Depth of Field (for isolating subjects).

I would use the 17-50mm because the 28mm end of the 28-75mm is not wide enough for many purposes.

 

[TheChort]

Originally posted by: fuzzybabybunny

I would use the 17-50mm because the 28mm end of the 28-75mm is not wide enough for many purposes.

I agree. I went with the 28-75 thinking I would want the extra zoom. Don't get me wrong, I'm extremely happy with my lens right now, but if I could make my choice all over again, I think I would go with the 17-50

 

[Jawo]

I have the Tamron 17-50 f/2.8 and have very much enjoyed the lens. The lens has a tendency to be soft, so you might want to look at several lenses before buying one. I really like the wide angle of the 17mm, with low distortion (look at photozone's charts). I do wish that the lens was longer, but think that its a good comprise.

 

[jamesbond007]

I have owned the Tamron 28-75 and I would agree with the others - I often found myself wanting a bit more wide-angle out of the lens than 28mm (especially on a crop body) could offer. The 75mm zoom on the long end was nice, but you can always crop the image to get the tighter feel. You cannot add more image to a photograph that was already taken.

Both lenses are great, but the 17-50 seems to be a bit more of a crap shoot to get a good copy. The 28-75 I had was insanely sharp and was a blast to use and people seem to get more good copies often. At least, this is what I've gathered from reading forums and talking to local shooters.

 

[ElFenix]

28 mm on a canon crop body isn't wide at all. it's actually slightly to the telephoto side of perfectly normal. 28 mm on a 1.5 crop body is slightly wider than perfectly normal. so i'd hardly call that wide.


normal is when the focal length is equal to the diagonal of the imager. in 35 mm film that is 43 mm. only pentax seems to make a lens that is exactly normal. longer lenses are also traditionally considered 'normal,' such as the typical 50/1.8, canon's FD 55 f/1.2, or nikon's 58 f/1.2 noct


17 to 18 mm on a crop body gives you a similar picture to the traditional 28 mm wide angle lens (which many consider the longest true wide angle for 35 mm photography).

 

[Eos]

Originally posted by: Zenmervolt

Originally posted by: corkyg

Originally posted by: OdiN
It's too bad Canon doesn't make a 10-400mm f/1.2L DO

Awesome! Can you imagine the diameter of the objective glass? That sucker would weigh close to 5+ lbs.

Diameter of the objective would have to be at least 333 1/3 mm. (400/1.2=333.3333)

For my 70-200 f/2.8 the filter threads are 77mm. Calculations show a minimum objective size of just over 71mm, so it looks like there's a safety margin of about 8%.

A 400mm f/1.2 would then probably have 360mm diameter filter threads. I would bet on a good deal more than 5 pounds.

ZV

10mm f/1.8
17mm f/1.8
24mm f/1.8
35mm f/1.8
50mm f/1.8
85mm f/1.8
70-200mm f/2.8
300mm f/2.8
400mm f/2.8
600mm f/4

All the lenses one could ever want (even the imagined ones).
Don't forget the burro to carry them in the field...