Lens Angles ???

Phimp

Gawd
Joined
Dec 9, 2006
Messages
596
I currently have the Canon EF 28-135 f/3.5-5.6 IS lens that I use with my Canon 40D...

obviously, this doesn't work well with indoor group portrait shots, or anything that could benefit from a wider angle lens.

last time i want to Vegas, I found myself in many situations where I just couldn't capture the full scene with the 28mm limitation..

i'm going back in a few months and want to be better equipped with a wide(r) angle lens this time.

OH, and I'm uber cheap!! (plan on losing too much money gambling =p )
So the f-stop isn't too much of a concern, especially since it's a several hundred dollar difference to get a low f-stop lens..

Anyways, this is the lens I have
and this is the lens i'm looking at

now, what has me confused is that my lens goes as wide as 28mm and the other lens, 18mm.
but the specifications show the 18mm as being 74 degrees FOV, and the 28mm as being 76 degrees...

how exactly does this work?

And since I'm obviously confused, any recommendations for a lens that will give me a wider field of view than the lens I have?
as cheap as possible =P
 
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SilverMK3

[H]ard|Gawd
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Dec 15, 2002
Messages
1,346
Since the 28-135 was designed as a walk-around lens for full-frame cameras like the 5D, it is likely that the stated FOV is based on having the lens mounted to such a camera. On your 40D, which has a 1.6X FOV crop factor, the lens behaves as if it had an effective focal length of 45-216mm which is not very wide at all.

The 18-55mm IS kit lens is a very competent lens with a great bang-for-buck value. It's the cheapest way to get a nice, sharp lens with image stabilization. You can pick them up used for next to nothing, in fact I sold mine for ~$100 when I upgraded.

If you're willing to stretch your budget to the $300ish range there are some great options to be had if you're buying used. The Sigma 18-50 f/2.8 and Tamron 17-50 f/2.8 are both great alternatives that offer increased sharpness, shallower DoF, and better focus accuracy, though they both lack image stabilization (OS and VC, respectively) at this price point.

Also, if you want to go extremely wide, you can pick up a used Sigma 10-20mm in the $350ish range if you're lucky. :D
 

Blue Fox

[H]F Junkie
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Jun 9, 2004
Messages
11,813
The differences can be attributed to the different mounts (EF vs EF-S) as the size of the rear elements is different and also placed at different lengths from the sensor. Keep in mind that your FOV will be much smaller on your 40D if you use the EF lens as it is APS-C instead of full frame and that results in an effective focal length of ~45-216mm due to the 1.6x crop. You will have a much wider FOV with the EF-S 18-55mm lens.
 

Zepher

[H]ipster Replacement
Joined
Sep 29, 2001
Messages
19,022
I have a Tamron 17-50 f/2.8 that I use with my Canon 40D. It's a very good lens for about $300-350 used (maybe a little less now since the IS model just came out).
 

darktiger

[H]ard|DCer of the Month - April 2007
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Apr 10, 2003
Messages
11,819
I say 17-40 or 10-22. I loved the 10-22, but had to sell it when I jumped on the full frame bandwagon :)
 

madFive

metal[H]ead
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Mar 26, 2008
Messages
9,118
You've already got the 28mm+ range covered - IMO, you should avoid overlapping ranges.

I'd go w/ something along the lines of a 10-24mm if I were you.
 

Phimp

Gawd
Joined
Dec 9, 2006
Messages
596
After looking at the available prices for all recommended lenses, I stumbled across the Canon EF 20mm f/2.8 USM

What's that max that this lens would be worth used in decent condition? If I were to start bidding for it used...

I like that it's a prime f/2.8, and 94 degrees viewing angle is more enticing that my current 74 degrees...


it just seems like anything at 100degrees or wider of a viewing angle for my 40D costs at least $400 used..
I'm broke =/
 

Phimp

Gawd
Joined
Dec 9, 2006
Messages
596
17mm EF-S on a 40D is (roughly) the same as a 28mm EF on a 5D, I understand this.
And every friggin mention of EF-S and EF in the same article/thread on the entire internet acknowledges this...

I know that the 40D (my camera) has a 1.6x crop factor. This means that if I take any lens and put my 40D on a tripod and take a picture, and then put a 5D on the same tripod and use the same lens that the 5D will have a wider Field Of View in the actual picture that was just taken.

So a 17mm EF-S lens on a 40D will have roughly the same FOV as a 28mm EF lens on a 5D.

But this is where I get confused...
Would a 28mm EF-S lens have the same FOV as a 28mm EF lens if they are BOTH being used on a 40D (1.6x crop factor)?

So basically I'm trying to figure out if a 17mm (or 18mm) EF-S lens will take WIDER FOV pictures on my 40D than my 28mm EF does...


ahh, it seems with a couple hours of scouring the corners of the internet I found EXACTLY what I was looking for =)



I'll be going from Orange to Green for about $70 =p
 
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