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MBEimage · by **MBEimage** on April 29th, 2004, 11:21 pm

I am thinking about buying this lens, but am a bit confused about the specs for it. At 17mm, I would expect a field of view of about 104 degrees, but Canon's specs state it is less than 80 degrees. What gives? It is billed as an ultra-wide angle zoom, but it doesn't seem very wide on paper. It was designed with a digital body in mind, so is it measured at the effective focal length of about 28mm (17mm x 1.6 factor)?

Does anyone own this lens and can help me out? I would like a wide for group shots on my film camera, but if it is only as wide as my 28-135, I will save myself the $1000.

Thanks,

W_King · by **W_King** on April 30th, 2004, 1:45 am

I have been trying to scan some really old slides and l want to know if you put the emusion side next to the light or the shiny side? Hope someone can help because l have hundreds of these to do.

MBEimage · by **MBEimage** on April 30th, 2004, 10:23 am

It should say on your scanner. There is usually an "R" in a diagram indicating "Right" reading as well as film orientation. If the diagram is a proper "R", then the only way you could obtain that configuration is emulsion-down.

pose4me · by **pose4me** on May 1st, 2004, 9:16 pm

Hey Mark,

I'm not all that familiar with Canon gear, but my 14mm f2.8 Nikon lens is effectively 21mm
when I put it on my D1H (digital).
It always blows me away when I put it on my F5 (film body) and see the TRUE ultra-wide
rendering!
I'm not "up" on the technology of lenses made specifically for digital bodies, but it's my understanding
that until they make the CCD the full size of a 35mm frame (24x36mm), you're going to have the 1.5x
factor to deal with.
It DOES come in handy when shooting stuff like field sports with a long lens.

Brian

MBEimage · by **MBEimage** on May 1st, 2004, 11:46 pm

That's what I thought too, but Canon Canada says different. This is what they sent me:

The only item affected by using a digital camera is the focal length. The
focal length is multiplied by 1.6 to get the true focal length when
attached to a EOS 10D or Digital Rebel. All other lens specification are
not affected. The field of view is the same for both digital and 35mm
cameras.

This still doesn't make sense to me, when the sensor is only recording the middle portion of the image "circle" that is being projected onto the film plane, but I guess I've been told otherwise.

Franks Photo · by **Franks Photo** on May 17th, 2004, 10:30 pm

This may be too late...

I'm not sure where you read 80 degrees, Canons web siteweb site lists the field of view to be 104 to 57 degrees.

Hope this helps,
Frank
My Webpage

MBEimage · by **MBEimage** on May 18th, 2004, 9:26 pm

Franks Photo wrote:I'm not sure where you read 80 degrees

If you download the EF Lens Specification chart on that same page (Lens Chart Download - spec.pdf) and look at the measurements there, you will see a diagonal field of view range of 74° - 29° for that lens. I think they might just have screwed it up, that's why I'm asking for a confirmation from someone that actually owns one.

Franks Photo · by **Franks Photo** on May 18th, 2004, 9:53 pm

Hmmm, I see what you mean, I would have to agree that it is likely a typo...

Here is a review of the lens from Popular Photography , they list the "view angle" as 104 to 57 degrees.

Pop Photo

Good luck,
Frank
My Webpage

MBEimage · by **MBEimage** on May 19th, 2004, 3:53 pm

Thanks for the link. It never seemed right to me how an "ultra-wide" zoom has the same diagonal field of view at 17mm as my 28-135mm does at 28mm, but Canon still seemed to disagree with me. They sent me this when I asked them why the 20-35mm zoom (and I meant the $500 one, not the f/2.8 one) had a wider field of view than the 17-40mm:

The 17-40mm lens is a F4 lens and the 20-35mm is a F 2.8 lens. The larger
opening for the aperture will provide a bigger field of view. The 17-40 mm
lens construction is also 12 elements in 9 groups and the 20-35 has 12
elements in 11 groups this also plays a factor. The 20-35 mm lens is more
expensive for these reasons.

Bizarre, but who knows. I want to do group shots this summer and need the wide angle, all I am doing now is waiting for Canon to release a new batch of 10Ds for me to buy...

Franks Photo · by **Franks Photo** on May 19th, 2004, 10:07 pm

Bizarre is right, Canon needs to do a better job training their reps. That quote couldn't be more wrong. Field of View is a function of Focal Length and Image size (Sensor Size), thats it. The size of the aperture effects how much light can be gathered by a given lens and has nothing to do with field of view. If this person's quote were true, the extents of what is seen in your viewfinder or picture would change as you turned your aperture ring! The number of elements also has nothing to do with field of view. More elements generaly yield a higher performance lens, and more elements are generaly needed with larger aperture lenses because it is harder to correct the various distortions and aberations as the aperture increases.

Hope this wasn't too much information, by day I'm an opto-mechanical engineer and spend my time with optical engineers designing the mechanics for everything from microscope objectives to video camera lenses. Photography is a part time thing for me and somewhat born out of my interest in optics in general.

Hope you get your 10D soon, waiting no fun at all!

Regards,
Frank

RayS · by **RayS** on May 20th, 2004, 5:08 am

Don't know if this will help but here goes. I have a number of Canon lenses including a 28 - 200 MM regular EOS seriers lense that I will get to later. However my primary Lenses are the 70-200MM "L" seriers f2.8, the 28 - 70MM " L" series f 2.8 and the newest addition the 17 - 40 MM "L" series f 4.0. When each of the lenses are on the camera the all act just like you would have thought they would. At the wide end of the zoom on the 17 MM is wider than the lens with 28MM at it's widest setting which is wider than the lens that has 70 MM at the wide end of each of the three "L" series lenses. If I put the 28 MM to 200 MM EOS lense on my camera it has basically the same field of view as my 28 - 70 MM "L" seriers lense at the wide end. When using the 17 - 40 MM "L" seriers lens it is has a much wider field of view at 17 MM than both the previous lenses at their wide focal length of 28MM.
The real difference is when you take all of the lenses off of your digital camera and put them on a film body to see what you lose at the wide end with the 1.6 multiplication of the less expensive digital bodies. However the good point is what you gain with that same 1.6 multiplier at the longest telephoto settings as a 200MM lenses becomes a 320 MM on a less expensive digital body. You can always spring for the top of the line Canon digital an avoid this compensation all together.
Most of my images are done with the Canon 10D
Yes the 17 MM is wider than the 28MM. Buy the lens you will love it.
RayS

MBEimage · by **MBEimage** on May 20th, 2004, 11:04 am

Thanks a lot, Ray!

I found out that I am #2 on the waiting list and Canon should be releasing a few 10D bodies at the end of the month, so it should all be in my hot little hands sometime in June!

RayS · by **RayS** on May 20th, 2004, 12:39 pm

Good luck! If I can be of any help with the Canon gear let me know.
RayS

wnymodels · by **wnymodels** on August 30th, 2004, 3:56 pm

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Canon lens question 17-40mm f/4 l usm - Question about lens specs

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