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mangaloreaviators
30th of December 2007 (Sun), 16:04
Hello Canonians !!

I'm a newbie to the World of Photography and learning Photography with my new Canon EOS 400D. One questions which is always bothered me when going through the specification of DSLR and DSLR Type Camera is that of Optical Zoom.

I have a 18-55MM IS Lens and would like to know if somebody can let me know how much of Optical Zoom it has.

Probably how to calculate the Optical Zoom of DSLR Lens would be great.

Q. How many X Optical Zoom does a Canon 17-85 MM Lens has ? How do you calculate ?

wimg
30th of December 2007 (Sun), 16:09
That's easy. The largest FL (focal length) divided by the smallest one.

So an 18-55 has 3X zoom (55/18 ) and a 17-88 has 5X zoom (85/17).

HTH, kind regards, Wim

30th of December 2007 (Sun), 16:09
basically take the longer end (55mm) and divide it by the short end (18) so you get right at 3x "optical zoom"

or 85/17=5x

Now that's not completely completely comparable to point and shoots and really the only people that seemed concerned with optical zoom factors either still use a point and shoot or just came from using them. Which is fine, but with a bit of use you'll know how wide 18mm is on your camera or how long 300mm is.

ANGUS
30th of December 2007 (Sun), 16:10
on a 1.6 Crop camera like your 400D it has an Optical Zoom of 27.2-136

mangaloreaviators
30th of December 2007 (Sun), 16:27
Thank you very much everybody. Simple Maths :)

I'm very happy that I found solution for my questions.

Regards
`Ravi

mangaloreaviators
30th of December 2007 (Sun), 16:38
Hello Canonians!!

Correct me if I'm wrong

Canon EF-S 17-85mm f/4-5.6 IS USM (ultra wide angle zoom lens) = 5X Zoom
Canon EF 24-105mm f/4 L IS USM (wide angle zoom lens) = 105/24 =5X Zoom
Canon EF 17-40mm f/4.0 L USM (ultra wide angle zoom lens) = 3X

ANGUS
30th of December 2007 (Sun), 16:41
Yes but that is irelivant in SLR Photography, The 1200mm f5.6 is ZERO Times zoom but you could shoot about anything you want out your bedroom window with it.

wimg
30th of December 2007 (Sun), 16:41
Hello Canonians!!

Correct me if I'm wrong

Canon EF-S 17-85mm f/4-5.6 IS USM (ultra wide angle zoom lens) = 5X Zoom
Canon EF 24-105mm f/4 L IS USM (wide angle zoom lens) = 105/24 =5X Zoom
Canon EF 17-40mm f/4.0 L USM (ultra wide angle zoom lens) = 3X

The 24-105 is 4.1X zoom.
The last lens, the 17-40, is 2.3X zoom, not 3X.

Kind regards, Wim

wimg
30th of December 2007 (Sun), 16:44
Yes but that is irelivant in SLR Photography, The 1200mm f5.6 is ZERO Times zoom but you could shoot about anything you want out your bedroom window with it.
No, theoretically is 1X zoom, and you can't shoot just anything with it...

:)

Oh, zoom range is important if you do want a one lens does it all solution.

Kind regards, Wim ;)

runninmann
30th of December 2007 (Sun), 16:48
No, theoretically is 1X zoom, and you can't shoot just anything with it...

:)

Oh, zoom range is important if you do want a one lens does it all solution.

Kind regards, Wim ;)Or, perhaps more accurately, focal length range.

JeffreyG
30th of December 2007 (Sun), 16:48
If you are looking to compare the "zoom" relative to a P&S, realize the a 22mm lens on a 1.6 crop dSLR is about the 1X position on most P&S.

So a 17-85 runs from the 0.77X to 3.8X range.

a 70-300 runs from 3.2X to 13.6X.

I think most people coming from a P&S to SLR find this type of conversion handier. I mean, the 70-300 is technically a 4.3X zoom and the 17-85 is a 5X zoom. But notice the 70-300 is the one that goes to what the layman might think of as a 13X zoom.

SkipD
30th of December 2007 (Sun), 17:27
One questions which is always bothered me when going through the specification of DSLR and DSLR Type Camera is that of Optical Zoom.

I have a 18-55MM IS Lens and would like to know if somebody can let me know how much of Optical Zoom it has.

Probably how to calculate the Optical Zoom of DSLR Lens would be great.

Q. How many X Optical Zoom does a Canon 17-85 MM Lens has ? How do you calculate ?Ravi - first off, I would suggest that you change your logon name. Having your email address as your logon name is a spam magnet. You wouldn't believe how much spam it will cause you to put up with.

The "X" factor for SLR zoom lenses means absolutely nothing when you are trying to compare SLR lenses to point-n-shoot lenses. "4X", for example (and as others have said) means nothing more than the fact that the longest focal length is four times the shortest focal length. There is not a shred of evidence in the "4X" about what the shortest or longest focal length actually is.

To compare the focal lengths between a point-n-shoot camera and an SLR, you need to use the point-n-shoot's "35mm equivalent" focal lengths as well as any "crop factor" for the SLR and do a little math to find out what focal lengths on the SLR will give you the same field (angle) of view as the lens on the point-n-shoot.

When buying lenses for an SLR, it is good to know that the larger the "X" factor lenses are a serious engineering compromise. A 10X or 12X super-zoom lens is usually going to either suffer poor image quality or have a very high price. It is much better to choose zoom lenses that have a lower zoom ration - typically 3X or 4X at most - to get a decent price with decent quality.

mangaloreaviators
31st of December 2007 (Mon), 18:16
Hello Skip D,

I would like to change my Log on Name as it was a accident when I registered it.

Could you please ehlp me change it ?

Mark_Cohran
31st of December 2007 (Mon), 18:26
Hello Skip D,

I would like to change my Log on Name as it was a accident when I registered it.

Could you please ehlp me change it ?

You need to PM one of the moderators (there's a list at the bottom of the main forum page). They can help you change it.