New Canon Lenses with "Distance information"

[jsch]

When you check the Product Specification for Canon lenses here:
http://www.canon-europe.com/For_Home/Produ...enses/index.asp
You will find that all new Canon L lenses (50/1.2L, 85/1.2L, 16-35/2.8L, 24-105/4L) have the new feature "Distance information". The older lenses don't give this information (Canon gave some weak reason for this up to now). Could this mean that Canon is planing to relase a lens correction software module for the computer or camera, like DXO or the Hasselblad 28mm? What do you think?

Best,
Johannes

P.S.: If I have missed an earlier discussion about this, I'm sorry.

[DiaAzul]

When you check the Product Specification for Canon lenses here:
http://www.canon-europe.com/For_Home/Produ...enses/index.asp
You will find that all new Canon L lenses (50/1.2L, 85/1.2L, 16-35/2.8L, 24-105/4L) have the new feature "Distance information". The older lenses don't give this information (Canon gave some weak reason for this up to now). Could this mean that Canon is planing to relase a lens correction software module for the computer or camera, like DXO or the Hasselblad 28mm? What do you think?

Best,
Johannes

P.S.: If I have missed an earlier discussion about this, I'm sorry.
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When Canon introduced ETTL-II on the EX580 flash they used distance information to improve the algorithm for calculating flash exposures. Nothing new and has been around nearly two years (or so). Hence the inclusion of which lenses can give the distance information and which can't.

This is not to say that the distance software isn't used by other software.

[BernardLanguillier]

Flash is indeed the reason.

Other brands, like Nikon, have been measuring subject distance with their lenses for many years. This can be checked by the presence of the D letter in the lens name, like in AF-D.

Regards,
Bernard

[Ray]

Flash is indeed the reason.

Other brands, like Nikon, have been measuring subject distance with their lenses for many years. This can be checked by the presence of the D letter in the lens name, like in AF-D.

Regards,
Bernard
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Bernard,
How accurate are such distance measurements and are they displayed anywhere before taking the shot?

[BernardLanguillier]

Bernard,
How accurate are such distance measurements and are they displayed anywhere before taking the shot?
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- don't know how accurate they are, but considering how consistent the flash results are with recent Nikon bodies, I'd say that it is reasonnably accurate,
- they are not diaplayed as far as I know,

DxO is seemingly able to extract that information from the Exif files to tune the distorsion correction based on the actual focussing distance of supported lenses. I assume that it means that it is accurate enough for practical usage.

Regards,
Bernard

[howiesmith]

It seems that Canon's DEP function would have to measure and remember some distances (near and far focus limits).

++++++++++++++++

Perhaps measuring accuracy is why Canon decided to dump DEP.  As the hyperfocal distance and the focus distance get closer together, accuracy becomes more important.  Maybe the new lenses allow better accuracy and maybe DEP will return.

If so, it might be nice to make the value of Circle of Confusion a default value of Canon's choice with a user specified override value of their choice.

[godtfred]

...or the Hasselblad 28mm? What do you think?
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Hasselblad has correction on all their H system lenses when used with a reasonably new HB MFDB.

-axel

[DiaAzul]

Bernard,
How accurate are such distance measurements and are they displayed anywhere before taking the shot?
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The accuracy depends on the lens and camera. The focus system is dependent upon the maximum aperture, available light and sensor system - so accuracy should be within the limites of the minimum depth of field for maximum aperture. As pointed out, this becomes quite large as you reach the hyperfocal distance, however, suspect the camera does a decent job of getting somewhere with the focus in the middle of the range.

On the back of the EX550 flash there is a distance indicator on the LCD display -  I need to go back and find out exactly what this represents - though it is not an accurate x m to focal point display.