scott kirkpatrick Posted July 31, 2007 Share #1 Posted July 31, 2007 Advertisement (gone after registration) The EXIF that is written when you mount a WATE in firmware 1.107 with lens detection "ON" doesn't indicate the lens focal length (previously it said 18mm whatever had been supplied and saved in the lens selection dialog box), and still gives the erroneous maximum aperture of 1.0, but the vignetting correction of the "ON" mode is being applied. Here are the three modes, shooting a white wall under not very even tungsten illumination (2400K), with a CV15 in a Milich adapter coded for the WATE. No filter. All three at f/4.5, 1/6 sec, ISO 160. First example, lens detection ON_UV/IR, focal length supplied as 16mm. (note the overcorrection for the red vignetting, giving pink corners) Second example, switch to ON without powering off or changing anything else. Third example, switch to lens detection OFF, no other changes. scott [ATTACH]47449[/ATTACH] [ATTACH]47450[/ATTACH] [ATTACH]47451[/ATTACH] Link to post Share on other sites More sharing options...
Advertisement Posted July 31, 2007 Posted July 31, 2007 Hi scott kirkpatrick, Take a look here Lens detection "ON" corrects WATE vignetting in 1.107. I'm sure you'll find what you were looking for!
gwelland Posted July 31, 2007 Share #2 Posted July 31, 2007 I've found that the quickest and easiest way to create these test images is to shoot against an Expodisc. It produces perfect vignette/cast images every time without the need to set up elaborate white wall/lighting combinations. I just shot about 120 reference image combinations for the Cornerfix port today ... Link to post Share on other sites More sharing options...
sandymc Posted July 31, 2007 Share #3 Posted July 31, 2007 I've found that the quickest and easiest way to create these test images is to shoot against an Expodisc. It produces perfect vignette/cast images every time without the need to set up elaborate white wall/lighting combinations. I just shot about 120 reference image combinations for the Cornerfix port today ... ohhhhhh, watch out - ExpoDisc can create vignetting all of its own. Another user of CornerFix first ran into this exerimentally, and the ExpoDisc folks have subsequently confirmed it to me that it is a real effect. Regards, Sandy Link to post Share on other sites More sharing options...
gwelland Posted July 31, 2007 Share #4 Posted July 31, 2007 I'm using the 4x4 large Expodisc for this vs the 77mm or so. I haven't really noticed any vignetting with this with straight shots without the IR filters mounted. Were the other folks shooting at the reference exposure or lifting by a couple of stops? Can you send me some of the info you have on this? I took this route based on the work of Bill Atkinson who uses the Expodisc to create Phase One colour shift maps for digital backs. I'd assumed that this would work for these targets too. Link to post Share on other sites More sharing options...
sandymc Posted July 31, 2007 Share #5 Posted July 31, 2007 Graham, ExpoDisc will work fine for chroma vignetting, because it doesn't add any color shift. It does add luminance vignetting. The ExpoDisc folks have actually looked at that quite extensively, and concluded that other than saying it is worse for wide lenses than short ones, can't be well predicted. It varies with size of the ExpoDisc, focal length, aperture, etc..... Regards, Sandy Link to post Share on other sites More sharing options...
cbretteville Posted July 31, 2007 Share #6 Posted July 31, 2007 I can confirm Scott's findings. 1.107 clearly corrects vignetting with a lens it thinks is a WATE attached. My own test shots of a white office wall shows the same as those posted by Scott. Although I fail to understand why the focal length is now set to 0 mm there is need to worry. - Carl Link to post Share on other sites More sharing options...
gwelland Posted July 31, 2007 Share #7 Posted July 31, 2007 Advertisement (gone after registration) Graham, ExpoDisc will work fine for chroma vignetting, because it doesn't add any color shift. It does add luminance vignetting. The ExpoDisc folks have actually looked at that quite extensively, and concluded that other than saying it is worse for wide lenses than short ones, can't be well predicted. It varies with size of the ExpoDisc, focal length, aperture, etc..... Regards, Sandy Damn ... time to break out the light tent again or set up a white target again! All I can say is that I'm getting pretty expert at shooting demo shots, vignette shots with detect on, off, UV/IR, WATE for each setting plus mis-settings, UV/IR on with no filter, etc etc etc! I thought I'd got it down to a fine art with the Expodisc - just sit back and change the settings and fire away whilst enjoying the sunshine this afternoon. Oh well, back to the drawing board. Link to post Share on other sites More sharing options...
sandymc Posted July 31, 2007 Share #8 Posted July 31, 2007 Damn ... time to break out the light tent again or set up a white target again! All I can say is that I'm getting pretty expert at shooting demo shots, vignette shots with detect on, off, UV/IR, WATE for each setting plus mis-settings, UV/IR on with no filter, etc etc etc! I thought I'd got it down to a fine art with the Expodisc - just sit back and change the settings and fire away whilst enjoying the sunshine this afternoon. Oh well, back to the drawing board. Well, if you just want to correct the cyan corners, you can use the ExpoDisc reference images - just turn the Luminance control in CornerFix to zero...... Sandy Link to post Share on other sites More sharing options...
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