Dr.Kildare Posted August 26, 2007 Share #1 Posted August 26, 2007 Advertisement (gone after registration) I have recently added a CV15 to my lens 'quiver' but not had much of a chance to use it as yet. The images it produces appear sharp, but when I view 100% crops, the lens will only resolve a certain amount of detail. Now, I know I will never normally be viewing or printing the images at 100%. When I compare the detail from the CV15 with the detail produced by my 28mm Elmarit ASPH, the leica lens resolves far more detail at 200% than the CV15 at 100%. Am I expecting too much from the CV15? If so, can someone describe a testing procedure that is more scientific and a fairer comparison? You comments are appreciated. 1. CV15 full frame - focused at infinity, shot at f8 2. CV15 crop 3. 28mm Elmarit ASPH crop Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/31938-am-i-expecting-too-much-from-my-cv15/?do=findComment&comment=338341'>More sharing options...
Advertisement Posted August 26, 2007 Posted August 26, 2007 Hi Dr.Kildare, Take a look here Am I Expecting Too Much From My CV15?. I'm sure you'll find what you were looking for!
norbertnl Posted August 26, 2007 Share #2 Posted August 26, 2007 Chris, It's not possible to tell differences without some additional information: from which distance did you take the picture with your 28? Same distance or adequate distance to get the licence plate number at a comparable scale? Perhaps you could post the 28mm overview photograph as well. Did you use a tripod or if not, what was the shutter speed? Best regards, Norbert Link to post Share on other sites More sharing options...
Dr.Kildare Posted August 26, 2007 Author Share #3 Posted August 26, 2007 Chris, It's not possible to tell differences without some additional information: from which distance did you take the picture with your 28? Same distance or adequate distance to get the licence plate number at a comparable scale? Perhaps you could post the 28mm overview photograph as well. Did you use a tripod or if not, what was the shutter speed? Best regards, Norbert Norbert, Here is the 28mm full frame. Both images were taken from the same location (my front gate) with tripod and cable release. Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/31938-am-i-expecting-too-much-from-my-cv15/?do=findComment&comment=338363'>More sharing options...
norbertnl Posted August 26, 2007 Share #4 Posted August 26, 2007 Thanks Chris! I'm looking forward to interpretations as well. Suggestion: requirements for an extreme wige angle are possibly lower because objects appear much smaller on a print than with longer lenses. Besides, Leica glass is much more expensive. Would be disappointing if there weren't any visible differences in quality.. I have also taken the step to purchase the 15mm. It's being sent to me right now. Best, Norbert Link to post Share on other sites More sharing options...
Bavaricus Posted August 26, 2007 Share #5 Posted August 26, 2007 Am I expecting too much from the CV15? If so, can someone describe a testing procedure that is more scientific and a fairer comparison? Hi Chris, when comparing shots by a 15 and a 28 made from the same point you have to enlarge the detail almost twice as much to get the same frame! Because of that the crop of the 15 hast to be less good! To compare lenses you have to make pictures out of different points to get a frame you can compare. The other way around a crop of the registration plate with the 15 has only a third of the pixel it has with the 28! Hope you understand what i mean, please excuse my bad english ... Best Reiner Link to post Share on other sites More sharing options...
sean_reid Posted August 26, 2007 Share #6 Posted August 26, 2007 Your CV 15 picture is out of focus (at the distance where that license plate is). DOF and correct focus, of course, are not the same thing. Cheers, Sean Link to post Share on other sites More sharing options...
Dr.Kildare Posted August 26, 2007 Author Share #7 Posted August 26, 2007 Advertisement (gone after registration) Your CV 15 picture is out of focus (at the distance where that license plate is). DOF and correct focus, of course, are not the same thing. Cheers, Sean Sean, The CV15 picture was taken at infinity and the licence plate was 11 metres from the lens. Am I to assume the lens won't focus at infinity and it needs attention? Link to post Share on other sites More sharing options...
carstenw Posted August 26, 2007 Share #8 Posted August 26, 2007 11m is not the same as infinity. Things will be acceptably sharp if printed, or viewed (in its entirety) on the computer, but not when zoomed in like that. Try to set the focus of the CV15 at a known distance, like one engraved on the lens, find a subject at that exact distance, and then take comparison shots again. This time, instead of zooming until the subject is the same size, zoom both to 100% and compare the quality of the pixels, not license plate to license plate or similar. Link to post Share on other sites More sharing options...
TEBnewyork Posted August 26, 2007 Share #9 Posted August 26, 2007 I've noticed and posted here that at infinity my CV lenses seemed to be a bit OOF in the rangefinder and had to back off a bit. A couple of others stated the same thing. I was also told that on a rangefinder infinity is more like the moon and not meters. Link to post Share on other sites More sharing options...
Guest guy_mancuso Posted August 26, 2007 Share #10 Posted August 26, 2007 Chris 11 meters is not exactly infinity, I would try the same scene and just back off ever so slightly on the focus. Critical focus is going to be harder to achieve since it is not coupled. I would try this again and pick some differnt focus points to see where this is coming up. Now if you want to compare it against another lens of longer focal length than you need to move in and cover the same exact area. Really the only way to see what the differences maybe. The CV 15mm is a good lens but there are limits to it and i found at F8 it is pretty good Link to post Share on other sites More sharing options...
carstenw Posted August 26, 2007 Share #11 Posted August 26, 2007 I have done the same test, but with 28 Cron Asph and CV15, since these are the two lenses I have. To demonstrate the problem, I have done it as you did it (except that I tried to focus at the correct distance, rather than relying on depth of field to make the license plate sharp), and then I have done it in a more fair way. First three shots, 28 Cron, the CV15 from the same spot, then CV15 from a closer spot, to make the crop the same as in the 28 Cron shot. 28 Cron Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! CV15 from 28 spot CV15 from closer, to give 28 field of view (although not perspective) . Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! CV15 from 28 spot CV15 from closer, to give 28 field of view (although not perspective) . ' data-webShareUrl='https://www.l-camera-forum.com/topic/31938-am-i-expecting-too-much-from-my-cv15/?do=findComment&comment=338621'>More sharing options...
carstenw Posted August 26, 2007 Share #12 Posted August 26, 2007 Now I have cropped the way you did, ie. to the license plate, and then I have resized to the same size, which is unfair, since the middle CV15 shot is a much smaller section of the image. The last one, having the same basic image as the 28 is fair, and you see that the crop looks as good as the 28. 28 Cron Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! CV15 from 28 spot CV15 from closer, same view as 28 Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! CV15 from 28 spot CV15 from closer, same view as 28 ' data-webShareUrl='https://www.l-camera-forum.com/topic/31938-am-i-expecting-too-much-from-my-cv15/?do=findComment&comment=338624'>More sharing options...
carstenw Posted August 26, 2007 Share #13 Posted August 26, 2007 To show what went wrong in the second crop, I here post the crops without resizing, so you can see how much area the license plate covers in actual pixels. 28 Cron Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! CV15 from 28 spot CV15 from closer, same view as 28 Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! CV15 from 28 spot CV15 from closer, same view as 28 ' data-webShareUrl='https://www.l-camera-forum.com/topic/31938-am-i-expecting-too-much-from-my-cv15/?do=findComment&comment=338626'>More sharing options...
carstenw Posted August 26, 2007 Share #14 Posted August 26, 2007 Hopefully this makes it clear why you observed your results in your comparison. In summary, to compare lenses for resolution, you must take features covering the same area in pixels and compare them. Either compare different, but comparable features, or go closer with the wider lens, until you get roughly the same view of the feature of interest. Btw, all were taken at f/8 at ISO 640. At ISO 160 they would have been a little sharper. I also had no IR filter on the CV15, so the colours are a little pinker. Link to post Share on other sites More sharing options...
Bavaricus Posted August 26, 2007 Share #15 Posted August 26, 2007 Hopefully this makes it clear why you observed your results in your comparison. In summary, to compare lenses for resolution, you must take features covering the same area in pixels and compare them. Either compare different, but comparable features, or go closer with the wider lens, until you get roughly the same view of the feature of interest. Btw, all were taken at f/8 at ISO 640. At ISO 160 they would have been a little sharper. I also had no IR filter on the CV15, so the colours are a little pinker. Thank you Carsten, thats exactly what i meant! Don't have a M8 now to do such tests immediately! Link to post Share on other sites More sharing options...
hdrmd Posted August 26, 2007 Share #16 Posted August 26, 2007 Carsten: excellent. DR Link to post Share on other sites More sharing options...
Jack_Flesher Posted August 26, 2007 Share #17 Posted August 26, 2007 Carsten, your crops show what an excellent lens the little VC 15 is It may be simply my preference for the slightly softer contrast in the VC15, but that aside, I would also give a slight resolution edge to it over the 28 Cron, when comparing the same size crops... Cheers, Link to post Share on other sites More sharing options...
carstenw Posted August 26, 2007 Share #18 Posted August 26, 2007 I would say that I misfocused. I was in a bit of a hurry. It was also hand-held at ISO 640, and I may have moved, which is more critical with the 28. Link to post Share on other sites More sharing options...
DavidStone Posted August 26, 2007 Share #19 Posted August 26, 2007 Well, I got my CV15 just a few days ago, and I just can't understand how they can make such a good lens for the price. The problem of course is that at this price, the odd sub-standard one could slip through. If I can make it work, I'll post one of my first shots with it below. David Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/31938-am-i-expecting-too-much-from-my-cv15/?do=findComment&comment=338923'>More sharing options...
geoffreyg Posted August 26, 2007 Share #20 Posted August 26, 2007 David - Great shot. Wonderful space, nicely captured. Carsten - The comparison is revealing - it seems to show the 15 CV in a very good light. Yes, at full resolution (100%) it is a wee bit tenderer than the Leica, but wow, how much for how little. Geoff G Link to post Share on other sites More sharing options...
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