rscheffler
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 p.247 #2 · Leica M/X/T/S/Q/CL/SL Picture Thread | |
joe88 wrote:
Ron, wonderful color shots from you, as always. Have you been using the CV15 lately? What are your thoughts so far?
Hi Joe,
I have not used it much since I find 21mm is suitable for most of my wide needs.
My issue with the CV15 on the M9 is primarily the heavy color shift and vignetting. When I first got it I experimented with a number of coding options, and I would have to look through those to see which worked best. But because I wanted to ID it with the closest possible EXIF focal length, I coded it as the Tri-Elmar, which apparently is not necessarily the best option. Anyway, I made some Cornerfix profiles for it, but those have resulted in OK fixes, but not perfect, and given certain subject matter, reveal uneven color across the image. Also the strength of the vignetting, means that CF opens up the borders of the image significantly, resulting in a lot of noise, but also greatly changes the character of the files. I always end up adding vignetting back in through LR. I wish CF would allow only color shift correction and not vignetting correction for the batch process, but even in single file adjustment, my CV15 profile looked really bad when trying to only fix the color shift.
At the moment I use it when I need really wide, and if it's a darker environment where the vignetting and color shift can be masked, such as some indoor use, it works quite well. Otherwise I might just use it for B&W applications.
It's been some time since I've looked at my initial test images with it, and in hindsight, I think it looks better than I remembered...
But another challenge with the lens, if photographing anything with straight lines, is convergence/divergence, assuming you want to control it to some degree. It's just really difficult to line things up perfectly. For more organic scenes it's not such an issue.
The lens though is quite nice. Small, light and image quality is very good. Some CA but that can be fixed in post. It can flare, but I haven't used it enough to figure out which situations will trigger that. There are some samples below to illustrate this.
I'm curious about the M module for the Ricoh GXR and might investigate that system as a back up to the M. Considering the APS-C sensor, I will keep the CV15 for wide applications, though the unknown at the moment is how bad the color shift and vignetting will be on that sensor. Based on NEX users and wide angle M lenses, it seems it might be an issue..
I have read that the CV12 is less prone to the vignetting and color shift issues on the M9. Perhaps some day I will try one, but it's not high on my list of priorities at the moment. I'd prefer the older LTM version since it's much smaller without the new integrated hood design, so maybe if I find a used one at a reasonable price...
Here's a recent example where the environment masked the vignetting and color shift issues. Hand held 1/8 second wide open at ISO 2500 - yeah, it was dark in there 
Some samples showing pre and post Cornerfix. Note my contrast and clarity settings are bumped up somewhat from the LR default. You can see in the CF files that there is a section right along the edge of the frame that shifts magenta. I'm assuming a better profile will resolve that. Or, I should investigate using a different lens code. Or shooting it uncoded... All of the images are coded as the Tri-Elmar and the CF'd images have all had some degree of vignetting reintroduced.
Here's an example where CF's vignetting removal destroyed the character of the sun flare. In the corrected image it was really blown out and trying to recover it in LR looked artificial. It might still be possible to rescue it in PS by layering both images...
Also, a few uncorrected images that I decided to process as B&W. With all thses lines, the 15mm focal length was really fun to work with to exaggerate the perspective effect. Sorry if I've posted these before:
Carsten: Doh!
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