D-Lux 4 conversions

[ho_co]

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My thanks to everyone who responded to my plea for assistance in http://www.l-camera-forum.com/leica-forum/digital-post-processing-forum/76724-what-am-i-doing-wrong-tiffs.html. Without their help I wouldn't have been able to post these pictures.

 

 

Here are examples of the three available correction levels from a single D-Lux 4 shot. I hope they're helpful in understanding the versatility of the camera.

 

When I shot, the camera wasn't square with the wall of mailboxes, so the horizontals and verticals converge. The camera also wasn't quite level, so the images seem to slope downhill to the right. I made a single shot with the lens set to its widest angle. All these images could have been produced from the RWL, using an Adobe product for the middle level of correction and Capture One for the lowest and highest levels of correction.

 

Capture One's TIFF from the RWL is just about fully corrected, with virtually no distortion:

 

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The JPG produced by the camera shows a bit more barrel distortion than the C1 TIFF. All Adobe options (PSD, DNG, JPG, TIFF etc) look the same as this. The little bit of distortion means you get just a little more information in the image--see the mailbox locks at the right edge. And the distortion can be removed easily in your image processor.

 

 

 

The Capture One DNG from the RWL shows the truly raw data, with chromatic aberration and a great deal of barrel distortion. The corrections you see in the other versions are done by software instructions generated by the camera and packed into the RWL file. This is one of the really innovative features of the latest Panasonic/Leica cameras. Take a look at the edges to see the tremendous amount more image information here than in the other two conversions. You could use this image as-is for special effect, or remove as much of the distortion as you want: With the C1 DNG, the choice is yours. But keep in mind that while Capture One Version 4.5 can produce DNGs from the D-Lux 4's RWL files, that option is no longer available in Version 4.6.

 

[Richard D]

Howard,

Thanks for the images. A couple of questions:

 

1) When you mention chromatic abberation, do you mean the blue cast on the right?

Usually when I think of CA, it's color fringing, but I don't notice any with the small images the forum allows.

 

2) What do you think accounts for the additional information at the edges on the JPEG? It seems to be greater on the right side, but that may be only because it's harder to judge on the other three sides.

 

Since the barrel distortion is so easily corrected, I don't mind it so much, but it certainly is a ton. Good for giving skinny women some curves??.......:-)

[ho_co]

Richard--

Thanks for your observations. I'm glad someone besides me found the comparison interesting!

...1) When you mention chromatic abberation, do you mean the blue cast on the right?

Usually when I think of CA, it's color fringing, but I don't notice any with the small images the forum allows. ...

Yes, it's red-cyan color fringing. In the bigger versions it's more noticeable. It's also more visible in the comparison I did with and without the wide angle converter (http://www.l-camera-forum.com/leica-forum/digital-forum/76883-d-lux-4-wa-conversion-lens.html). But you're right to question whether that's the correct term for it. I think so, but I may be wrong.

 

 

... 2) What do you think accounts for the additional information at the edges on the JPEG? It seems to be greater on the right side, but that may be only because it's harder to judge on the other three sides. ...

I think that's it. It's just that the locks at the right are easy to observe. Using the originals, I've flipped back and forth between the JPG and the TIFF, and the JPG is extended on all sides, not just the right. That is, after all, what barrel distortion does. (You should see the image from the C1 DNG with the WA converter. I didn't post it because it falls between these two threads' topics. It's not much exaggeration to say that the coverage and barrel distortion remind of a fish-eye lens.)

 

 

Since the barrel distortion is so easily corrected, I don't mind it so much, but it certainly is a ton. ...

That's what's interesting to me: Since the C1 TIFF almost fully corrects the distortion, that's clearly doable from the information packed in the RWL. But the camera leaves some in the JPG (LFI said something like "The 3% barrel distortion is manageable"). And Adobe said somewhere that their software corrects the image to the degree that Leica (and Panasonic) wanted.

 

Having said that, however, in some images, the less-corrected versions (the JPG and sometimes even the C1 DNG) are actually more pleasing to the eye. By leaving some uncorrected barrel distortion, they avoid some of the so-called "wide angle distortion" at the edges. The fully-corrected TIFF in those cases seems to stretch the corners unnaturally, and the version with less-corrected distortion looks better.

[Richard D]

Richard--

 

 

 

I think that's it. It's just that the locks at the right are easy to observe. Using the originals, I've flipped back and forth between the JPG and the TIFF, and the JPG is extended on all sides, not just the right. That is, after all, what barrel distortion does. (You should see the image from the C1 DNG with the WA converter. I didn't post it because it falls between these two threads' topics. It's not much exaggeration to say that the coverage and barrel distortion remind of a fish-eye lens.)

 

 

Howard,

Thanks for the additional test photos of the converter, and an excellent post. I've been wondering about investing in the WA converter myself, but the plastic threads sorta scare me.

 

Back to the barrel distortion. I still don't understand why there is more info in the distorted (uncorrected) version. It seems to me that the correction just moves the information around- squeezing it here, squeezing not so much there, stretching it in the corners, etc. What's wrong with my thinking?

Thanks,

Rich

[ho_co]

Richard--

I'm bothered by the plastic threads on the camera as well. Both the adapter ring and the conversion lens mount seem to be of aluminum, so I didn't like the feel of the way they screwed together. And in comparison, I was pleased that the feel of mounting the adapter ring to the camera was fairly smooth. But the instructions warn you not to overtighten. Of course, that's SOP, isn't it?

 

I'd like to get someone's view of this plastic, though. I'm no engineer, but this plastic is definitely not the same as grocery-store bottled water packaging. It's rather interesting in appearance and in shape (remove the lens flange to see what I mean). Quite curious.

 

 

As for the barrel distortion: I don't think there's much to understand. Because of distortion, the lens takes in a lot more information than it would if it were rectilinearly corrected. (Think fisheye, where distortion is used specifically to widen the field as much as possible.)

 

That is, for a good final output there are two approaches: The 'old way,' used by everyone before this latest series of cameras, was to produce a lens with as few distortions as possible. How to do this? Use lens-design software to tweak the lens to fill the format with as few residual aberrations as possible.

 

The 'new way' just moves that final software step into the camera: The lens isn't physically that well corrected, but the final adjustments are programmed in firmware. Again, think fisheye: Because of its distortion, the lens sees a bigger area than will fit into the alloted format. (Fisheye lenses are fisheyes because of their rampant barrel distortion.) So your explanation is exactly right: To make the picture "look right," i.e. to make it more or less rectilinear, the firmware just corrects the distortion, which is done by 'moving things around.'

 

Similarly, Nikon lets you buy software to match their fisheyes: The fisheye produces distorted images (by definition as fisheye), but you can use the software to stretch the edges back to where they would be if the picture had been shot by a rectilinear lens.

 

In other words, because of distortion in both cases the lens sees more than will fit on a standard frame. Now you've got your choice of leaving all the curved lines for effect, or correcting them. If you straighten the distortions inside the frame offered (16:9, 3:2, 4:3), some of the information moves outside the boundaries of the format. It was only captured because the lens didn't "see straight," and if we bend those lines straight, the edge data move out of the frame, where they would have been to start with if we had used a rectilinear lens.

 

So your observation is correct: It's just straightening the lines, which means moving them by stretching the image. In the case of the Panasonic/Leica cameras, that's done in firmware or software after taking the picture. In the case of more usual designs, specifically cameras with interchangeable lenses, distortion correction comes at the lens design stage before the lens is built.

 

 

Thanks for your interest! As you see, I'm fascinated by these new ideas in lens design, and enjoying do what little I can to understand it better.

 

As for the converter, I think it's more useful for special effects than as a general 18 mm equivalent lens. As such, I don't think the plastic thread on the camera is likely to produce any problem. But I've only had the conversion lens for a week, so I have yet to se how it fits itself into my arsenal.

[Richard D]

Howard

I got it - I'm correct but I'm wrong......;->

No really, thanks. I have a headache.

Rich

[Richard D]

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PS:

I think I've talked myself out of the WA conversion. With Leica not locking the lens position and the worry that I might be in a hurry sometime and strip the threads. Besides, the 24mm equivalent is enough. One thing I've always noticed in my own photography, however, is that if I'm carrying the wrong focal length, it's invariably the wide angle I'm looking for, and not the tele.

 

Still waiting for Panasonic to start shipping their viewfinders to dealers again. At the right price, there's one in my future.

[ho_co]

I got it - I'm correct but I'm wrong......;->

Gee, Rich, I didn't think I was that harsh! After all my techno-gibberish, I realized that your description of sliding bits around is exactly right.

 

Actually, you've given me the idea of not only using the distortion for 'artistic' purposes, but also trying straightening it to see the effect. To straighten the bent lines would mean enlarging the canvas size and making a pincushion-shaped image. Maybe that would be interesting. (Think I've got too much time on my hands? )

No really, thanks. I have a headache.

Funny, I had one as well when I finished with that last post.

 

 

I think I've talked myself out of the WA conversion. With Leica not locking the lens position and the worry that I might be in a hurry sometime and strip the threads.

No, on this you're wrong. (Direct, huh?) (If I understand you right, that is. )

 

First: The adapter screws to the camera. No part of the mount moves. When you unscrew the covering ring on the camera, you'll see that the mount is fixed.

 

Second: The lens at its widest (24 mm equivalent) protrudes furthest from the body, and doesn't conflict with the conversion lens (or any other accessory mounted to the adapter ring). As you zoom toward longer focal lengths, the lens retracts.

 

So the only time you could mess up and possibly strip the threads is when you're actually mounting or unmounting the adapter.

 

I think the question of buying the wide-angle attachment or not should be based on whether you think the wider coverage would be nice to have (I do) and whether you can accept the lessened image quality. I'll need to do some more shooting before I can answer that. So far, I'm fairly satisfied.

[Richard D]

"So the only time you could mess up and possibly strip the threads is when you're actually mounting or unmounting the adapter."

 

Yes, that's what I meant. Plastic threads, and me not being careful or in a hurry.

 

"Second: The lens at its widest (24 mm equivalent) protrudes furthest from the body, and doesn't conflict with the conversion lens (or any other accessory mounted to the adapter ring). As you zoom toward longer focal lengths, the lens retracts."

 

Farthest from the body; yes I realize that. Peculiar, huh? But because Leica doesn't lock the lens into position (as Panny does from its menu),

I'm not comfortable that it's always in the exactly correct position. Even though it seems to be farthest from the body.

[Richard D]

I just now noticed your other thread about the LX3 and the WA conversion. I downloaded the Panasonic instructions months ago, because they are so much more complete than the Leica version. Like you, I was struck by the inference that the LX3 may be making other corrections than simply locking the lens. You may want to pose the same question on a Panny forum.

[ho_co]

"So the only time you could mess up and possibly strip the threads is when you're actually mounting or unmounting the adapter."

 

Yes, that's what I meant. Plastic threads, and me not being careful or in a hurry.

 

"Second: The lens at its widest (24 mm equivalent) protrudes furthest from the body, and doesn't conflict with the conversion lens (or any other accessory mounted to the adapter ring). As you zoom toward longer focal lengths, the lens retracts."

 

Farthest from the body; yes I realize that. Peculiar, huh? But because Leica doesn't lock the lens into position (as Panny does from its menu),

I'm not comfortable that it's always in the exactly correct position. Even though it seems to be farthest from the body.

Rich--

I figured you were aware of these points, but didn't want to make wrong assumptions.

 

As a matter of fact, I tried using the zoom with the WA attachment. I haven't compared the result at high res, but my initial impression is that it works. The wide-angle attachment was designed to match the lens at full wide angle, I'm sure, so performance wouldn't be so good as you zoom to telephoto, but I think it's adequate. So we've got more focal latitude on the D-Lux 4. That is, if you wanted an 18-45 mm equivalent, the WA conversion lens gives it to you.

 

Yes, it's an interesting design that makes the widest angle of view also the physically longest.

 

But then, I'm still trying to find the results of all this.

[ho_co]

Here are two D-Lux 4 examples from the Houston Via Colori Festival, Nov 23-24, 2008. Both were processed in Capture One and are shown in two versions, one from the full-info Capture One DNG, and the other from the fully-corrected Capture One TIFF.

 

This is from the DNG and looks quite natural to me.

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Distortion has been removed from the TIFF, but look at the objects near the edges of the frame, both the shape of the artwork and the shape of the people. To me, they seem stretched and unnatural. This is a case of "perspective exaggeration," in which the technically better corrected, less distorted image below actually doesn't look as good as the less corrected one above.

 

 

I feel the same way about this pair. Again, the first 'feels' good to me. It comes from the Capture One DNG.

 

Again, the TIFF is technically better corrected, with less barrel distortion than the DNG, but removal of that distortion adds to the so-called "wide-angle distortion" or "perspective exaggeration," and objects (including people) near the image edges look stretched and unnatural.

 

 

There were only three or four of the 57 shots I made with the D-Lux 4 at this event in which I felt the uncorrected DNG looked better. But that's enough, in my opinion, to leave the DNG available for use.

 

Both Leica and Panasonic have now denied us that option, and done so (AFAIK) without offering a reason. As far as that goes, I doubt that they could offer a reason good enough that I would accept it, since at first the full-info original was made available.

 

I'm reminded of the US Administration's generally successful efforts in 2001-2008 to re-classify government records that had been available to the public, and make them Classified or Secret.

 

With government that may be defensible, but denying artistic information? Isn't this analogous to the photo lab saying, "You may have the print, but the negative is ours"?

 

 

 

BTW and FWIW, I've posted two other threads on D-Lux 4 imaging that are deader than this. One of them (http://www.l-camera-forum.com/leica-forum/digital-forum/76883-d-lux-4-wa-conversion-lens.html) shows the effects of the wide-angle conversion lens, while the other (http://www.l-camera-forum.com/leica-forum/digital-forum/77023-question-lx3-owners.html) raises a question about whether we D-Lux 4 owners got cheated in regard to using that conversion lens as compared to our Panasonic brethren. After Rich's suggestion above, I posted a repeat of that third thread at Effects of menu setting for wide-angle conversion lens: Panasonic Talk Forum: Digital Photography Review.