19mm Canon stinks on R-D1, great on M8 ?

[kkdanamatt]

Help me with this. My Canon FL 19mm f/3.5 lens vignettes and is soft at every aperture and at every distance on my Epson R-D1. But on the M8, the images are sharp with almost no vignetting. I am using the Canon B Adapter to Leica thread and a Leica thread-to-M adapter ring. There is no six-bit coding.
My logic tells me that the smaller sensor of the Epson should vignette less than the M8 sensor. Plus, the equivalent focal length is 28mm vs. 25mm, so I figured more problems would occur with the M8.
Isn't the R-D1 using more of the center, the "sweet spot" of the lens, than the M8 is using? Or, does the problem occur because the rear element of the 19mm lens is very close to both sensors? Does the M8 correct for this and the R-D1 doesn't?
Oh, BTW, all my other Canon RF lenses (25mm, 28mm, 35mm, 50mm) are fine on both bodies.

 

[Phil_F_NM]

I think the theory is that there is a bit of microlens array in the M8 to correct for this but I may be wrong about that.
Regardless, the M8 is quite usable with lenses like this and the 21mm Super Angulon where the rear element is almost touching the shutter.
It could be that the thicker filtration over the sensor of the RD1 is causing scattering and softness of the image when using one of these true non-retrofocal wide-angles with a nodal point so close to the sensor.
The light rays coming in at such a steep angle might "smear" inside the filtration glass giving your soft effect. The M8 doesn't have any of that sensor filtration.
I'm just grasping at a few straws here.
Feel free to send me that 19mm FL if you get fed up with it. 😀

Good luck!
Phil Forrest

 

[menos]

Phil, you are completely right about that.
The R-D1 is a lot less usable with the critical lenses, that are close to the sensor.

It can give quite different image quality with same lenses between M8 and R-D1.
I almost sold a Leica 35 Cron ASPH, when I used it on the R-D1, just to find, that it is one brilliant lens with the digital Leica and shows none of the severe imaging issues, it shows with the R-D1.

 

[kkdanamatt]

Thanks, I suspected that the R-D1 was at fault, not the lens. I uploaded the R-D1S firmware and re-tested with the Canon 19mm and the results still look terrible. Do you think that the same problems would occur with the 15mm Heliar on the R-D1S? Can anyone comment on that combination?

 

[The Meaness]

I've had nothing but great results with the 15mm, but I don't think the rear element protrudes into the camera much more than my 28mm zm does. Kind of amazing when you think about that.

R-D1, cv15 (m mount)

 

[menos]

Thanks, I suspected that the R-D1 was at fault, not the lens. I uploaded the R-D1S firmware and re-tested with the Canon 19mm and the results still look terrible. Do you think that the same problems would occur with the 15mm Heliar on the R-D1S? Can anyone comment on that combination?

It does work better on film or the M8. The R-D1 vignettes strongly with the 15mm.
I don't use the 15mm on the R-D1, but that is mainly, that I end up with a not so wide anymore, slow lens.
I can not comment on comparing the Canon with the 15mm.
I don't think also, that the protruding measurement of the rear element alone is a sole factor of image degradation with the R-D1.

I suppose, there are other things going on as well (the 35 Cron ASPH is not that extreme a lens after all, yet, it nets some very strange issues on the R-D1).

If really wide, but sharp and no vignetting is, what you're after, I guess, you won't come around a nice film body (Bessa) or spend much more on a digital M 🙁 There is no free lunch with wides on the R-D1.

If I remember correctly, there has been a great article on wide angle lenses by Sean Reid on either his (excellent) pay site or as a guest article on Luminous Landscape. It is not dedicated to the 15mm, but to more medium wides (~28mm), if memory serves me right.
There might be some commenting towards vignetting, and alike + remedies.

 

[ferider]

The wider the lens the more sensitive to variations of registration distance.

My bet is it has nothing to do with vignetting, etc, in particular if you look at center sharpness.

Do some focus tests on the RD1. Use a test target a few meters away and change focus minimally and see what happens. If this positively affects the behavior, you can correct by modifying the M/LTM adapter.

Roland.

 

[stupid leica]

i'd like to see some test pics, i am curious how terrible it is.

 

[kkdanamatt]

I trashed all the test shots with the Canon 19 and the R-D1 and re-formatted the SD card. I'll try to do some re-testing next week, but I fear the results will be the same. I shot RAW, at a 45 degree angle on a stucco sided house, focused at 3 feet, then 3.5 feet, then 4 feet, etc. Then took some outdoor scenic shots with grass, trees, etc @f/3.5, 5.6 and f/8. Every shot was somewhat soft, with edge vignette, and lackluster saturation. RAW conversion using the Epson software helped somewhat, but not nearly enough.
However, with the M8, all is well. But, as I said in my original post, I'm quite happy with the Canon RF 25, 28, 35, and 50mm on the R-D1.