I really need to get a fast wide for night photography and the RF 20mm F1.4 VCM has got amazing reviews for Astro/northern lights photography with reportedly the best coma control than any other Canon Wide angle lens.
It’s also reportedly extremely sharp at 1.4.
Questions I have is how good is this lens as a general landscape lens, if stopped down to F11 Older lenses designs usually gap optimal sharpness when stopped down 3-4 stops. Which on the RF 20mm F1.4 VCam would be F4 to F5.6. Any idea for those that have lens, how it performs when shooting in that F9-F11 rang When does diffraction become an issue with this lens
The question I have is how good is the lens stopped down
In the TDP comparison tool test for this lens appears to show this lens to be diffraction limited at around f/2.8. It's somewhat difficult to see the difference between f/2 thru f/5.6 as this lens is very high resolution overall.
You may have to cut & past the link into your browser. You may also need to go find the lens again if both test subject fields are not populated with the RF 20mm F1.4L VCM and its comparison settings when the web page opens.
For comparison of this lens, set f/2.8 on one test subject sample side and then again to itself set at f/4 on the other test subject side.
If you are not familiar with the use of this web page, remember to use your curser to flip the direction of the large red arrow that indicates which test sample is being viewed.
I debated over the 20 VCM and ended up getting one. The lens has really good image quality easily bested my 24ts-e II. So much so I recently sold the TS-e. It's sharp fast and focuses really close allowing for some really unique perspectives. The only real drawback is reliant on digital distortion corrections. If you can accept that you will not be disappointed. I have not yet photographed the aurora, but the milky way shots that can be made are stunning wide open. I haven't pushed it to see about diffraction but I have been happy out to f11 with my R5, I typically don't push any lens past that anyway.
khurram1 wrote:
I really need to get a fast wide for night photography and the RF 20mm F1.4 VCM has got amazing reviews for Astro/northern lights photography with reportedly the best coma control than any other Canon Wide angle lens.
It’s also reportedly extremely sharp at 1.4.
Questions I have is how good is this lens as a general landscape lens, if stopped down to F11 Older lenses designs usually gap optimal sharpness when stopped down 3-4 stops.
Two or three stops for the image center, four to five stops for the corners.
Which on the RF 20mm F1.4 VCam would be F4 to F5.6. Any idea for those that have lens, how it performs when shooting in that F9-F11 rang When does diffraction become an issue with this lens
The question I have is how good is the lens stopped down
I have the lens, and find its performance excellent. I don't think I have used it at f/11, but the performance of any lens cannot be better than the theoretical diffraction limit for a given f-number.
Pete73 wrote:
I debated over the 20 VCM and ended up getting one. The lens has really good image quality easily bested my 24ts-e II. So much so I recently sold the TS-e. It's sharp fast and focuses really close allowing for some really unique perspectives. The only real drawback is reliant on digital distortion corrections. If you can accept that you will not be disappointed.
Without the corrections you would not have such good image quality in such a small package.I wonder what those who are still objecting are thinking.
Photonadave wrote:
In the TDP comparison tool test for this lens...
Those tests are consistent, but unlikely to be relevant to the OP’s intended use for the lens, because of subject distance. A lens may perform differently at different distances.
According to TDP’s description of their test setup, it’s a test chart in a dedicated space, with heavy components not easily moved. It doesn’t say, but unless the dedicated space is huge and he had a crane to get the 1/2 inch glass backing plate in, the target is unlikely to be more than 1.5m or so across. For a 20mm lens, that would put the distance at around 750mm × (20/18) = 830mm. Even if the chart were wall-sized it would still be only 2 to 3 metres away.
For this lens and this use case, you’d want inifinity tests like Gordon Laing’s ones of Brighton Pier. In the absence of those, anecdotal observations from people here having used it at long distances and infinity would be more useful than standardised tests of the wrong thing. It is complicated in this case by it being a VCM lens, which means it might be optimised for the mid-range distances most videographers will be using.
Photonadave wrote:
In the TDP comparison tool test for this lens appears to show this lens to be diffraction limited at around f/2.8. It's somewhat difficult to see the difference between f/2 thru f/5.6 as this lens is very high resolution overall.
You may have to cut & past the link into your browser. You may also need to go find the lens again if both test subject fields are not populated with the RF 20mm F1.4L VCM and its comparison settings when the web page opens.
For comparison of this lens, set f/2.8 on one test subject sample side and then again to itself set at f/4 on the other test subject side.
If you are not familiar with the use of this web page, remember to use your curser to flip the direction of the large red arrow that indicates which test sample is being viewed....Show more →
Thanks! I rarely go above F11 and used to have the TSE 24 and 17. If it’s better than the 24, than I think I should be good. I’m satisfied with the 14-35 digital corrections, so not concerned that the lens profile will be required to correct distortion and vignetting.
Pete73 wrote:
I debated over the 20 VCM and ended up getting one. The lens has really good image quality easily bested my 24ts-e II. So much so I recently sold the TS-e. It's sharp fast and focuses really close allowing for some really unique perspectives. The only real drawback is reliant on digital distortion corrections. If you can accept that you will not be disappointed. I have not yet photographed the aurora, but the milky way shots that can be made are stunning wide open. I haven't pushed it to see about diffraction but I have been happy out to f11 with my R5, I typically don't push any lens past that anyway....Show more →
melcat wrote:
Those tests are consistent, but unlikely to be relevant to the OP’s intended use for the lens, because of subject distance. A lens may perform differently at different distances.
According to TDP’s description of their test setup, it’s a test chart in a dedicated space, with heavy components not easily moved. It doesn’t say, but unless the dedicated space is huge and he had a crane to get the 1/2 inch glass backing plate in, the target is unlikely to be more than 1.5m or so across. For a 20mm lens, that would put the distance at around 750mm × (20/18) = 830mm. Even if the chart were wall-sized it would still be only 2 to 3 metres away.
For this lens and this use case, you’d want inifinity tests like Gordon Laing’s ones of Brighton Pier. In the absence of those, anecdotal observations from people here having used it at long distances and infinity would be more useful than standardised tests of the wrong thing. It is complicated in this case by it being a VCM lens, which means it might be optimised for the mid-range distances most videographers will be using. ...Show more →
Older lenses designs usually gap optimal sharpness when stopped down 3-4 stops. Which on the RF 20mm F1.4 VCam would be F4 to F5.6. Any idea for those that have lens, how it performs when shooting in that F9-F11 rang