EOS Ra: A great Full Frame Astrophotography mirrorless camera...

Franz Kerschbaum wrote:

Thanks!

One naive question: why are you not saving raws?

Hi Franz.  I'm not a fan of RAW images for non-critical work and I like to get what I can out of that processor Canon seemed so keep to bill me for.  The processors on the modern Canon cameras offer me a lot of versatility these days with plenty of DR and NR to play with.  I will certainly consider RAW when I'm using a more sophisticated mount for longer exposures and smaller apertures.  Even when shooting RAW, you still get the best results by accurately calibrating the Custom White Balance with the usual daylight/greycard method at midday (in direct sunlight) to ensure the right WB for Milky Way photography - if color accuracy is essential.  This is especially important with modified cameras.  But I know what I can expect from RAW so unless I really need it I don't often bother with them.  The RAW files from Ra cameras were annoying the heck out of some of the experienced astronomer reviewers who voiced their annoyance on YouTube .  I'm sure I'll get around to RAW later when using an EQ Mount, especially if stacking is involved.  These are non-critical tests for me.  Canon also designed the Ra to be used as a JPEG-friendly camera for those who wanted to treat it like one.

Would prevent you from most of your problems and uncertainies. Moreover, you can do your vignetting tests easily at home in front of a indor wall....

I did that.  The same vignette appears with or without a lens hood.  I also turned off all the Lens Corrections and then turned them back on again.  And with or without a filter on the lens, the results were the same.  I ran the same exposure times and settings with a shot of my white ceiling at night with no lights on.  The result was the very same vignetting with this lens.
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Obviously a wider aperture will increase the light-falloff in the corners of a fast lens with a wide FOV.  I am unable to reproduce the effect unless using wider apertures and higher ISO.  I'm just surprised that Canon says all our regular EF lenses will work the same on the R as on our DSLRs.
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Here's one from the other night (unedited and reduced to 1500 pixels).  The vignette is quite circular and closely follows the shape of the coma of this lens..

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I can only conclude that the wider apertures coupled with a potential projection difference on the EOS R sensor result in the sensor on the Ra seeing the edges of either the hood or the lens barrel itself.  I'd sure love to hear from another user with this same lens and an EOS R.  It's such a shame because this lens has been a solid performer for me over the recent years on both APS-C and FF DSLRs.
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Now the 50mm lens also vignettes.  I expected that it might but it's not quite as bold. It's still annoying and even with the lens registered with the camera and all three Lens Corrections made active with the EOS Ra menu, the lenses appear to be unaffected.  There appears to be an oversight in the design of the camera and or mount when dealing with certain wide aperture EF lenses because I've used these lenses on half a dozen cameras without the same degree of issue.
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I've applied:
* Lens aberration correction
* Digital Lens Optimizer
I've even applied Distortion Correction (which is likely to crop the image) with no success.  it's as if these features have no function with either of these lenses.  Now I'm reading about some RF lenses vignetting and in some instances non-Canon EF lenses have been shown to vignette hideously on the EOS R.  The only other method available appears to be to apply the "digital scissors" via the EOS R's 1.6x Internal Crop.

Bes wishes

Franz

PS: For same optics I have always less vignetting with the R/Ra than with my old 5D3 because of the more open lightpath. Especially the lower framecorner - where a dslr has its mirrorbox is mproved.

Are you using the same lens?!
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I was just about to sign off when I noticed that my Firmware is 1.5.0 on the EOS Ra I am using.  There's now a Firmware update (1.6.0) available.  I've just downloaded it and will update the firmware when my batteries are charged and I've removed the lens and mount adapter.  I don't imagine it will have any effect on the vignetting but I guess I'll find out.  I've sometimes been surprised at what a Firmware update can do.  Will report in when if the Firmware update produces any changes.