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Disappointing Canon Quality Control with RF 15-35 F2.8???

Started 3 weeks ago | Discussions thread
R2D2 Forum Pro • Posts: 26,536
Re: Disappointing Canon Quality Control with RF 15-35 F2.8???

johnpul wrote:

I think I'm going to keep the lens and mail it into a Canon repair center for some tweaking. Can anyone tell me what is causing this "ghosting effect" in the image? An aspherical element issue? I hope to steer them toward the problem. Note in particular

the mountain states toyota lettering.

The distinct double image in the far corners points toward astigmatism (common in ultra-wide designs).  My far corners at UWA exhibit a little of this too (but it’s really only seen wide open at high mags).  During normal shooting stopping down helps this.  If astig was better corrected then another area would likely suffer (given the same lens cost).

Of course shooting wide-field astro you wouldn’t be stopping down, so you’ll either have to crop it out, or buy a dedicated prime for this.  You can get good recommendations over in the Astro Forum.  Best of luck!

R2

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