That’s exactly why they are using commercial lenses! Canon’s modern AR coatings are so good that the performance for low-surface brightness imaging beats large

That’s exactly why they are using commercial lenses! Canon’s modern AR coatings are so good that the performance for low-surface brightness imaging beats larger-aperture telescopes which can gather more light but scatter it around the image. See the third page of https://arxiv.org/abs/1401.5473 https://arxiv.org/abs/1401.5473