As seeing will effectively make stars extended objects a low focal ratio should get me fainter stars without very long exposures. Combined with the larger apature to give me more photons and better signal to noise ratio, I thought a hyperstar would be a good choice. However I say a review that said they weren’t suitable for photometry, but it gave no explanation as to why, and I couldn’t think of one. To me it looked like a win, win situaction. How bad would undersampling need to be before it is an issue?