Astigmatism and focusing a camera A thought experiment: assume I have poor eyesight, but using a viewfinder or an LCD screen I was able to focus a camera on an object or landscape with what seemed to me perfect clarity. I took the picture.
Because the image was created under the conditions of my vision, will the developed picture still be in focus for me when held out at some appropriate distance from my eyes? And will it be blurry for others with better eyesight when held out at any distance from their eyes?
 A: There could be several things going on here.
First, the LCD and viewfinder are much closer to your eye than the object you're photographing. If your astigmatism makes you more near-sighted, then the LCDs could be easier to see and focus on compared with the faraway object being photographed.
Second, the LCD and viewfinder (which I'm assuming is also an LCD) screens are bright light sources. This means that your pupils are probably contracted when you look at them. When your iris is contracted, it is a smaller aperture that increases the depth of field, which makes all optical systems (your eyes and a camera) easier to focus. If you have an SLR camera where the viewfinder looks through the lens, then you are seeing an image created from light gathered by a lens much larger than your iris, making the image brighter, leading to a similar result.
Third, the LCDs on your camera are much lower resolution than either natural vision or the photograph that is ultimately taken. Low resolution displays tend to make images look sharper than they actually are. There could be other things going on as discussed in this answer from the Photography Stack Exchange.
A: If the camera was not producing an indicated in focus image at the viewfinder screen, which the crosshatching or that round mirror in the middle of the prism (however your given camera viewfinder optics work) would indicate image focus to the optics of the camera regardless of how in focus out of focus or astigmatic you see the viewfinder screen, than the developed image would be blurry, period. The incoming rays would not have been brought into a sharp focused plane at the film/sensor plane. The produced image would not appear clear to you, as you would be seeing a blurry image through blurry eyes. The image would appear blurry to everyone, but more blurry to you. To the best of my knowledge you can't do a corrective optics function after the fact. An image captured blurry will be a blurry image. Of course, thats for standard realms of photography. That deconvolution stuff is getting crazy these days.....
