I recently ordered some lenses in an attempt to gather more light from an object being imaged in very low light conditions. I'm trying to use a converging lens with the object > 2f from the lens so it projects a smaller real image at the camera lens. Unfortunately I ordered some 75mm plano-convex lenses with a 75mm focal distance only to find they are very distorting like fish eye lenses.
Image quality is important, so I'm wondering at what d/f or other physical attribute starts to cause extreme image warping?
Below is a concept of what we are doing. As for how much distortion is tolerable, i don't know how to specify that, other then we are open to some, as a trade off for more light.
Also, this was a concept I had, I have yet to verify it will send more photons towards the camera... I believe it will, but no one has confirmed or denied it yet... So let me know if this is just a poor idea.