R5 lunar photography with stacked EF extenders

Marco Nero wrote:

PhotosFlight wrote:

A little help please. I have the 1.4 MII and 2x MIII. I'm missing something because it feals like I would be forcing it were I were to stack them.

The EF 1.4x II is not as sharp (optically) as and EF 1.4x III Extender because it's an older design that was produced for pre-digital lenses. Adding one to an EF 2x Mk III Extender would result in (A) softening of the image from the EF 1.4x III Extender and (B) a further reduction of contrast and loss of image resolving due to the longer focal length of the 2x Extender being coupled with it. We do get more actual magnification from stacking two extenders together but there's a cost. The trade-off is in the amount of light lost and the optical consequences of putting too many glass elements between the subject and the sensor.

Technically the light is not lost, it's just spread out over more pixels, or photo-buckets, if you will. So, the buckets still collect essentially the same number of photons, but each one has fewer photons in it. Each pixel is noisier, but when you take them together in scale, the overall image is not noisier.

The converter increases the focal length, and therefore the aperture ratio (f/number), but the overall aperture is the same. The diameter of the optical tube doesn't change, so the same flow of photons from the subject are captured.

The trade-off is whether the extra glass hurts more than the extra pixels help.