WestCoastCannuck wrote in post #18535898
Actually... for shooting the moon, or any distant object, the 7D2, or most current crop frame cameras are MORE crop-able than the A7rii or my A99ii which has the same sensor. That is why I shoot the moon with my A77ii. 24mp.... compared to the 18mp in the same sensor area of the A99ii when using crop mode.
EDIT: It just occurred to me that you probably know this and are comparing the two cameras in a general way rather than specific to shooting the moon. If so, my apologies - and we shall just let the above statement stand for those who don't!! lol
Just to point out, for all parties here, the resolution of your sensor won't pull anything more than the aperture size of the instrument used can allow, as its the determination of actual resolution before you even begin to try to capture the image. So at the end of the day, whether you're using 10MP or 50MP or any sensor size with pixel sizes ranging from 5.8um to 2.5um, you'll not have optimal sampling in most cases because of the pixel size match to focal-ratio and all of which is being captured through, at least in these examples, small aperture instruments, which means the detail is limited to that scale where you're way oversampled. This is why you can't resolve detail in craters or around structure on the surface with these smaller aperture lenses, whether you're using an A7S or a 5DSR, because a lot of these lenses being used have barely between 2.5 to 3 inches of actual aperture which is the limit of resolution here.IMAGE LINK: https://flic.kr/p/PxjZNs GassendiCrater_MareHumorum_12102016
If you really want to get detail on the moon, you need aperture, not megapixels, and sensor size doesn't matter (pixel size with appropriate focal-ratio does matter to achieve ideal sampling). Sensor size tells you surface, and number of pixels on that surface determine's pixel size. It will effect field of view with the instrument, but if you want to capture detail, matching the pixel size to the focal-ratio for sampling is what's important, second to simply having a large enough aperture to resolve what you even want to resolve. The whole system is about optimizing the physics of light and the limitations of reducing blur sources in the system.
For example, the camera used to capture the following detail was only 6.4MP (3096 x 2080, with 2.4um pixel size for surface) and it was much, much smaller than an APS-C sensor (1/1.8"), and a fraction of the cost of a dSLR/mSLR (ASI178MC, $350). The reason I was able to resolve detail within a small crater (gassendi Crater) to show mountains, craterlets, and other small surface details was because the aperture of the instrument used was 150mm (6 inches). This a humble $399 new instrument (Celestron C6). But the physical principles here are being used for the purpose. Bigger aperture is how you resolve detail, it's the beginning of resolution. Good seeing is the absolute limit of magnification (which limits focal length). Sampling ideally will go much farther too (and here, I'm not ideally sampled, I pushed the system only because I had good seeing and could risk it):
by Martin Wise
, on Flickr