Please don’t be put off by the length of this post
2 things on my mind
First; if I take a picture with a 300mm lens on either a full frame or a crop the resulting image on the actual sensor will be the same size. This means that a full frame will have more space around the point of interest than the crop if its at the extreme of the zoom
So if I enlarge the point of interest to the same size – say fill an A4 sheet with a building 400m away the enlargement will be the same on both full frame and crop as the image was the same size on the sensor.
So take the case where the image size on the sensor measured 20mm – almost filling the crop viewfinder but just over half of the full frame available size - then I am going to have substantially more pixels on the point of interest with the crop than the full frame as the pixel density on the crop is much higher than the full frame. For example the 7D is 18Mp on 22.3x14.9 (around 54000 pixels per square mm) and on a 22Mp 5Diii at 36x24 (around 25500 pixels per square mm). I know the 5D pixels, being better spaced are of better quality than the 7D but are they twice as good
Second; the 7D has been out for a few years now and electronics etc have advanced a lot since its introduction. Will a 7D bought today have exactly the same circuitry etc as one manufactured a few years ago or do Canon introduce minor improvements during the life of the camera as most of industry do. For example have they slightly reduced the triple A filter strength due to criticism or is it the same as on the initial cameras
I’m trying to decide/justify looking at the 5Diii and I am having ‘issues’ convincing myself its worth the cost difference. I currently have a 50D
I would appreciate some feedback and either agreement with what I say or reasons why I’m wrong because it does seem to simple to be correct