Lens laws

[Journeyman]

Thanks for the info Arthur, some time needed to digest and understand.

I was thinking about the loss of focus and sharpness. When I am setting up to take a photo the focus point (mostly one point) moves almost the length of the bird, above the bird and below the bird. Quite a bit of drift involved. (Mono/tripod required)

I did not lose the photos as often on my previous Canon a 750D. Entry level and more importantly no back button focus. That meant that when I took the shot the bird was within the frame. After some thought I realised that I don’t fire the shutter as confidently with the 90.

I am going back to shutter button release, maybe use the back button to close in to the subject then use the shutter button to complete focus and shot. I have read that many photographers don’t use back button. I have always said, for me, that too much choice can be counter productive.

Neither of the two photos were cropped. Reduced in size to meet the forum guidelines. The rocks are all beautifully sharp. I have 3 lenses all 400. I am still considering which one to keep, something has to go. Probably, quality wise the 100-400. Although there are reviews of Sigma’s 50-500. Too many parts to that I reckon.

As far as lens/camera combinations work, does it follow that the true processing power of a fast lens lies in it’s ability to make full use of the system, writing plenty of data to the card and thus allowing for the image to cropped and processed to a full frame equivalent?

I need to relax and produce good pics. Back to the one item menu.

As always your advice is gratefully received,
Kind regards, Journeyman