Blue Tit arrives at nesting box

I made a new nesting box over the winter and have been rewarded by the appearance of a pair of blue tits who, by the evidence of the noise, have managed to start a family.

My aged Tamron SP 500mm mirror lens was used for these shots. The depth of field is about 2.5 inches at this subject distance, so accurate focus is essential.

I found that live view with 10 x magnification was better for focusing than the optical viewfinder with a Canon angle finder giving a 2.5 x magnification. This may be down to my eyesight, I can use my reading glasses with live view, but not with the optical viewfinder.

I may also try the Sigma 100-300 f4 with 1.4 converter and compare the results.

Canon 5D II.