Spitfire Gunsight adjustment?

[SEE]

British ac had 105mill gunsights, simply put a FW wing tip to wing tip in your sight ring is 100m away - half the size in your gunsights (dot to edge of circle) and he is 200m away, etc.

A BF109 is pretty well similar but a HE111 has approx twice the wing span, if he is wing tip to wing tip in your sights then he is 200m away. So, if your convergence is set to 200 yds (very slightly less than 200m but close enough in combat sits) you can gauge the distance of your ac to your gun convergence.

The sight crosshairs can be moved to correspond to set distances/wing spans but the Spit/Hurri gunsight circle remains unchanged and the rule still applies (if you are Ok with estimations based on flying Spits in IL1946).

Not used Icons so interested to see if there is a dicrepancy.

EDIT: Checked and spot on.....