Sagitar Posted June 29, 2015 Report Share Posted June 29, 2015 Fuji issued a firmware update for my camera today. It is intended to improve the follow-focus function used to keep a moving object in focus. Having installed the update I fitted a long-focus lens and took the camera into the back garden to see if I could try it on birds or passing aeroplanes. A micro-light appeared and flew around for a while giving me a good chance to use the follow focus function. Here is one of the pics I took of him. I guess he was at about 500 to 1000 feet and as I tracked him, a passenger aeroplane, probably just having taken off from Luton Airport, crossed his path at a much higher altitude giving me the chance to get both aircraft in frame. They look close together, but there might be as much as 10,000 feet or so of vertical separation. Quote Link to comment Share on other sites More sharing options...
Tony Posted June 30, 2015 Report Share Posted June 30, 2015 Stunningly clear and as for the plans position what luck was that..... Makes me think though how does it manage to focus objects that are different distances? Quote Link to comment Share on other sites More sharing options...
Sagitar Posted June 30, 2015 Author Report Share Posted June 30, 2015 Stunningly clear and as for the plans position what luck was that..... Makes me think though how does it manage to focus objects that are different distances? As objects get nearer or further from the lens, the angle subtended by the light rays passing from the object to the lens get bigger or smaller so we have to change the distance from the lens to the camera sensor in order to bring the rays into focus at the sensor plane. When the object is a long distance from the lens the rays reaching the lens are effectively parallel to each other and moving the object further away makes no effective difference i.e. the rays remain parallel and no change is required in the lens to sensor distance. This is the concept of "infinity" applied to a lens. The reason why both objects are in focus is that they are both beyond the distance at which the lens is focused at "infinity". So as far as the lens is concerned they are both at the same distance. Quote Link to comment Share on other sites More sharing options...
Tony Posted June 30, 2015 Report Share Posted June 30, 2015 Thanks.... I actually understood that. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.