I wanted to test the Elmarit M 90 on set. Lately I have been using the Leica M Typ 240 for all my photography and so far so good. What I want to say about this longer lens is that it is difficult to achieve perfect focus. I was shooting at f/4 and still kept missing the focus point. I may have to recalibrate this lens though, I bought it used and it feels a bit wobbly. The reason for the lens to be harder to focus is not because the patch changes size or because is always non calibrated. Mostly it is because at a distance, the triangular focusing method used on a rangefinder has less separation. For example, the closer you would focus on the line where someone’s eye meets the edge of an eyelid but when you are about 15ft away, you simply cannot see that line so you focus on bigger lines, but bigger lines means there is more margin for error. That’s why it is more difficult to achieve perfect focus on longer lenses, its your distance to your object and where your eye lines become to hard to see. The magnifier will aid in this aspect, helping you magnify those eyelids or brows and help you achieve better focus.
The following is a good example on how I keep focusing front at a distance, it may be the lens. I focused on the closer deer on the right and it focused all the way back on the furthest deer.