What is the focal length you use the least ?

10mm-23mm

I use a 10-18 some but I use it for fun venue/environmental shots.
I use my Sigma 18-35 for most wedding photos but I tend to stick in the 24-35 range.

85mm. very rarely. Actually 51mm to 99mm to be exact.

My thoughts too.

i like this thread. very interesting in regards to the behaviors of other photographers

in my use, i tend to use the extremes of each of my lenses
so the middle gets relatively ignored.
so 24-105 - the 40-60 gets ignored
the 70-200 which I dont use that much I would say is mostly used at 150-200, and rarely at 70-100
and the 100-400 is usued pretty much evenly.

my macro lenses as macro lenses get less work than that...
but that is my busy schedule more than true desire....

in regards to the aperures.... i usually use them as open as I can get on the specific lens.
macro I dont do fully open
and the 85 1.2 i have stopped down multiple times for DOF control
but usally wide open as wide open can be....

I have a 50mm F/1.8 that acts as a dust-cover for my 20D (neither have been used in over 5 years...)

with my eos 50d mostly interiors 12-40 outside 140-190

I only have 3 lenses as seen in my sig. I use the 10-18 STM the least.

ceriltheblade wrote in post #17778279
i like this thread. very interesting in regards to the behaviors of other photographers

in my use, i tend to use the extremes of each of my lenses
so the middle gets relatively ignored.
so 24-105 - the 40-60 gets ignored
the 70-200 which I dont use that much I would say is mostly used at 150-200, and rarely at 70-100
and the 100-400 is usued pretty much evenly.
...

That's quite common to use the zooms at their extremes.
I used to have most of my zooms deciding the FL in relation to the frame and (sometimes) amount of blur I wanted to achieve.
Getting more into primes I have learnt how each FL can render differently in terms of compression, perspective, distorsion and very importantly ultimate intimate relationship with the subject. And this is not only true for portraits but also for landscapes.

Now when using zooms I tend to think which FL would help achieving that effect and I find myself looking at the distance scale to select the FL as I had to decide which lens to mount...

70-100mm