Log Scale for pure negative numbers

I often show isocontours for Lambda2 criterion and need a logarithmic scale for purely negative numbers, e.g. from -.01 to -.1. If I want to use the log scale I first need to insert a calculator flipping the sign, which takes ages for 500M cells. So please change the colour and opacity log scale to allow pure negative numbers (by flipping the sign) (like the range generator can) as long as 0 is not part of it. It’s also impossible to manually change the colour mapping, so I can’t fudge it.