Lense, sensor height, firmware, mouse feet height(affects sensor height) will all affect dpi, most mice aren't TRUE 800 or 1600 etc. you can test it over at Mousesensitivity.com or there's software to show the active dpi when moving the mouse.

 

Here's what I have from Zowie and the DPI measurements

Zowie ZA12 (white logo) - 804 DPI
Zowie EC2-A (red logo) - 773 DPI
Zowie ZA12 (red logo) - 788 DPI
Zowie Fk2 (red logo) - 807 DPI
Zowie FK1 (red logo) - 805 DPI
Zowie Fk1+(red logo) - 770DPI

In conclusion - there is variance between samples as well as my test bench having a certain amount of error

Also for example the fk1 will feel faster in hand to the ec2-a also because of sensor position relative to you thumb. Ie on the ec2-a it will be further back than on the fk1. Same applies to the smaller fk2

 

Aliandro1d: thanks will check that site out.

2shellbonus : what did you use to determine your dpi for those mice? I just realised I don't know the true DPI of my various mice.

 

thanks fellas.

2shellbonus : what did you use to determine your dpi for those mice?

My sliding rig.
You can see me testing the basilisk with it for example
https://youtu.be/asd2xqLdDHY?t=6m44s

6 min 44 sec is the spot

 

It's common. Using the high LOD setting mine used to be even closer to a 1000 dpi (I have to set my Revel to 1000 dpi to roughly match my FK2).