Camera suggestion

need a small camera for aerial mapping purpose compatible with pixhawk cube black.
need suggestions

IS IT COMPATIBLE WITH DROTAGX CABLE strong text

There are lot options in Canon small camera which run CHDK.
https://ardupilot.org/copter/docs/common-apm-to-chdk-camera-link-tutorial.html
If you need DroTag compatible camera, Then try Sony cameras.

i am using sony alpha 6000 but i’m not getting desired photo quality and correct ratio at which drone should fly . i usually fly at 100 m alt

You need to check camera settings. I used A6000 too.

i want to know whether you fly in 3:2 or 16:9 ratio.

16:9
But that shouldn’t make much difference.

do you upload a sample photo or just select sony alpha 6000 from camera options in mission planner

You can do both. You can upload a picture or use available Sony A6000 option. What lens are you using?
You’ll get wrong GSD if your lens is different.

16-50mm lens come with sony alpha 6000