Why does my A7III shoot grainy at higher ISO

[Aase_SK]

I bought my A7iii this summer and is really pleased with it, but as I live far north and have entered the polar nights I`ve discovered my pictures get very grainy if i turn up the ISO due to the low light even during daytime. I`ve got a Sony 24-70 mm. F/2.8. I often shoot while ice-skating, hiking etc. and have to increase my shutterspeed to avoid motionblur. When I shoot northernlights with my 12mm. f/2.8 I have no issues with grainy results.

I see other photographers talking about how well this camera performs even in the higher ISO range, so I don`t know if I`m doing something wrong or if there is some setting in my camera I should change. 

Help?

[The_Black_Rose]

Hi Aase_SK ,

Are you able to upload any of the pictures taken so that we can check this?

Regards,

The_Black_Rose