Sigma 30mm f1.4 first impressions

Hello everyone,

Amateur photographer, trying to improve my skills. I do this as a hobby, so trying to get best out of equipment that I have.

I recently bought Sigma 30mm f1.4 fast prime for indoor shooting and outdoor in bad weather conditions. I live in UK where we don't get much sun

Reviews for this lens were good, so I decided to get it. I went to Geneva motor show last weekend and that was my first time when I tried my new lens in action.

Overall i am satisfied with results, lens performed very well, though I had many dark, over-exposed and blurry images. I have Tamron 17-50 2.8 VC as my general walkaround lens, so didn't have much experience shooting with only prime lens. It was interesting to try to find proper angles to fit the subject matter fully or come close enough.

Most of the shots were made at f1.8 and ISO 400 settings. Below are some samples, please give your critique/comments. Also if you can share tips/advice on how best to use this lens would be much appreciated!
Thanks!

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New SLR user: Canon 450d