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There are a few tips and tricks for taking good photos.
Literal
Good photos [object-を] take [purpose-のには] a-little trick [and-と] knack [subject-が] exist [explanatory-のです].
The compound particle のには ('for the purpose of doing X') wraps a nominalized action (うまい写真をとる) and marks it as the target goal. ちょっとした is an adjectival phrase meaning 'a bit of / slight' — literally the past form of ちょっとする, frozen into an attributive. コツ is 'knack' or 'the trick to something.' The sentence-final んです (のです) frames the whole thing as an explanation, as though answering 'how do you take good photos?'