Yes, you can use ''can't''. But there would be no doubt that the camera is as good as the cheaper one. If you say: ''it might not be as good as the cheaper one there's is more hesitation. I would use ''might not'' instead of ''mightn't''.

"Might not" means a possibility that it "may not" be the case on what ever you are talking about. But you are not sure. It "can not" means you are quite sure.

[Can] is used to express details that can become possibly true. [Might] is used to express details that are hypothetical/speculative (When you see this word, assume that the sentence is not true). Although for your example, the sentence is grammatically wrong because when you say "as good," it should be "as good as." This is used when comparing two things that are somewhat similar. source: https://dictionary.cambridge.org/grammar/british-grammar/as-and-as-expressions/as-as For your given example, it makes more sense and it's more natural to read the first sentence: This camera is a bit cheaper than the other one, although it might not be as good as [noun/pronoun], of course. (I think it's more natural to just say "might not" instead of "mightn't.") [In this sentence, the camera PROBABLY (meaning it's not sure) isn't as good as the other object being compared to.] The sentence is also grammatically correct, but if you use "can't" instead, the meaning will change. This camera is a bit cheaper than the other one, although it can't be as good as [noun/pronoun], of course. [The camera is REALLY NOT as good as the other object being compared to.] Also, maybe you can get confused because in spoken English, the object being compared to is often omitted. This omitting can be OK in spoken English, as long as the speakers know what they are talking about. Hope this helps~!

Hey Kate, 'Might' is the past tense form of 'may' and it is used to talk about a future event that is a remote possibility. In the sentence ''This camera is a bit cheaper than the other one, although it might not be as good, of course'', the usage of ''might not' is justified by the fact that there is a remote possibility that the camera concerned could not be as good as the other one. Now, if you are certain (almost a hundred percent sure) that the camera is not as good as the other one, then you could use 'can' instead of 'might'. ***HOWEVER, I suggest that you should use 'might' or 'may' (may is more 'formal' than might) when you are 50% sure that something is true or will happen in the future. Examples: 1) It may not rain today = (you are 50% sure that it is not possible that it will rain today) 2) I might do my homework = (I am 50% sure that I will do my homework) 3) That camera might not be as good as the other one (that camera is not likely to be as good as the other one) 4) I won't buy that camera - it can't be as good as the other one = (I am stating that the camera is not that good - in this case, I am 70% sure that the camera is not worth buying) ***NOTICE: 'Can' reveals a stronger possibility compared to the usage of 'might / may'. Hope that helps!

I think might not is better