"How long have you [had/been having] this?" - Cont. or Simple?

Solution 1:

You don't normally use Present Perfect with stative verbs (have, be, like, seem, prefer, understand, doubt, know, etc.) Here's a longer list - in general, they apply to states that last for some time.

In some contexts, such as "How long have you had/been having these symptoms?", there's no real difference. Arguably, been having calls more attention to the fact that you're still having the symptoms, but I doubt many people would consciously either make or hear that distinction.

A "rule of thumb" for to have is: when it means to experience, you might want to use Present Perfect; when it means to own, you almost certainly don't.

Here's an example for to be using the "slightly unusual" Present Perfect in a construction which is perfectly valid, and is probably the most succinct way of expressing the intended meaning...

By now the new cook will have been being introduced to her duties for several weeks.

Solution 2:

You would use "had" for a possession or other permanent object like the camera in your example.

You would use "been having" for events (especially a series of events) or other duration-based things:

How long have you been having these parties?

How long have you been having these symptoms?

How long have you been having problems with greedy relatives?

As @Andrew Leach noted, the event/occasion/occurrence must be continuing in the present, or you would use "had been" instead of "have been":

"How long had you been having these parties?" "Since graduating from college, but I had to stop last month after the police issued a restraining order."

Solution 3:

How long have you had that camera?

The following sentence if we add context to it could be:

When did you buy it? / When did you get it?

Which would imply more or less the same meaning, as the answer would be the period of time (e.g. 2 years, or 2 years ago ) The question itself implies that the camera is still in possession of the hearer, s/he still owns it.

Past simple of have in this sentence is used as an ordinary verb and its meaning suggests to posses or to suffer. But it is not the case.

The use of present perfect is correct in this sense as has the reference to the present moment. Present Perfect Continuous form would suggest - to me , I am not a native speaker though - that you have been carrying something with you for a certain amount of time.

Martinet in his " A Practical English Grammar " suggests that, as you correctly have noticed, that

Verbs not normally used in the continuous tenses are:
a) verbs of the senses ( feel, hear, see, smell etc.)
b) verbs expressing feelings and emotions ( admire, adore, like, loath, respect etc. )
c) verbs of mental activity ( agree, forget, know, recollect, understand etc.)
d) verbs of possession ( possess, owe, own, belong etc.)
e) the auxiliaries , except BE and HAVE in certain uses.

I went through the certain uses of HAVE as an ordinary verb which can be used in the progressive aspect, and they are:

WE are having a breakfast early tomorrow - as a reference to the near future
I am having a bath - expresses the present moment which will have its continuity in the nearest future
I am having a wonderful time
- expressing present

etc.

Transferring them to the Present Perfect Continuous may make them incorrect at some point, as Past Perfect Continuous describes incompleteness of the situation therefore something which would last at least to the moment of speaking or even further.

In my opinion, the safest option is to use the simplest solution. If I were you I would stick to the Present Perfect tense and rules given.

Did I answer the question at least partially?