If I were to take a picture of an item I own, lets say a backpack. And were to photograph it for product photo website portfolio. Are there any chances for legal repercussions for using this product? There are no visible tags or brand indicators. Thanks for your answers in advance!
IANAL* - this is an engineer's opinion.
If the product is not readily discernible as being of a particular brand you MAY be OK.
In most cases I'd expect that there would be no problems. You asked however re "any chances", and I'd expect there may be a small chance of problems in two possible areas.
There may be some attribute that very clearly brands the product for some people but which is inobvious to you.
Two possible instances where this could cause problems are
If you tried to use the image in a context where the branded product was different to a brand being promoted
If the brand owner objected to the way the image was used.
*I am not a lawyer - you knew that.
You can look at the policies of stock and micro stock houses here as a guide. In general for products or companies, any visible identifying logo makes the image unusable for stock. (with people, you need a model release for commercial work).
So it's fairly safe to take a picture of something if its not identifiable to a brand or a specific item.
Usage also matters here, there's more leeway if it's for personal or editorial use and a lot less if it's for commercial (advertising or sales).
When creating a photograph of a 3-dimensional object, you are not at risk for violating the copyrights that rest on that object. This is primarily, because you are not creating an actual copy of the object, but merely a 2-dimensional representation of it.
Having the photograph of a backpack does not give you an item with the identical function of a backpack and therefore it can't be a copy.
If an object has a very distinctive design (that is more than utilitarian), then it is likely to be protected by Industrial Design Rights, which means that you are not free to reproduce the design of the product, not even in a completely different medium, such as a photograph.
This, for example, holds also for buildings designed as a one-off by an architect, where you can´t just take/publish pictures of the building without permission from the architect (unless it is more of an overview shot with the building in its surroundings).