Hi, not sure I am following the question here, whether it is do they enhance the photos or is the only advantage a DSLR camera?
I assume it is what is the point of a JC penney style shoot generally over doing it at home? hope that is right.
I don't know the JC service specifically but judging by similar services here in the UK, the main difference is down to the availability of a decent lighting setup. I am not sure the ones here do any smoothing of wrinkles at all (for that reason alone I stay behind the camera!). They do do minor lighting tweaks but I don't think they do anything major. Their key is they have a constant light setup so all of their white balance, shadow control and flash settings are setup beforehand so it is as close to click print repeat as they can get.
For £200, you can get a basic white backdrop, a reflector or two, a pair of Youngno speedlites and a radio trigger and have a play yourself. It is not beyond your reach to get at least semi professional looking images for yourself that you then own the rights to. Then you can take as many pictures as you like and wont be restricted to a time boxed 20 minute photoshoot either.
Based on the pricing of the photo studios, then maybe having a bash at DiY'ing it is an option? plus by learning to play with these simple setups, you can use them in all manner of other ways for example, trying out some low key images, you can really play about with it more yourself.
Did I miss the mark? I am sure others have other opinions as I am not really a pro or anything.
You can get some really good images of people by sitting them at a window (within a meter), turning their body away from the window slightly so they get a shadow in the middle of their chest, then turning their head back towards the window (sounds painful I know). Then with a £7 reflector and even a sheet tacked up behind them, or some aluminium foil, you can light them up and get some lovely shots. It works surprisingly well. Obviously not going to replace a £4-5,000 lighting rig but it is great to do and can be fun. This image was taken this way. Spur of the moment, messing about with a reflector I got off Amazon, stood next to the window. Not going to win any awards but i think it is nice (I am biased of course as this is my little monkey).
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