Why are you converting ARW files to DNG?
If the reason is the lack of Lightroom or latest Camera Raw then I would suggest downloading the free applications for ARW files processing such as Rawtherapee
or Light Zone
(just to name a couple of them).
You may just convert your ARW files to TIFF and thereby process them in your version of photoshop.
But frankly, I guess you'll be satisfied with the processing in those applications alone.