I have an art project that I need to document and could really use some help picking a lens and possibly a camera for it. I did the documentation process a long time ago when I was applying to art school and used my Pentax K1000 and slide film, which I could do again, but I was hoping to go digital with this. I have a Pentax K10D with the old 10-55 kit lens that I've been using pretty happily for the past 10 years, but this project makes me think I should upgrade the lens at the very least, but to what?
Do I want a macro for this? I'm fine with getting a prime lens, but doubt I want one with a fixed aperture as a shallow depth of field could mean having to layer images and there will be 100s of them (there's 60 odd separate pieces of sculpture to document). Should I just upgrade to something like a Pentax SMC DA 18-135mm F/3.5-5.6 WR Lens or something more specific like a 20-40? If I had infinity money this wouldn't be a problem, but I don't. I was hoping to spend under $500 on lens(es).
The other major issue is that my digital camera is 10 years old and has fewer megapix than my phone. Of course my phone can barely focus, so was planning on using a real camera even if it ends up being a K1000. I've been looking at the Pentax K3 III, but it's so expensive. I'm not too, too invested in Pentax glass (just a 20 year old Sigma 70-300 that I bought for my K1000 that's too zoomy and slow for anything but tripod work), but I am comfortable with the Pentax and like the physical view finder of the DSLRs and that is also worth something. A lot of what I use the K10D for is taking pictures of the grass on the side of the highway from the passenger seat of a moving car, so the quick and accurate autofocus is what makes it (rather than the K1 II) so tempting. All together, we're talking $2500 which I can do if I have to, but I had a better paying job 10 year ago when I bought the K10D and this is more than twice as much.
Thank you in advanced for any advice you have!