Regarding the recent posting on photographing jewelry. The tent,
flash and using a 35mm camera are excellent ideas. I would suggest
adding one component to that setup and some advice.
Using a polarizing filter in front of the lens will take away or
reduce hot spots. First place a 100 watt ordinary light where the
flash will be and while viewing the object through the lens rotate
the front of the filter. When the reflections [hot spots] are
subdued or eliminated remove the light and replace with the flash.
Stopping down to, say f:22, will give you more apparent depth of
field, i.e., more of the object will be in focus, but that is not
the best diaphragm opening for really sharp pictures. A lens [any
lens] is at it’s sharpest when the diaphragm is opened about 3 or 4
stops from wide open, i.e., somewhere around f:8 or f:11.
There is another way, where you can have everything in perfect
focus from just in front of the lens to infinity, but it cannot be
done with a 35mm camera. It requires a camera with an adjustable
front and back. A note in passing, while there have been great
advances in films in the last 40 years and lenses [for special
applications] there is not a camera lens made today for general
photography that can take a better picture than the best lenses of
the 60’s, i.e., Leica, Schneider and some others.