As has been said many times in various threads, recorded shutter actuations means nothing, as this data can be altered or reset.
As far I know, the camera keeps a total count of shutter actuations and it writes it to the EXIF block that is attached to any NEF/JPG file that comes out from the camera, and read that field with any EXIF reader tool.
Now, curiosity killed the cat: How can you reset/change the value the camera controls?
- It is not affected by resetting the camera, nor by the naming conventions
you use on files created by the camera.
- I do not have the intentions to change it, just curiosity killed the cat!
I am considering purchasing a used D90 or D300 from craigslist. I dont want to get stuck with a beat up camera. I know the obvious things like look for damage to the camera. Also, I would love to learn any other advice on purchasing a used camera from an unknown person.
1) You can feel that the camera has been used a lot by looking on the printed icons over the buttons on the back of the camera, if they were used a lot, they even may be hard to read, specially he "playback arrow", "menu" and "delete" button.
2) Look on the different covers the camera has: Battery, memory-cards-slots, connectors. If they open to easy, they were used more than if they don't.
3) Look on the dirt inside the different compartments of the camera (memory-card-slots, connectors, battery)
4) Take a sensor-dust-reference-photo, there you can see how clean/dirty or even damaged the sensor is:
4.1) Put the lens on manual focusing, focus to infinite.
4.2) Use Aperture mode ("A") and select the smallest possible aperture (f/39?)
4.3) point the camera to a white or plain wall, 2 feet apart (60cm).
4.4) Take a test shot, while the camera is taking the photo move the camera to blur the details of the wall.
4.5) view the resulting photo on the camera LCD, use zoom and pane to see the details of the whole sensor.. you may discover other problems than just dust on it, for example if the camera was not properly cleaned by the previous user.
Now, if the camera comes with some lenses, that is another story, checking lenses is not my expertise, but common sense tells me to see for:
1) The mechanics of the lenses (if they move OK),
2) look on the front and back of the glass to see if it contains scratches,
3) look on the filter threads to see if they are OK,
4) Do a though-the-lens test to see if the interior of the lenses is OK, with no fungus, dust, etc.
BTW, do a Gooogle search on Lens Test and you will find nice hints as well.