I hooked one up to an over the air HDTV receiver and used it as a big screen TV for a while.

Unless you have a lot of experience dis- and re-assembling electromechanical devices I wouldn't suggest tearing them down yourself. That being said, it would be feasible to get 1 or 2 working units out of 4 dead, even than, the working unit(s) would likely need to go somewhere for professional calibration. I'd take the other advice offered above and see if Tamron would cut you a deal based on the fact that this is for a school.

True. But if you push the right button, you'll at least get a coffee cup holder...

Install the software that came with the camera. It will do exactly what you want.

You can find that lens used for around $350 - 450

I took it apart a bit, just the back end. The problem was a plastic gear that was cracked. Ultimately I gave it to my brother along with a 6MP Rebel camera. Fine pictures, just have to use manual focus.

Try using a different browser. Firefox, Chrome or Safari.

If you run Windows and got "upgraded" to Internet Explorer 11, go to the tools menu and hit "Compatibility view settings" and add the site to that list.

My lens was pretty much free to me. It came with a bunch of lenses and a 10D body. After getting it and selling the lenses that were duplicates, that and a set of Kenco automatic macro extenders is what I kept. I wouldn't pay list price or eBay price for it after playing with it, but it is fun to play with and I learned a bit.

It really is a 650-1300 with a range doubler. I have one and hardly use it, but wouldn't sell it either. It does do a reasonable job of moon shots (dang near full sensor on my T1i and Xs) and still, well lit wildlife. I never used it with the doubler.

This is a fully manual lens. It is also a T-mount, so you will need a T-mount to Canon (or Nikon or whatever) adapter. I just got a T-Mount to Pentax adapter that I'll try. My Pentax has IS built in to the camera which may make this lens easier to use. That adapter was on a Rokinon 500mm non mirror lens which is much lighter and I like a little better.

Once I made a rig that will hold it right, the Opteka lens became a lot more usable. Here is a picture of the lens and rig: http://www.uglyhedgehog.com/t-142918-1.html#2419182

If you put the text on the file name and after the .jpg (or .dng, cr2, etc...) just rename them back.

Sadly you aren't specific enough on what you did for more than a guess on fixing.

Did you rename them on the PC and are you trying to read them from the camera? Maybe the camera can't handle long file names or spaces - most cameras use the old 8.3 file naming convention.

FireFox has an EXIF Viewer Extension that I use all the time. It does need to be added in by the user. Once installed, hit the download link, then right click the image and choose "View Image EXIF Data"

Exactly the answer.

However...

With the amount of personal data that lives on phones these days, you may want to enable the passcode and set the the "Require Passcode" setting set to 5 minutes. I find that is convenient for getting right back into the device without a passcode, but if you leave it at a restaurant the finder won't be able to get in. Use the "Find My iPhone" feature to give an honest finder a button to push and call you for return arrangements.

Go to eBay, search for what you have, then tell it to show you "sold items" as opposed to "completed listings". On the ones that went for a high price or a really low price, look at the auction to see if there is a reason why. On the low end it may be broke or have a minor problem (or a high shipping price), on the high prices it may have a seller warranty or have extras. Then take the average of the rest. Now you have a reasonable ballpark price.

What is the price?

And does the dust affect the picture? (it may not)

I once asked if there was a place where people could list their gear so others who need to ask questions about particular pieces could go in a good direction. Admin suggested listing it in my signature.