1st timer question - eyepiece projection

I am trying to figure out how to figure out eyepiece projection exposure times. ( I have a good book, but still unsure).

The focal Length of my scope is 1000mm, and it is a 5" f/8.

I can attach my 35mm SLR camera, (sans the 50mm standard lens) with a T adapter and an eyepiece holding tube that various eyepiece's fit into, which then connects to the focuser on the scope (the camera adapter came with the scope).

My question is:

When calculating exposure times, do I need to take into consideration the camera adapter length when figuring out focal length? Does the camera adapter change the effective focal length of the telescope from the stated 1000mm? If so, how to I compensate?

Thanks

Any adition to the system, beit an eyepiece, camera adapter, different projection distances, etc. changes the focal length and thusly the f/ratio of your system. I can't give you any details personally on how to adjust the focal length calculation, but check around on the web, you should be able to find info. Try:
http://www.mapug.com/AstroDesigns/MAPUG/CalFRato.htm

http://home.earthlink.net/~tkurkowski/Photo_Basics/35mm___Film/F-Ratio_for_Eyepiece_Projectio/f-ratio_for_eyepiece_projectio.html