MP-E65 with add-ons

I just recently bought an MP-E65 and I'm wondering what the maximum magnification ratio I could achieve would be if I were to use the following combinations...

MP-E65 (at 5:1) + 68 mm of extension tubes

MP-E65 (at 5:1) + 68 mm of extension tubes + Raynox 250

Also, if anyone has had any experience with the MSN-202 Super Macro filter or the MSN-505 Ultra Macro filter, both from Raynox, please let me know if you would recommend them for use with the MP-E65.

Thanks so much.

Sorry I can't answer your questions directly, although I do seem to recall someone here posting about the MP-E with tubes.

But I was going to ask if you've had a chance to use it at 5:1 yet. It's very dark in the viewfinder, and with tubes it will only make it even harder to focus and get light in. Then there's the issue of working distance being ridiculously small. And on top of that there's the issues of depth of field and diffraction softening at those magnifications.

Don't mean to sound negative, just some thoughts on possible stumbling blocks you may not have though of. What are you intending to shoot? eg bugs/living/moving things, or still life? Handheld or tripod/rails? Assume you have flash?

PS - this was posted in the "photo sharing" section, the "discussion" sub-forum might be better. There's one specific for macro.

Can answer the first part with just the extension tubes you will get about 6.8 :1 not exactly a huge increase in max mag.
Brian v.