In my opinion, it's a DIY project. I did three of my own bathroom fans, and one was in between levels of the house. The first thing I noticed is that you have missing insulation between these two fans. Another missing item is insulation that should wrap those ducts for the fans. I don't know what your area is, but I've heard around here that it's not generally recommended to join two fans to one vent, but if it must be done that the joint should be close to the exhaust vent itself. Yes, those bends are certainly going to be one source of problem. The vent on the left of your picture also looks like it still has an old 90° elbow attached to the new duct. If properly done, you would have a roof vent for each fan. The ducts would be composed of rigid ducting. This is available at Home Depot and Lowe's. You should use foil tape to seal the connections. Lastly you would need to wrap the ducts with insulation (foil backed insulation rolls are easy to find). Don't forget to locate your missing insulation that should be laying between those fans!

A bathroom exhaust fan should produce 4 air exchanges per hour. Your bathroom is 7 x 7 which is 49sq.ft Assuming an 8' ceiling the total volume would be 49 x 8 = 392cu.ft We want four complete air exchanges per hour so that would be 392cu.ft x 4 = 1568cu.ft per hour. There are 60 minutes in an hour so we divide 1568 by 60min and it equals 26.13cfm. You currently have a 50cfm fan, which is twice the size you really require yet your having problems with the mirror fogging up. I suspect your problem is not the fan. Nature abhors a vacuum therefore a fan cannot push air out of a room unless there is provision for an equal amount of air to enter the room. You can test the theory by running the shower and leaving the bathroom door slightly ajar to allow more air to enter the room. Generally they make a slightly higer gap under the bottom of a bathroom door to allow more space for makeup air to enter the room but in some circumstances that does not provide enough makeup air. The solution then is to install a duct through the wall to an adjacent room and put a grille on either side. That will allow the additional air.

ok, thank you for that input. I will leave that vent alone, other than replacing the ugly bent looking grille. I thought it would have been an option rather than cutting a new hole. The other bathroom on the main floor vents out a side wall (northside of house) And i have never had any problems with it. The fan is installed on the ceiling about 4-5 feet away from the wall. Not sure what kind of treatment they did with that as it is original to the house. lol - that upper area on my side of house looks like a good spot. how about if i run pipe (not a flexible one) and insulate the pipe to a different spot and do same? (still kinda stuck there) what if i did solid pipe to the vent and insulated it? and far enough away from attic vent so nothing flows back in that way? I've also seen vents that go on outside wall, and also ductless vents (did not look like a good choice).

Thanks PPF, I saw those. They say its is for 3" and 4" but it has a 4" hole and no sleeve mechanism. So my 3" duct penetrating through the roof will have to be enlarged above the roof cut and somehow joined to the receiver in the vent cap. There is <3/4" clearance between the base and the 4" receiver hole in the unit to accommodate a reducer without having to cut 4" into the roofing deck to make room. Reducers with clearance to join both ends would need 3-4". I can either fashion something and tape it all up and hope for the best or I can simply extend the 3" pipe into the 4" receiver as far as possible and hope that the general seal around 3/4 of the base of the unit is enough to allow the venting air to activate the baffle and exit without too much bleed. The unit also seems to have a really small base which does not provide much flashing surface to mount under the shingles. May not be a concern but it does seem to be narrower than other models. Thanks for the suggestion. I will have to think on it some more.