Hemi,
It is wrong to say that an f/4 Newt is more "picky" of difficult to collimate. This is a common complaint though from owners of these fast Newts that are mass produced. What these have in common is they are all poorly manufactured, using components that are undersized or of poor material selection or poorly prepared. It is a real shame as the material choices made by the mass production manufacturers is just to save a few cents per scope, but it means that there are now thousands upon thousands of pages on the net dedicated to fixing their cockups,
What is never heard is of collimation problems with all those big dobs or high end Newts that are f/4 and faster! What
these all have in common is they have all been designed and built using the appropriate materials.
I have two 8" f/4 Newts, one is a dedicated visual instrument that I made, the other is a solid tube OTA I can couple to a dob mount or pop onto a gem. The solid tube is a GSO scope, but I've modified the secondary mirror holder and made the primary mirror cell myself. No collimation issues with either scope than with any other Newtonian.
,
Also, collimation is far more critical for photo than for visual, as our eyes are not just an active part of the optical train, but also very adaptive, which cameras are not.
There is some good news though about the very fast mass produced scopes. There are some simple mods that can be done to fix what really should have been implemented by the manufacturers. If you want to know what these are I'm happy to explain them. These will cost only a few dollars, which if these had been done at the factory would have cost only cents...
Alex.