IR-conversion: Focus adjustment?
I am about to send in one of my cameras (EOS 20D or 40D) for conversion to infrared (IR) photography, with a >630nm filter. I have the choice between
1. a cheaper option (236€; DSLR AstroTEC) who would do the focus adjustment for one lens (my choice would be the EF-S 17-85mm IS)
2. a more expensive option (299€ + 45€ for the filter; Optik Makario) who would do a general adjustment for the range 18-200mm, not just for one lens. They did not even ask to send in one lens, just the body.
I wish to ask those of you who also had their DSLRs IR converted if this is promised too much or whether adjustment can really be done for several lenses over this range? If the focus adjustment were not confined to the 17-85mm IS it would be worth the additional cost, particularly as the EOS 20D has not liveview, and while the EOS 40D does have, it is not very convenient to use on its screen.
I would be interested to use my midrange lens (EF-S 17-85mm IS or Sigma 18-50mm f2.8 Macro), a light telephoto zoom (EF-S 55-250mm IS) and possibly my EF-S 10-22mm and Sigma 50mm Macro on the IR converted camera.
So what is you experience with af adjustment after IR conversion? Also, does the focus error increase with focal length?
Thank you for your answers.
PS: Thanks to the forum member who, in a previous thread, informed me about DSLR AstroTEC.