Whilst telecentricity may be a factor I've never noticed any issues with film lenses as wide as 28mm.
Wider than that is fairly rare in film SLR lenses. Has anyone had any problems in real life? I've not seen any reports as yet, that haven't been down to pure pixel peeping.
I think I've seen images from film era fisheye lenses (which I expect to give the biggest effect) and nothing was noticable with the on-line images.
Theoretically it may be an issue, but like pretty much all the reply's I don't consider it a problem.

The AA filter may absorb a little IR so the K5iis may be very slightly more sensitive than the K5 but the AA filter could probably be removed during the conversion of the K5 anyway so there may not be any real gain.
Personally I wouldn't expect the difference to be noticable.

As Aliengrove says the conversion gets round the poor IR sensitivity of the standard K5. All the previous posts (other than comments on focus shift) relate to unconverted cameras.
Once converted outdoor exposures with a 720nm filter are typically similar to normal visible light exposures. Reasonable results are acheivable with the K100 & earlier models when unconverted, it doesn't seem worthwhile to convert these unless you're trying the conversion yourself and already have them as a spare body. If your paying >£200 to have the internal cut filter removed you may as well splash out a little more & get it done to a more recent body.

With an unconverted K100 hand held exposures are possible with fast lenses at high ISO.
I have managed to get IR images from an unconverted K7, but they wern't any use & took a lot of effort. There could easily have been half the exposure from trace visible light getting past the 720nm filter as IR effects were much less noticable than I've got with the K100. To get anything at all I had to use long exposures at high ISO.
My converted camera is micro four thirds so I don't post it's images here (see my Flickr or the IR forum), but it can eailsy manage fast shutter speeds even with an 850nm filter. Getting a conversion completely opens up IR!

You still have the decision of which conversion to get as well. If you're using liveview a full spectrum conversion gives the most flexibilty - you can add any filter to the frontof the lens to change the focal length you're working with. IMO that makes the K-01 worth considering despite it's looks!

I suspect Larry will find it difficult to reply having had his hands bitten off by people after the FA50!
It's not the only lens there that looks a bargain either, but the SMC 50 seems to me somewhat expensive

I'm very tempted by the 10-20 having wanted one for years, but I've been overdoing the spending recently & can't afford it now.

I've ordered about half a dozen times from Rocky.
Service can be somewhat variable, twice I've had items missing from the delivery and had no reply to my queries - both have been cheap things so I've let it drop - not worth the hastle for

I've connected both a very cheap spotting scope (£76 so not a high class job!) & a newtonian reflector to my DSLRs.
The spotting scope worked moderately on the K100d as a 1000mm f/16 MF lens (no apperture so wide open only). By the time I had my K7 I also had a F100-300 which gave better images when cropped to an equivalent FOV. Zooming in the scope didn't really gain anything even on the K100d as diffraction lost anything gained by magnification.
As a scope zooming it to the 4000mm f/64 equivalent works perfectly well.
For this there was very little effort needed as the scope included a T2 adapter, which was easily changed to a PK version.

The newtonian scope had insufficent focus movement for focusing without an eyepiece - (Prime focus is possible with µ4/3 as this has a shorter flange distance) IIRC both positive & negative projection has been possible with the Newtonian but it's hardly a portable system so hardly ever gets used!

If you already have the scope, connecting a K5 shouldn't be too dificult, though using a compact camera will be easier. From the images I've seen results depend very much on the quality of the scope.

Modified TC received today, many thanks David!
Gaining aperture control of my DA lenses whilst on an extension tube should increase the flexibility of my macro kit nicely!!!

ME now on it's way to Jonathan.

Jonathan-Mac has first Dibbs on the ME.

Inspired by Davids generosity, I'll offer my old ME body.
Last time I checked it was working fine though the hot shoe is missing, and no doubt the body will have a few marks.

I haven't done much film photography in the last decade, so don't need a MX, a ME, and a ME super...
I want to keep the MX, and I 'm not sure where the ME super is now - it might get listed too if I turn it up!

The ME is available for collection in N. Essex or can be posted at cost.
If anyones interested PM me & I'll give it a more thorough check over.

David if the extension tubes have electrical contacts I'd be very glad of them. Otherwise the modified teleconverter would do the job nicely!