Originally posted by GerryL I have read again of the SDM being not reliable and maybe this was the cause why not so many of this lenses/mounts are also in use or in circulation.
I just dawned on me that of all the mounts I have seen even those ones being sold on the Marketplace, is that all of them are screw drive!
So, this made me curious too as to what contacts where actually in use for these SDM mounts.
I also have the K100D super, and it is the first Pentax DSLR supposed to be compatible with the SDM lenses but I also have never tried one on it.
I'm not even really sure it my K100D super would be compatible or if it really works on SDM lenses.
In any case, I guess I just have to Google more.
Thanks Nater. It really isn't that important, it just got me curious so what better way to find out about something than to ask here at the forums..and by the responses to this post, it would seem that the SDM isn't really that popular.
I think a decent number of SDM lenses are in circulation, however there are a few factors:
- SDM (and HSM) motors are used on higher-end lenses, and only in the last 5 years, so in the secondhand marketplace they will constitute a minority for some time to come
- Some SDM lenses have had motor failures for some fraction of people both in and out of warranty. There have been some posts about it here, however it is hard to gauge actual percentage failure rates since it is not information that Pentax has released and people who haven't had any problems don't necessarily post about it.
- For what it's worth I haven't seen any posts about Sigma HSM lenses having motor failures, however Sigma brought HSM to Pentax mount later than SDM, and in some cases has released some lenses for Pentax with screw drive that have had HSM on other camera bodies, so it's a pretty small fraction of Sigma lenses. Also I'd assume there are fewer Sigma HSM lenses sold for Pentax than there are Pentax SDM lenses sold, so the number of Sigma HSM lenses in the secondhand marketplace is an even smaller fraction.
- There has been some recent anecdotal evidence of a revised motor being used when failed SDM lenses are repaired, so it's possible that going forward SDM failures could be even more uncommon than they have been.
- Pentax recently introduced a new motor in their DA 18-135mm lens that they call DC (so a new sub-type of SDM lens)
Your K100D Super definitely does support SDM lenses, and while it was the first Pentax body to ship with SDM support out of the box, the K10D like I said supported SDM lenses with firmware update 1.30 (and the K10D did technically come out a year before, so it could be argued it was the first SDM body).
SDM has been a bit of a divisive issue on the forums, with some people saying they're avoiding SDM lenses due to the problems some have had. (I simply haven't bought any because they've been out of my price range, or because I've wanted to use a teleconverter, and old Pz-AF teleconverters aren't quite compatible in practice, even though they happen to have the requisite contacts).
I hope this info helps.