Some older dedicated pentax auto flashes do transmit or receive iso and aperture information. Some flash models can be set to P mode. The camera sets the correct aperture for the lens and the flash exposes in normal auto mode. Is this the digital interface you mentioned. I would be surprised if any non ttl or pttl ringflash supports this. The flash or the body would also need to calculate the correction for the magnification of the macro lens or the length of the extension tubes.
On 8/24/07, Toralf Lund <[EMAIL PROTECTED]> wrote: > Toine wrote: > > P-TTL ringflashes for Pentax don't exist (I have never found one). The > > TTL models won't work on K10D etc. > > > Perhaps I need another clarification. > > When I said "digital interface" I wasn't referring to the flash metering > setup on the digital bodies, but rather digital encoding of the exposure > information etc. exchanged between the body and the flash. As far as I > understand, all Pentax AF bodies support such a digital transfer, but > that does not necessarily mean they have a P-TTL interface; P-TTL also > refers to how the light is metered - but please correct me if I'm wrong. > > The ringflash I use is a no name version like this > > http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=160146845797 > > > > They vary in branding, logos etc and sometimes as cheap as $50. These > > units can do Autoflash which is a little strange on a ringflash. > Why? > > I > > never use Autoflash and set the unit to full manual. resulting in good > > exposures at f16, 100 ISO for a F100macro at 1:1. > > > That's useful info, as I was also sort of wondering how well these work > with the F-100 macro. I was worried that the operation on a lens with > 58mm filter size would be problematic, based on the fact that the units > have adapter rings for only up to 55mm. > > Thanks. > > - Toralf > > This works very easy even if a PTTL ringflash was available I doubt I > > would want one > > > > > > > > On 8/24/07, Toralf Lund <[EMAIL PROTECTED]> wrote: > > > >> The thread started by Jostein a few days ago made me realise that I just > >> have to buy a ring flash. I'm looking at the cheap options, though, > >> specifically I very nearly ordered a Vivitar 6000 yesterday, but then I > >> thought I should perhaps try to find out more about it first. > >> Unfortunately, not a lot of information seem to be available online, but > >> didn't someone on the list mention using such a unit a while back? > >> I mainly have two questions about it: > >> > >> 1. The specs say this unit is for Pentax AF. Does that mean that it > >> uses the newer digital TTL mode and is incompatible with e.g. my > >> MESuper? > >> 2. Does this flash also have "traditional" auto operation, or does it > >> support TTL automation only? > >> > >> Also, if any of you lot have tested another, similar unit, please feel > >> free to share your experiences... > >> > >> - Toralf > >> > >> > >> -- > >> PDML Pentax-Discuss Mail List > >> [email protected] > >> http://pdml.net/mailman/listinfo/pdml_pdml.net > >> > >> > > > > > > > > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net > -- Toine http://leende.net -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
