"If on the other hand the purpose is to replace the rechargeable
D-Li50s with rechargeable AA Lithium or NiMH, I'd have to ask:
whats the point?"
The point is that proprietary Lithium batteries are prohibitively
expensive and have a finite life of about 3 years WHETHER OR NOT
THEY ARE USED!
Thats well understood, and I've posted comments on this point over the past couple of months, but what I think we have to face here is that Pentax have in effect split their current product line into K100D and K110D for novices, amateurs, and travellers/backpackers, and K10D (and forthcoming K1D and 645D) for pros and semi-pros -- so unless Pentax or a third party provides means to use AA/CRV3 form-factors by means of battery-compartment inserts, we as buyers are going to have to take a long hard look at which camp we see ourselves in.
To elaborate:
When members of this forum compiled a wishlist of features to be included in what we now know as the K10D, prominent on the list were small camera with faster AF, quieter AF, in-lens motors, Li-ion battery "like all the other brands", and an "increase in maximum camera voltage" (see copy of list at
http://forums.dpreview.com/forums/read.asp?forum=1036&message=18544785 ). Although AA retention was also requested, those six core requirements which were requested by more than 50% of respondents effectively eliminated AA and CRV3 cells from the body -- and by extension, the grip. From what is known of competing brands that offer in-lens motors and fast AF systems (Canon and Nikon being prominent), we either know or can infer that:
1) the speed of an AF system is governed by the maximum possible speed of the AF motor, and that is governed by the voltage driving it. Higher voltage is better because it improves AF speed.
2) In-lens motors may require higher voltages to operate at acceptable speeds.
3) A maximum of 2 CRV3 or 4 AA cells can be fitted in the camera' s body. 5 or 6 AAs or 3 CRV3s makes the on-camera grip too large to hold comfortably -- yet those same 5-6 AA or 3 CRV3 cells would be required to provide the higher voltages indicated above.
4) A permanently integrated vertical battery grip for portrait-orientated shots would make the camera too large for the majority of people, and small was considered better -- not to mention the fact that a permanently attached vertical grip would make installing and removing batteries from the body section more difficult.
As such, the only rechargeable battery solution that provides sufficient power while keeping size and weight down is a proprietary Li-ion in the body, with another in the optional grip. What this means in turn is that people looking at the K10D are going to have to decide if the lack of AA is a deal breaker or not. If it is, the K100D, K110D, and earlier models (D, DS, DL, DS2, and DL2) are the only offerings from Pentax that meet their power requirements in standard form. If they choose to jump ship over the AA battery issue, then the only manufacturers that still support AA in current models are Fuji and Sigma; Canon, Nikon, Olympus, and Sony having all gone the proprietary Li-ion route for their re-chargeable battery offerings.
What however remains is the lack of field-available emergency power sources when you standardise on a proprietary rechargeable battery. If the optional grip can take two proprietary batteries rather than one, that goes much further to preventing power outages in the field than just having one battery in the body and one in the grip, and a grip with one battery goes much further than just a battery in the body. The really big downside however is that people
can forget to re-charge or they
can go on a trip where they're away from mains or vehicle power for an extended period, and as you pointed out, Li-ions
do have a finite life of around two to three years and hold less and less voltage and current as time goes by. So whats the fix? Battery-compartment or grip inserts that take stock-standard, long-life disposable AA, CRV3, or CR2 batteries -- which is what Canon and Nikon have both done for selected camera models, and which Pentax should do to fix that hole.
I can get 2500mAh NiMH for $1+ each, fill my pocket with them and
could care less about throwing them out whenever they fail.
This is not a trivial point, but as I am planning on getting the
camera, I will live with it.
Stew Corman from sunny Endicott