Rob Brigham wrote:
You could also build in a lever to activate 'stop down' on the lens so that the *ist D could meter properly on pre-A lenses. Then everybody would be (almost) happy!
-----Original Message-----
From: Peter Loveday [mailto:[EMAIL PROTECTED] Sent: 08 October 2003 23:43
To: [EMAIL PROTECTED]
Subject: *istD teleconvertor idea
I was thinking about the *istD last night (which I seem to do a lot of these days :), and thought of something; is it possible to make a 0.67x TC for it? I'm not talking about some wide-angle adapter on the end of the lens, but exactly the same principle as the 1.4x and 2.0x TCs that currently exist.
I would assume the major limitation with making a <1.0 TC has always been lack of image circle beyone the outside of the lens? This is not the case with the *istD, as there is plenty of image circle spare. Is there something I'm missing here, or can this be done? And if so, why hasn't anyon (Canon, Nikon) already done it... I for one would pay good money for such a convertor.
And the really good bit... it seems to me, with this TC you would actually GAIN just over stop of light? As it would effectively be squashing the 35mm image circle into the APS sensor size, all the original light would be gained, but in a smaller area. Which makes sense anyway, given that apertures are relative to F stop. Then I could choose between my FA50/1.4 as a nice portrait lens, with FOV crop, or a normal lens at F1.0.... Or perhaps an A50/1.2, or would that be A50/.85...
So is any of this possible, or have I missed some fatal problem in the whole idea? If it is, Pentax, please make one! I'd buy one, and I'm sure many other users would too.
Perhaps Cotty could rig something up with custom engineering and a FA1.4xS adapter mounted backwards? :)
Love, Light and Peace, - Peter Loveday Director of Development, eyeon Software
-- graywolf http://graywolfphoto.com
"You might as well accept people as they are, you are not going to be able to change them anyway."
