Closer but Farther

Another lorikeet. Not as close, but much closer. ;-) Closer because this is a tree in our front garden. Busy day today - always seems to be so at Springwood lately - but I managed to keep on top of it - which is not always the case at Springwood lately. ;-)

Anyway...

Miss 7 got an award today for greatly improved handwriting and bookwork ... I can guarantee it's neater than mine. xP

I'm shortly to order my Sigma 30 mm f/1.4 YUMNESS. Won't be able to use it till my birthday, with the K-30, of course, but I had a bit of silly fun, trying to figure out what would happen if I were to use my Pentax to micro 4/3 adaptor, and mount it on my Lumix. If it sat flush on the body it would of course be effectively a 60 mm lens in full-frame terms. But the adaptor is fully 50 mm long itself. With the Pentax 50 mm that has meant it is still effectively 100 mm, but (as far as I can surmise) not because the sensor only sees a cropped bit of the view, but because it's actually physically 100 mm, with the back of the lens 50 mm away from the camera, and - I think - therefore the whole 100 mm focal length view is seen by the sensor, without cropping (I'm sure if it were 100 mm and then cropped - therefore 200 mm - I'd have noticed xP ).

Ok, so I'd guess the same would apply for a 30 mm long adaptor for a 30 mm lens, so what about a 50 mm long adaptor? Would it make it 80 mm, or would it just mean the image wouldn't even take up the whole sensor and there'd be circular emptiness at the edges?

And then the aperture. My 50 mm f/2 became effectively f/4, as it has a 25 mm diameter, and was effectively 100 mm long instead of 50 mm. Soooo ... 30 mm f/1.4 means thhe glass on the Sigma must be about 21.43 mm diameter, so 80 mm focal length would mean f/3.7 - I think.

Pointless thoughts, as I wouldn't be doing it anyway, but a bit of harmless fun. ;-)