hi all,

i never realised how compact the fa limiteds were!

one annoying thing about my 70/2.4 is that the hood doubles the size of it. it makes me think that the 77/1.8 is pretty much the same size, but has an integrated hood, so essentially there is no size penalty for the extra speed.

so does anyone have any idea about the size of the 77/1.8 compared to the 70/2.4 with hood attached?

thanks for your help!

i don't know why, but i have in my head that pentax are 49mm: da limiteds, 50/1.4 fa, 77/1.8 fa limited, 43/1.9 fa limited.

to me, what's important is that the standardisation is done according to series. the da limiteds go together, and they all match. that way, one photographer who chooses a set of lenses always has compatibility. compatibility across the whole range of a manufacturer is asking too much, especially if you expect the manufacturer to make a diversity of glass.

that's really interesting. i can get one from japan? i might go on holiday there soon, and am on the lookout for one. do you have any more information on that?

on the other side, a 600mm with a 1.7x tc and a cropped sensor gives the field of view of a 1530mm on a 135 camera, which is some serious bit of wildlife kit.

yeah, and the performance of the lens is inextricably linked to sensors as well. diffraction issues become more apparent with sensors with a high pixel density, and i think this increased sensitivity to diffraction means that it is sometimes better to use a lens a bit wider open on modern sensors.

but it really is nitpicking. if a shot at f/16 isn't sharp enough for you because of diffraction, you really need to think about how sharp you need your pictures to be, or a bigger sensor.

i digress. sorry.

i have been on the look out for an sdm too for use with my 200/2.8. preferably a 2x.

i gather a Kenko 1.5x Pz-AF Teleplus DG hits the spot for sdm lenses, but i'd rather a 2x. i've heard a tamron 1.4x (dont know which one) also works.

don't hold me to the above—i'm new to the k-mount, and read the above things elsewhere, but haven't tried either tc for myself.

i don't think the focusing distance is 1m. i reckon 1m is the focusing mark, but that doesn't mean the camera is 1m away.

edit: but clearly i should take the reviewer's (and your) word for it (sorry for being stubborn just now) since they mention the focus shift. still, note that the 100mm point, even though further from the field of optimum focus, is still very much sharper at f/8 than it is at f/1.4, so i don't think it's focus shift that is causing soft results at small apertures.

generally, the extra depth of field gained from stopping down more than compensates for the focus shift.

but it might be an issue for ultra-wide aperture lenses. i can see that it might affect a f/1.4 lens being shot at f/2, and this is certainly the case with the samyang 85/1.4.

generally the depth of field in front of the plane of focus is less than the depth of field behind the plane of focus, particularly when close to the subject. i think this is at play to a large extent in that link that you posted.

a provisional deal already arranged (much faster than i thought!). thanks all for looking.

i'm not sure what you mean. i didn't link to anything. but rest assured, it's not spam—i'm genuinely looking for a lens trade!

edit: no problem kris! i think i've used computers with that same issue before.