100-300 , 50-500, TC, tele - please help

[shayt]

hi,

i want to buy a tele-zoom for my K100D.
i would like as much zoom as possible (animals & birds)
and i want to have fast focus !

important note, if AF or SR will not work in some cases, please point it, because i like to have them.

another important note, i looked at my pictures, and with the 50-200 i am using almost just the 200mm !!!

so this is the reason i want bigger zoom

currently i have 18-55 & 50-200 & TC tamron 1.4x

my thoughts were -

Sigma 100-300 F4,
this way i will have 100-300 with the best quality
with the TC 1.4 i will have a very good quality at 420mm F5.6 (i assume that TC will lower the quality)

and now... lets talk about bigma (50-500 F4.0-6.3)
it's heavy ! i am afraid from it !
but 50-500mm... tempting

but if you will say that 100-300 is so much better, and with TC, it will still be better, then there is no issue.

but if the use of the TC will demage my use of the SR/AF, maybe this will be the best option.

please help...

thanks !

Shay

[coldrain]

The camera must know the used focal length to calculate its IS.... so I really do not think you can use a TC and keep havinf IS to work fine on your Pentax. The camera will compensate for 300mm when in effect it is 300 x 1.4 = 420mm. So yes, it will "damage" your SR. AF should still be possible, especially on good light.

[shayt]

thanks,

Shay

[SpecialK]

The camera must know the used focal length to calculate its IS.... so I really do not think you can use a TC and keep havinf IS to work fine on your Pentax. The camera will compensate for 300mm when in effect it is 300 x 1.4 = 420mm. So yes, it will "damage" your SR. AF should still be possible, especially on good light.


You manually enter the FL of older lenses for the SR to work properly. You have to go into the custom set up for that, and "allow" the aperture ring to be used, as well. Maybe it will see the TC/Lens as an ancient K mount.

Edit - with the zoom, I'm not sure if that would work, but if you always shoot at the long end, it may be OK.

[rprii]

I have had the Bigma for a couple of months and it has practically become my walk-around lens . . . the more you use it the better the results. All of my shots are hand-held . . . SR is effective at slow SS. The weight may seem imposing but after a few days, it is no big deal. Any quality lens, not made out of plastic, is going to be a bit heavy. You will not regret getting the Bigma. :D

[Joe Davis]

I use the Sigma 170-500 on my K10D. I use it mostly for sports. It is a pretty fast lens but it is big. It makes it hard to put in a bag with another lens, flash and accessories.