This is probably a newbie question but better safe the sorrow.
I've been reading some sites on Bird photography and they mostly recomend a lens wit ha focal lenght of 500mm (or more).
now since I don't have the money for a Sigma 500mm EX DG F: 4.5 Pentax AF I was thinking of adding a TC to my "new" old Telezoom lens.
my local store only has 2 Pentax compatible Teleconvertors (I guess the USA and Asia are bigger markets for Pentax the Europe since we seem to be dominated by Nikon and Canon). :
- Sigma Teleconverter 1.4X DG APO Pentax
- Sigma Teleconverter 2.0X DG APO Pentax
now as I understand it correctly this would bring my focal range to eighter :
1.4 : 70-210 for 35mm -> 105-315mm dSLR -> 147-441mm TC 1.4
2.0 : 70-210 for 35mm -> 105-315mm dSLR -> 210-630mm TC 2.0
Now the questions are :
- Is my math correct and does this actually work (I read on the stores website that the Aperture of the lens goes up F2.5 to F4)
- Would this be a good idea for this "old" manual focus lenght (since most people sugest a fast autofocus lens and setting the camera to AF-C (continuous)
I'm not sure if I want to focus on bird photography at the moment, My main interest is nature so both Landscape and animals are included but I don't want to spend a lot of money on an expensive tele or zoom lens to maybe find out later that it's not my thing.
Anyways, since the store has a limited range of Pentax glass (does Tamron make Telezoom lenses ?? since I don't see any of those at my store only Widezoom lenses that go from 28 to 200 and 300mm but I read these are bad since the range is to high).
could someone advise me on the following lenses (quality and such).
- Sigma 55-200mm DC F: 4.0-5.6 Pentax Digitaal
- Sigma 70-300mm APO DG Macro F: 4.0-5.6 Pentax AF
- Sigma 135-400mm DG F: 4.5-5.6 Pentax AF
- Pentax SMC-DA 50-200mm F:4.0-5.6 ED
- Pentax SMC-DA* 50-135mm F:2.8 ED IF SDM
- Tamron AF 28-200mm F:3.8-5.6 XR Di Asp.Mac. Pentax
- Tamron AF 28-300mm XR F:3.5-6.3 Di Asp.Mac Pentax
- Tamron SP AF 28-75mm XR F:2.8 Di LD Asp. Pentax
- Tamron AF 18-200mm F:3.5-6.3 XR Di II Pentax
- Tamron SP AF 17-35mm XR F:2.8-4.0 Di LD Asp.Pentax
- Tamron AF 18-250mm F:3.5-6.3 XR DiII LD Asp.Pentax
based on this I would think the Sigma lenses are the best or maybe the DA* but that's also the most expensive one in the list
so all advise (information) is welcome.