Oh thanks a lot

I was reading these texts yesterday so I've must have taken it all wrong/ backwards..

; ) Now I see the difference, nice

. It's clear for me now that using TC isn't actually some waste of money (at least speaking about TC APO 1.4..), some practical proof from which I'm really greatful of..
And what is BIF

; ). English is not my national language, so I sometimes don't get every expression/abbr for which I come across

.
Also one more thing - would you be able even right now, to tell me from which "combination" I would get a better result/quality of the image:
1) Sigma 150 EX Macro + TC 1.4 which gives
336 mm
2) or Sigma 70-300 APO DG Macro at 210 which would give me (with a 1.6 crop) also 336 mm just curiosity or some practical solution also ( I don't know right now, just thinking..).
I don't compare to Sigma at higher focal length (210-300), as I understand that quality after 200 mm on Sigma is at most AVERAGE/POOR (especially on borders..).
You know, I would use it probably more for insects but if the image quality is so good/sharp then why don't use it also for the birds I was thinking..
ALSO the cost of APO 1.4 and Sigma 70-300 APO DG Macro in Poland is quite similar.. so it really becomes some tricky question for me

; ).
Obvious reason of asking there is some budget limit which makes me think this way (only MACRO LENS for now..)
I think this way: if I buy a lens for me, I buy the best one for which I can afford for/good one (as I really want to make my shots look pretty and nice..).
And I'm also afraid how SLOOW AF would be if I were using this Sigma 150 Macro with TC 1.4 (I'm also aware of MF at the closest range (you've checked that out, yes?)).. I guess you've tested this solution/option also for birds.. I'm sure that less light of that set makes AF running even slower than w/o TC.. -
Do you use Canon body to this lens?
Because if it comes to birds they can sometimes sit on one branch for a very loong time, so it is enough time to make a shot

; ). But mostly if we're talking about wild birds they move actually pretty fast (especially when the human presence is really close..), SO if the AF is so slow that I can't shot a bird then I would have to use MF anyways, cause with MF i would probably do it faster..
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Do you think (now, after monts of using Sigma 150 Macro..) that your lens gives you OPTIMAL distance from flying insects or is it too less or maybe too more (which I doubt). Have you got any shots of birds also (especially with this new range/set)?
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And I guess that the MAIN advantage of TC from ET (extension tubes) and Close-Up lens is that getting bigger magnification is possible without the need of getting closer to the subject, right? The two other ways allow us to focus at infinity? Are they of any usage at normal/far distances or they (close-up lens and extension tubes..) work simply for macro and close range?
I was also wondering if ET and close-up lens needs (if I get it right) closer distance to get better maginification, so at the same distance from the subject the maginification is the same than without it?