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View Full Version : Teleconverters: What are the trade-offs?


WhoDo
31-05-2011, 8:26am
I have a new Sigma 70-300 APO DG Tele/Macro Zoom lens and I am enjoying exploring its possibilities, but for some things I'd like to try it just doesn't have enough reach. I can't afford a bigger lens so I've been looking at TC's, 1.4x in particular. These are within reach for me but I wonder about any trade-offs they bring in terms of IQ, AF issues or anything else. Is there anyone able to give me some feedback on these, particularly in combo with my lovely new Siggy or similar lens? TIA.
PH005
31-05-2011, 8:52am
From what I have read up on Waz, while awaiting the arrival of my new 300L f4 and X1.4 TC, you will lose 1 f stop on a 1.4 or 2 on a X2.0. So I'm guessing your 70-300 will become a 5.6-something in suitable conditions. I've also read that in some instances you lose AF and maybe IS. I'm sure there will be a member here with such a combo ( the Sigma ) that can enlighten you further. :)
kiwi
31-05-2011, 9:01am
I dont think you'll have much luck with a TC for that lens, there are compatability charts if you google them.


Usually TC's only work on F/4 or F/2.8
WhoDo
31-05-2011, 9:48am
From what I have read up on Waz, while awaiting the arrival of my new 300L f4 and X1.4 TC, you will lose 1 f stop on a 1.4 or 2 on a X2.0. So I'm guessing your 70-300 will become a 5.6-something in suitable conditions. I've also read that in some instances you lose AF and maybe IS. I'm sure there will be a member here with such a combo ( the Sigma ) that can enlighten you further. :)
Thanks, Paul. I wouldn't even consider the X2.0 on my lens, given the limitations but there are a number of forums suggesting that, despite Sigma's compatibility list, the X1.4 does work. My physical lens doesn't appear in Sigma's compatibility list so I guess it's too new for that anyway. You shouldn't have any problems on the 300L f/4 prime though.
WhoDo
31-05-2011, 9:51am
I dont think you'll have much luck with a TC for that lens, there are compatability charts if you google them.


Usually TC's only work on F/4 or F/2.8

Thanks, Darren. I think my Siggy has f/4 at 300mm but that's no guarantee. If I wasn't so iffy about 2nd hand and refurbished gear I might be better off looking in that direction instead. I can ill afford to spend $360 for a TC that isn't going to do the job without bumping ISO and my little K-x is ok but still not great above 800. Thanks for the suggestion. :th3:
dulvariprestige
01-06-2011, 8:47pm
Waz I think you'll find that your lens starts at F4 @ 70mm, but when you're at 300mm it'll be 5.6, I wouldn't bother unless you can try someone else's first.
Derek-C
05-06-2011, 11:58am
Waz,I have a 1.5 Kenko if you want to give it a go .

PM me and we can arrange a time and place.

Derek
WhoDo
05-06-2011, 1:30pm
Waz,I have a 1.5 Kenko if you want to give it a go .

PM me and we can arrange a time and place.
Thanks, Derek, but I'm pretty certain I'm floggin' a dead horse with that one ... oops! Sorry. Thought I was back in Kym's Cobber lingo thread! :lol:

I think I'm going to have to start looking for good, second-hand primes first. We do need to get together again real soon, though. What about a sunset at Pelican?
Tommo1965
05-06-2011, 1:43pm
i had a Kenko 1.5 TC coupled with a Sigma 70-200 F2.8 HSM II.....its was only used in dire emergency's..as the lens AF was almost non existent at 200mm..{ the end where the extra reach was required !}...hunting was almost always assured at the FL

with a F4-F5.6 lens..Id have to say it would be a worthless addition and any extra reach would be ruined by either very slow AF/image softness and slow Aperture....

IMHO..the results that PP cropping can achieve would outweigh a Kenko 1.5 TC ..


not all TCs are made the same however, but using a Pentax system will have its limitations as far as choice goes..I know as I used to shoot pentax too.....the great TC's nikon makes is a reason I switched to that brand
fabian628
05-06-2011, 2:08pm
not sure with this lens, but generally slower AF, lost lens speed, potentially No AF, increased CA's, loss of sharpness and contrast.
Not so noticable on high quality lenses, but it may affect the IQ of lenses with slightly more imperfection.
Kym
05-06-2011, 3:23pm
This moon shot with a 500mm and a 1.4TC - ok in my books
http://www.ausphotography.net.au/forum/showthread.php?75156-Kym-s-52-2011-(try-something-new)&p=765605&viewfull=1#post765605

There are some tradeoffs, but generally TCs are ok until you stack them
Derek-C
06-06-2011, 8:57am
Sounds good but will have to be after the 15th as I have a two day comp at Taree 11-12 and are stopping a few exrea days.

How about I give you a phone call when we get back.

Derek
WhoDo
06-06-2011, 12:45pm
Sounds good but will have to be after the 15th as I have a two day comp at Taree 11-12 and are stopping a few exrea days.

How about I give you a phone call when we get back.
Done. Take care of Alma and the Evil will take care of itself! :p