[joe28]

Hello all, hope everyones well.
Im in the market for a teleconverter and was wondering if you lads could help me out.
1 of my lens's is the sigma 70-300mm telephoto lens and Ive read that getting a 2x teleconverter will get the lens up to a 600mm which would be great but im stuck at choosing the right one.
I want the auto focus to still work and some teleconverters that ive seen only offer AF if the lens aperture is F4 or brighter, my sigma is F4-5.6 so does that count ?
Does anyone else use teleconverters and if so are they that good ?
Thanks alot in advance
Joe

[SSB]

I would honestly recommend against a TC with that lens. You'll most likely struggle to get AF and picture quality will be mediocre. Plus, with a slow lens like this you'll struggle to get sufficient shutter speed to get good exposure and overcome the shakes.

[T0MAT01]

With a 2x TC it'll become an F8-11 140-600mm lens. I don't know what camera you're using, but most will only AF with a lens aperture of F5.6 or faster. Even a 1D body will only AF down to F8, so coupled with the fact that it'll seriously hurt the IQ I think you'd be waisting your time if I'm honest.

[joe28]

Ok thanks alot lads
Youve just saved me some money. I suppose the best option then is to save up for a proper 500mm or 600mm lens right ?
Would the teleconverter help me get better magnification with my tamron 90mm macro lens ? or is that down to the extension tubes alone ?
Also how do you know what a fast and slow lens is ? Sorry if thats dumb but im still not 100% on the jargon lol.

[johnaalex]

Originally Posted by joe28

Youve just saved me some money. I suppose the best option then is to save up for a proper 500mm or 600mm lens right ?

Ah-ah the classic dichotomy faced by us togs - save a relative few quid now only to spend a small fortune in the future!

Originally Posted by joe28

Would the teleconverter help me get better magnification with my tamron 90mm macro lens ? or is that down to the extension tubes alone ?

I think a TC would work with the Tamron, but remember TC's can be lens specific, for example a Sigma TC may not work with a Tamron lens.

Originally Posted by joe28

Also how do you know what a fast and slow lens is ? Sorry if thats dumb but im still not 100% on the jargon lol.

The phrase "fast lens" tends to apply to lenses with a low f stop, 2.8 and lower as the wide apertures allow fast shutter speeds. So a 50mm 1.4 is much faster you f4-5.6.

[SSB]

You might want to try extension tubes with the tamron rather than TCs. A TC will help magnify distant objects, whereas extension tubes allow you to get closer to near subjects.

[anthony566]

Joe I went down the 2x TC road and I have to say I was disapointed with the results so I sold it along with a few lenses and got myself a Sigma 50-500mm and its fantastic

[RobDickinson]

Its unlikely a teleconvertor will mount on the 70-300 anyhow.

It also adds 2 stops to the maximum aperture which means for you f11 , which will be soft + the TC softness, no AF either.

Stick to f2.8 and faster or primes for tc's

[Tobers]

Yep - you're a bit stuffed I think.

If you want longer than 300mm you're starting to get into expensive territory. A 600mm Canon prime lens will be £8000 or so. Canon teleconverters only work with their L-series lenses (I think this is the case!) so you'll need to get some proper expensive kit in the first place before you start adding teleconverters to your bag.

So the main question I have is why you want 600mm? Are you shooting very small things from very far away, or is it possible to get closer and live with the 300mm?

[Pirate!!]

Originally Posted by RobDickinson

Its unlikely a teleconvertor will mount on the 70-300 anyhow.

It also adds 2 stops to the maximum aperture which means for you f11 , which will be soft + the TC softness, no AF either.

Stick to f2.8 and faster or primes for tc's

Am I right in thinking the maximum lens aperture is f4 in order for AF to work with a TC? I would opt for a 1.4x as opposed to 2x. Bear in mind that the type of TC that can be used may depend on the lens type. Internal focus or extending zoom.

[anthony566]

I have just picked up an as new Sigma APO 1.4 EX TC to go with my Sigma 50-500mm as I think using a 1.4 minimises the distortion. ( if any ) I got it from Dyxum sales forum..

[Pirate!!]

Originally Posted by anthony566

I have just picked up an as new Sigma APO 1.4 TC to go with my Sigma 50-500mm as I think using a 1.4 minimises the distortion. ( if any ) I got it from Dyxum sales forum..

f6.3 with a 1.4x TC . . . watch out for the rear lens element movement and be aware you'll lose 1 stop of light. Pray for VERY sunny days.

[anthony566]

Originally Posted by Pirate!!

f6.3 with a 1.4x TC . . . watch out for the rear lens element movement.

Why ?

[Pirate!!]

Originally Posted by anthony566

Why ?

Because the rear element may hit the TC and you will not get full functionality of the zoom. Internal focus lenses have no rear moving element and work best with the Sigma TC. I tried the 1.4x TC on one one my own Sigma zoom lenses, and the rear element butted up to the TC and thus will only allow a minimal amount of focal range as a result.

[anthony566]

No not on the Sigma 50-500mm that I have ?? it has a TC mode for the lens that prevents the lens from going to far back and touching the TC, Dont all the big Sigma lenses have this ?

[Pirate!!]

Originally Posted by anthony566

No not on the Sigma 50-500mm that I have ?? it has a TC mode for the lens that prevents the lens from going to far back and touching the TC, Dont all the big Sigma lenses have this ?

No. Not to my knowledge. That is to say, not all Sigma's as opposed to all BIG Sigma's. Fortunately, I have the 100-300mm f4 EX DG (IF) . . no rear moving element, thus no issues in that department :o)

[anthony566]

Had a quick go in the back garden, its quite windy but with my monopod and my 50-500mm + 1.4 TC straight from my camera no cropping just saved it as a jpeg 800 * 600 ISO 400, F11, 1/400 @ 140mm second one ISO 200, F6.3, 1/1000 @ 330mm