Teleconvters.

Corbin Lane · May 26, 2008

My last thread, IMO is not Bump worthy because it's not on this subject, However I have a Sigma 70mm - 300mm Macro lens (canon mount). My question is, What teleconverter should I get?

I was thinking about http://www.bhphotovideo.com/bnh/con...tSiblingItemDetail&Q=next&Csku=390168&Cis=USA
Or
http://www.tamron.com/lenses/prod/2x_teleconverter_pro.asp
Maybe this one
http://www.tamron.com/lenses/prod/2x_teleconverter.asp

If you have another suggestion, Let me know.

Thanks,
Corbin.

Big Mike · May 26, 2008

Keep in mind that using that lens with a teleconverter will probably disable your autofocus and also require you to use fairly slow shutter speeds...meaning that it you would probably need a tripod in all but the very best light.

Corbin Lane · May 26, 2008

Big Mike said:
Keep in mind that using that lens with a teleconverter will probably disable your autofocus and also require you to use fairly slow shutter speeds...meaning that it you would probably need a tripod in all but the very best light.

Yeah, I'm going to be using it for sports photography. Mainly outside so I figure that is not a big deal but, If I'm wrong do let me know.

Big Mike · May 26, 2008

I think you will probably be better off without the TC for sports.

When shooting sports, you usually want to freeze the action. This requires fast shutter speeds. In order to get fast shutter speeds, it's greatly beneficial to have a large maximum aperture.

The lens is question does not have a large maximum aperture, especially at the long end of the zoom. That in itself will make this lens a hard choice for shooting sports. When you add a teleconverter, it steals some light which makes it even harder to get a usable shutter speed.

That is why you usually see pro sports shooters with very large lenses...they need those long lenses to have large apertures in order to freeze the movement of their subjects.
Of course those lenses are extremely expensive.

In your scenario, if you can't get a better lens...I'd suggest going without the TC and just cropping your images when needed.

Corbin Lane · May 26, 2008

Big Mike said:
I think you will probably be better off without the TC for sports.

When shooting sports, you usually want to freeze the action. This requires fast shutter speeds. In order to get fast shutter speeds, it's greatly beneficial to have a large maximum aperture.

The lens is question does not have a large maximum aperture, especially at the long end of the zoom. That in itself will make this lens a hard choice for shooting sports. When you add a teleconverter, it steals some light which makes it even harder to get a usable shutter speed.

That is why you usually see pro sports shooters with very large lenses...they need those long lenses to have large apertures in order to freeze the movement of their subjects.
Of course those lenses are extremely expensive.

In your scenario, if you can't get a better lens...I'd suggest going without the TC and just cropping your images when needed.

Alright, Thanks for the help.

JimmyO · May 26, 2008

Big mike is dead on. You will regret spending money on a TC. Ivest your money in some new faster glass. This will be MUCH more beneficial then having a 600mm f/11 lens with crappy IQ

Corbin Lane · May 26, 2008

JimmyO said:
Big mike is dead on. You will regret spending money on a TC. Ivest your money in some new faster glass. This will be MUCH more beneficial then having a 600mm f/11 lens with crappy IQ

Lol Alright, Thanks again.

Tinstafl · May 26, 2008

What about on a f 2.8 lens you could get away with it there I would think.

Overread · May 26, 2008

You can get away with teleconverters on slower lenses - up to f4 and probably f5 as well - however there are 2 things to consider:

1) desired speed - if you are taking shots of buildings then a TC on a slower lens is not much of a problem as you don't need the speed in the lens. However for sports or wildlife you need that speed to capture the action and slowing down a lens is not helping.

2) image quality - I had similar thoughts as to the OP here about using TCs to get more out of my sigma and was educated that a TC is only ever going to really work on a high end lens. The reason is that a TC on any lens is going to reduce image quality because less light is getting to the sensor - there is more glass in the whole assembly. On a high end lens the loss of quality only reduces by a small fraction, but on lower end lenese the reduction is rapid and harsh - and chances are you won't get the quality out of the lens.

As a user of the 70-300mm sigma macro I would not go out to get a TC for this lens (even the APO version) I would save up for a better overall lens. I find the sigma soft enough at 300mm most of the time anyway and that is with a tripod - so adding a TC and I would expect most to all shots to be soft, if its sports and panning then its not going to work (IMO)

Alfred D. · May 26, 2008

Agree with all the above negative advice: TCs wreak havoc on image quality. Focus softening, increased flare and chromatic aberration (a.k.a. purple fringeing), and you lose 2 vital stops for sports photography!
Built-in disappointment.
Get a better tripod instead!

Overread · May 26, 2008

A good tripod or monopod if you are not allowed to use a tripod is a good investment to any photography kit - however don't disregard the TCs too quick Aflred. On something like (as I know canon best) canon L lenses and the top range sigma and tamron lenses the TCs might lower overall quality, but with such high class glass to start with a 1.4 is often such a small reduction that it is hardly noticable on most - the 2* is a little bit harsher, but most times can still get very good results (though prime high class is where the 2* is really going to work best)

Alfred D. · May 26, 2008

Overread said:
[...] don't disregard the TCs too quick. On something like (as I know canon best) canon L lenses and the top range sigma and tamron lenses the TCs might lower overall quality, but with such high class glass to start with a 1.4 is often such a small reduction that it is hardly noticable on most - the 2* is a little bit harsher, but most times can still get very good results (though prime high class is where the 2* is really going to work best)

That's a whole different ballpark, Overread. Especially dollar-wise!
I don't think you can compare the two.

Converters work wonders on orbiting astronomical telescopes too, I understand. But I don't think that's very relevant to someone who posts a question in a beginners forum about converters for SLR lenses.