Soren-a From Denmark, joined Sep 2001, 235 posts, RR: 0 Posted (10 years 12 months 4 days 15 hours ago) and read 840 times:
I just have a quick question about teleconverters.
I have thought about buying a Sigma 2x APO teleconverter to use mainly with my Sigma 170-500mm APO lens.
I also have a 75-300mm Canon lens, and I was wondering if a Sigma 2x APO converter can be used with this Canon lens?? I ask in my local photoshop and he told me that he was not sure, so does anyone here know??
Craigy From United Kingdom, joined Jun 2001, 1118 posts, RR: 0 Reply 1, posted (10 years 12 months 4 days 12 hours ago) and read 797 times:
The first thing to consider is can you afford to lose 2 stops with the 170-500?
I assume that you want to use it in the 500-1000mm range, which would require extremely fast shutter speed or fast film. I am assuming that you are shooting fast moving aircraft.
Jwenting From Netherlands, joined Apr 2001, 10213 posts, RR: 21 Reply 2, posted (10 years 12 months 4 days 5 hours ago) and read 788 times:
Indeed use at least a monopod and preferably a tripod with that combo!
It's slow, long and heavy which is an open invitation to severely shaken images.
Usually, teleconverters are designed for specific lenses. I believe the Sigma converters are optimised only for certain of their lenses. They may work on other brand lenses, but with less than optimal results.
Teleconverters are also not usually designed for zoomlenses (with exceptions like the Nikon 80-200 f/2.8 AF-S). You'd best check with a reputable dealer about it before making the purchase and ask to try it as the Sigma catalogue and website do NOT list the 170-500 as being compatible with their teleconverters http://www.sigmaphoto.com/html/pages/ConvComptChart.htm.
At best you just loose your autofocus and/or aperture settings, at worst you'll damage one or more of the components of lens, TC or camera when mounting the TC.
You're probably better off getting 2 Canon 2x teleconverters and stacking those (possible, but costs even more light). This would give you a very slow 300-1200mm lens