Does the canon 75-300mm f/4-5.6 III USM lens can be used with tele converter?
Don't do it! A) the Canon teleconverters WILL NOT work. You risk trashing the rear element of the lens and mashing the teleconvertor A third party option such as the sigma teleconverter may well work but.. B) The quality of your lens beyond 200mm on a DSLR is pretty poor. Ghosting. Flare. Softness. The teleconverter will magnify these flaws by either 1.4 or 2x C) You will lose autofocus completely with the 2x convertor, you will lose autofocus for most of the zoom range with the 1.4x. D) The depth of field will become so shallow at the effective focal length that it will be very very diffiuclt to accurately focus with the small dark viewfinder of the EOS400D E) The lens will become potentially an effective 670mm with a widest aperture f11. So you will need to use fast shutter speeds to avoid shake. Fast shutters at f11 require fast ISOs, all of which degrades the image. If you don't have the 75-300 already then don't get it. If you have it aready consider getting rid and replacing it with something better. This is before you consider teleconvertors. If you want big reach then look at a 70-200 with a 1.4x or 2x. And it all has to be Canon L. The Sigma EX 70-200 f2.8 with sigmas 2x conv may be a decent option with faster max aperture for similar cash. A similar costed option would be the sigma 50-500mm aka bigma. Not as fast but very good range and less messing about. And as said elsewhere.... You need a monopod or tripod. This may not be the advice you want, but it's the best advice I can give you. If all of this is toomuch cash then look at the Canon 70-300 IS and forget the teleconverter. If you want good tele images, you need to review your 75-300 decision.
I have Canon EF 70-200mm f/2.8L IS II USM Telephoto Zoom Lens, would it serve me better if I purchase the Canon EF 2.0X III Telephoto Extender vs. purchasing a 100-400mm Telephoto Lens?
The 70-200mm f/2.8 is a superior lens to the 100-400mm f/4. I haven't tested the combination with a 2X extender so I cannot comment on the combination. I do however use a 1.4x extender on a 300mm lens with some regularity. On that lens shooting wide open I can see some loss of clarity but the loss is acceptable when weighed against the cost and additional carry of a 400mm len in my kit. Still, if I were shooting a higher percentage of my photos at 400mm I would likely opt to purchase the longer lens.If you want to extend your zoom lens range you could add a 200-400mm f/4 to your kit (if the expense is no barrier). But this is out-of-range for most.Here is my suggestion. You can rent a 2x extender for 4 days from lensrentals.com for $25. Weigh this against the cost of a purchase and it is fairly easy to see this is an inexpensive approach to shooting in your environment and using your 70-200mm lens to determine if the results are suitable before you purchase.
Which Canon DSLRs and lenses are recommended for a safari to Botswana and Namibia?
I've been to both countries twice. This is what I'd take again...You want two bodies, in case one fails and to minimise lens swapping. One of this bodies would be a 7D MkII for the frame rate and AF. The other would be either another 7D MkII or a 5D MkIII.You want one long lens. I prefer a 300mm f2.8 with a 1.4x TC but that's heavy and expensive. As is the 200-400 which would be a great safari lens. A good compromise is the new 100-400 MkII and would probably be my choice next time. Forget trying a 2x TC with this lens, unless you enjoy frustration, but it's worth taking a 1.4x for when you need the extra length.Next you want a mid-range zoom. The 70-200 f4 IS is excellent quality and fairly lightweight (especially compared to the f2.8 alternatives. I would put this on the 5D.For Namibia, where there are some amazing landscapes, I highly recommend an Ultra-Wide Angle lens. The best would be the 10-22 on the 7D.To fill the gap a 24-105 would be a good choice.Don't forget to bring plenty of spare batteries and memory. A device like the Hyperdrive ColorSpace is great for backing up those amazing images you'll grab.I wouldn't bother with a monopod or tripod for when out on safari (they're very awkward to use in a vehicle). I would recommend a bean bag and a small, very light tripod, for shooting starscapes with the UWA.
Camera Lenses: Why is the Canon EF 70-200mm f/2.8L IS USM II better than the EF 70-200mm f/4L IS USM, even at F9?
One big reason is likely that the f/4 lens was released in 2006 and might simply have added an IS module to the existing non-IS lens without otherwise altering the optical formula. The f/2.8 IS II lens was released in four years later, and as the "70-200 f/2.8 lens" is a much hotter segment for photographers there was more tech thrown at it. The f/4 lens is more of a compromise for weight. That said, the Nikon 70-200 f/4 (which is newer than even its 70-200 f/2.8 VRII) is pretty much sharper all around than its larger sibling.The reason that a general f/2.8 lens is often sharper than a general f/4 lens is this: Except for the real exotic telephotos and maybe the new Zeiss Otus lenses, lenses are sharpest when stopped down one or two stops. This minimizes the effects of existing aberrations in the lens. Stop down too much, however, and things like diffraction start to rob you of sharpness. Generally, if you start with a wider aperture lens, you can be stopped down and not be into diffraction. This is why most f/3.5-5.6 kit lenses don't see much improvements in sharpness towards the long end: you can only stop down once before hitting the diffraction limit with most higher-megapixel bodies.
What is the best Zoom lens for wildlife photography?
Canon EF 200-400mm f/4L IS USM Ext 1.4x is beautiful lens, and so as Nikon 200-400mm f/4G AF-S VR II.I am biased toward Canon, but if you have to pick one of the zoom lens to start wildlife photography, then I think either one of these will not disappoint you.But there are expensive lens, if you are little tight on budget, Canon EF 100-400mm f/4.5-5.6L IS II USM, Canon EF 70-300mm f/4-5.6L IS USM Lens or even 70–200mm f4L IS or 70–200mm f2.8L IS II lens will do.Another budget conscious choice is using lens like Sigma 150-600mm f/5-6.3 DG OS HSM, and this is actually not bad choice if you want 600mm range and beyond for under $1000 that is available in Nikon, Canon or Sigma foveon camera.