Teleconverters for Canon
Teleconverters are small or moderately sized optical elements with lenses in it. There are the following types: 1.4x, 1.7x, 2x, 3x. Teleconverters are like extra optical zoom elements.
We usually attach them between the lens and the camera body in the same way as we attach the lens to the camera. First we attach usually the converter on the lens, and after together on the camera as normally we attach the lens itself. As the lens will be longer higher shutter speed is needed for the sharp photo, than before. Let’s say I have a 200mm lens. I want more reach. If I attach the
it will be 200*1.4=280mm
with the 1.7x will be 200*1.7=340mm
with the 2x will be 200*2=400mm
with the 3x will be 200*3=600mm
As the focal length is increasing so narrowing the field of view and will be more pixel on the distant object, which results better picture quality.
But..no meaning for using the converter for close distances, and comparing results.. why? In this case you don’t need a converter. This is not the reason converters designed for.
Try the following: make a picture with a lens without the converter of a small subject far from you, than make the same picture with a converter. Then you will see what the converter is designed for.
Or make a picture of a small detailed subject not so far from you and check if the lens with a converter gives better detail or not, than the lens itself.
There is one exception: macro, here converters can help to gain more magnification.
Teleconverters pros and cons
-having more reach
-usually cheaper than having a longer lens
-lighter than a longer lens
-versatile like zooming with converters
-reduce brightness (1.4xconverter 1 stops, 2x converter 2x stops)
-lower optical quality, reduce contrast and sharpness
-makes autofocus slower, or not usable
-darken viewfinder image below f8 not really usable
Teleconverters are used to lengthen the focal length of the lens. There are different types of converters: 1,4 1,7, 2x and 3x converters (the numbers shows the multiplication factor). The teleconverter is relatively small piece of glass connected between the lens and the reflex camera body. If somebody tries to make a photo of a distant bird or animal can face the fact that the given lens magnification is not enough to tightly frame the the distant bird or animal. The teleconverters are like optical magnificators.
Some explanation about focal length:
On Aps-C format camera (canon 20d, 30d, 40d, 50d, 7d, rebels, nikon d300, d90, d3000, etc) a 200mm focal length lens has approximately 1.13m field of view from 10 meters. A 300 mm focal length lens has 0,75m from 10 meters, a 400 m lens has 0,56m field of view, a 500mm has 0,46m, a 560mm has 0,4m, a 600 mm has 0,377 m, a 800mm 0,285m from 10 meters.
How much reach we need ?
It depends what we want to shoot. The deadly combination is the small bird from a distance. It is much easier to have good results with bigger targets like deer, eagle, bigger animals. For photograph a smaller bird with a 200mm lens, the ideal distance is about 3-4.5 m. It is possible to make pictures from 10-15m as well, but the bird going to be small (not going to be so many detail), and even focusing is not so easy, with a small viewfinder image. With a 400mm lens the distance is double 6-9mm, that is much more easy to reach. For a bigger target like roe deer for example we can make decent pictures from 30-50 m with a very good 200mm lens, from 60-100 m with a 400mm lens.
Lenses compatible with teleconverters ?
The teleconverter gives good result, and designed to work with a high quality bright prime lenses. (Like canon L primes: 200/2 L, 200/2.8 L, 300/4L, 300/2.8L, 400/5.6L, 400/2.8L, 500/4 L, 600/4 L, 800/5.6L, etc.
The teleconverters can be used with zoom lenses as well, the result depend on the lens capabilities.
The teleconverters significantly lower the picture quality. This means less sharpness, less contrast, less brightness – slower lens, worse autofocus operation, but with a very good quality lens the result can be satisfying. If we don’t want to compromise in picture quality the other way to buy longer lenses. The end result also depend on the camera body capabilities.
The 1,4 converters lower the picture quality slightly, the 2x teleconverters lower more significantly.
The viewfinder image going to be darker in same proportion listed next, the lens going to be slower: we lose 1 stops with 1.4 converters, 2 stops with 2x converter, 3 stops with 3x converters.
Non 1 series canon cameras don’t autofocus with darker lenses than f5,6 (lens+converter attached for example f2.8lenswith 2x converter=f5.6, f5.6 lens+1,4 converter=f8 this combination won’t autofocus normally.
If the teleconverters lower picture quality why to use them ?
1. We want more reach.
2. We have not enough cash to buy a longer good quality lens, or don’t want the attached weight and bulk.
If there is any reason to use teleconverters at all are depend on several factors: financial situation, available lenses, wanted reach. I suggest to check the teleconverter before buy, for 3 reasons: avoid defective sample, make sure you like the end result, satisfied with the new field of view. If you have some of the listed primes above, it makes sense to have a converter if you want more reach.
1,4, 2 or 3x converters ?
The 1,4 converters usually a better bet. More usable in varible conditions, better sharpness, contrast, quicker focus operation. For the 2x converter needs a very good quality, bright lenses to work in good quality. My canon 200/2.8 L gives good, reasonable (not excellent) result with a 1.4 converter wide open, but with a 2x converter needs to stop down to f4 to have good contrast, and sharpness (still the 1.4 better wide open). With a 3x converters needs plenty of light, a tripod and preferably a bright lens to have any meaning. I think this converter is just for fun if we have enough spare money to buy one.
On the picture above you can see how the same picture crop looks like through different converters (target is about 50m). I made a picture with 200mm, 280mm, 400m and 560 mm focal length. Bright sunlight, and I try to use the best aperture setting (around 4 – 4,5 on my canon 200/2.8 L) the pictures made by canon 30D camera body. On the picture it is obvious that the biggest difference is contrast, you can see which combination is which without explanation. The quality with the Kenko 1.4dgx is very good. The Soligor 2x overexposes the images with 2/3 stops.
When using the Canon 2x Mk II for the same test the contrast difference is not so obvious. I came out that the Soligor 2x over exposes by 2/3 stops compare the Canon 2x Mk II.
See below. Same spot, and distance 560mm,400mm,280mm, 200mm. The 200m picture has a biggest crop. Right up 560mm, left up 400mm, right down 280mm, right below200 mm. The quality at 200m is not shows lens weekness but the 8Mp sensor limitation. First I thought it is focus problem and made the shot several times, The original picture was quite sharp. Naturally the lens sharpest at 200mm.
Available converters on the market:
Canon has 1,4 and 2x converters: the are Mark I, II, and III converters.
I have using the canon 2x MkII version with my canon 200/2.8 L lens. Compare to the Soligor 2x version the autofocus performance is slow and not so precise(I tried several canon 2x MkII converters before bought mine which autofocusing a little better with the lens). Optically the canon is better especially the colours, and more sharp wide open, stopped than the Soligor is also quite good, but 2/3 stops overexposing compare to the Canon, the camera needs to adjust that way. The main thing with the 2x converter same with the canon and the soligor: the picture wide open are more soft than with the 1,4 converters (little contrast). Both need to stop down to f4 to reach really good results. Which one to choose ? If we have a budget a canon 2x Mk II for sure, but I suggest to test with the lens before buy, if we don’t have the budget the Soligor can have at half price.
Nikon has 1,4 1,7 and 2x converters
Kenko has 1,4 2x and 3x converters
Sigma also has 1,4 and 2x converters
Bottom line:First recommendation: longer good lens, always better if your budget allows, and the bigger weight and bulk not a problem. My second recommendation 1.4 teleconverter for a good quality lens (Check before buy if you not sure). If the reach is not enough you can try the 2x as well. (Only for the very best, bright lenses (f2.8-4)). For the 3x needs plenty of light (ISO800 at best, more ISO1600 in bright sunlight without tripod).
Photos with canon 200/2.8 L with Kenko 1.4 dgx teleconverter.
Photos with canon 200/2.8 L with Soligor 2x teleconverter.
Photos with canon 200/2.8 L with Canon MkII 2x teleconverter.
Photos with canon 200/2.8 L kenko 1.4dgx and Soligor 2x converter (560 mm) Some photos are post processed some are not. The photos without post processing is not usable, soft, little contrast, but with good post processing with closer objects can make good pictures. Plenty of light or very high iso needed. This combination tend to over expose. The field of view is very nice.
Photos with canon 200/2.8 L kenko 1.4dgx and Canon 2x MkII converter (560 mm). Only cropping, no sharpening. The quality is surprisingly good even wide open(f8). Plenty of light needed, preferred shutter speed 1/1600s. Autofocus operation is not perfect if not enough light, in smaller distances(up to 10-15m) the correct focus is crucial, smallest misfocus ruin the picture.
Canon 50/1.8 II with Kenko 1.4 dgx