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Old Feb 14, 2013, 11:13 AM   #1
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Hello, I am thinking of getting a Kenko TelePlus MC7 AF 2.0X DGX Teleconverter. I have a T2i with efs 55-250mm is, I am interested in shooting shots of Eagles, Hawks, Owls and sometimes smaller Cardinals and Blue jays. So far the 55-250 has not been too successful at getting good shots.



Will this teleconverter get the job done or not? This is just a secondary hobby so spending $1,200 on a great lens is not going to happen.
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Old Feb 14, 2013, 1:18 PM   #2
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A 2X teleconverter not only doubles the focal length of a lens, it also adds two stops to the maximum aperture. That will turn your 55-250mm f/4-5.6 into a 110-500mm f/8-11. The consequences of that are that you'll need to use shutter speeds that are 4 times longer to get a proper exposure in the same lighting conditions, and your autofocus won't work. Now, the AF not working isn't much of a problem since, for shooting BIFs, you can switch to manual focus and focus at infinity. But using a much slower shutter speed means you're four times more likely to get motion blur due to subject movement.

An additional problem is that, optically, the Kenko TelePlus MC7 AF 2.0X DGX Teleconverter isn't very good. The resulting images aren't nearly as sharp, and they contain a lot more chromatic aberration.

It'll work after a fashion, but you'll probably be very disappointed with the image quality.

There are some very good reasons why a Sigma 150-500mm f/5-6.3 costs a lot more than the Canon 55-250 plus a generic 2X teleconverter.
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Old Feb 15, 2013, 3:31 PM   #3
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I guess I should clarify my question. Will this be an improvement over the kit lens at all? The Sigma 150-500mm is $1,000 and that is about $600 more than I will pull from my summer and #1 hobby. The eagle shot I posted a few weeks ago was the only shot out of 50 that was usable and it was the last shot I took before he spooked. The Canon 2x III is $200 more than the Kenko. Would this be a far better option? $400 is the max I will spend.
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Old Feb 15, 2013, 4:35 PM   #4
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The Canon "Extender" is optically better, but it's a matched teleconverter, which means it only works with certain lenses, and the 55-250 is not among them. And even if it did, it still wouldn't permit autofocus because the maximum aperture would still be too small.

And to clarify, you can't ever add anything to a lens to make it better. Anything and everything you add to a lens will decrease image quality to some extent.
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Old Feb 15, 2013, 8:00 PM   #5
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There isn't really a good way to give you the extra reach you want by simply working with the leses you've got, and a new lens will cost significantly more than your budget will allow.

But the used market is a great way to find what you're looking for, without spending a boatload of money. Lenses are pretty reliable, for the most part, and lens problems are pretty simple to identify, so the idea of buying a used lens shouldn't discourage you. Here are some used lenses that I found that might work well for you:

Sigma 135-400 4.5-5.6 Apo Dg Af F/eos E+ condition $449

Sigma 170-500 5-6.3 Dg Apo Asp Af F/eos E- condition $664

150-500 F5-6.3 SIGMA APO DG OS HSM (86) WITH CAPS DIGITAL SLR ZOOM TELEPHOTO LENS EX+ condition $819

200-500 F5-6.3 TAMRON SP DI INTERNAL FOCUS LD (86) (A08) WITH HOOD, CAPS, 35MM SLR AUTO FOCUS ZOOM TELEPHOTO LENS EX condition $525
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Old Feb 19, 2013, 1:59 PM   #6
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Kenko converter seems to get pretty good reviews on amazon .com users. It is a pretty much hit or missed thing when you buy an off-brand converter. Read a lot of reviews and try to a get some idea whether it works on the lenses you intend to use it on. Most converters are made for EF mount lenses and not the Canon made EF-S lenses which the bottom lens element sticks out and prevent you from mounting it. Canon made EF mount converters are well made but cost an arm and a leg. You can check the compatibility list on their website.

The Sigma 150-500mm seems to get pretty good reviews. I am actually looking at this lens and thinking about getting one in the near future. It is a heavy monster weighing 4 1/2 lbs. With a heavy camera like my 5DMKII, it is a lot of weight to carry. Meanwhile, I dug out a Quantaray 2X AF converter and mount it on Sigma 18-250mm and do some trial shooting to see if it works on taking bird pictures. The converter can AF focus up to 50mm and after that I have to go manual focus. It does not work on any Canon lenses I own except this one. It is raining today so I made a few indoor test shoots indoors with this lens plus the converter on a Canon T3i.
The focal length used are (X2): 36mm, 48mm, 100mm, 160mm, 270mm. The 500 mm will be posted on the next posting.
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Canon 5D MKII, EF 24-105mm f/4L, EF 50mm f/1.8, EF 100mm f/2.8L Macro, Tamron 70-300mm f/4.0-5.6 SP Di VC USD XLD, Sigma DG 150-500mm f/5.-6.3 APO HSM.
Canon EOS T3i, 7D and 70D EF 17-40mm f/4L, EF-S 55-250mm f/4-5.6, Sigma 18-250mm f/3.5-6.3 DC OS HSM, 430 EXII Flash.
Sony A200, SLT-A58 System with HVL-F42AM Flash.
Mirrorless APS-C camera: Samsung NX100, Canon EOS-M.
M4/3 systems: Olympus OM-D-E-M5 and Panasonic DMC-G3.

Last edited by WCKSer; Feb 19, 2013 at 2:24 PM.
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Old Feb 19, 2013, 2:31 PM   #7
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Quantaray 2X AF converter with Sigma 18-250mm at 500mm (2x250mm).

This converter is made by Sigma and perhaps, that is why it works with this lens. All picture wer taken with room light at f/8 with aperture priority metering on a tripod. I notice there is degradation IQ, I guess this something I have to sacrifice for convenience. The manual focused pictures may not be very sharp because of my bad eye sight and inability to get a real good focus on the subjects.
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Canon 5D MKII, EF 24-105mm f/4L, EF 50mm f/1.8, EF 100mm f/2.8L Macro, Tamron 70-300mm f/4.0-5.6 SP Di VC USD XLD, Sigma DG 150-500mm f/5.-6.3 APO HSM.
Canon EOS T3i, 7D and 70D EF 17-40mm f/4L, EF-S 55-250mm f/4-5.6, Sigma 18-250mm f/3.5-6.3 DC OS HSM, 430 EXII Flash.
Sony A200, SLT-A58 System with HVL-F42AM Flash.
Mirrorless APS-C camera: Samsung NX100, Canon EOS-M.
M4/3 systems: Olympus OM-D-E-M5 and Panasonic DMC-G3.
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Old Feb 19, 2013, 3:32 PM   #8
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Actually, no, Sigma only makes matched teleconverters, which won't work with that lens. The Quantaray TCs are rebadged Kenkos. Quantaray is a house brand for Ritz and Wolf.

Kenko's (Rokinon's, Vivitar's, etc.) 1.4X TC gets good marks everywhere, but the 2X TC is not very good.
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Last edited by TCav; Feb 19, 2013 at 3:39 PM.
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Old Feb 19, 2013, 6:35 PM   #9
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That looks very good to me WCKser. I don't know how the Canon 55-250 compares with the Sigma 18-250mm, but if I could expect very close to this with $400 canon 2x and my Canon 55-250 I will go that way. Thanks.
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Old Feb 19, 2013, 9:20 PM   #10
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Quote:
Originally Posted by Jbird87 View Post
That looks very good to me WCKser. I don't know how the Canon 55-250 compares with the Sigma 18-250mm, but if I could expect very close to this with $400 canon 2x and my Canon 55-250 I will go that way. Thanks.
I also have a Canon EF-S 55-250mm lens, it will not work on Tamron or Kenko made TC because of the bottom lens protruding out thus prevents the lens from mounting on the TC. Perhaps, other members on the forum know another brand of TC which will work on EF-S lenses. The only reason why the Sigma 18-250mm works on the Quantaray TC is because the bottom lens element is flat and fits into the TC.

The Canon made TC will not on work EF-S lenses and basically works only on the expensive big white EF mount L lenses.

The Canon 55-250mm has a pretty useful range for a kit tele-zoom and is sufficient for most application unless you are getting into photographing birds. Then you may think about getting a zoom lens in the 400-500mm range. Then it can get expensive.
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Canon 5D MKII, EF 24-105mm f/4L, EF 50mm f/1.8, EF 100mm f/2.8L Macro, Tamron 70-300mm f/4.0-5.6 SP Di VC USD XLD, Sigma DG 150-500mm f/5.-6.3 APO HSM.
Canon EOS T3i, 7D and 70D EF 17-40mm f/4L, EF-S 55-250mm f/4-5.6, Sigma 18-250mm f/3.5-6.3 DC OS HSM, 430 EXII Flash.
Sony A200, SLT-A58 System with HVL-F42AM Flash.
Mirrorless APS-C camera: Samsung NX100, Canon EOS-M.
M4/3 systems: Olympus OM-D-E-M5 and Panasonic DMC-G3.
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