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07-19-2012, 08:11 PM   #1
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which tele-converter lens is good ?

I am considering to add a teleconverter lens for my 55-300 lens on K-5. and then go to yellowstone shooting wildlife... animals that are far from the road... it seems that 2x lens is enough. any good suggestions? which brand is a good buy?

07-19-2012, 08:50 PM - 1 Like   #2
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I think you will find the general consensus is that the 55-300, although an excellent consumer grade tele, is not fast enough or sharp enough to use any TC without significant degredation and of course, no AF (other than the pentax 1.7x AF). If you have to have 500mm for your trip, consider renting a Sigma 50-500mm or 150-500mm for a better experience. Otherwise just crop from 300mm as best you can. Opinions will vary but I have been there and tried it.
07-20-2012, 06:46 AM   #3
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I tried a Promaster 1.7x with the 55-300mm and the results were less than spectacular. A crop was better. It did auto focus in daylight just fine though.
07-20-2012, 06:48 AM   #4
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I'm with Lee. You need a sharp and fast lens to make good use of a teleconverter, and even then I wouldn't go above 1.4x unless I planned on using a tripod or monopod. With your gear I think you'll find you get better results from cropping.

Russ

07-20-2012, 10:04 AM   #5
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my experience has been that unless the combined lens plus TC native aperture is not F6.9 or better (read better as faster) that pentax AF will not work reliably and achieve focus lock under all but extremely bright conditions.

as a result, any TC when put on the 55-300 will NOT work at the long end, which is what you are looking to get.

to get reliable AF confirmation, you shoud consider starting with a lens that has a maximum aperture at the long focal length of F4 or better.
07-23-2012, 01:59 AM   #6
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Just tested 55-300 + canon TC-DC52B 1.6x ... result is sharp and great. 1-2 stop slower but its fine for such combination ...
can AF until original 260mm + TC (ca. 400mm) must manual at 300mm * TC (480mm) and NO vignetting !!

Last edited by raimaster; 07-23-2012 at 07:11 AM. Reason: add text
07-23-2012, 04:49 AM   #7
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I have a 55-300 & it's a great lens, but I would be willing to bet it would be a lot less great with a teleconverter on it. I've never had good luck with any of the many TCs I've owned, so I don't even bother with them anymore.

When I need something longer than 300mm, I grab my Tair 3M-5CA 500mm mirror lens. I was about ready to swear off mirror lenses too, 'til I got the Tair. It's head and shoulders (along with the Tamron 55BB) above the other mirror lenses. If you don't have a ton of money to spend, I'd look for nice used copy.

Good luck,
Bobbo :-)
07-23-2012, 05:41 AM   #8
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just so every one is clear, the canon "TC" reported here is not a teleconverter but a front magnifier.

07-23-2012, 06:01 AM   #9
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QuoteOriginally posted by Lowell Goudge Quote
just so every one is clear, the canon "TC" reported here is not a teleconverter but a front magnifier.
Just looked it up, and it also has 52mm threads, so it wold require a step-down ring to work with the 58mm threads on the 55-300. I would think that might also present a vignetting problem. I always figured a front-mounted converter would be worse than using a rear converter.
07-23-2012, 06:18 AM   #10
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QuoteOriginally posted by GibbyTheMole Quote
Just looked it up, and it also has 52mm threads, so it wold require a step-down ring to work with the 58mm threads on the 55-300. I would think that might also present a vignetting problem. I always figured a front-mounted converter would be worse than using a rear converter.
I can't comment on the vignetting or quality, as I have never tried. but consider the 55-300 is F5.8 at 300mm, this implies a front element diameter of 51.7mm so yes, it is very close to causing vignetting because the front element is set back just a little,

I would also expect if the magnification ration is truely 1.6 then more than 1 stop light loss, more like 1.4 stops. but again, that's just theory, since I own neither the lens or TC

the biggest issue I see is that these lenses are meant to work on video cameras and P&S cameras, etc, and the edge performance of front adaptors is not that great when applied to slr lenses. but again, unless there are posted shots, who knows, and if the user is happy with his results, then that is what matters, it would be interesting to see a test shot, though, with the converter and with cropping in to get the same FOV on the two shots.
07-23-2012, 06:54 AM   #11
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QuoteOriginally posted by Lowell Goudge Quote
it would be interesting to see a test shot, though, with the converter and with cropping in to get the same FOV on the two shots.
Yeah, I wouldn't mind seeing those shots as well. :-)
07-23-2012, 07:03 AM   #12
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posted result DA 55-300ED plus TC-DC52B ...

55-300mm with TCs, slower but the result is good (sharp): Pentax SLR Talk Forum: Digital Photography Review

not bad for $ 40 TC

cheers
Rai
07-23-2012, 07:35 AM   #13
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QuoteOriginally posted by raimaster Quote
Just tested 55-300 + canon TC-DC52B 1.6x ... result is sharp and great. 1-2 stop slower but its fine for such combination ...
can AF until original 260mm + TC (ca. 400mm) must manual at 300mm * TC (480mm) and NO vignetting !!
Is the photo at 300mm with this particular TC better than the appropriately magnified photo without TC?

That defines its utility for me; edges don't matter too much because my typical subjects are birds or other relatively small things at the center of the image.

We'd really appreciate your posting examples for critical comparison.

Dave in Iowa
07-23-2012, 07:44 AM   #14
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similar result with or without TC, but slightly more CA with TC (very little) ... at native 300mm, i use AF, with TC I do manually .. all test handheld, so you can see the result... can see my posting at dpreview. tested with another TCs, the result was soft at longest FL..
07-23-2012, 07:51 AM   #15
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Ok ... here is the camera with TC


At 300mm - f/5.8 - 1/500sec - Iso 100 full size


At 300mm + 1.6x TC f/5.8 1/125 - Iso 100 full size


Without TC crop 100%


With TC crop 100%


At 300mm f/5.8 - 1/800sec - Iso 100 full size


At 300mm + 1.6x TC f/5.8 1/160 - Iso 100 full size


Without TC crop 100%


With TC Crop 100%



k5 with another TC

Last edited by raimaster; 07-23-2012 at 07:58 AM.
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