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08-23-2011, 07:21 AM   #1
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2x convert do not seem to work well

I have a pentax k-x and i can not get the coverter to work well at all.

08-23-2011, 07:48 AM   #2
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need more details... type of converter, focal length of lens you're mounting to it. AF or Manual. How its not working. Help us.. .help you.

cheers
08-23-2011, 09:00 PM   #3
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I agree, we need more info to be able to help.

To take a guess, I'm thinking it's probably the most common issue with teleconverters, degraded image quality. I have the same problem with mine, and wasn't impressed when I used one with my 35mm Pentax (and Minolta) cameras either. I get one acceptable shot now and then, but not often. Maybe others can give you a more detailed answer, but I'm thinking it's simply more glass between the camera and the subject. The more glass you have, the more chance of image degradation. The extra magnification also magnifies atmospheric disturbance and camera/photographer motion, and reduces light transmission. I rarely use mine for those reasons. I have 3 now, one K mount and 2 screw mount (M42). same results with all 3, noisy images when I do get a decent shot, very difficult to get clear focus.

But that's just a guess, having no information to go on.
08-24-2011, 12:52 AM   #4
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QuoteOriginally posted by bmarcia115 Quote
I have a pentax k-x and i can not get the coverter to work well at all.
The problem(s) with teleconverters are hardly ever related to the camera body but to the lenses they are being used with; (zoom or prime? moving or fixed rear element? fast or slow?....)

So as others have requested above: More details please.

08-25-2011, 07:19 PM   #5
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I've never used a teleconverter with a dslr, but I used a good-quality (but not dedicated) 2x, and a 1.5x, with my 35mm cameras. The quality, at least with zoom lenses, wasn't the greatest. But today you really have less need for a converter, because you can buy a very low cost 300mm(450mm) lens that will clearly outperform anything but the best lens/converter combinations. And with the newer cameras you can crop, which will probably still leave you with better image quality than most combinations will produce. Especially with the 2x, you're eliminating so much light that there are other issues involved in image quality: difficulty holding the camera steady, difficultly focusing, etc. So I'm not sure the justification for a teleconverter is what it was in 35mm.

Paul
08-25-2011, 07:38 PM   #6
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There are exceptions, BUT... except for a good TC matched to a good long lens, TC's generally suck. They can be fun and handy, as long as you don't expect decent image quality. Use a cheap TC when content is more important than quality, like for blackmail, surveillance, crime-planning, etc. Otherwise, unless you're spending lotsa money on optics, it's usually better just to crop the image.
08-27-2011, 07:11 PM   #7
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Here's a shot of a peacock feather with a Takumar-A 2X TC, with a 55-300 mm DA, on a Pentax K-m.Name:  bhp1 (Medium).jpg
Views: 194
Size:  89.3 KB

Last edited by KennyV; 08-27-2011 at 07:17 PM. Reason: forgot camera type
08-28-2011, 09:11 AM   #8
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Obviously, they work to take a picture, and they can look OK at web size. But the question is, do they look better than simply cropping and resizing the image (which is feee, doesn't cost two two stops of light, doesn't interfere with AF, and takes no room in the camera bag or time to install).

08-28-2011, 09:44 AM   #9
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With slow lenses (F5.6 or above), a 2x converter will make the lens very difficult to use, if not unusable becuase of the amount of light lost. You'll also observe a minor IQ degradation with almost all lenses.
08-28-2011, 12:57 PM   #10
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Well, when I was photographing this bald eagle today in Sidney, BC, the K-m was giving me focus beeps.
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08-28-2011, 01:03 PM   #11
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Great photo. Did you use the 300 lens for the bald eagle?
08-28-2011, 01:08 PM   #12
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Yes, I did. It is my long lens. I run a gas station, so the shekels are none too plentiful. I like the fact that the Pentax legacy gear works on the new digital cameras. My thinking was also that the rear element on the 55-300 was smaller than the area of the TC, so I should be more in the "sweet spot". Seems to be OK. Not National Geographic- worthy, but it looks good on the 22" 10:6 monitor.
08-28-2011, 01:09 PM   #13
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Oh, and thank you for the kudos.
08-28-2011, 03:08 PM   #14
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Better to get the gas at the source; that way you'd be "in clover" (financially).
08-28-2011, 10:31 PM   #15
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Hi
There are indeed exceptions, albeit expensive ones.
When I travel I like to keep things as light as possible and a TC works well with me. But both lens and TC have to be of good quality!
In my case the PENTAX 60-250 DA* is usually all I need for most of my long distance shots. However occasionally I would like a bit of extra reach and rather than schlepp around another lens I opted for the PENTAX-F 1.7 X AF Adapter. This is a bloody expensive peace of gear but is also rendering stunning IQ. IMO.

Below are three pictures, the first is there only to indicate roughly the position from where the following two were taken. The next two were taken with the 60-250 and TC at full stretch. In the third picture, please observe the chicken wire at the top of the pic. Now I am quite sure there will be people here who will say a dedicated 4 or 500mm lens will do a better job and I certainly won't deny this, but in my book the above mentioned combination is more than acceptable. (but as I said, bloody expensive)

Greetings

Last edited by Schraubstock; 10-31-2011 at 07:16 AM.
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