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Thread: 2x Converter

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    Default 2x Converter

    Does anyone here use the 2X converters? Do they actually work or is this just a "gadget" to spend money on?
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    Member danattherock's Avatar
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    I have not used one but have read lots about them. Many report a big drop in images quality when going up to the 2x converter. Also, people often loose the ability to AF with it depending on the camera/lens it is used on. I read some good info on the Luminous Landscapes website. Seems like it was a comparison test. At any rate, some good info to be found on that site. Go to www.photo.net and look in the Nature forums and also the forum for your camera maker. Put converter in the "search" box at the top of the forum. You will find lots of info that should help you out. Very active forums there.
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    I agree with Dan, I believe that you perty much have to start out with just about the best lens before the converters start to pay off. I have a 1.4-converter and I do not even try to use it on my 100-400mm lens. Degrades image quality and robs some valuable light through the lens. Might be worth borrowing or renting one before you purchase.
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    Quote Originally Posted by tull777 View Post
    Might be worth borrowing or renting one before you purchase.
    That is really good advice.

    One of the more difficult problems with choosing a teleconverter is that results will vary depending both on the lens and on the teleconverter. Hence the best way to choose is to compare different teleconverters on the one specific lens that it will be used with, and buy the one that works the best. If it also works well on
    any other lens, consider that just good fortune!

    The alternate way is to own a lot of lenses, and when you spot a good deal on a reputedly quality teleconverter... buy it. Then test it on every lens you own to find out which ones it can be used with! :-)

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    Quote Originally Posted by tull777 View Post
    I agree with Dan, I believe that you perty much have to start out with just about the best lens before the converters start to pay off. I have a 1.4-converter and I do not even try to use it on my 100-400mm lens. Degrades image quality and robs some valuable light through the lens. Might be worth borrowing or renting one before you purchase.
    Tull777,

    Over at the Canon photography forum, there is a lens/tele compatibility for Canon lenses. Depending on the lens one can go to 2x, but most often 1.4x does better with most lenses. I use a Kenko DG Pro 300 1.4 paired to a Canon EF 200mm f/2.8L USM, and it does very well. However, before I bought it, I checked what Canon and the people at the forum below had to say about it.
    http://photography-on-the.net/forum/...ad.php?t=41922
    The thread is so long that it continues here:
    http://photography-on-the.net/forum/...d.php?t=457299

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    Eddie brings up maybe the biggest issue with TC's, the loss of light. a 1.4x will cost a loss of 1 full stop of light, a 1.7x cost 1.5 stops, and a 2x costs a full 2 stops of light. Which means that when I tag my Tamron 1.4x onto my 300mm f/4, I turn it into a 450mm f/5.6, which is useful really only a tripod on bright sunny days. If I use it with my 80-200mm f/2.8, it turns into a 120-300mm f/4 lens, which is OK. There is a slight loss of IQ, but sometimes it's worth it. Sometimes not. There are times when I need to reach a subject, and only the TC will allow me to do it, but the circumstances are very narrow.

    Now that my new D300 has arrived, I'll take advantage of the higher resolution that will allow me to crop just a little tighter and maintain the IQ I'm looking for, so I'll use the TC less (possibly).

    Cheers,

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    I have used my 2x TC on my 100-400, but as others have said, the light becomes a big issue. You really need to be using a tripod and whatever yours subject is, it must stand still! I am anxious to try it on some faster lenses in the future. I hoping to get the 500 f4 this year!! It'll happen if I can stay out of the doghouse at home!!
    EricL

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    I have owned both the Canon 1.4 and 2x converters for over 15 years. When either is coupled to a good Canon lense no one (including myself) can see any loss of quality.
    Tennessee

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    Bob Atkins is a well known guy in the photography world. He does lots of test with lenses and what not. Below is an article he wrote that may offer some insights.

    http://photo.net/learn/nature/telezoom_tc


    Below is another test of the converters and the effect they may have on image quality.

    http://photo.net/equipment/canon/tc1/
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    Quote Originally Posted by Snowwolfe View Post
    I have owned both the Canon 1.4 and 2x converters for over 15 years. When either is coupled to a good Canon lense no one (including myself) can see any loss of quality.
    That's the key.

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    Quote Originally Posted by Snowwolfe View Post
    I have owned both the Canon 1.4 and 2x converters for over 15 years. When either is coupled to a good Canon lense no one (including myself) can see any loss of quality.
    Actually there is a significant difference which can easily be measured, but seeing the difference requires a display mechanism which exceeds the resolution where the difference is apparent, and therefore in many common uses it isn't visible.

    For example, photos that go in the Family Photo Album, printed out at 5x7 or smaller, will not show any differences. The same is true for digital displays up to at least 1024x768. (Assuming in each case that basically the full frame image is displayed.)

    But, alas, if an image is intended for a gallery display, printed at say 16x20 (or maybe even 10x14), yes the loss of quality from using the 2x teleconverter will be visible for all but the best combinations of a matched teleconverter and lens. Many combinations using a 1.5x teleconverter can exceed the requirements for those sizes, but obviously at even larger print sizes that can be a problem too.

    Of course, many lenses even without a teleconverter, have exactly the same problem! Indeed, virtually all zooms with more than a 3x zoom range have clearly obvious softening at the longer focal lengths. (And a 2x teleconverter is guaranteed to make it even softer.)

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    Maybe there is something you can "measure" but so what? I have some horned puffin photos that were taken at Round Island using the 300 2.8 with the 2X converter attached and you can see all the details in the feathers. I sell this image up to 16x20 and it still looks fantastic.

    The point is if you start with excellent prime lenses and add excellent converters such as the top of the lines Canon's or Nikon's there is no noticeable loss in quality. Now, start with a crappy lense and a $100 converter and you end up with trash.
    Enjoy
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    Quote Originally Posted by Snowwolfe View Post
    I have some horned puffin photos that were taken at Round Island using the 300 2.8 with the 2X converter attached and you can see all the details in the feathers. )

    Lets see them man! I like puffins
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    Quote Originally Posted by Snowwolfe View Post
    The point is if you start with excellent prime lenses and add excellent converters such as the top of the lines Canon's or Nikon's there is no noticeable loss in quality.
    I have a Canon 800mm f/5.6 lens and have tested 7 or 8 different quality 2x telconverters with it. Some of them result in relatively horrible results, 1 or 2 were useable, but none were as sharp as the lens is without a teleconverter.

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    With an 800 5.6 and adding a 2X converter you would be at 1600 at F11.
    I would not blame a high quality 2X converter for poor images. Unless you had the camera locked down in a concrete vault it would be dang near impossible to remove any camera induced vibration. Then there is mirage to consider as well.

    Agreed a prime lense by itself will always be better. But I still contend using a good prime lense with a matched converter will not result in any significant loss of quality. All good usefull information if we are testing on resolution charts but the customer who purchases an images to display on there wall could care less.
    Personally I think photographers are way more picky than there customers
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    Quote Originally Posted by Snowwolfe View Post
    With an 800 5.6 and adding a 2X converter you would be at 1600 at F11.
    I would not blame a high quality 2X converter for poor images. Unless you had the camera locked down in a concrete vault it would be dang near impossible to remove any camera induced vibration. Then there is mirage to consider as well.
    Some of the 2x teleconverters work well, some don't. The difference is which teleconverter is used.

    And the same is also true of a Nikon 80-200mm f/2.8 AF-ED lens that I have. Basically I'm talking about two classic, very high quality lenses.
    Agreed a prime lense by itself will always be better. But I still contend using a good prime lense with a matched converter will not result in any significant loss of quality.
    But what you said was that any high quality teleconverter would work with any high quality lens. And I've just shown where that is not true. And I am hardly the only one who says that. What I said was that they have to be matched, and even then there is some loss in quality (which may or may not be significant given the circumstances).

    You will find virtually the same thing from many sources if you research the topic.
    All good usefull information if we are testing on resolution charts but the customer who purchases an images to display on there wall could care less.
    Personally I think photographers are way more picky than there customers
    They necessarily have to be. One customer is picky here, another is picky there... the photographer has to be picky in both directions to keep both customers.

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    I read down through bits and peices of some of the responses but did not read in depth so hopefully I am not repeating what everyone else said. If you have really good quality glass and the factory matched 2x teleconvertor for that lens and there is plenty of light you will be just fine. I have one and use it regularly with birds and some other small critters. The biggest key is the quality of your equipment and the amount of available light. Alot of people tell me that they do no use a teleconvertor because of the loss of image quality. Thats when I pull out this shot.



    I took this image with a Canon 500mm F4 lens on a 1D MkII body(1.3x crop) and 2 stacked teleconverters, both the 1.4x and the 2x for an effective total focal length of 1820mm. I dont think you will notice any image quality loss as you can see just about every detail in every feather. Especially in the full size image!

    So the answer is as long as you know when not to use it you will be fine with a quality 2x.
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    Quote Originally Posted by Floyd_Davidson View Post
    I have a Canon 800mm f/5.6 lens and have tested 7 or 8 different quality 2x telconverters with it. Some of them result in relatively horrible results, 1 or 2 were useable, but none were as sharp as the lens is without a teleconverter.
    f/5.6 is not the best aperture for using teleconverters. f/2.8, and even a 400mm f/4L prime would be much better.

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    Quote Originally Posted by RayfromAK View Post
    f/5.6 is not the best aperture for using teleconverters. f/2.8, and even a 400mm f/4L prime would be much better.
    A good f/8 lens would be vastly superior to a poor f/2.8 model. That is because aperture has no direct significance to the image quality loss from use of a teleconverter. What matters is the optical design match between the lens and the teleconverter, not the aperture.

    Regardless of that, do you have or even know of an 800mm lens that is f/2.8, or even f/4??? An 800mm f/5.6 is a monster, but you'd need a small truck to move an 800mm f/2.8... it simply isn't practical.

    The point is to get a 1600mm focal length lens with decently high enough resolution. Doing that with a 400mm lens, regardless of its aperture, would require use of 2 each 2x teleconverters to get to 1600mm. You would then of course almost certainly have too soft an image, plus the widest aperture would be f/16. On the other hand, an 800mm f/5.6 lens with only a single teleconverter is f/11 and produces (when the teleconverter is carefully selected) useable images.

    Regardless, keep in mind that the example was of a very high quality lens that has been tested with multiple different 2x teleconverters to demonstrate that just any high quality lens and just any high quality teleconverter does not necessarily make a good match. Whether it is a Canon 800mm f/5.6, or some other quality lens, best results are obtained by comparing different telextenders and choosing the best match.

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