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Thread: Teleconverter Advice

  1. #1
    kdoc856's Avatar
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    Teleconverter Advice

    I had a bad experience with a teleconverter a couple years ago- bought a cheap one, and rued the day ever since (distortion; slow; auto focus didnt work with it). Do'nt even know where it is anymore. I'd also read that if one buys one, to not go over 1.4x, as the 2x invariably introduces excessive distortion. Mark Ventz' recent and fantastic moon post reveals the lie of of that bit of wisdom.

    so, looking for any input re: personal experience, best buys, general info, etc. I cant afford a particularly good long lense, and MarkV's photo has renewed my interest in gaining some focal length (I've got a 18-250)

    thanks all

    Kevin

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    Re: Teleconverter Advice

    Hi Kevin,

    I agree Marks moon photo appears to put paid to the gossip that 2X converters loose quality as it an exceptional photo, but without anything to compare it to, we will never know. I have an after market Kenko 2X converter and you can see the difference in the detail with sharpness compared to taking the photo without it and cropping.

    I've talked about this with a professional and he (Dave Hancock) says that he wont use over a 1.4 or he can see the difference. The other thing is that unless your using a 2.8 you will not have the speed you need with a 2X as you loose 2 stops (2.8 will be 5.6 and so on). I certainly dont regret having one in my bag but perhaps you can be the judge with these images.

    With 2X converter and a 70-200, F 2.8 Canon
    Teleconverter Advice

    Without with same lens
    Teleconverter Advice

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    Re: Teleconverter Advice

    Which brand of lens, Kevin? I think Tamron produce an 18-250 is that the one?

    Anyway, basically, converters need good lenses to work successfully and the cheaper zooms aren't recommended. And by cheaper I'm actually talking about needing something which sells for over 500 as a very rough statement.

    Canon converters for instance will only physically fit a small number of lenses which are mostly primes plus a small number of zooms from the somewhat expensive range.

    So even if you get a third party converter you will need good quality glass as well, otherwise my advice would be don't waste your money if you want top quality results.

    And even if you have good lenses you may still lose autofocus, particularly with x2.

    But having issued the warnings. I use a Canon 1.4x with my Canon 70-200 which works OK and I have managed to adapt this converter to work with my Sigma 180 macro by inserting a 12 mm extension tube to work as a spacer.

    I lose the ability to focus at infinity but as I only manually focus and very close up it works OK. But I wouldn't try to use a converter with any of my other lenses.

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    Re: Teleconverter Advice

    I too am in the market for a Nikon teleconverter in the very near future. For the 2.0 I've heard the same comments that the results are just not up to expectations however those notes were on older versions and I have no reference for anything newer. The 1.4 seemed a bit short for me so the 1.7 is what I'm looking for. I don't think there are any 3rd party ones in production. Nikon's new price is a bit steep and I just missed out on a used one. It's a bit hard to justify at the moment seeing as how I only have one lens it will work with. The cost has me juggling back and forth between the 1.7 or extension tubes. It will be nice to see some feedback here as the 2.0 are easier to come by in the used market.

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    Re: Teleconverter Advice

    Extension tubes, Andrew, will get you closer to the subject for macro work, but you also lose the ability to focus at infinity.

    I won't comment on Nikon converters except to say that for any x2 converter you really do need top class lenses and might still forfeit autofocus.

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    Re: Teleconverter Advice

    Acknowledged, I just have no preference right now as to whether I could use longer shots or closeups. I use the macro settings a lens quite a bit on my film camera but not enough to kick out the cash for a new lens suitable for the digital. Eventually I'll have both but need to make a choice now. Sorry if my wording made it seem they were similar in use.

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    Re: Teleconverter Advice

    Just to add - a TC works best with primes with negligible loss of IQ. Losing a stop or 2 of light does not quite matter as you can always compensate with upping the ISO. There will be slightly slower focus acquisition so one needs to make sure to focus on something contrasty and AF is pretty good with that.

    As long as the TC will not take you beyond f8, AF "should" work but will be slower at focusing etc.

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    Re: Teleconverter Advice

    How would a 1.4 teleconverter work on a Canon 100-400mm zoom? I have the lens but several times thought about getting one for it but always hesitated on getting it. I have a 30D right now but intend on a new Canon not to far off in the near future.

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    Re: Teleconverter Advice

    Quote Originally Posted by Gold Coast View Post
    How would a 1.4 teleconverter work on a Canon 100-400mm zoom? I have the lens but several times thought about getting one for it but always hesitated on getting it. I have a 30D right now but intend on a new Canon not to far off in the near future.
    If you add a converter (any converter) to a 100-400 you will loose autofocus, unless you have a 1D series camera. Then you can add a 1.4X to it and still have autofocus.

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    Re: Teleconverter Advice

    Quote Originally Posted by kdoc856 View Post
    I had a bad experience with a teleconverter a couple years ago- bought a cheap one, and rued the day ever since (distortion; slow; auto focus didnt work with it). Do'nt even know where it is anymore. I'd also read that if one buys one, to not go over 1.4x, as the 2x invariably introduces excessive distortion. Mark Ventz' recent and fantastic moon post reveals the lie of of that bit of wisdom.

    so, looking for any input re: personal experience, best buys, general info, etc. I cant afford a particularly good long lense, and MarkV's photo has renewed my interest in gaining some focal length (I've got a 18-250)

    thanks all

    Kevin
    Kevin, teleconverters will only work on certain lenses. ON canon lenses, any prime 135mm or larger>>>70-200 zoom or larger, i believe. With a 1.4TC you will loose 1 stop, and with the 2X , you will loose 2 stops. If the Tc increases your f/stop to f/8 or greater, you will loose autofocus. The 1D series of cameras will retain autofocus up to f/8.

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    Re: Teleconverter Advice

    Quote Originally Posted by Andrew1 View Post
    Acknowledged, I just have no preference right now as to whether I could use longer shots or closeups. I use the macro settings a lens quite a bit on my film camera but not enough to kick out the cash for a new lens suitable for the digital. Eventually I'll have both but need to make a choice now. Sorry if my wording made it seem they were similar in use.
    Andrew. For me, the choice between an extension tube and converter for macro work is relatively simple.

    A tube gets you closer so therefore a larger image but there is no loss of quality although a slight loss of light. A converter provides extra magnification at the same distance but with some loss of quality (variable) plus light loss.

    So it comes down to 'how close can you get to your subject'? When shooting insects, I generally reckon on not being able to approach closer than 12 ins, and that is on a good day, so if my lens will focus at 12 ins a converter is my only real option.

    But in reality, I normally use a small (12 mm) tube plus 1.4x converter with my 180 macro lens when I need to get really close. And I am talking about being able to 'count the toes' on a fly's leg for identification purposes. Mostly, I use flash to counter the light loss problem.

    However, I started getting interested in macro work with a Canon 70-300 lens so the best option in that case was a larger tube (25 mm) as that lens isn't really of a sufficient quality to work well with a converter.

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    Re: Teleconverter Advice

    Thanks, everyone for your input, which I am reading with great interest. My well of ignorance is, as usual, deeper than I thought. I understand why the loss of autofocus with the TC, but why the loss of focusing at infinty?

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    Re: Teleconverter Advice

    Quote Originally Posted by kdoc856 View Post
    Thanks, everyone for your input, which I am reading with great interest. My well of ignorance is, as usual, deeper than I thought. I understand why the loss of autofocus with the TC, but why the loss of focusing at infinty?
    If you use an extention tube (basically a hollow tube with no glass), it will allow you to focus closer (and allow you to attach a TC to a lens that it isn't supposed to be attached to it), and take away your ability to focus far away.

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    Re: Teleconverter Advice

    Quote Originally Posted by Geoff F View Post
    However, I started getting interested in macro work with a Canon 70-300 lens so the best option in that case was a larger tube (25 mm) as that lens isn't really of a sufficient quality to work well with a converter.
    I do most of my close-ups with the 70-300L as it has an excellent minimum focus distance of just under 4 feet. Sometimes will sling on a 12 or 25mm but never considered adding a TC to that. Will try it out and see. I want toe-counting!!!

    What is the sequence of attachment? TC + Tube + Lens or Tube + TC + Lens?

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    Re: Teleconverter Advice

    I use the Canon 1.4x Mk-I converter on two of my lenses: 70-200mm f/4L IS and 300mm f/4L IS. Both of these lenses are near the upper echelons of quality (and price) and both of these lenses will function well with the 1.4x TC. The autofocus and the image quality will take a slight hit when I add the TC but, I can often live with that. Here is an example of a shot with the 1.4x TC on my 70-200mm f/4L IS lens...

    Teleconverter Advice

    The 1.4x TC weighs only 8 ounces (226.8 Grams) so the weight doesn't impact the total weight of my kit by that much. I will often carry the 1.4x TC when traveling and when I don't want to carry the weight of an additional lens such as my 300mm f/4L IS.

    Traveling is about the only time I will use my 70-200mm f/4L IS + 1.4x TC combination. If I am home based, I will use my 300mm f/4L IS lens bare when I need extra focal length or slip on the 1.4x TC when I need extra range or a larger image ratio.

    I do like the 1.4x TC on my 300mm f/4L IS lens for close-up shooting because when used bare, that lens can focus down to 59.1 inches. Adding the 1.4x TC will increase the focal length to 420mm but will retain the same MFD. While not a macro lens, the 300mm + 1.4x TC will give you a pretty nice image ratio shooting from a distance of five feet or so. It is, in a way better than using an extension tube for shooting small moving subjects like butterflies because I retain focus out to infinity.

    I had very briefly considered the 2x TC but, since I would lose autofocus with either of my lenses and since the viewfinder at f/8 would be rather dark and difficult to manually focus, I decided that this was not going to be part of my kit.

    I don't usually regurgitate information posted by other photographers regarding equipment but, I have heard some very good things about the combination of the Canon 70-200mm f/2.8L IS Mkii lens and the Canon 2x TC Mkiii converter. If I had a 70-200L IS Mkii, I would definitely be interested in trying that combination.

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    Re: Teleconverter Advice

    Quote Originally Posted by Bobobird View Post
    I do most of my close-ups with the 70-300L as it has an excellent minimum focus distance of just under 4 feet. Sometimes will sling on a 12 or 25mm but never considered adding a TC to that. Will try it out and see. I want toe-counting!!!

    What is the sequence of attachment? TC + Tube + Lens or Tube + TC + Lens?
    With a Canon converter you need to insert a 12 mm tube between the converter and lens, obviously with the converter attached directly to the camera. The problem is due to the shape of the outer end of the converter which will not fit inside many lenses.

    Some third party converters are OK.

    I originally bought this equipment to get closer with my Canon 70-300 lens but found out, too late, that the quality does degrade with this lens and I wasn't happy with the results. But the Sigma macro lenses will work with just a minimal quality loss which isn't really noticeable most of the time.

    And with regard to Kevin's question about tubes. You really need someone else to give a scientific answer but very basically, a tube alters the focusing distance which allows the assembly to move forward a little while retaining good focus.

    But this focusing point move also affects the point of infinity. The maximum focusing distance will vary slightly depending on the size of tube. The thicker the tube the more you lose from the infinity end of the focusing distance.

    ps. this is the sort of closeness which I require on a live fly, shot in the wild, to confirm a definite identification. 180 macro lens plus 1.4x converter.

    Teleconverter Advice
    Last edited by Geoff F; 8th January 2012 at 06:14 PM. Reason: photo added

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