Opinions on lens outfit...

Discussion in 'Digital Discussion & Q&A' started by Tiberius47, May 28, 2008.

  1. Tiberius47

    Tiberius47 TPF Noob!

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    I'd like your opinion on an idea I had for a lens collection.

    I have a Canon 40D and the tamron 17-50 f2.8.

    I was thinking of getting the new Tammy 70-200 f2.8 (I love fast glas, and from I've read this is a pretty decent lens), as well as a 2x teleconverter.

    This will give me the equivilent of:

    17-50 with the wide angle zoom by itself.
    36-100 with the wide angle zoom combined with the 2x TC.
    70-200 with the telephoto zoom by itself
    140-400 with the telephoto zoom and the 2x TC.

    I'll lose a few stops with the TC, but considering that the glass is fast to begin with I don't see this as a probem. According to THIS page, I'll lose two stops. Starting with a maximum aperture of f2.8, that still gives me f4, which isn't too bad.

    The advantages I see are:

    • it gives me the 17-400 zoom range with just two lenses and a TC (27-640 efl), and that's the same as a 23 times zoom if it was in one lens, so I've got a huge range to play with
    • I'll have pretty fast apertures over the whole range
    • I won't have any gaps between the focal ranges. In fact, I'll be doubling up on focal lengths between 36-50mm, 70-100mm and 140-200mm.

    My questions are:

    Will the image quality I get from such a set up be good? How much will I lose by using a teleconverter? And which teleconverter should I get to make sure it works with the Tamron lenses, or will any TC that will work with Canon lenses work on the Tammy's (seeing as they are the same mounts)?
     
  2. JimmyO

    JimmyO TPF Noob!

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    Be careful. I dont think that you can use teleconverters on most short lenses. And you might want to look at 1.4x or 1.7x instead unless you want to buy a really good TC to keep good IQ
     
  3. Steph

    Steph No longer a newbie, moving up!

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    You are right. With a 2X converter you will loose 2 stops but loosing 2 stops from f2.8 gets you to f5.6 not f4.
     
  4. Tiberius47

    Tiberius47 TPF Noob!

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    Gah, you're right, my math was off.

    Still, a 400mm set up at f5.6 is pretty good. And the lenses are nice quality too, from everything I have read (The telephoto Tammy).

    So I need to get a good quality TC and see if it is usable on a short lens.
     
  5. gryphonslair99

    gryphonslair99 Been spending a lot of time on here!

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    Yes
    Well, Kinda, sorta maybe once. After you try this you will understand why
    Yes
    Well, Kinda, sorta maybe once. After you try this you will understand why

    As previously posted this will give you a f5.6, not f4. Slow glass and something that has not been mentioned, slow auto focus speed.

    The disadvantages I see are:
    • TC's are made to be used with lenses in the 100mm and above range. I have the Tamron you are talking about. It's now relegated to backup duty. I have Canons EF1.4 TCII, a top line TC. It does not fit on the Tamron 17-50mm. I have used the Kenko 1.4 300DG TC and the image quality on the Tamron with the 1.4 was poor, with a 2X it would be worse. The Kenko 1.4 300DG is considered by many as the equivilent to Canons 1.4 TC. TC's and short focal lengths do not play well together.
    • A 1.4 TC will cause you to loose 1 f-stop and a 2X TC will cause you to loose 2 f-stops. An f4 lens is not "fast glass" and an f5.6 is even slower. Keep in mind, a wide open lens tends to be soft. Add a TC and you magnify the flaw of the lens it is on. Soft = Softer, etc.
    • You will have huge image quality gaps in the focal range. The good ranges will be 17-50mm and 70-200mm. With a top line 1.4 TC from Canon or Kenko's 300DG series the 70-200 can be useable at the upper end of the range and at least from my experience on my Canon 70-200 f2.8L with the above mentioned TC at the 70-100mm range barely useable if it is stopped down quite a bit.
    • Unless you are willing to spend the money for a good TC then you will have additional problems. A TC magnifies every flaw the lens has. It slows the auto focus down and increases minimum aperture. Add a cheap TC and you now not only magnify the flaws of the lens but the flaws of the TC. Kinda like buying a Corvette and putting Walmart's cheapest tires on it. It will not be a good combination.
    See above.
    See above again.
    Canon TC's are designed basicly for most of, but not all of their Long L glass. The only way to know if it will even attach to the 70-200 is to try it. If it was me, I would look at the Kenko 300DG series 1.4TC. It is designed differently than the Canon. I can't speak to the top line Tamron, Sigma, or Tokina TC's as I have never used them.

    TC's are a specialized piece of equipment that can be tempermental. I only use my Canon 1.4 on my 200mm f2.8L prime and my 400mm f2.8L prime. Only for relatively static subjects. AF speed is reduced making the combination unsuitable for sports. For wildlife however it is a great combination and the image quality is top notch.
     
  6. Tiberius47

    Tiberius47 TPF Noob!

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    Okay...

    Still, f5.6 on a 640mm efl lens is pretty good, i think. Might not be that fast over all, but compared to some of the other lenses around that focal length, it's still faster than them. Autofocus will be slower, and I'll need a high quality TC to get good results. What happens with a TC on a shorter focal length lens?
     
  7. gryphonslair99

    gryphonslair99 Been spending a lot of time on here!

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    A whole lot of distortion when you use a TC on short glass

    The Canon 600mm is a whole stop faster, f4, and of course the AF is faster. The new 800mm is f5.6 and again faster AF. The famed and now fabled Canon 1200mm lens was a f5.6. One recently sold used at B&H for $99,000.00. My wife said I could buy it. Right after I invented a way to make gasoline out of dirt at a penny a gallon.:lol: I guess I didn't get the process worked out in time because someone else bought it. :lmao:

    The 2X TC only makes the 200mm a 400mm lens at f5.6.Remember the 2X TC doubles the focal length. The crop factor is not a magnification, it is a crop factor. There is a difference there. Plus it doubles the inherent problems of the lens. One inherent problem of a 70-200mm or for that matter any zoom lens is that they are a compromise where a prime is designed for that single focal length. My 200mm f2.8L is sharper than my 70-200 f2.8L. That is the nature of zooms vs primes. A 1.4 on a quality zoom like a 70-200 works well. A 2X TC does not. At least not to my standards of image quality. I did find it acceptable on my 200 f2.8L prime.

    The best thing to do would be to take the 70-200 to a photo shop that has a 2X TC. Shoot some test shots on your body and see if it is acceptable to you. That is the real test.
     

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