Chris — whoa, now that's some hardcore pixel peeping, with math thrown in to boot! Makes my head hurt so early in the morning... I'm gonna go shoot some soccer. ;-)
For me, generally, the answer is yes. I always have my 1.4 with me, and take the 2.0 on trips---but I haven't used the 2.0 in a looong time and the 1.4 is very rarely used.
I'm an image quality junkie, and the extenders are an optical compromise, anyway you look at it. (Albeit, a compromise that can save the day, at times)
I agree with Michael's comments from earlier. I use the 1.4 TC mostly with the TS-E lenses for nature close-ups and landscape. The 24II & 90 TS-E are both lenses with a little "resolution to spare". The image quality is pretty good - my biggest disappointment is the additional CA - kinda s*cks in landscape. An aspherical TC would be a wonderful tool - and while being wishful a second version of the 45 & 90 TS-E's as their bigger weakness is the CA.
Thinking out loud here, without test results to back any of this up.....
All a TC does is to take the image produced by the lens and spread it wider on the sensor. It certainly doesn't magically invent more photons to be recorded. That's why a 1.4X TC loses you a stop of light. Same amount of light, spread more thinly. (That's if we ignore inefficiences and aberrations added by the TC itself.)
So, if you have plenty of light, or can use apertures, shutter speeds and ISOs to fill up your pixel wells then that's great. The TC should buy you some advantage. But if you are struggling to get enough light in, and already using higher ISOs to make up the photon shortfall then I doubt very much that a TC is going to add much value. It's robbing Peter to pay Paul. You can get a larger image but the noise will be worse, so you will need to downsize more to get you back to where you would have been or apply more NR, which will rob detail. Would that be a better solution than shooting with the bare lens (less noise, sharper image, better AF) and then upscaling, or simply downscaling less? I'm thinking not.
So I would say that a TC adds value so long as your focusing is not compromised (too much) and your pixel level noise does not rise to unacceptable levels.
tdodd wrote:
So I would say that a TC adds value so long as your focusing is not compromised (too much) and your pixel level noise does not rise to unacceptable levels.
And let's not forget that shooting at a longer focal length might require higher shutter speeds, especially when handholding an unstabilised lens, and with 1 stop of light already lost, can you afford another 0.5 stop of light loss in shutter speed to maintain the same degree of blur at the pixel level. If all you will otherwise do is to magnify pixel level blur more with the TC then you are again back to square one.
tdodd wrote:
In my opinion, yes, that's a "maybe".
And let's not forget that shooting at a longer focal length might require higher shutter speeds, especially when handholding an unstabilised lens, and with 1 stop of light already lost, can you afford another 0.5 stop of light loss in shutter speed to maintain the same degree of blur at the pixel level. If all you will otherwise do is to magnify pixel level blur more with the TC then you are again back to square one.
But if you need to 'pull up' the centre of an image by the equivalent of a 1.4x then you must allow for a higher shutter speed to balance the extra magnification anyway.
PaulB wrote:
But if you need to 'pull up' the centre of an image by the equivalent of a 1.4x then you must allow for a higher shutter speed to balance the extra magnification anyway.
True. But the point is that the extra magnification might come with strings attached, one way or the other.
Just my two cents, but the answer to this question may be more art than science. I have and use several TCs of various flavors in multiple combinations; some with good results and some not so good. But it is easy for me to post a link to the page where Romy has multiple shoot outs using TCs and looking at many of his pix it seems clear to me that using a TC can produce great results; here is the link
My take is that a lot of the IQ in these images is the result of Romy's skill rather than the camera, lens, or TC used; not to mention post processing after the fact.
How ever I do think some of the examples provided in this thread are not really good ones. I have a 70-200/2.8; but I would never think of using a TC on it. Instead I would just grab the 120-300/2.8 or the 400/5.6 or the 500/f4 or the 300-800.
For me the bottom line is that a TC is useful on my 150/2.8 macro; but that is the only lens under 300mm I would consider using a TC on.
Also remember that you can afford to raise the pixel noise with the extender. Because the image is larger. With the same pixel noise, the larger image will always look better after down-sizing both to the same size
Mar 13, 2010 at 12:30 PM
Lars Johnsson Offline • • • • • • • Upload & Sell: Off
Also remember that you can afford to raise the pixel noise with the extender. Because the image is larger. With the same pixel noise, the larger image will always look better after down-sizing both to the same size
Mar 13, 2010 at 12:30 PM
Lars Johnsson Offline • • • • • • • Upload & Sell: Off
Also remember that you can afford to raise the pixel noise with the extender. Because the image is larger. With the same pixel noise, the larger image will always look better after down-sizing both to the same size
Mar 13, 2010 at 12:31 PM
Lars Johnsson Offline • • • • • • • Upload & Sell: Off
Also remember that you can afford to raise the pixel noise with the extender. Because the image is larger. With the same pixel noise, the larger image will always look better after down-sizing both to the same size
Mar 13, 2010 at 12:32 PM
Lars Johnsson Offline • • • • • • • Upload & Sell: Off
Also remember that you can afford to raise the pixel noise with the extender. Because the image is larger. With the same pixel noise, the larger image will always look better after down-sizing both to the same size
