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01-11-2011, 01:27 PM   #1
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DFA 100mm + 2X TC vs. cheap zoom

I'm going on a long trip in a couple of weeks, and I'll be taking my favourite lenses (Sig 10-20, DA40, A50, DFA 100 WR) and a new K-5 which I will have by then.

I also have a Tamron 70-300 which I don't often use and I don't really want to bring - space is limited. But sometimes it's useful to have a longer lens.

I'm wondering if my optically wonderful DFA 100 with a reasonable teleconverter (2X, 1.7X, something like that) will give me similar image quality to the zoom at the same focal length - or better/worse?


(Looking at Kenko or Tamron TC's, as that's what's available for a reasonable price.)

01-11-2011, 11:02 PM   #2
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i think its a matter of how you order that limited space. the TC plus the A50 must occupy the same space and weight as the 70-300, and maybe the 50 is redundant as you'll take the much more advanced 40.
maybe its better to save the money from the TC and sell the zoom, (that is clear that you don't like it, poor little tammy ) and buy a better one.
01-12-2011, 02:27 AM   #3
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Well... I really just want to compare the quality of those two options, right now.

TC + A50 would be significantly smaller than the 70-300 which is quite a bulky lens for the weight.

I'm only taking the A50 because I'll want something for low light work, and none of the other lenses are great for that (2.8 vs 1.7). And it's tiny, anyway.

Long term the question is whether to swap the 40 for a 35 Ltd macro, tearfully sell the 100 macro and the 70-300 and invest in a high quality tele zoom. But I haven't found a tele zoom with the right weight/speed/quality combination yet (something in between the 55-300 and the DA*60-250 would be perfect). That's for another time though.
01-12-2011, 01:28 PM   #4
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QuoteOriginally posted by timh Quote
I'm going on a long trip ...my favourite lenses (Sig 10-20, DA40, A50, DFA 100 WR) and a new K-5 which I will have by then.
I also have a Tamron 70-300 which I don't often use and I don't really want to bring - space is limited. But sometimes it's useful to have a longer lens.
I'm wondering if my optically wonderful DFA 100 with a reasonable teleconverter (2X, 1.7X, something like that) will give me similar image quality to the zoom at the same focal length - or better/worse?
Well, obviously it's going to take more than one TC to turn your DFA100 into a 300. Stacking two TC's would surely be a waste of time. But that admitted, here's one opinion of TC's:

I've only used the Tamron 1.7 and Vivitar 2.0 teleconverters, so my experience is limited. But I found with a Tamron 90 macro lens, I could get JUST as good an image from the 90 alone and cropping in post-processing, as I could using the 90 plus the 1.7 TC. In other words, for image quality, the 1.7 TC gets you absolutely nothing you don't already have.

When you add in the cost of the 1.7 TC and the hassle of adding it to the camera when you need it, it's a waste of both money and time. Also you need to consider that in most cases the TC causes the camera to save inaccurate EXIF data. Also, of course a TC cuts out a LOT of light, so it can prevent you from taking a picture in a low-light situation. In fact, in marginal conditions the TC can cut out so much light that the AF refuses to focus.

My experience with the 2.0 TC + 90 was VERY slightly better: under some conditions, cropping or digital zooming really could not give quite the image quality the TC did; close, but not quite. But even with the 2.0 TC, considering all the tradeoffs of cost, hassle to install, low-light, plus one more item to carry on your trip, made the TC a bad idea.

There's no free lunch. That's why there's the Tamron 70-300, and the DA* 60-250. And large camera bags.


Last edited by infosyn; 01-12-2011 at 07:20 PM.
01-12-2011, 01:55 PM   #5
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Fair enough! Thanks for the feedback.

I wasn't planning to try to get it to 300mm - and in fact I avoid 220-300mm on the Tamron anyway. 170mm or 200mm would be fine for my purposes, as long as the quality is something like the quality of the Tamron. Same pictures, 1/4 of the bulk, that was my idea.

I'm surprised that in your experience a TC is little better than cropping - they do seem to be widely used, which is strange if there's absolutely no point to them. I'll always put more faith in practical experience than a logical conclusion when it comes to technology though, a product doesn't have to work if people will buy it regardless.

I knew about the light reduction (but with 2.8 as a starting point vs 5.6 on the zoom it's comparable) but didn't think attaching it would be an issue - it's just two K-mounts, right? Not like zooming, but I usually know what shot I want to take when I attach the lens anyway.

Large camera bags - not a fan.
01-12-2011, 04:17 PM   #6
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I'd say take the tamron.
f2.8 + 2xTC get's you 200mm f5.6 lens, I'd bet you that Tamron at 200mm f5.6 would be better...

my 2p
01-12-2011, 06:53 PM   #7
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QuoteOriginally posted by axl Quote
I'd say take the tamron.
f2.8 + 2xTC get's you 200mm f5.6 lens, I'd bet you that Tamron at 200mm f5.6 would be better...
As a lover of TCs on good fast glass I wouldn't say that (it would be an interesting subject for a technical comparison). Click my Tanzania link and you'll find most photos (except the first posts made on the first page, obvious wide-angle shots, and some other shots so marked) are taken w/a 2X TC mounted. I've got numerous other thread extolling the virtue of a great TC. two examples:

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/35674-told-not...u-tell-me.html
https://www.pentaxforums.com/forums/photo-critique/21886-dog-art-distracting-...ix-inside.html

I will say however if you choose to use a 2X TC, shoot RAW as you're likely going to find you need to bump the contrast, color, vividness and make other adjustments that are far better to do in the likes of Lightroom or equiv than to do in-camera.

Last edited by m8o; 01-12-2011 at 07:04 PM.
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