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07-11-2011, 01:49 PM   #1
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teleconverters between lens and body vs after lens

Hello everyone,

I assume if one is to have a teleconverter then the best option is an AF between the lens and body - however there is a clear difference in cost for this approach.

So, which is better on the remaining optio, having a it between the body n lens or after the lens? Does one create a greater loss of quality than the other? As in between the lens and body expect to loose 1 stop but after the lens expect to loose over 2.

I quess there is better flexibility in having it after the lens and not between since it can simply be added or removed as needed.

I am basically looking to add a TC to a a Tamron 28-300 (older model).

Thank you all.

07-11-2011, 02:15 PM   #2
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The "converters" that mount like filters on the end of the lens can be classified with extremely rare exceptions as garbage. Those that are not garbage are for specific camera models. Between the lens and camera body converters have some of garbage versions as well. Before you spend your hard earned cash on one, check them out in the review forums on this site. I have two converters and both are Pentax branded and neither was inexpensive. One is the AFA 1.7X and I can highly recommend it. On my Flickr site there are some shots I did to test it behind my DA* 50-135/2.8. I also have an A 1.4X-S that I use mostly with the M 400/5.6 to turn it into a 680/8 when there is enough light to do so.
07-11-2011, 02:59 PM   #3
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C.R. is right on. If you don't have cash for a good / premium TC, you will do better just to crop. It's free! What you are asking about are what I call strap-ons. They have their place, but usually not on our dSLRs. The types of strap-ons:

* Tele adapters (what you asked about)
* Wide, ultrawide, and fisheye adapters
* Corrected close-up adapters (like Raynox)
* Uncorrected meniscus +dioptre close-up adapters
* Split +dioptre close-up adapters
* Weird geometric effect adapters

Tele, wide, ultrawide, and fisheye adapters may work well (or at least acceptably) with camcorders and cine cams. But that's because 1) these inherently have lower resolution, and 2) the human visual system is very forgiving of aberrations in moving images. They do NOT work well with still images, because we'll notice how crappy the images are. I have a couple high-end tele+wide adapters my dad used on his Hi8 camcorder. They're fine there. I've put them onto 5mpx digicams. The tele isn't too bad; the wide is fairly bad. I've put them onto lenses on my K20D. They suck terribly. And I've used high-end made-for-dSLR tele+wide adapters on my K20D. They still suck.

Of the others I mentioned above: Corrected closeup adapters (like Raynox) are quite good. All the rest... well, they have their uses, but I won't go into those now. Suffice to say that you can use a cheap tele adapter or TC if you aren't real interested in image quality. If content matters more than IQ, like with surveillance or blackmail shots, then they're fine. Otherwise, avoid. Save your money. Buy a 500mm mirror.
07-11-2011, 03:36 PM   #4
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A few months back I asked in the accessories forum if anyone thought it would be a good idea for me to pick up a high-end apochromatic diopter ($120 for a 77mm) rather than rely on teleconverters (1.5x, 1.7x, 2.0x) or extension tubes that I already have, or if there'd be any benefit to combining a high-end diopter with either the teleconverters or tubes, and I never got a reply.

07-11-2011, 04:15 PM   #5
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QuoteOriginally posted by bergerak Quote
I am basically looking to add a TC to a a Tamron 28-300 (older model).
It's not worth it. A while back I did a controlled test with a Pentax 55-300 + Kenko 2x TC, and found that using the exact same parameters - ISO, aperture, etc - that images from the Pentax 55-300 cropped to match the Pentax 55-300 + TC were at least 90% as good. Once you factor in field conditions - that is, boosting ISO to increase shutter speed in order to handle the TC, reducing the aperture to gain sufficient DOF, etc. - the 2x TC winds up being a losing proposition. The only times TC's really work is a) if it actually helps you find and focus on your subject and b) when you mate a high quality TC with a high quality lens.

Oh, and adding a TC to your Tammy 28-300 may make it unable to AF.
07-11-2011, 04:34 PM   #6
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Canada Rockies - thanks for your response and link to samples of the Pentax products you use.
I have read on the forum review lens section and had an eye on the Tamron 1.4 AF which seems to have gotten some good reviews.

Rio - thanks for your feedback. I also have an eye on a 500mm and would like to put my money on at least the f6.3 - wont commit to the f8.0.

On another thought - I have a Meade telescope and could spend a few dollars for the adapter though not sure what magnification I get out of it. Haven't done the proper research for a Meade AT-60.

Thanks again for your responses.
07-12-2011, 11:57 AM   #7
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Dear Bergerak, the front mounting lenses are called auxiliary lenses. Some come in sets like my Yashica 2x Tele and 0.7x Wide with 55 mm rear mount (to attach directly to lenses with a 55 mm filter mount), and a 72 mm front filter mount.
You can use Step UP/Down Adapters to mount it on any lens. The photos are pretty good - 100% crops attached. The first photo is with the auxiliary, and the second one without. The Yashica appears to be a good auxiliary lens.
I am neither a Pro nor a a pixel peeper, and my Yashica auxiliary lenses serves my purpose very well.

Last edited by nanhi; 11-19-2012 at 08:31 AM.
07-12-2011, 12:44 PM   #8
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There are two uses for which I would recommend the auxiliary, + diopter "filters".

1. A stacked set of one or two "filters" takes up very little room when packing light for the trail, travel or job and offer an option for unexpected close-up shots that would otherwise not be possible without carrying/risking more expensive/heavier gear. They aren't that terrible-bad when properly used under typical field conditions when you don't have comparison shots to display. I used to use 'em quite a bit for work related stuff where detailed close-ups of "broken things" was needed. Also note, there's no effective increase in exposure which can be helpful in the field especially.

2. They're a very economical way to determine if someone is really interested enough in close-up/macro subjects to splurge on the more expensive gear. I've known folks who spent lots of money on either extreme telephoto or macro gear only to discover that for one reason or another they just didn't like the time, place or effort that went with using it. Bug spray, oh-dark thirty wake-ups, muddy waders, no one to shoot with, etc. The +diopter "filters" and economy-class tele lenses would have been a lot less expensive lesson and an upgrade later can be better informed as to what's best for them.

H2


Last edited by pacerr; 07-12-2011 at 12:56 PM.
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