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11-20-2015, 04:18 PM   #1
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It's final: Teleconverters Suck

Came across this article today from a friend of mine. I guess Brandx over in DPR can stop shooting lamps posts with stacked converters. LOL

Stacking Five 2x Teleconverters to Create a Ridiculous 9600mm Lens

11-20-2015, 04:21 PM   #2
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But a single TC can help.

It also depends on the quality of the TCs.
11-20-2015, 04:47 PM   #3
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One of the contributors to mflenses.com did a similar test.

Fun with Teleconverters

The resized crops indicate that although the images got very mushy, more information was being pulled by the multiplied focal length.
Quality of the base lens is most important factor IMO, as long as the tc's are also good. But I tend to agree that the need/usefulnesss of tc's has diminished in the digital age, if not perhaps entirely disappeared - I find one useful quite often when out birding.

And I shall remark that the test the OP links to is technically dubious, the support for the lens needed to be extended eg manfrotto telephoto lens support or even just a macro rail and a wedge.
11-20-2015, 05:01 PM   #4
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My only converter (other than an ancient knock off 2x in screw mount) is the AFA 1.7x Pentax. I was pleasantly surprised by how well it worked with my less than perfect M 400/5.6 on my K10D. My next set of tries will be with the K3 on the back. I suspect I won't gain anything from the extra resolution, but might lower the noise level in the images. To control CA and PF, the 400 has to be stopped down to f/11.

11-20-2015, 05:09 PM   #5
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I'm content with the performance my Pentax K T6-2X provides.

Tak 200/4
11-20-2015, 08:16 PM   #6
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QuoteOriginally posted by Canada_Rockies Quote
other than an ancient knock off 2x in screw mount
You have one of the too, eh? Mine is wretched, simply wretched.


Steve
11-20-2015, 08:18 PM   #7
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I've got one too.
11-21-2015, 02:17 AM   #8
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SO many variables !
Just need to find a combination that works ...

11-21-2015, 05:14 AM   #9
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This all about the TC performance and the lens performance. And the longer the length, the more expensive it is to get one that perform well.

If I look at the DA*300 f/4 from DxO point of view, it doesn't outresolve a 24MP sensor and doesn't match what a DA35 macro or DA*55 provide. It is sharp but not extremely sharp. But if I look for the sigma 300mm f/2.8 then the story is different. But already people are happy with their DA*300 + TC even if it doesn't match say a 150-450 at 420mm.

People report that when they put the TC on their DFA 100 macro they don't get any optical issue and they get many more details.

So this all about the lense and the TC.
11-21-2015, 05:38 AM - 1 Like   #10
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It'a also A LOT about atmospheric haze for distant targets. And proper infinity focusing/infinity stop.
You wouldn't believe how much those things matter, esp. for very distant targets until you try it yourself.

Last edited by LensBeginner; 11-21-2015 at 05:47 AM.
11-21-2015, 06:08 AM   #11
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QuoteOriginally posted by Nicolas06 Quote
But already people are happy with their DA*300 + TC even if it doesn't match say a 150-450 at 420mm.
The only direct comparison I've seen was provided by Brandrx on DPR, and showed the DA*300 + HD 1.4X was about a stop sharper than the 150-450 (i.e. the prime combo had the same sharpness at f5.6 as the zoom at 450mm and f8).

QuoteOriginally posted by Nicolas06 Quote
People report that when they put the TC on their DFA 100 macro they don't get any optical issue and they get many more details.

So this all about the lense and the TC.
I completely agree, it is about the specific lens and the specific TC. My experience with Pentax and Vivitar 2X TC's was very poor, but I would not be without a good 1.4X. If one can't afford the Pentax HD, then a Kenko SHQ 1.5X PZ Teleplus, Tamron PZ 1.4X or Sigma APO is worth having, as long as you don't need it focus SDM lenses.

I know some use a 55-300mm with TC, but IME the lens is too weak to benefit. I like the DA 55-300 a lot as long as I don't have to crop too hard.

PS This thread title is kind of a troll job.
11-21-2015, 06:28 AM   #12
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QuoteQuote:
PS This thread title is kind of a troll job.
Ya, we'll, he thought we should read the article, and he had to get our attention somehow. I'm pretty impressed with how well the stacked TCs did. When you consider that you've added another20 pieces of glass that aren't even designed to work together, that's pretty amazing. Pentax says the degradation is 3% for the 1.4. I'm guessing it would be at least 5% for the 2x. Now add five of them. The fact that you can see a difference using 5, mostly due to contrast, doesn't mean you can see a difference using one.

You just have to be careful how you interpret this.

---------- Post added 11-21-15 at 08:58 AM ----------

Adding the 1.4 to macro was just an un-anticipated bonus surprise. I bought it for telephoto. The day it arrived Tess put it on her Tamron 90 macro and went out shooting. I've gone with it on my Sigma 70 macro quite often as well.

Last edited by normhead; 11-21-2015 at 07:28 AM.
11-21-2015, 09:16 AM   #13
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TC bring a benefit when used with "low resolution" sensors that aren't great for cropping (e.g getting more reach with a Nikon D750). When used with higher res. sensors such a K-3, D7200, D810, 5Ds, crop is as good or even better than using a TC. I suppose that use of FF sensor can compensate for the one stop light loss and resolution of a x1.4 TC (should be confirmed by real images).

Last edited by biz-engineer; 11-21-2015 at 09:22 AM.
11-21-2015, 09:27 AM   #14
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QuoteOriginally posted by audiobomber Quote
The only direct comparison I've seen was provided by Brandrx on DPR, and showed the DA*300 + HD 1.4X was about a stop sharper than the 150-450 (i.e. the prime combo had the same sharpness at f5.6 as the zoom at 450mm and f8).


I completely agree, it is about the specific lens and the specific TC. My experience with Pentax and Vivitar 2X TC's was very poor, but I would not be without a good 1.4X. If one can't afford the Pentax HD, then a Kenko SHQ 1.5X PZ Teleplus, Tamron PZ 1.4X or Sigma APO is worth having, as long as you don't need it focus SDM lenses.

I know some use a 55-300mm with TC, but IME the lens is too weak to benefit. I like the DA 55-300 a lot as long as I don't have to crop too hard.

PS This thread title is kind of a troll job.
Troll job or not, here's my take:
DA*300/4 + HD 1.4X TC = not sharp most of the time, even stopped down.

JP
11-21-2015, 09:35 AM - 1 Like   #15
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Stacking 50 UV filters is also bad news LensRentals.com - Good Times with Bad Filters

...but what I really want to know is what kind of quality can I expect if I stack five 2x tele-converters and 50 UV filters at the same time? I've got a pile of filters and TC ready to go in my cart at BandH*, but I'm not going to pull the trigger if the quality will be poor. I'm just stymied on the lack of information out there for this combined usage.


* I actually have ten of the Pentax 1.4x converters, will that be ok, or would five older 2x be better?
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