July 29, 2014, 06:54:10 AM

Poll

Does a teleconverter reduce the iq?

Yes
44 (97.8%)
No
1 (2.2%)

Total Members Voted: 45

Author Topic: Teleconverter  (Read 4909 times)

Kerry B

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Re: Teleconverter
« Reply #15 on: March 27, 2013, 04:33:21 AM »
I agree with Alan F, the question posed has to wide a gambit. An extender on a lens such as the 100-400 will degrade IQ. If the native lens has flaws this will be replicated with the addition of an extender. On my 300f2.8mkii the addition of the new 1.4mkiii extender does not degrade image quality, I am constantly amazed at the images this combo can achieve. I have yet to try the new mkiii 2 x extender.

From a personal point of view I think to much is made of so called bench tests, yes they have their place but real world photography is where it counts. Wherever possible I will always use a sturdy tripod when mounting long lenses and extender, whilst I may loose some control over composition, images in the main tend to be very sharp.

I have recently conducted some tests where I have compared the 300/1.4 combo mounted on a tripod as well as hand held at shutter speeds exceeding 1/2000 of a second. The images taken with the help of the tripod always look sharper.   

So many people complain that their images are not sharp and has poor IQ, they blame the equipment, the environment but never themselves. If my images are poor then it is my technique that needs to be looked at and not the equipment used.
Canon 5d mkiii, Canon 1d mk1v, Canon 300f2.8 IS mkii, 70-200f2.8 Mkii IS, 24-105f4, 1.4 mkiii extender and 2 x extender mkiii

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Re: Teleconverter
« Reply #15 on: March 27, 2013, 04:33:21 AM »

bycostello

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Re: Teleconverter
« Reply #16 on: March 27, 2013, 04:41:08 AM »
every extra bit of glass will reduce iq

mb66energy

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Re: Teleconverter
« Reply #17 on: March 27, 2013, 04:45:53 AM »
I'm considering getting a 2.0 teleconverter for my 70-200 2.8. Other than going to 5.6 does it also reduce the iq?   Thanks I'm still learning here.

1 A TC reduces the IQ systematically because it blows up the image of the naked lens by a factor of 2 (for a 2x converter you are considering) - lens flaws are scaled too. The upscaling by a factor of 2 means that the same light is distributed to a 4 times larger area reducing in 2 stops light reduction.

2 A TC introduces additional glas elements and reflects/scatters light. Modern zooms have 10-20 lens groups, the 4-6 lens groups of a TC will have some effect in this department, but it will be moderate.

3 Some TCs are co-optimized with one ore a few lenses. I am shure that Canon optimizes them for the 2.8 300 and the 2.8 400 lenses and that different TC series are optimized for the corresponding lens series. If you have an old 2.8 300 the 2x TC of the first series MIGHT match better.

I have the 2x TC version I (170 bucks 2nd hand) and it works well with my 4.0/70-200 L 4.0 non-IS and the 5.6/400. I decided to get the 5.6/400 because it's IQ is very fine from f/5.6 and I have a longer reach with TC.

Best you can do: Try your telezoom with a 2x TC (optimum: I + II + III series) and check the results for YOUR PHOTOGRAPHIC APPLICATION)

ADD (just seen): Kerry B's remarks about the 300 support my 3rd point!
TOOLS: EF-S 10-22 | 60 || EF 2.8/24 | 2.8/40 | 2.8+2.0/100 | 4.0/70-200 | 5.6/400 || 2 x 40D || 2x TC ||| 600D for video ||| EOS M + bunch of FD chrome rings

mb66energy

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Re: Teleconverter
« Reply #18 on: March 27, 2013, 04:48:42 AM »
every extra bit of glass will reduce iq

O.k. so I will put my eye glasses down ... asüdü aüfbis fiasbfsl lxc ... no, with eye glasses IQ is better and I see what I am typing!
TOOLS: EF-S 10-22 | 60 || EF 2.8/24 | 2.8/40 | 2.8+2.0/100 | 4.0/70-200 | 5.6/400 || 2 x 40D || 2x TC ||| 600D for video ||| EOS M + bunch of FD chrome rings

neuroanatomist

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Re: Teleconverter
« Reply #19 on: March 27, 2013, 10:34:30 AM »
every extra bit of glass will reduce iq

O.k. so I will put my eye glasses down ... asüdü aüfbis fiasbfsl lxc ... no, with eye glasses IQ is better and I see what I am typing!

LOL.  Ok, now put on two pair of glasses.  Is that better than one?
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mb66energy

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Re: Teleconverter
« Reply #20 on: March 27, 2013, 03:20:53 PM »
every extra bit of glass will reduce iq

O.k. so I will put my eye glasses down ... asüdü aüfbis fiasbfsl lxc ... no, with eye glasses IQ is better and I see what I am typing!

LOL.  Ok, now put on two pair of glasses.  Is that better than one?

I always dreamed to get rid of the CAs by an achromatic correction - post processing doesn't remove them completely despite of a massive parallel processing system  ;)
TOOLS: EF-S 10-22 | 60 || EF 2.8/24 | 2.8/40 | 2.8+2.0/100 | 4.0/70-200 | 5.6/400 || 2 x 40D || 2x TC ||| 600D for video ||| EOS M + bunch of FD chrome rings

LetTheRightLensIn

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Re: Teleconverter
« Reply #21 on: March 28, 2013, 07:55:15 PM »
I'm considering getting a 2.0 teleconverter for my 70-200 2.8. Other than going to 5.6 does it also reduce the iq?   Thanks I'm still learning here.

Yes, but it is usually worth it all the same if you need more reach. The 2x can get a bit dicey on some lenses where even if you do grab a trace more detail the other downsides might not be worth it.

2x on a 70-200 is pushing it past where I'd want to unless you are talking the 2.8 IS II. If you are not talking that version then I'd stick to the 1.4x TC. The 2x TC works better on the big white primes.

They do slow AF and make it a bit less precise.

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Re: Teleconverter
« Reply #21 on: March 28, 2013, 07:55:15 PM »

Mt Spokane Photography

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Re: Teleconverter
« Reply #22 on: March 28, 2013, 08:15:59 PM »
I was out this afternoon playing with my new 70-200 f/2.8 MK II to see how well it worked with TC's for hand held photos in low light.  Its a very dark day, so the ISO on the images is high.  Before I started using the 2X TC, a thunder storm hit and ISO's went up to 10,000 so I'll try again tomorrow.  Each TC I add reduces the IQ, but the new 70-200 takes TC's very well, so it is quite usable with a 2X TC, but far from pixel sharp.
 
The first is at 200mm + 1.4X
 

 
 
 
 
 
This one has the 2X + 1.4X.  AF is slow, but works.
 

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Re: Teleconverter
« Reply #22 on: March 28, 2013, 08:15:59 PM »