Telephoto Zoom comparison

oldracer

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... I disagree that "it's just physics" but my PhD is not in optics...
Well, it really doesn't need a PhD in anything but the school of hard knocks. All you have to know is that there is no such thing as a free lunch. Adding a TC is guaranteed by the TANSTAAFL rule to degrade the image.
 

ralf-11

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the cost of the lunch is the loss of light - 2 stops

I am unaware of an optical principle dictating an IQ loss for a tele-extender.

But moot point - as the gear is on its way back now.

To bad there was no collusion between the lens and tele-extender
 

wjiang

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I am unaware of an optical principle dictating an IQ loss for a tele-extender.
Glass manufacturing and design is not perfect, each element introduced has defects and aberrations. A TC not only introduces it's own aberrations, but being an enlarger, magnifies existing lens aberrations. The stronger the TC the larger this effect is.

This is a well known limitation for any and all TCs. It's why 2x TCs are rarely any good, especially on a zoom. They are only typically used on a very good fast prime to start with.
 

ralf-11

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I'm glad I saved others from this - OTOH, it could possibly be just the particular examples I got.

BTW, Panny did not advertise the 2x as working with the 50-200 - that doesn't mean they aren't compatible.
 

ralf-11

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Glass manufacturing and design is not perfect, each element introduced has defects and aberrations. A TC not only introduces it's own aberrations, but being an enlarger, magnifies existing lens aberrations. The stronger the TC the larger this effect is.

This is a well known limitation for any and all TCs. It's why 2x TCs are rarely any good, especially on a zoom. They are only typically used on a very good fast prime to start with.
each element introduced to make a 100-400 has defects and aberrations also...
 

wjiang

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each element introduced to make a 100-400 has defects and aberrations also...
A 100-400 does not have to operate in two modes, switching the extra elements in and out. The 50-200 is optimised for it's native performance, trading off performance with extra TC elements added. The 100-400 is also optimised for it's native performance, but the 'extra' elements are already in place and optimised for.
 

davidzvi

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I suppose it physically fits but the IQ is not up to snuff for them to promote it. Well, there goes any feelings of GAS I had for it.
My gas for the 50-200 was for use with the 1.4TC, but I'm still holding out hope for one of the two lenses on the Olympus roadmap.

As to compatibility, what's the minimum rating for Panasonic and Olympus lenses to actually AF correctly on either bodies? I know in the Nikon world it was f/5.6 and then f/8 for the central cross type points? This might have changed with the D850/D5/D500, but it was/is the case with the older 51 point AF systems. The 50-200 is f/4 so the TC makes is f/8, what's DFD capable of?

Just a thought.
 

wjiang

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Sorry but all zooms operate in many modes
They don't switch elements in and out. The TC is also stuck by always being the last optical group, in zooms the moving elements aren't limited to being the last group.

The key difference is that a zoom is optimised for its elements already. A lens is never optimised to perform best with an optional TC attached. The best that can be done is to optimise a TC for a given lens.
 

T N Args

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....I disagree that it is "just physics" that might make a 2x extender on a lens not have equal IQ to a lens twice the FL. Think about how a lens is designed.....
Here is a short article by Zeiss on why teleconverters degrade the IQ. Particularly note their suggestion to use them "with a fixed focal length lens except in a “do-or-die” situation."
 

T N Args

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You would be better off by far using a Panasonic 100-300 in a comparison with the Nikon 80-400. It might not win (totally unfair cost comparison), but it would fight on the basis of being designed to do the job.

Sample P100-300 at 300mm
Subscribe to see EXIF info for this image (if available)
 

ralf-11

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Here is a short article by Zeiss on why teleconverters degrade the IQ. Particularly note their suggestion to use them "with a fixed focal length lens except in a “do-or-die” situation."
Thx, but the IQ con they mention is increasing residual aberrations, and the problem here is greater than that.

I do have 2 Zeiss lens for my Hasselblad system and like them quite a bit...


I will probably try the PL 100-400 at a later date. I'll have a 'hole' in the FL range from 60 to 100 but that won't kill me.
 

Machi

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I don't understand this discussion. It's really so hard to take photos of the same object from different distances with matching FOVs with both lenses without TC?
Then it would be immediately clear if it's problem with TC or with the lens.
(It's true that atmospheric turbulences can affect even this test but then Nikon would have disadvantage because of higher magnification)
 

Machi

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@T N Args I understand part about 700mm eq lenses.
I don't understand part about TC and its effects on the image which is going now for 2 pages and without meaningful result.
BTW, I think that would be much better theme for review.
"IQ of 50-200 PanaLeica with 2×TC"
 

StefanKruse

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Here is a short article by Zeiss on why teleconverters degrade the IQ. Particularly note their suggestion to use them "with a fixed focal length lens except in a “do-or-die” situation."
Hmm "do-or-die" seems a bit over the top :) Hasnt there been a lot of people using the old 50-200 oly 4/3 lens with the 1.4 TC? and as I recollect with people be ok happy with the results? but maybe those were do or die situations :)
 
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