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100-400mm + Kenko 1.4x converter - 1st impressions (1 Viewer)

Hi Websurfer,

here's a different perspective for you to muse over:

"a TC will provide you with more feather detail..."

As soon as I started using a TC I got the real impression that I was getting more detail. I'm convinced it's because I need to crop into my picture much less than I generally need to without the TC, in order to get the required image size and composition.

Think about it: all other things being equal, a 1.4x TC makes the subject 40% bigger in the frame which means that any given element of the scene - including the feather detail - has 40% more pixels on it.

Logically that must mean more detail.

The tiny impact the extra glass in the TC has on IQ is more than made up for by being (optically) 40% nearer to the subject.

Discuss.

;)
 
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Keith Reeder said:
Hi Websurfer,

here's a different perspective for you to muse over:

"a TC will provide you with more feather detail..."

As soon as I started using a TC I got the real impression that I was getting more detail. I'm convinced it's because I need to crop into my picture much less than I generally need to without the TC, in order to get the required image size and composition.

Think about it: all other things being equal, a 1.4x TC makes the subject 40% bigger in the frame which means that any given element of the scene - including the feather detail - has 40% more pixels on it.

Logically that must mean more detail.

The tiny impact the extra glass in the TC has on IQ is more than made up for by being (optically) 40% nearer to the subject.

Discuss.

;)
Click to expand...

So you mean:
all other things being equal, a 2.0x TC makes the subject 100% bigger in the frame which means that any given element of the scene - including the feather detail - has 100% more pixels on it. :)

I am not so convinced of this advantage - but I see your point.
 
Keith Reeder said:
Think about it: all other things being equal, a 1.4x TC makes the subject 40% bigger in the frame which means that any given element of the scene - including the feather detail - has 40% more pixels on it.

Logically that must mean more detail.

The tiny impact the extra glass in the TC has on IQ is more than made up for by being (optically) 40% nearer to the subject.

Discuss.

;)
Click to expand...

You can think of this in a different way. Let's assume the TC is really good. Then, assuming exposure, AF, etc. is good, the detail in the picture is mostly limited by two factors:
  1. The resolving power of the lens
  2. The resolving power of the sensor

TC helps you in the case where the lens can outresolve the sensor by itself. In this case, the lens by itself will render detail on the sensor which would exceed the pixel pitch of the sensor. The TC will "spread" the middle section of the image rendered by the lens to cover more of the sensor area, therefore giving you better detail than what is possible with simply scaling the image.

This is one of the reasons why people get much better results with a TC on higher quality lenses. Most of Canon's high end telephoto primes can outresolve the 8MP sensors found in the 350D/20D/30D when the weather conditions permit.
 
Mark and Keith
I couldn't have said it better, even though I am still a "shoemaker", and not the "pro" you guys are.

As you can see from the Cardinal pic I posted, you can even see the dust flying around his head. (I hope it wasn't noise, because I did use really high ISO, because of the weather, and I was really trying to get a shot at something different)

Gunter
 
What Macshark said.

Before getting to the end of the thread, I was going to state it in terms of magnifying the the lens aberrations and comparing that to the sensor pixel size, but it's the same thing.
Looking at it this way implies to me that whilst very ggo (or very poor) lenses won't be affected but a converter, there will be some not quite so good lenses that look sharp as the aberrations are just less than the pixel size, but look noticeably less good with a converter as the magnified aberrations are now bigger than the pixels.
 
Thanks Steve and Andrew - you make the point better than I did!

I guess that we walk a fine line with TCs, and sticking one on a lens that is only OK when used alone is pushing things: but providing that the lens plus TC can still resolve to the size of the sensor pixel pitch or better (and it needs a very good lens, to be sure) then theoretically there's no Real World IQ downside to TCs purely in resolution terms.

Of course we can start to butt up against other limitations caused by TCs - AF problems, the need to increase ISO and/or aperture to maintain shutter speed etc - all of which can have an effect on the perceived detail captured.
 
Just to close: the attached bearded tits were taken at 560mm (100-400mm + TC) and were handheld and were wide open and were at 800 ISO and have had noise reduction applied.

If you can't see the individual feather strands on these, you need a new monitor..!

;) ;) ;)

The black stork is at 1000 ISO, wide open, hand-held - though only 476mm (340mm x 1.4).

Don't get me wrong, they're not great pictures, but there's feather detail there...

I should also add that I've got dumb-as-a-rock post processing skills: someone who knew what they're doing could probably drag a ton more fine detail out of these...
 

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Keith Reeder said:
The black stork is at 1000 ISO.
Click to expand...
Hi Keith, this leads me to another thing re ISO on the 30D. I was reading about 'Fake' 1/3 stop ISO Setting on the 30D. I guess from the Stork shot you do not subscribe to this although if it were true it would not have mattered anyway with the small Dynamic range of a black Stork. What do you and others think?

Here is a posing I read recently:


http://forums.dpreview.com/forums/read.asp?forum=1019&message=18348853

The claim is that the intermediate 1/3-stop ISO settings on the 30D are achieved by remapping the digital intensity scale (leading to a potential loss of 2/3 stop of dynamic range, if I understand correctly) rather than by adjusting the amplifier gain in 1/3-stop steps. It is generally known that a similar technique is used openly for the ISO3200 (H) setting, so this would not be too surprising, and it may even be the case that the amplifier gain steps are determined at a level deeply buried within what is after all the 20D sensor, and cannot be adjusted more finely.

The implication seems to be that whereas the 1/3 stop steps may be useful for in-camera generation of a JPEG, there is no benefit in using them in RAW mode.
 
Keith Reeder said:
Just to close: the attached bearded tits were taken at 560mm (100-400mm + TC) and were handheld and were wide open and were at 800 ISO and have had noise reduction applied.

If you can't see the individual feather strands on these, you need a new monitor..!

;) ;) ;)

The black stork is at 1000 ISO, wide open, hand-held - though only 476mm (340mm x 1.4).

Don't get me wrong, they're not great pictures, but there's feather detail there...

I should also add that I've got dumb-as-a-rock post processing skills: someone who knew what they're doing could probably drag a ton more fine detail out of these...
Click to expand...

You simply don´t understand what i am saying or won´t understand.
Yes these pics are OK and I can see feather detail - but I have never seen very great shots with clear and outstanding feather details when a TC is used. Shots with outstandig feather details can be delivered with the bare lens or with primes in another league with a TC on - BUT putting a TC on, will always mean some softening of details. Pics are not quite as clear as when a bare lens was used. Your shots are fine but no outstanding feather details are visible. I think you need a first class prime like the Canon EF 500mm f/4 IS or others in this league. If you don´t have such a good lens and are using lenses in not quite the same league - then you should avoid putting a TC on, because every test shows that the amount of visible lines is reduced, when a TC is added.
That naturally dosn´t mean, that you cannot get acceptable shots from your gear and maybe a TC is very useful under circumstances, where you cannot get so close to the subject.
As I said in my first post - I knew some of you would disagree with me - but nothing mentioned in this debate has changed my mind.
I do see many great shots in here but some could have been better if no TC was on I am sure. That´s all I am saying.
 
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websurfer said:
Yes these pics are OK and I can see feather detail - but I have never seen very great shots with clear and outstanding feather details when a TC is used. Shots with outstandig feather details can be delivered with the bare lens or with primes in another league with a TC on - BUT putting a TC on, will always mean some softening of details. Pics are not quite as clear as when a bare lens was used. Your shots are fine but no outstanding feather details are visible.
Click to expand...

I guess it's just a matter of what you expect/want from your images. Personally I'd be very pleased to have taken any shots that Keith, Roy and Gunter posted as example of shots with a tc. I'm happy with the quality of shots that I get from my Sigma even with a 1.4x on it. No doubt a better photographer would get better results with this lens, it's really not too far off the Canon 500 f4 in image quality.
 
Roy C said:
I guess from the Stork shot you do not subscribe to this
Click to expand...

Actually Roy, I do!

;)

As you say it probably didn't matter much for the stork (although I think I meant to be on 800 ISO but maybe bumped the dial), but ever since I first read John Sheehey on "fake" intermediate ISOs I've taken it seriously - and I have noticed a small difference. I seem to get less noise at 400 ISO than I used to get at 320 ISO (it wasn't a big difference, but I noticed it), so now I make a point of shooting RAW and sticking to the real ISO values.

I don't really see any downside to this approach.
 
Hi Websurfer,

I give up, defeated..!

;)

Seriously though, if you believe that when you get your bird lens (assuming that it's a good one) there is going to be such a difference in IQ between the lens with and without a TC that you'll be able to say "see? I told you so!", I think you're going to be very disappointed.

Gernerally speaking, being (optically or physically) close to the bird has much more to do with how much feather detail you'll get than the quality of the "raw" lens alone. I'll post up a robin close-up tonight that makes the point - more feather detail than you can shake a stick at, and there was a TC in there...
 
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Its a fairly well stated fact that the big primes can outresolve the sensors in the lower end camera's, so I guess that the pursuit of perfection would not just involve a lens purchase but also a 1Ds mkII.

Got to admit I'm also curious as to how much 'feather detail' is actually oversharpening. I can normally tell an image taken with a good lens not because of how sharp it is, or even how much detail is retained, but by the fact the image looks 'natural.' the bird actually looks like a bird rather than something you'd clean the loo with ;)
That natural look is what I strive to achieve

edit: forgot to add,
And thats exactly how many of the shots on this thread look like to me, no need for them to be any more detailed/sharper.


Paul
 
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I had a very quick go at Keith's image, now, if I had the original and a spare few hours, I could get this image to really jump off the printed page and grace any magazine cover. It would be pin sharp and perfect.

All images will need a degree of sharpening. The secret is to know just what area to sharpen.
 

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pe'rigin said:
I had a very quick go at Keith's image, now, if I had the original and a spare few hours, I could get this image to really jump off the printed page and grace any magazine cover. It would be pin sharp and perfect.

All images will need a degree of sharpening. The secret is to know just what area to sharpen.
Click to expand...

Just wonder, why the signature is so unclear. Has too much pp perhaps taken place?
BTW a great shot, indeed!
 
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pe'rigin said:
I had a very quick go at Keith's image, now, if I had the original and a spare few hours, I could get this image to really jump off the printed page and grace any magazine cover. It would be pin sharp and perfect.

All images will need a degree of sharpening. The secret is to know just what area to sharpen.
Click to expand...

I'm sorry pe'rigin but thats highlighted the point I was making. To me that image now looks oversharpened. I know its virtually impossible to work on a compressed image on the web, but I honestly prefer the look of the original, from a sharpening point of view. Could be my crummy laptop monitor but aren't the highlights now blown on the grass below the bird?
 
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The bottom line is that 'Websurfer' thinks that a £4000 lens is better than a £1000 lens - I guess everyone would agree with this but remember that it started out with the statement 'almost everytime TCs are used, feather details on pics are mostly gone'. This has surely been disproved.

P.S. I agree with Paul, I think Pe'rigin's edit is oversharpened (something I am guilty of myself all to often)
 
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Roy C said:
The bottom line is that 'Websurfer' thinks that a £4000 lens is better than a £1000 lens - I guess everyone would agree with this but remember that it started out with the statement 'almost everytime TCs are used, feather details on pics are mostly gone'. This has surely been disproved.

P.S. I agree with Paul, I think Pe'rigin's edit is oversharpened (something I am guilty of myself all to often)
Click to expand...

the bottom line is: Image quality does degrade when using a TC. I have always said that and I stand by my words. I haven´t seen anyone agreeing with me, yet.??? I did only mention expensive lenses to emphasize which lenses were most acceptable to use a TC on IMO:
Then you have to consider how big the costs will be for your lens in terms of IQ.
 
websurfer said:
the bottom line is: Image quality does degrade when using a TC. I have always said that and I stand by my words. I haven´t seen anyone agreeing with me, yet.??? I did only mention expensive lenses to emphasize which lenses were most acceptable to use a TC on IMO:
Then you have to consider how big the costs will be for your lens in terms of IQ.
Click to expand...
Please see my first post on the subject in which I said 'Sure tc's will degrade the IQ' if that is not agreeing with you I don't not know what is.
 
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