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Just thought I'd share this little test I did with my 70-200VR and TC-20EII.

These 100% crops were all taken with my D70 tripod mounted with an SB-800 on camera at ISO 400, and 1/400s.

70-200VR shots were taken at 200mm.

70-200VR + TC-20EII shots were taken at 400mm at a camera to subject distance twice that of the 70-200VR shots.

Note: Both my 70-200VR and my TC-20EII were not purchaced new, so these results may or may not reflect others results.

Good tests... thanks for this as this is a combo I am considering.

From what I can see, there is a small loss in contrast with the TC.

Don't you lose two stops with the TC attached? So f/8 with TC is more equivalent to f5.6 without? Or is this a silly question?

It would also be interesting to see f/11 with TC and without...

Thanks, nice test.
Did you try at f11? I find that my 70-200vr has a sweet spot at f8 to f11, much the same as your results (minus f11)
Cheers
Albert

Justin wrote:Don't you lose two stops with the TC attached? So f/8 with TC is more equivalent to f5.6 without? Or is this a silly question?

No, that's correct. That's why I put the f/8 with TC beneath the f/5.6 without TC.

Justin wrote:It would also be interesting to see f/11 with TC and without...

I'm not sure why I didn't try an f/11? I might try it sometime.

Brad

This is an interesting experiment, but the real niggle for me is the with and without images show two different pieces of text and so don't exclude the possibility that the text being photographed has contributed to any differences in acuity or contrast.

stubbsy wrote:This is an interesting experiment, but the real niggle for me is the with and without images show two different pieces of text and so don't exclude the possibility that the text being photographed has contributed to any differences in acuity or contrast.

All the images were from the same page in a newspaper, same style/size text etc. So I don't see how it could have contributed to any differences.

Brad I think I know what Peter is saying.

please excuse my long-winded post...

Scientific method is to reduce as many variables as possible and only vary the one you are interested in testing. So with this test there are a number of assumptions made.

So whilst your tests are valid and educational and achieve what you set out to achieve, the fact that the text shot with / without is different is another variable. therefore your test is actually

without teleconverter on text selection (a)
with teleconverter on text selection (b)

Also, to get the same size with the TC on you also moved the camera and used the same focal length and different flash strength (assuming TTL) so it goes to something like this:

(case 1) without teleconverter on text selection (a1) at distance (a2) at focal length (a3) at flash strength (a4)

(case 2) with teleconverter on text selection (b1) at distance (b2) at focal length (a3) at flash strength (b4)

So with (a3) being the same between the two tests, we are shown that at maximum focal length for the 70-200 with / without the TC there is a difference in sharpness/ contrast - which is good to know as I said previously.

These are just another way of saying what you have already said above - and l got a lot out of your test. My gut feel is the other variables would not have significantly altered the result you got, however to close the loop with so many variables it is still an assumption.

Exhaustive testing of lenses is for the boffins IMHO

Justin/Peter,

I understand what you're both getting at.

How would you suggest I could overcome those variables?

I'd also like to see a similar test on the 70-200VR and the TC-17EII.

Anyone volunteering?

lend me your 70-200VR for six months of exhaustive testing and I will contribute the TC17

Justin wrote:lend me your 70-200VR for six months of exhaustive testing and I will contribute the TC17

Justin does the TC work with your 18-200 VR ?

greencardigan wrote:Justin/Peter,

I understand what you're both getting at.

How would you suggest I could overcome those variables?

Brad

Justin said it well. I was probably too succinct - sorry

Ideally you'd have something with a more uniform repating identical pattern to resolve the text differences, or if not move the text on the same focal plane to have the same words in the same spot of each image (harder). Either way that would remove the text as a variable. Similarly you want even illumination (eg in a lightbox) to rule that out.

Don't get me wrong though. What you have done was a good and useful test, I'd have just liked a little more (I'm a greedy bugger)

Thanks

stubbsy wrote:

greencardigan wrote:Justin/Peter,

I understand what you're both getting at.

How would you suggest I could overcome those variables?

Brad

Justin said it well. I was probably too succinct - sorry

Ideally you'd have something with a more uniform repating identical pattern to resolve the text differences, or if not move the text on the same focal plane to have the same words in the same spot of each image (harder). Either way that would remove the text as a variable. Similarly you want even illumination (eg in a lightbox) to rule that out.

Don't get me wrong though. What you have done was a good and useful test, I'd have just liked a little more (I'm a greedy bugger)

Thanks

You could still use text, but have a repeating pattern, so "The quick brown fox jumps over the lazy dog" Or whatever (DSLRUSERS Rule!) and just print a page full. As long as the printer can produce indentical looking lines, then you have a fair comparison.

No TC will work with the 18-200

greencardigan wrote:I'd also like to see a similar test on the 70-200VR and the TC-17EII.

Anyone volunteering?

For some it may be interesting, but you'd need to use the same 70 - 200 with the 1.7 and the 2.0 to even start to make a comparison. I have the 70 - 200 VR/1.7 combo, but what if your 70 - 200 is sharper than mine? Then your 70-200/2.0 TC will perform better than my 70-200/1.7 TC. That's fine, but it does imply that the 2.0 TC is better than the 1.7 when the real problem is with my suboptimal 70-200 VR and not with the 1.7 TC.

Bit of an edit...On re reading your post you may be interested in comparing the 70 - 200 images with and without the 1.7, rather than 1.7 vs 2.0.

Sorry I if I got your drift misconstrued..

Hey shakey I think an assumption that I would back would be quality control - check your serial numbers and check for any known issues with any batches.

But if you both are getting good photos from your lenses then I don't see why you couldn't assume the lenses were basically good.

Exec summary: this combo (1.7x) is fine from f/6.3, 1.4x is better, 2x is criminally pointless.

I have been using this combo now for about 4 months for sports and in good light it's great stopped down from 6.3. Dont buy this lens and a 2x converter thats just silly. This is like using a Rolls Royce as a door stop and should be considered a crime! The image quality (with the 2x) is not better than 80-400. If f/8 is the sweet spot, better off getting the newer 70-300VR. Oh and another blow, if I had my time again I'd buy the 1.4 as even the 1.7 is a little soft for my liking and AF is a lot more hit and miss even on a D200 - that said its still great and well worth the penthouse buying price difference to the 200-400 (which with all the second body stuffing around or shot missing lens changing involved for me, is I think, a silly and impractical focal length) and the 400 2.8 that I think is the real swoon lens here! I've made 14x18 prints from the 1.7x +70-200 combo shot f/6.3 510mm ISO 320 1/1600 on D200 and cant see any subject softness.