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12-12-2015, 01:37 PM   #16
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Thanks again, Mark, for some very nice testing that confirms - at least with this particular FA 80-200 and these particular TCs - that the prime makes a big difference. And the sample of the zoom is consistent with the meager test reports out there.

Having looked at what Ron (brandx) has indicated in tests over at the other forum, it does seem that the Pentax HD is a very high quality optic. If you have a Pz-SHQ that matches it, you might have gotten a marginal copy of the Pentax. A lot of the lens matching can be hit or miss. I suspect that the FA 80-200 would do quite a bit better with the HD or other high end TC such as the Tamron 140 series (but not available in Pentax mount). However, the testing by Mark pretty clearly shows that if there's a deficit in a lens, you might see it exaggerated - and the TC isn't entirely at fault.

My Pz SHQ is definitely a 1.4x based on my testing. I've played around with it on the DA 50 in the past few days and they seem to work well together with little or no IQ loss. In fact the focus is a little less nervous than when the 50 is mounted on its own (a real pain). It slightly outperforms the A-35-105 f/3.5 at equal length (which has been dropped so not an entirely fair comparison) with no TC, but the Samyang 85mm on its own is quite a bit better - not surprising.

12-12-2015, 02:09 PM   #17
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QuoteOriginally posted by audiobomber Quote
Tamron-F 1.4X Pz-AF MC4
I did actually test that teleconverter - I just left the 'Pz-AF MC4' off for brevity. That is the exact one used.

While I did not name the teleconverter as completely as you have, I have accurately identified the one used. However, thanks for the pick up re: Kenko 'DG' version.

Seriously, people, I think it fair to say that questions before making uninformed inaccurate statements is the go as these inaccurate statements derail the thread.

---------- Post added 12-13-15 at 08:14 AM ----------

QuoteOriginally posted by sergysergy Quote
Ok, this helps
Too many similar names
Sergysergy

Please know that audio bomber has bombed the thread with partly inaccurate statements. Sorry for sounding frustrated, but, Kev started the ball rolling.

General note: I am not a guru tester and know all. But, as a scientist I do know how to make 'similar' comparisons between things. Sorry - really frustrated here as I was making a solid comparison between three TCs, one of which is an unknown entity (so it would seem).

---------- Post added 12-13-15 at 08:20 AM ----------

QuoteOriginally posted by ScooterMaxi Jim Quote
Thanks again, Mark, for some very nice testing that confirms - at least with this particular FA 80-200 and these particular TCs - that the prime makes a big difference. And the sample of the zoom is consistent with the meager test reports out there.
Cheers ScooterMaxi Jim. The FA*80-200 is a very fine lens. The F*300 is simply better.

The real surprise for me was the performance of the Sigma TC. No one, except perhaps sergysergy, has picked up on this. There is next to nothing on the internet for this TC and so I felt encumbered to test/ compare against recognised TCs . In so doing I have learned a thing or two, not only through the testing but through this thread.

I wish I could test the F*300 + Sigma TC side by site with the Pentax 150-450 at the long end. I suspect my combo will rival the zoom performance.
12-12-2015, 03:03 PM   #18
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thanks for the clarification then!
12-12-2015, 04:56 PM   #19
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Thanks for sharing Mark. Very good comparison and well tested.

My take-home message is that on a sharp prime there isn't a huge difference between the third-placed Kenko and the Sigma, even at f5/f5.6 and certainly at f8. On the zoom, where there is more risk of CA, the differences are wider.

The tougher question in the field is the age-old one: in a particular situation should I use my TC or just crop? Depends on the lens and body combination of course, and on the conditions, particularly the available light. My limited experience with the Sigma 400 f5.6 on the K-30 is that if the subject is a wading bird 80m away in good light, maybe the TC at f8; but at some point between, the advantage is in just cropping. Now I have a K-3 the field-distance where the TC is worthwhile might have increased.

12-12-2015, 05:31 PM   #20
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QuoteOriginally posted by Des Quote
The tougher question in the field is the age-old one: in a particular situation should I use my TC or just crop?
Cheers Des. Our thinking is in alignment. The TC might actually be of benefit somewhere between infinity and an intermediate but far field focal point where cropping becomes less useful. That is my next investigation path as I continue to question the keeping of TCs.
12-13-2015, 05:40 AM   #21
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QuoteOriginally posted by sergysergy Quote
I read somewhere that the tamron and the kenko might be the same TC?
QuoteOriginally posted by Wild Mark Quote
I have read this too. I have by chance had the opportunity to test this idea (only on one sample of each) and found the Kenko wanting! They cosmetically/ design wise look identical - they definitely look the same beast.
QuoteOriginally posted by Wild Mark Quote
Please know that audio bomber has bombed the thread with partly inaccurate statements. Sorry for sounding frustrated, but, Kev started the ball rolling.
This is a public forum, anyone can contribute. If you intended to post a private thread, you're in the wrong place.

There were inaccurate statements posted regarding "the Kenko", and you contributed actively to the confusion through partial nomenclature and misinformation, as shown in the quote above. Tamron and Kenko make a number of TC's. People interested in TC's read these threads. They are entitled to clarity, not partial names and mistaken identity. I'm glad I "bombed" the thread, because now anyone reading it will arrive at the correct conclusions.
12-13-2015, 05:53 AM   #22
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QuoteOriginally posted by audiobomber Quote
They are entitled to clarity, not partial names and mistaken identity. I'm glad I "bombed" the thread, because now anyone reading it will arrive at the correct conclusions.
Mate seriously, take a chill pill. In normal discourse one might ask a question about something requiring clarity rather than assert oneself misinformed. You asserted yourself misinformed and did so in a manner inconsistent with the tone of the thread. I certainly took exception to your approach and made my feelings clear. If you are offended then I apologise for that.

Yes a public forum, and I accept that. It works both ways.

Oh and as for your quoting, easy to make me look silly. But I had no intent of misinforming, simple error. Your assertions suggested otherwise.

And yes I am annoyed. Perhaps the first time since joining Pentaxforums.
12-24-2015, 04:21 AM   #23
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Someone in Western Australia has one of the Sigmas for sale on Gumtree, asking $150: PENTAX (fit K-mount) Sigma 1.4x tele converter Quality!!!!!+ | Lenses | Gumtree Australia Stirling Area - Joondanna | 1098743816 Looks the same as the one Mark showed in post #8.

12-24-2015, 05:14 AM   #24
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Yes it does look the same.
12-29-2015, 11:19 PM   #25
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As a very odd happenstance, I just purchased one of these old sigma tc's today from a brick and mortar store in their going out of business sale. It's got the gold box, 5/5 optical formula, not designated APO. I got this one for $50, and they had the EX APO version for $100. The latter seems to go cheaper on eBay.

I had just read this thread a couple days prior, did a similar internet search in the store, and pretty much only found your review Wild Mark.

Can you fill me in on why you think the tc will perform better than cropping at far field to infinity, and specifically - what designates "far field"? I wanted to do some testing on moon shots tonight, but the clouds were too thick.

The store was an interesting one. I found a set of extension tubes with Pentax AF contacts, a FA 20-35/4 for $100, and a manual focus sigma 75-300/4-5.6 APO for $40. The shop had been around for 65 years, and you could tell they rarely cleared out old inventory.
12-29-2015, 11:46 PM - 1 Like   #26
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Top store - wish we had such stores here in Australia.

What I meant by far field was somewhere between infinity and long range where the master lens IQ resolves less (if that makes sense). My logic is that the TC may actually prove better than the master lens in these situations. I might go out and try this idea now using the F*300 at photograph objects at about 50-100m. I have a laser range finder so I will know distances. Will report back soon.

---------- Post added 12-30-15 at 06:28 PM ----------

I was intersted to see if there was a range where the TC was superior to image crops of the master lens (F*300mm).

I tested complex objects at 36m, 62m, 69m and 93m. Tripod + SR off + K3 + f6.3 for all images. Shutter speed varied due to TC influence.

Results are as follows.


F*300mm + TC @ 36m (f6.3 1/200)


F*300mm @ 36m (f6.3 1/500)


F*300mm + TC @ 62m (f6.3 1/400)


F*300mm @ 62m (f6.3 1/1000)


F*300mm + TC @ 69m (f6.3 1/400)


F*300mm @ 69m (f6.3 1/1000)


F*300mm + TC @ 93m (f6.3 1/250)


F*300mm @ 93m (f6.3 1/500)

---------- Post added 12-30-15 at 06:34 PM ----------

All in all, the F*300 probably wins still at 'far field' but the differences seem to be mostly contrast related. A little PP tweek to ramp up contrast and also a tiny week in the sharpness department and I imagine the only difference would be colours (sigma TC dulls colours a tiny little bit). Again, a little week in the colour department and I suspect that difference can also be accounted for.

So, based on this rapid comparison I find no reason to NOT use the TC if one is less inclined to PP/ crop images. The extra reach does sacrifice IQ but perhaps only 5% or there about. The above images are quite please imho.

The Sigma 1.4X Tele Converter is definitely a good TC when matched with the F*300mm

Last edited by Wild Mark; 12-30-2015 at 01:10 AM.
12-30-2015, 04:40 AM - 1 Like   #27
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On reflection I decided to look even closer at the images - yes pixel peaking. And, I think I have to refine my observations.

Firstly, the F*300mm + TC resolves better than the F*300mm at all distances except @ 36m. So somewhere between 36 and 62m may represent the threshold where the TC improves the resolution of the master lens.

The difference is, as previously stated, a little loss in contrast. So cleaning that up and the sharpness difference would become obvious. Additional sharpening is a choice - not a requirement. Slight colour adjustment is needed as the TC seems to starve the sensor a little (perhaps the inferior? coatings on the TC???).

As pervasively commented, I would love to test this TC lens combo against the DFA 150-450 at the long end. I suspect this combo is actually going to be better

Last edited by Wild Mark; 12-30-2015 at 04:52 AM. Reason: Error in 36m observation
12-30-2015, 08:06 AM   #28
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I think your test pics illustrate an essential TC's rule of thumb: good light!

Here's a couple of links to some tests some others have done:
Fun with Teleconverters

Teleconverter Comparison: Tamron 01F vs. Vivitar Macro
Certainly the resized pic comparison in the stacked tc's test by cooltouch illustrates the point that with good optics, while absolute iq degrades pretty dramatically, overall the increase in magnification is pulling in smaller scale information.
12-30-2015, 05:42 PM   #29
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QuoteOriginally posted by Wild Mark Quote
So somewhere between 36 and 62m may represent the threshold where the TC improves the resolution of the master lens.
Thanks Mark. You've answered what I thought was a rhetorical question.

Of course there are several variables:
- quality of the lens
- quality of the TC
- as @MarcusBMG points out, good light.
Your test gives an answer based on typical Australian conditions, comparing one of the better TCs with a stellar prime alone. Can't ask for more than that.
12-30-2015, 06:26 PM   #30
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QuoteOriginally posted by Des Quote
You've answered what I thought was a rhetorical question.
LOL - I didn't pick it - Oh well

Yes good light is definitely the key. Selecting a shutter speed that roughly matches or exceeds the focal length is another key (i.e. 1/450+) although when mounted on the tripod the shutter speed matters less.

Another after thought. The addition of the TC might actually be enhancing the resolving power of the lens - and so what I am saying is, it is the sensor that is the limitation, not the lens. More MP would probably reduce the benefit of the TC even more so.
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