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02-12-2018, 10:00 PM   #46
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QuoteOriginally posted by desert-tiger Quote
Hi I am looking to get a tc for my K1 for my 100macro and my 150-450. Since its ff I am not sufe about these old tc. Is the 1.4 better or a 7 element 2x? Can someone recommend the best avabile pleas
IME. a 2X TC is not viable if you care about IQ.

Don't use a TC with the K-1. You will get better AF and better image quality if you shoot in crop mode vs. using a TC.

For maximum range, use the K-1 in crop mode with a Pentax HD 1.4X RC.

02-12-2018, 11:42 PM   #47
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Ah well, think they are coming out with a ff one? What about the Tamron-F AF Tele-Converter 1.4X Pz-AF MC4 Teleconverter for Pentax K KAF3 Mount | eBay
02-13-2018, 02:40 PM   #48
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QuoteOriginally posted by desert-tiger Quote
Ah well, think they are coming out with a ff one? What about the Tamron-F AF Tele-Converter 1.4X Pz-AF MC4 Teleconverter for Pentax K KAF3 Mount | eBay
IQ is very good and it is FF compatible. AF is good with screwdrive lenses but not with in-lens motors.

Why do you want a TC with attendant IQ and AF compromises vs. shooting in crop mode?
02-13-2018, 05:06 PM - 1 Like   #49
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QuoteOriginally posted by audiobomber Quote
For maximum range, use the K-1 in crop mode with a Pentax HD 1.4X RC.
Or use one of the crop bodies with a 24mp sensor. Using the K-1 in crop mode is kind of like using a K-5iis (albeit with better AF and better high ISO performance). Even a second-hand K-3 would be worth considering.

Opinions are divided about TC v crop. There is no single right answer. It depends on a lot of factors, including light, subject size and distance to subject. The comparison by WildMark at post #26 above is done with a K-3. It might be different with a K-1, even in good light with the same size subject. It also depends on how big an image you want to finish with. For posting on the web or viewing on a phone, 1200 x 800 pixels might be enough. But most DSLR users are probably going to want more than that (certainly if you want to print at more than 6x4).

QuoteOriginally posted by desert-tiger Quote
Ah well, think they are coming out with a ff one?
Don't bank on it. It's not on the Pentax roadmap.

QuoteOriginally posted by desert-tiger Quote
What about the Tamron-F AF Tele-Converter 1.4X Pz-AF MC4 Teleconverter for Pentax K KAF3 Mount | eBay
My personal view, from experience, is that a decent TC is a worthwhile tool for birding, particularly with a 300mm f4 or f4.5 lens (or faster), just as a 400mm f5.6 lens is a useful tool. In fact since I got the FA*300 f4.5 and Kenko Pz-AF 1.5x Teleplus SHQ (i.e. the one that is said to be the twin of the Tamron which Mark tested, rather than the Kenko used in Mark's test), I don't use my Sigma 400mm f5.6 tele macro very much. The IQ is better with the FA*300 + TC (effectively 420mm f6.3), even though the Sigma is quite a good lens and one-third of a stop faster.

But the returns diminish when your effective maximum aperture goes beyond f5.6 or f6.3 - from trying it, I'd need to have a compelling reason to use the Sigma with the TC again (for an effective 560mm f8). Some people have got good results with the DFA 150-450 at maximum reach with a TC (effectively 630mm f8) - good luck to them. But you'd need ideal conditions.

The Kenko works very well (on the K-3) with the DFA 100 f2.8 macro WR (effectively 140mm f4).


Last edited by Des; 02-13-2018 at 05:16 PM.
02-15-2018, 03:22 AM   #50
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Third party TCs on old FA* glass - nothing really dedicated.
Neither Pentax nor Tamron 1.4TCs could convince me on DA*300. A longer * lens would be much more interesting.
I can see a need for a decent FF TC for Pentax at least.
02-15-2018, 10:15 AM   #51
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QuoteOriginally posted by Des Quote

FA*300 f4.5 and Kenko Pz-AF 1.5x Teleplus SHQ (i.e. the one that is said to be the twin of the Tamron which Mark tested, rather than the Kenko used in Mark's test),
The Kenko works very well (on the K-3) with the DFA 100 f2.8 macro WR (effectively 140mm f4).
I have the same Kenko, as well as the Pentax 1.4X. The Pentax TC is slightly superior in IQ but radically better for auto-focus with in-lens motors.
04-16-2018, 03:37 PM - 1 Like   #52
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sigma 1.4x tc non-apo

I now have a copy of the sigma 1.4x tc that Mark was testing at the start of this thread. So here's some comparitive test crops.
Samsung NX20, tamron adaptall SP 300mm f2.8 60B, same test subjest - the musselmans raft.




[/img]





Looking at these crops and comparing to those of the "apo" version (see post #40) , though the comparison is compromised a bit by using a different camera, that the "apo" is better is clear, specifically in terms of contrast and fringing at the wide apertures. As the lens is stopped down IQ improves and pretty much becomes the same.

Just for interest I stacked the sigma 1.4x tc with the adaptall 014F tc, making a 588mm f5.6'ish combo. Thse came out better than I thought they would actually.





Last edited by marcusBMG; 04-16-2018 at 03:55 PM.
04-16-2018, 03:46 PM   #53
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QuoteOriginally posted by marcusBMG Quote
I now have a copy of the sigma 1.4x tc that Mark was testing at the start of this thread. So here's some comparitive test crops.
Samsung NX20, tamron adaptall SP 300mm f2.8 60B, same test subjest - the musselmans raft.








Looking at these crops and comparing to those of the "apo" version (see post #40) , though the comparison is compromised a bit by using a different camera, that the "apo" is better is clear, specifically in terms of contrast and fringing at the wide apertures. As the lens is stopped down IQ improves and pretty much becomes the same.

Just for interest I stacked the sigma 1.4x tc with the adaptall 014F tc, making a 588mm f5.6'ish combo. Thse came out better than I thought they would actually.



The f numbers you are showing are the lens value not the actual f number - correct? Meaning with the 1.4x when the lens reads f/5.6 the actual f stop is f/8, etc.

04-16-2018, 03:52 PM   #54
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QuoteOriginally posted by UncleVanya Quote
The f numbers you are showing are the lens value not the actual f number - correct?
Correct
(still updating...)

Actually I need to redo the apo test pics with the NX20. Crop doesn't really illustrate my conclusion...
04-16-2018, 07:59 PM   #55
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That Tamron is way too expensive also when that model usually goes for under $200.00 USD not 240 as posted. I have had good luck with that model though.
07-15-2019, 07:26 AM   #56
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I picked up a tamron Af 1.4x tc and a kenko 1.5x tc, and as discussed earlier in this thread these are both basically the same TC. The teleplus 1.7x tc I also have is also virtually identical, just slightly higher magnification. The kenko 1.4x I sold is also the same. We can assume these all emanate from the same manufacturer.
The actual magnifications from these TC's are (determined by linear pixel ratios acrosss the roof as per pic for the tamron, teleplus 1.7x and kenko 1.5x, the kenko 1.4x from a previous measurement; adaptall 300mm lens):

TC magnification
Tamron 1.4x
Kenko 1.4x 1.37x
Kenko 1.5x 1.4X
Teleplus 1.7x 1.54x
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Last edited by marcusBMG; 07-15-2019 at 07:42 AM.
07-16-2019, 01:04 PM   #57
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I have now tested these 3 tc's on my DFA 150-450mm. First priority was to see if the SD contacts worked. All passed this test in these conditions (good sunlight, tripod mounted K3) - lens auto focussed easily, full data transmision. Then I tried a far subject and a near subject to get an impression of IQ. Lens alone was at 450mm, lens + tc lens was set at 320mm (1.4x) or 300mm (teleplus). Cable release, 2 secs timer (remote subject only), autofocus.
The more I try doing this the more I find that results are a bit arbitrary, subject to random factors eg atmospherics so results are not to be taken as anything definitive, just indicative. Red outlines show the crop exported from LR3, white the 1:1 pixelpeep crop.







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