teleconverter question

bobore · 06-22-2021, 02:13 AM

There is a film era 5-element AF Sigma 1.4x teleconverter that I've satisfyingly used going back to the PZ1-P. It is screw-drive only, but quite sharp, and will autofocus at f5.6 in good light. In the review section on aftermarket teleconverters, it's the last one in the list (as of this writing).

These don't come up very often on the used market, but I recently grabbed a second one on ebay - so they do show up from time to time.

**Lowell Goudge** · 06-22-2021, 03:54 AM

There are sigma APO -EX 1.4x and 2x teleconverters for screw drive sigma tele lenses, BUT they only work on long fast lenses with recessed rear elements and a lens bore (at the mount) of 35mm. They work on lenses such as the older screw drive 70-200/2.8, 100-300/4, 300/2.8 500/4.5 and some of the 150-500. And 170-500 lenses. They will also work on similar Pentax FA lenses like the 70-200/2.8, 300/2.8, 400/2.8 etc

vonBaloney · 06-22-2021, 06:52 AM

The prices on the Tamron have come way way down (and the Kenko should follow since it is the same thing, but not everybody knows that). I seen them for $50ish lots of times in the last couple years. I actually have one or two I need to get rid of myself.

**Sakura** · 06-22-2021, 01:16 PM - **1 Like**

Originally posted by jon.partsch

Indeed, but that one is just for APS‐C, correct? Just wanted to make sure that was pointed out.

It is for APS-C, but in fact, it is also for full frame.
Just to be absolutely sure, i just tested it again with my D-FA 24-70 and my Full-frame modded DA* 60-250.
There is absolutely no vignetting visible.

**mikesbike** · 06-22-2021, 03:25 PM

Originally posted by Sakura

It is for APS-C, but in fact, it is also for full frame.
Just to be absolutely sure, i just tested it again with my D-FA 24-70 and my Full-frame modded DA* 60-250.
There is absolutely no vignetting visible.

This being true with wider angle lenses like these, obviously there should be no problem when using it with the usual telephoto lenses, like the DA*200mm or the DA* 300mm on the K-1 II. I've had the FA* 300mm f/4.5 for years. That the DA Pentax TC used with FF shooting works just fine should be made more well-known.

I have the Tamron PZ AF 1.4 TC which I bought for film use, and seems to work well, but the Pentax is more up to date and may bring me better results.

**DWS1** · 06-22-2021, 07:39 PM

Originally posted by Sakura

It is for APS-C, but in fact, it is also for full frame.
Just to be absolutely sure, i just tested it again with my D-FA 24-70 and my Full-frame modded DA* 60-250.
There is absolutely no vignetting visible.

Originally posted by mikesbike

This being true with wider angle lenses like these, obviously there should be no problem when using it with the usual telephoto lenses, like the DA*200mm or the DA* 300mm on the K-1 II. I've had the FA* 300mm f/4.5 for years. That the DA Pentax TC used with FF shooting works just fine should be made more well-known.

I have the Tamron PZ AF 1.4 TC which I bought for film use, and seems to work well, but the Pentax is more up to date and may bring me better results.

Just to be clear, are you saying the current Pentax DA 1.4x teleconverter works just fine with the DA* 60-250mm at all focal lengths, the DA* 200mm, and DA* 300mm on a K1 in full frame mode with no problems? This is something I have not heard before.

**Sakura** · 06-23-2021, 08:45 AM

Originally posted by DWS1

Just to be clear, are you saying the current Pentax DA 1.4x teleconverter works just fine with the DA* 60-250mm at all focal lengths, the DA* 200mm, and DA* 300mm on a K1 in full frame mode with no problems? This is something I have not heard before.

Yes, depending on the diafragma without serious vignetting visible.i was really surprised with these results.
Today i even tested it with my D FA 150-450. It works fine up to something like 400mm. Longer than that you will see some vignetting.

Attached Images

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View Picture EXIF

Last edited by Sakura; 06-23-2021 at 11:17 AM.

**Sakura** · 06-23-2021, 11:10 AM

Some more test shots with my 24-70 at 70 mm with different diafragma settings:

**Sakura** · 06-23-2021, 11:15 AM

And some test shots with my to Full frame converted 60-250 at 250 mm (the converted lens without teleconverter hasn't any vignetting at any setting)
Up to F8 the vignetting is easy removable with PP. and the combination is good usable.
Above F8 it is really severe and only a crop will fix it, but that makes the combination useless of course.

06-22-2021, 03:25 PM	#20
mikesbike Site Supporter Join Date: Dec 2016 Location: Southeastern Michigan Posts: 4,558	Originally posted by Sakura It is for APS-C, but in fact, it is also for full frame. Just to be absolutely sure, i just tested it again with my D-FA 24-70 and my Full-frame modded DA* 60-250. There is absolutely no vignetting visible. This being true with wider angle lenses like these, obviously there should be no problem when using it with the usual telephoto lenses, like the DA200mm or the DA 300mm on the K-1 II. I've had the FA* 300mm f/4.5 for years. That the DA Pentax TC used with FF shooting works just fine should be made more well-known. I have the Tamron PZ AF 1.4 TC which I bought for film use, and seems to work well, but the Pentax is more up to date and may bring me better results. Last edited by mikesbike; 06-22-2021 at 03:45 PM.

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06-22-2021, 02:13 AM	#16
bobore Senior Member Join Date: Oct 2009 Location: North Oregon Coast Posts: 162	There is a film era 5-element AF Sigma 1.4x teleconverter that I've satisfyingly used going back to the PZ1-P. It is screw-drive only, but quite sharp, and will autofocus at f5.6 in good light. In the review section on aftermarket teleconverters, it's the last one in the list (as of this writing). These don't come up very often on the used market, but I recently grabbed a second one on ebay - so they do show up from time to time.

06-22-2021, 03:54 AM	#17
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,891	There are sigma APO -EX 1.4x and 2x teleconverters for screw drive sigma tele lenses, BUT they only work on long fast lenses with recessed rear elements and a lens bore (at the mount) of 35mm. They work on lenses such as the older screw drive 70-200/2.8, 100-300/4, 300/2.8 500/4.5 and some of the 150-500. And 170-500 lenses. They will also work on similar Pentax FA lenses like the 70-200/2.8, 300/2.8, 400/2.8 etc

06-22-2021, 06:52 AM	#18
vonBaloney Pentaxian Join Date: Oct 2011 Location: Albuquerque, NM Posts: 6,029	The prices on the Tamron have come way way down (and the Kenko should follow since it is the same thing, but not everybody knows that). I seen them for $50ish lots of times in the last couple years. I actually have one or two I need to get rid of myself.

06-22-2021, 01:16 PM - 1 Like	#19
Sakura Site Supporter Join Date: Jan 2010 Location: Netherlands Photos: Gallery Posts: 438	Originally posted by jon.partsch Indeed, but that one is just for APS‐C, correct? Just wanted to make sure that was pointed out. It is for APS-C, but in fact, it is also for full frame. Just to be absolutely sure, i just tested it again with my D-FA 24-70 and my Full-frame modded DA* 60-250. There is absolutely no vignetting visible.

06-22-2021, 07:39 PM	#21
DWS1 Site Supporter Join Date: Aug 2018 Location: Arkansas, USA Posts: 1,169	Originally posted by Sakura It is for APS-C, but in fact, it is also for full frame. Just to be absolutely sure, i just tested it again with my D-FA 24-70 and my Full-frame modded DA* 60-250. There is absolutely no vignetting visible. Originally posted by mikesbike This being true with wider angle lenses like these, obviously there should be no problem when using it with the usual telephoto lenses, like the DA200mm or the DA 300mm on the K-1 II. I've had the FA* 300mm f/4.5 for years. That the DA Pentax TC used with FF shooting works just fine should be made more well-known. I have the Tamron PZ AF 1.4 TC which I bought for film use, and seems to work well, but the Pentax is more up to date and may bring me better results. Just to be clear, are you saying the current Pentax DA 1.4x teleconverter works just fine with the DA* 60-250mm at all focal lengths, the DA* 200mm, and DA* 300mm on a K1 in full frame mode with no problems? This is something I have not heard before.