FF TC - full frame teleconverter

Mistral75 · 01-28-2019, 09:07 AM - **1 Like**

Indeed, a teleconverter enlarges the image circle (and a focal reducer shrinks it).

normhead · 01-29-2019, 07:13 AM

Originally posted by biz-engineer

I've had TC, sold them, buy TC again and sold again. Image comparison of crop vs TC told me that TC is only valuable when the sensor resolution doesn't allow to crop, e.g 24Mpixel instead of 36Mp or 45Mp. AF generally works better without TC, so unless the lens out-resolve the sensor by a good margin TC don't bring anything (get the image on the whole frame and bump iso to compensate for loss of light => no better than cropping of high res. sensor). So, unless Pentax makes a fast 16Mp or 24Mp camera, I'll never get any TC again. TC is great with a 16Mp full frame that boast 10 frames per seconds, OTOH TC on a K1 is a waste

For the 487 bazilyionth time.
Understanding folks saying a TC doesn't ad more detail. - PentaxForums.com

**acoufap** · 01-29-2019, 01:32 PM

Originally posted by normhead

For the 487 bazilyionth time.
Understanding folks saying a TC doesn't ad more detail. - PentaxForums.com

I already waited for your comment.

**acoufap** · 01-29-2019, 01:41 PM - **1 Like**

Originally posted by Mistral75

Indeed, a teleconverter enlarges the image circle (and a focal reducer shrinks it).

If I put the DA TC1.4x on the DFA100WR and use it in K-1 FF mode the image shows strong vignette. So precondition FF TC is needed to generalize for a FF sensor. Not surprising anyway ... Things depend on lens design. My M1.7/50 doesn't vignette on FF with DA TC1.4x.

normhead · 01-29-2019, 06:20 PM

Originally posted by acoufap

If I put the DA TC1.4x on the DFA100WR and use it in K-1 FF mode the image shows strong vignette. So precondition FF TC is needed to generalize for a FF sensor. Not surprising anyway ... Things depend on lens design. My M1.7/50 doesn't vignette on FF with DA TC1.4x.

The DA 1.4 is a crop TC. When I want macro on the k-1 I use the F 1.7x AF adapter, although on the K-3 it's even more macro than with the 1.4.

**acoufap** · 01-29-2019, 10:07 PM

Originally posted by normhead

The DA 1.4 is a crop TC. When I want macro on the k-1 I use the F 1.7x AF adapter, although on the K-3 it's even more macro than with the 1.4.

Of course - I was not clear enough. A DA TC1.4x doesn‘t enlarge the image circle not that much that it covers the FF circle for every lens.

bobell69 · 01-31-2019, 09:12 AM

I'm really hoping for one to come out as it would be my next lens purchase. The problem of course is that if it comes out, I may just have to sell my Sigma 70-200 and buy the Pentax 70-200.

normhead · 01-31-2019, 09:14 AM

Originally posted by bobell69

I'm really hoping for one to come out as it would be my next lens purchase. The problem of course is that if it comes out, I may just have to sell my Sigma 70-200 and buy the Pentax 70-200.

No TC was definitely instrumental in my decision to pass on the DFA* 70-200.
There is a TC for the Sigma though, so at least you can sit tight.

**JensE** · 01-31-2019, 11:00 AM

Originally posted by normhead

There is a TC for the Sigma though, so at least you can sit tight.

Is there? For the HSM OS variant? I couldn't find one.

normhead · 01-31-2019, 11:06 AM

Originally posted by JensE

Is there? For the HSM OS variant? I couldn't find one.

I might be wrong, I just remember when I bought my *ist D they thought I should buy the Sigma 70-200 instead of the 70-300 because there was aTC for the 200. But that was like 94 or something.

bobell69 · 01-31-2019, 11:11 AM

Originally posted by normhead

No TC was definitely instrumental in my decision to pass on the DFA* 70-200.
There is a TC for the Sigma though, so at least you can sit tight.

For my Sigma model there is no TC that will work with it. Lens just hunts around almost forever before it locks and then it starts searching right away again.

**JensE** · 01-31-2019, 11:24 AM - **1 Like**

According to what I have been able to find, Sigma has never released a TC with SDM contacts, and no company other than Pentax has released an "intelligent" TC, which converts focal length. Pentax doesn't cover the full image circle, others prevent IBIS from working correctly - under-corrected by the TC factor.

Therefore, I spent some time finding a nice Sigma HSM OS lens in good shape. For TC use (Kenko 1.4x), I can turn off IBIS and use the lens OS, giving me full image circle and OS. I do have to stop down at least to (nominal) f/4 though for good image quality. So unless there'll be new FF-TC this year from Pentax, I may still get the DA-TC. Or maybe just a KP instead for effectively the same result :-)

xmeda · 02-03-2019, 04:19 PM - **3 Likes**

oh .. a teleconverter.. to teleconvert everything!

**BigMackCam** · 02-03-2019, 04:22 PM - **1 Like**

Originally posted by xmeda

oh .. a teleconverter.. to teleconvert everything!

Given that setup, I'm surprised to see the hood is on the correct way round...

Paul the Sunman · 02-03-2019, 04:24 PM

Originally posted by xmeda

oh .. a teleconverter.. to teleconvert everything!

I'd like to see a sample shot from that setup.

01-29-2019, 01:32 PM	#168
acoufap Site Supporter Join Date: Jan 2011 Location: Munich, Germany Photos: Gallery \| Albums Posts: 4,187	Originally posted by normhead For the 487 bazilyionth time. Understanding folks saying a TC doesn't ad more detail. - PentaxForums.com I already waited for your comment. Last edited by acoufap; 01-29-2019 at 01:41 PM.

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01-28-2019, 09:07 AM - 1 Like	#166
Mistral75 Pentaxian Join Date: Feb 2009 Location: Paris, France Posts: 7,526	Indeed, a teleconverter enlarges the image circle (and a focal reducer shrinks it).

01-29-2019, 07:13 AM	#167
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	Originally posted by biz-engineer I've had TC, sold them, buy TC again and sold again. Image comparison of crop vs TC told me that TC is only valuable when the sensor resolution doesn't allow to crop, e.g 24Mpixel instead of 36Mp or 45Mp. AF generally works better without TC, so unless the lens out-resolve the sensor by a good margin TC don't bring anything (get the image on the whole frame and bump iso to compensate for loss of light => no better than cropping of high res. sensor). So, unless Pentax makes a fast 16Mp or 24Mp camera, I'll never get any TC again. TC is great with a 16Mp full frame that boast 10 frames per seconds, OTOH TC on a K1 is a waste For the 487 bazilyionth time. Understanding folks saying a TC doesn't ad more detail. - PentaxForums.com

01-29-2019, 01:41 PM - 1 Like	#169
acoufap Site Supporter Join Date: Jan 2011 Location: Munich, Germany Photos: Gallery \| Albums Posts: 4,187	Originally posted by Mistral75 Indeed, a teleconverter enlarges the image circle (and a focal reducer shrinks it). If I put the DA TC1.4x on the DFA100WR and use it in K-1 FF mode the image shows strong vignette. So precondition FF TC is needed to generalize for a FF sensor. Not surprising anyway ... Things depend on lens design. My M1.7/50 doesn't vignette on FF with DA TC1.4x.

01-29-2019, 06:20 PM	#170
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	Originally posted by acoufap If I put the DA TC1.4x on the DFA100WR and use it in K-1 FF mode the image shows strong vignette. So precondition FF TC is needed to generalize for a FF sensor. Not surprising anyway ... Things depend on lens design. My M1.7/50 doesn't vignette on FF with DA TC1.4x. The DA 1.4 is a crop TC. When I want macro on the k-1 I use the F 1.7x AF adapter, although on the K-3 it's even more macro than with the 1.4.

01-29-2019, 10:07 PM	#171
acoufap Site Supporter Join Date: Jan 2011 Location: Munich, Germany Photos: Gallery \| Albums Posts: 4,187	Originally posted by normhead The DA 1.4 is a crop TC. When I want macro on the k-1 I use the F 1.7x AF adapter, although on the K-3 it's even more macro than with the 1.4. Of course - I was not clear enough. A DA TC1.4x doesn‘t enlarge the image circle not that much that it covers the FF circle for every lens.

01-31-2019, 09:12 AM	#172
bobell69 Veteran Member Join Date: Sep 2007 Location: Courtenay BC Photos: Gallery \| Albums Posts: 498	I'm really hoping for one to come out as it would be my next lens purchase. The problem of course is that if it comes out, I may just have to sell my Sigma 70-200 and buy the Pentax 70-200.

01-31-2019, 09:14 AM	#173
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	Originally posted by bobell69 I'm really hoping for one to come out as it would be my next lens purchase. The problem of course is that if it comes out, I may just have to sell my Sigma 70-200 and buy the Pentax 70-200. No TC was definitely instrumental in my decision to pass on the DFA* 70-200. There is a TC for the Sigma though, so at least you can sit tight.

01-31-2019, 11:00 AM	#174
JensE Site Supporter Join Date: Dec 2015 Location: Leipzig Photos: Gallery \| Albums Posts: 1,966	Originally posted by normhead There is a TC for the Sigma though, so at least you can sit tight. Is there? For the HSM OS variant? I couldn't find one.

01-31-2019, 11:06 AM	#175
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	Originally posted by JensE Is there? For the HSM OS variant? I couldn't find one. I might be wrong, I just remember when I bought my *ist D they thought I should buy the Sigma 70-200 instead of the 70-300 because there was aTC for the 200. But that was like 94 or something.

01-31-2019, 11:11 AM	#176
bobell69 Veteran Member Join Date: Sep 2007 Location: Courtenay BC Photos: Gallery \| Albums Posts: 498	Originally posted by normhead No TC was definitely instrumental in my decision to pass on the DFA* 70-200. There is a TC for the Sigma though, so at least you can sit tight. For my Sigma model there is no TC that will work with it. Lens just hunts around almost forever before it locks and then it starts searching right away again.

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01-31-2019, 11:24 AM - 1 Like	#177
JensE Site Supporter Join Date: Dec 2015 Location: Leipzig Photos: Gallery \| Albums Posts: 1,966	According to what I have been able to find, Sigma has never released a TC with SDM contacts, and no company other than Pentax has released an "intelligent" TC, which converts focal length. Pentax doesn't cover the full image circle, others prevent IBIS from working correctly - under-corrected by the TC factor. Therefore, I spent some time finding a nice Sigma HSM OS lens in good shape. For TC use (Kenko 1.4x), I can turn off IBIS and use the lens OS, giving me full image circle and OS. I do have to stop down at least to (nominal) f/4 though for good image quality. So unless there'll be new FF-TC this year from Pentax, I may still get the DA-TC. Or maybe just a KP instead for effectively the same result :-)

02-03-2019, 04:19 PM - 3 Likes	#178
xmeda Senior Member Join Date: Feb 2011 Location: Brno Posts: 295	oh .. a teleconverter.. to teleconvert everything!

02-03-2019, 04:22 PM - 1 Like	#179
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,656	Originally posted by xmeda oh .. a teleconverter.. to teleconvert everything! Given that setup, I'm surprised to see the hood is on the correct way round...

02-03-2019, 04:24 PM	#180
Paul the Sunman Pentaxian Join Date: Aug 2011 Location: Melbourne Photos: Gallery Posts: 4,842	Originally posted by xmeda oh .. a teleconverter.. to teleconvert everything! I'd like to see a sample shot from that setup.