Pentax AF Teleconverter 1.4x and some lenses Pentax and Sigma

Grokh · 08-20-2021, 01:30 PM - **1 Like**

Dear colleagues, good afternoon!
Please tell me if any of you have any practical experience of using the Pentax 1.4x teleconverter with the following lenses:
1. Pentax * 2.8 / 50-135
2. Sigma EX 2.8 / 70-200
3. Sigma 4,5-6,3 / 50-500 DG OS HSM?
How efficient are these lenses together with a converter in terms of AF speed?
How much does the image quality drop?

kypfer · 08-20-2021, 01:54 PM - **1 Like**

I can only offer experience using a non-Pentax (Kenko) 1.5x converter.
Performance will depend on which camera you are using. The newer cameras seem to have a more sensitive a/f system than the earlier models.
I would expect no problems with either of the f/2.8 lenses. I use my Sigma 70-200mm f/2.8 with it's dedicated 2x adaptor with no problems and have done since it was purchased with my *ist film camera.
The 50-500mm with a 1.4x adaptor will start to stretch the capabilities of your a/f system! In good light on a high contrast static subject it'll be OK most of the time, provided you give the camera time to make up it's mind … the K-3iii is not so bad in this respect, but the K-70 and the KP can struggle.
I'm coming to the conclusion that, with a 24m.pixel camera, a teleconverter is very much a final option solution. Very often, heat haze or similar will affect image quality before any gain in detail is achieved by optical magnification.
Inevitably, YMMV

**UncleVanya** · 08-20-2021, 03:01 PM - **2 Likes**

The HD DA 1.4x works very well with the DA* 50-135. Focusing speed and accuracy is mostly unchanged. Image quality is excellent.

Unregistered User 8 · 08-20-2021, 07:20 PM - **2 Likes**

Originally posted by Grokh

Dear colleagues, good afternoon!
Please tell me if any of you have any practical experience of using the Pentax 1.4x teleconverter with the following lenses:
1. Pentax * 2.8 / 50-135
2. Sigma EX 2.8 / 70-200
3. Sigma 4,5-6,3 / 50-500 DG OS HSM?
How efficient are these lenses together with a converter in terms of AF speed?
How much does the image quality drop?

Originally posted by UncleVanya

The HD DA 1.4x works very well with the DA* 50-135. Focusing speed and accuracy is mostly unchanged. Image quality is excellent.

I can also confirm that the DA* 50-135 works very well. Premium Pentax lenses will work very well with this TC, and lesser quality lenses will give lesser quality images. But I personally won't use non-Pentax lenses with my Pentax TC. Below I have linked the rear converter from the Ricoh site. At the bottom is shown the list of Pentax lenses which are both compatible and not compatible. As non-Pentax lenses are not listed, there is a risk of damage to either the lens or TC if attached. For your Sigma lenses, I would recommend you get the dedicated Sigma TC, as there are also restrictions on some Sigma lens/TC combinations.

Good luck.

HD PENTAX-DA AF REAR CONVERTER 1.4X AW / Converter / AF Lens Adapter / K-mount Lenses / Lenses / Products | RICOH IMAGING

**ramseybuckeye** · 08-20-2021, 07:58 PM - **1 Like**

I don’t have those lenses, but it does not slow down the Pentax lenses that I use.

**UncleVanya** · 08-20-2021, 09:02 PM - **1 Like**

Originally posted by pjv

But I personally won't use non-Pentax lenses with my Pentax TC. Below I have linked the rear converter from the Ricoh site. At the bottom is shown the list of Pentax lenses which are both compatible and not compatible. As non-Pentax lenses are not listed, there is a risk of damage to either the lens or TC if attached. For your Sigma lenses, I would recommend you get the dedicated Sigma TC, as there are also restrictions on some Sigma lens/TC combinations.

Good luck.

HD PENTAX-DA AF REAR CONVERTER 1.4X AW / Converter / AF Lens Adapter / K-mount Lenses / Lenses / Products | RICOH IMAGING

This is a fair point, but it is worth noting that the position of the rear element is what seems to be the main concern. On any lens where the rear element is recessed well back from the end there shouldn’t be any damage but actual use would be the only real test.

The adapter works best with f4 or faster lenses, but exceptions do occur. For example the da 55-300 plm lens works with the hd da 1.4x reasonably well in good light by most reports.

Unregistered User 8 · 08-20-2021, 09:06 PM - **1 Like**

Originally posted by UncleVanya

This is a fair point, but it is worth noting that the position of the rear element is what seems to be the main concern. On any lens where the rear element is recessed well back from the end there shouldn’t be any damage but actual use would be the only real test.

Agreed, Brad, just giving the OP (and others) something to think about, and maybe check their Pentax lenses on the list.....

**UncleVanya** · 08-21-2021, 06:15 AM - **2 Likes**

Originally posted by pjv

Agreed, Brad, just giving the OP (and others) something to think about, and maybe check their Pentax lenses on the list.....

Definitely worth warning people.

08-20-2021, 01:30 PM - 1 Like	#1
Grokh Senior Member Join Date: Feb 2011 Location: St.-Petersburg Photos: Albums Posts: 267	Pentax AF Teleconverter 1.4x and some lenses Pentax and Sigma Dear colleagues, good afternoon! Please tell me if any of you have any practical experience of using the Pentax 1.4x teleconverter with the following lenses: 1. Pentax * 2.8 / 50-135 2. Sigma EX 2.8 / 70-200 3. Sigma 4,5-6,3 / 50-500 DG OS HSM? How efficient are these lenses together with a converter in terms of AF speed? How much does the image quality drop?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
For Sale - Sold: Pentax 1.4x HD DA AF Rear Converter Teleconverter AW for K-Mount Lenses	EBS238	Sold Items	5	03-02-2021 08:02 AM
For Sale - Sold: Sigma 1.4X K-mount AF Teleconverter (P-AF Model) (Free US Shipping)	fwcetus	Sold Items	7	12-12-2015 07:44 PM
For Sale - Sold: Tamron 1.4x Pz-AF MC4 Teleconverter & Quantaray 2x Teleconverter	DaveInPA	Sold Items	15	09-24-2009 06:28 AM

08-20-2021, 01:54 PM - 1 Like	#2
kypfer Pentaxian Join Date: Jan 2018 Location: Jersey C.I. Posts: 3,594	I can only offer experience using a non-Pentax (Kenko) 1.5x converter. Performance will depend on which camera you are using. The newer cameras seem to have a more sensitive a/f system than the earlier models. I would expect no problems with either of the f/2.8 lenses. I use my Sigma 70-200mm f/2.8 with it's dedicated 2x adaptor with no problems and have done since it was purchased with my *ist film camera. The 50-500mm with a 1.4x adaptor will start to stretch the capabilities of your a/f system! In good light on a high contrast static subject it'll be OK most of the time, provided you give the camera time to make up it's mind … the K-3iii is not so bad in this respect, but the K-70 and the KP can struggle. I'm coming to the conclusion that, with a 24m.pixel camera, a teleconverter is very much a final option solution. Very often, heat haze or similar will affect image quality before any gain in detail is achieved by optical magnification. Inevitably, YMMV

08-20-2021, 03:01 PM - 2 Likes	#3
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,404	The HD DA 1.4x works very well with the DA* 50-135. Focusing speed and accuracy is mostly unchanged. Image quality is excellent.

08-20-2021, 07:20 PM - 2 Likes	#4
Unregistered User 8 Closed Account Join Date: Mar 2015 Photos: Gallery Posts: 8,694	Originally posted by Grokh Dear colleagues, good afternoon! Please tell me if any of you have any practical experience of using the Pentax 1.4x teleconverter with the following lenses: 1. Pentax * 2.8 / 50-135 2. Sigma EX 2.8 / 70-200 3. Sigma 4,5-6,3 / 50-500 DG OS HSM? How efficient are these lenses together with a converter in terms of AF speed? How much does the image quality drop? Originally posted by UncleVanya The HD DA 1.4x works very well with the DA* 50-135. Focusing speed and accuracy is mostly unchanged. Image quality is excellent. I can also confirm that the DA* 50-135 works very well. Premium Pentax lenses will work very well with this TC, and lesser quality lenses will give lesser quality images. But I personally won't use non-Pentax lenses with my Pentax TC. Below I have linked the rear converter from the Ricoh site. At the bottom is shown the list of Pentax lenses which are both compatible and not compatible. As non-Pentax lenses are not listed, there is a risk of damage to either the lens or TC if attached. For your Sigma lenses, I would recommend you get the dedicated Sigma TC, as there are also restrictions on some Sigma lens/TC combinations. Good luck. HD PENTAX-DA AF REAR CONVERTER 1.4X AW / Converter / AF Lens Adapter / K-mount Lenses / Lenses / Products \| RICOH IMAGING

08-20-2021, 07:58 PM - 1 Like	#5
ramseybuckeye Site Supporter Join Date: Apr 2009 Location: Hampstead, NC Photos: Gallery Posts: 17,292	I don’t have those lenses, but it does not slow down the Pentax lenses that I use.

08-20-2021, 09:02 PM - 1 Like	#6
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,404	Originally posted by pjv But I personally won't use non-Pentax lenses with my Pentax TC. Below I have linked the rear converter from the Ricoh site. At the bottom is shown the list of Pentax lenses which are both compatible and not compatible. As non-Pentax lenses are not listed, there is a risk of damage to either the lens or TC if attached. For your Sigma lenses, I would recommend you get the dedicated Sigma TC, as there are also restrictions on some Sigma lens/TC combinations. Good luck. HD PENTAX-DA AF REAR CONVERTER 1.4X AW / Converter / AF Lens Adapter / K-mount Lenses / Lenses / Products \| RICOH IMAGING This is a fair point, but it is worth noting that the position of the rear element is what seems to be the main concern. On any lens where the rear element is recessed well back from the end there shouldn’t be any damage but actual use would be the only real test. The adapter works best with f4 or faster lenses, but exceptions do occur. For example the da 55-300 plm lens works with the hd da 1.4x reasonably well in good light by most reports.

08-20-2021, 09:06 PM - 1 Like	#7
Unregistered User 8 Closed Account Join Date: Mar 2015 Photos: Gallery Posts: 8,694	Originally posted by UncleVanya This is a fair point, but it is worth noting that the position of the rear element is what seems to be the main concern. On any lens where the rear element is recessed well back from the end there shouldn’t be any damage but actual use would be the only real test. Agreed, Brad, just giving the OP (and others) something to think about, and maybe check their Pentax lenses on the list.....

08-21-2021, 06:15 AM - 2 Likes	#8
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,404	Originally posted by pjv Agreed, Brad, just giving the OP (and others) something to think about, and maybe check their Pentax lenses on the list..... Definitely worth warning people.