Image of HD Pentax 1.4x Teleconverter

Alizarine · 02-06-2014, 05:25 PM

Originally posted by falconeye

On another note and probably worth an extra post

Pentax specifies the image circle of the "HD Pentax DA AF 1.4X AW Rear Converter" to be up to 35mm full frame. Still, it is named DA.

Therefore and for the first time, we are learning that Ricoh isn't going to name full frame lenses differently from DA.

This got me quite confused too. DA but compatible with 135. But not DFA! Pentax's secrecy on their FF project is messing up their naming pattern (which was already messy from the start, lol K-30 didn't fly from K20D, nor was there a K-40 but skipped to K-50! The only proper one so far was the K-7>K-5>K-3 pattern)

VisualDarkness · 02-06-2014, 06:46 PM

Some shots with the converter:
DigitalFotoNetz.de :: Thema anzeigen - PENTAX-DA AF-KONVERTER 1,4x + Flu Card im Kurztest

**Pål Jensen** · 02-06-2014, 07:00 PM

Originally posted by falconeye

asahi man, thanks and something to learn

Can you tell me more about S and L versions, and why an S version, despite its simpler construction, would be optically on par?

The L converters were specifically designed to match optically the A* super telephotos. They had protruding elements so that they did not fit most lenses. The S converters were for general usage. I guess the quality of the S converter very much depended on the lenses they were used with.

A converter for digital must be very good to makes sense over cropping.

ElJamoquio · 02-06-2014, 07:20 PM

Originally posted by Pål Jensen

A converter for digital must be very good to makes sense over cropping.

Indeed; and even more so with 24MP APS-C sensors.... ... and the Q is cheaper than this T/C...

**baro-nite** · 02-07-2014, 08:08 AM - **1 Like**

So, a little testing of the old Pentax 1.4x-S and 1.4x-L converters.

My test subject was the compact edition of the Oxford English Dictionary (a reduced-size facsimile of the full edition; most people need a magnifying lens to read it), illuminated by an off-camera flash. I used the DA*200, as the best lens I have that is compatible with the L converter. Subject distance was about 9 meters; I wanted a subject and distance where it would be clear whether or not the TCs gave more detail. I took one series of shots with the lens alone, then a series with each of the TCs. I used f/8, ISO 100 (K-5) for all shots and increased the flash power by one stop for the TC shots. Focus using Live View, refocusing each time, and then comparing to find the best focus from each series. Same settings applied to all images, including what I consider standard capture sharpening. Crops are from near the center of the image circle, so I didn't examine edge performance.

100% crop from the lens alone and downscaled crops from the TCs:

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Tighter crops, upscaled to double the above size (arranged in a different order compared to the above):

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Both TCs magnified a bit more than 1.4x. I kept the camera in the same position, so with TC the lens was a little closer to the subject, but only 25 to 30mm, 0.3% of the subject distance. One TC gave about 1.43x and the other 1.46x.

Any suggestions for better testing would be appreciated!

normhead · 02-07-2014, 08:25 AM - **1 Like**

Originally posted by VisualDarkness

Some shots with the converter:
DigitalFotoNetz.de :: Thema anzeigen - PENTAX-DA AF-KONVERTER 1,4x + Flu Card im Kurztest

Those test shots are really good.... encouraging.

ElJamoquio · 02-07-2014, 08:26 AM

Baro-nite: That's a good protocol.

From my view the upper left is clearly inferior to the other two highly cropped versions. The Lower left looks the best to me.

I guess I'd rate it

Upper Left - 5
Upper Right - 7.5
Lower Left - 8

In real life though... other things are usually at play. In my experience, you need to have dead-on tracking and dead-on focus and plenty of light and a great lens and a great T/C for a T/C to be better than a cropped image.

**baro-nite** · 02-07-2014, 10:41 AM

Originally posted by ElJamoquio

In real life though... other things are usually at play. In my experience, you need to have dead-on tracking and dead-on focus and plenty of light and a great lens and a great T/C for a T/C to be better than a cropped image.

Agreed, which is one reason an AF TC has so much potential. Nailing focus manually, especially with a lightly damped focus ring, is very hit or miss.

If your monitor is wide enough you'll see each set of images above in a single row. For the highly cropped set the first is no TC, the second is the L converter, and the third is the S. I agree the S looks best. Contrast seems better if not resolution per se. Given the reputation of the L this surprised me. But of course this is only one lens and one small test.

normhead · 02-07-2014, 12:59 PM

Well as long as we're doing this, a couple of images from the last week, one is my A-400, one is the DA* 60-250 with the 1.7 TC... so should be about 425.. it'll be 450 in the exif... so there'd be no confusion and because there is no 425 to select... I'm pretty happy with both.... The difference is, with the AF on the 1.7 TC, I get a lot more pictures to choose from than I would with the hand focussed A-400.

audiobomber · 02-07-2014, 01:05 PM

Originally posted by baro-nite

I agree the S looks best. Contrast seems better if not resolution per se. Given the reputation of the L this surprised me. But of course this is only one lens and one small test.

I thought the S was designed for shorter focal length lenses (under 300mm) and L for longer focal lengths.

**BigDave** · 02-07-2014, 01:15 PM

Getting a resolution target to work from would be good. The page is OK, but it becomes more anecdotal as we do not understand the type size. Also, this is fine for closeup work, but what happens with a telephoto lens, or a normal lens? Here is an example of one:

http://printlab.rit.edu/pdf/Specs_AirForce_Tgt_4-1.pdf

make something like this up (paint) on a 4ft x 4ft board and place it out 100 yrds. See what happens then!

Regards,

thibs · 02-07-2014, 01:40 PM

Originally posted by Alizarine

This got me quite confused too. DA but compatible with 135. But not DFA!

?? What are you talking about ?

Zygonyx · 02-07-2014, 02:10 PM

If you never heard af 135 film, better send your CV to RIC's branding dept.

Btw, very good shots Norm

thibs · 02-07-2014, 02:40 PM

Originally posted by Zygonyx

If you never heard af 135 film, better send your CV to RIC's branding dept.

Btw, very good shots Norm

Are you completely ********* (autocensored) or doing it on purpose ?

Read the sentence for once !

**baro-nite** · 02-07-2014, 03:12 PM

Originally posted by audiobomber

I thought the S was designed for shorter focal length lenses (under 300mm) and L for longer focal lengths.

So says the literature although there seems to be some debate about whether this is simply because very few shorter FL lenses can fit the L converters. But you're right that it would certainly be interesting to test this with one of the Pentax 300/2.8s or something longer. (I could test with the A400/5.6 but there I think the lens itself is the limiting factor.)

02-07-2014, 08:08 AM - 1 Like	#185
baro-nite Loyal Site Supporter Join Date: Aug 2011 Location: North Carolina, USA Photos: Gallery \| Albums Posts: 5,294	So, a little testing of the old Pentax 1.4x-S and 1.4x-L converters. My test subject was the compact edition of the Oxford English Dictionary (a reduced-size facsimile of the full edition; most people need a magnifying lens to read it), illuminated by an off-camera flash. I used the DA*200, as the best lens I have that is compatible with the L converter. Subject distance was about 9 meters; I wanted a subject and distance where it would be clear whether or not the TCs gave more detail. I took one series of shots with the lens alone, then a series with each of the TCs. I used f/8, ISO 100 (K-5) for all shots and increased the flash power by one stop for the TC shots. Focus using Live View, refocusing each time, and then comparing to find the best focus from each series. Same settings applied to all images, including what I consider standard capture sharpening. Crops are from near the center of the image circle, so I didn't examine edge performance. 100% crop from the lens alone and downscaled crops from the TCs: Tighter crops, upscaled to double the above size (arranged in a different order compared to the above): Both TCs magnified a bit more than 1.4x. I kept the camera in the same position, so with TC the lens was a little closer to the subject, but only 25 to 30mm, 0.3% of the subject distance. One TC gave about 1.43x and the other 1.46x. Any suggestions for better testing would be appreciated!

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02-06-2014, 05:25 PM	#181
Alizarine Veteran Member Join Date: Dec 2010 Location: Manila Photos: Gallery \| Albums Posts: 2,185	Originally posted by falconeye On another note and probably worth an extra post Pentax specifies the image circle of the "HD Pentax DA AF 1.4X AW Rear Converter" to be up to 35mm full frame. Still, it is named DA. Therefore and for the first time, we are learning that Ricoh isn't going to name full frame lenses differently from DA. This got me quite confused too. DA but compatible with 135. But not DFA! Pentax's secrecy on their FF project is messing up their naming pattern (which was already messy from the start, lol K-30 didn't fly from K20D, nor was there a K-40 but skipped to K-50! The only proper one so far was the K-7>K-5>K-3 pattern)

02-06-2014, 06:46 PM	#182
VisualDarkness Veteran Member Join Date: Nov 2011 Location: Uppsala, Sweden Photos: Gallery Posts: 4,439	Some shots with the converter: DigitalFotoNetz.de :: Thema anzeigen - PENTAX-DA AF-KONVERTER 1,4x + Flu Card im Kurztest

02-06-2014, 07:00 PM	#183
Pål Jensen Site Supporter Join Date: Dec 2007 Location: Norway Photos: Albums Posts: 4,371	Originally posted by falconeye asahi man, thanks and something to learn Can you tell me more about S and L versions, and why an S version, despite its simpler construction, would be optically on par? The L converters were specifically designed to match optically the A* super telephotos. They had protruding elements so that they did not fit most lenses. The S converters were for general usage. I guess the quality of the S converter very much depended on the lenses they were used with. A converter for digital must be very good to makes sense over cropping.

02-06-2014, 07:20 PM	#184
ElJamoquio Veteran Member Join Date: Feb 2011 Posts: 4,873	Originally posted by Pål Jensen A converter for digital must be very good to makes sense over cropping. Indeed; and even more so with 24MP APS-C sensors.... ... and the Q is cheaper than this T/C...

02-07-2014, 08:25 AM - 1 Like	#186
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,448	Originally posted by VisualDarkness Some shots with the converter: DigitalFotoNetz.de :: Thema anzeigen - PENTAX-DA AF-KONVERTER 1,4x + Flu Card im Kurztest Those test shots are really good.... encouraging.

02-07-2014, 08:26 AM	#187
ElJamoquio Veteran Member Join Date: Feb 2011 Posts: 4,873	Baro-nite: That's a good protocol. From my view the upper left is clearly inferior to the other two highly cropped versions. The Lower left looks the best to me. I guess I'd rate it Upper Left - 5 Upper Right - 7.5 Lower Left - 8 In real life though... other things are usually at play. In my experience, you need to have dead-on tracking and dead-on focus and plenty of light and a great lens and a great T/C for a T/C to be better than a cropped image.

02-07-2014, 10:41 AM	#188
baro-nite Loyal Site Supporter Join Date: Aug 2011 Location: North Carolina, USA Photos: Gallery \| Albums Posts: 5,294	Originally posted by ElJamoquio In real life though... other things are usually at play. In my experience, you need to have dead-on tracking and dead-on focus and plenty of light and a great lens and a great T/C for a T/C to be better than a cropped image. Agreed, which is one reason an AF TC has so much potential. Nailing focus manually, especially with a lightly damped focus ring, is very hit or miss. If your monitor is wide enough you'll see each set of images above in a single row. For the highly cropped set the first is no TC, the second is the L converter, and the third is the S. I agree the S looks best. Contrast seems better if not resolution per se. Given the reputation of the L this surprised me. But of course this is only one lens and one small test.

02-07-2014, 12:59 PM	#189
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,448	Well as long as we're doing this, a couple of images from the last week, one is my A-400, one is the DA* 60-250 with the 1.7 TC... so should be about 425.. it'll be 450 in the exif... so there'd be no confusion and because there is no 425 to select... I'm pretty happy with both.... The difference is, with the AF on the 1.7 TC, I get a lot more pictures to choose from than I would with the hand focussed A-400.

02-07-2014, 01:05 PM	#190
audiobomber Veteran Member Join Date: May 2008 Location: Sudbury, Ontario Photos: Albums Posts: 6,806	Originally posted by baro-nite I agree the S looks best. Contrast seems better if not resolution per se. Given the reputation of the L this surprised me. But of course this is only one lens and one small test. I thought the S was designed for shorter focal length lenses (under 300mm) and L for longer focal lengths.

02-07-2014, 01:15 PM	#191
BigDave Site Supporter Join Date: Sep 2010 Location: Hudson Valley, NY Photos: Gallery \| Albums Posts: 2,626	Getting a resolution target to work from would be good. The page is OK, but it becomes more anecdotal as we do not understand the type size. Also, this is fine for closeup work, but what happens with a telephoto lens, or a normal lens? Here is an example of one: http://printlab.rit.edu/pdf/Specs_AirForce_Tgt_4-1.pdf make something like this up (paint) on a 4ft x 4ft board and place it out 100 yrds. See what happens then! Regards,

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02-07-2014, 01:40 PM	#192
thibs Pentaxian Join Date: Jun 2007 Location: Belgium Photos: Albums Posts: 7,001	Originally posted by Alizarine This got me quite confused too. DA but compatible with 135. But not DFA! ?? What are you talking about ?

02-07-2014, 02:10 PM	#193
Zygonyx Pentaxian Join Date: Jun 2011 Location: Ile de France Posts: 4,032	If you never heard af 135 film, better send your CV to RIC's branding dept. Btw, very good shots Norm

02-07-2014, 02:40 PM	#194
thibs Pentaxian Join Date: Jun 2007 Location: Belgium Photos: Albums Posts: 7,001	Originally posted by Zygonyx If you never heard af 135 film, better send your CV to RIC's branding dept. Btw, very good shots Norm Are you completely ********* (autocensored) or doing it on purpose ? Read the sentence for once !

02-07-2014, 03:12 PM	#195
baro-nite Loyal Site Supporter Join Date: Aug 2011 Location: North Carolina, USA Photos: Gallery \| Albums Posts: 5,294	Originally posted by audiobomber I thought the S was designed for shorter focal length lenses (under 300mm) and L for longer focal lengths. So says the literature although there seems to be some debate about whether this is simply because very few shorter FL lenses can fit the L converters. But you're right that it would certainly be interesting to test this with one of the Pentax 300/2.8s or something longer. (I could test with the A400/5.6 but there I think the lens itself is the limiting factor.)