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02-06-2014, 05:25 PM   #181
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QuoteOriginally posted by falconeye Quote
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
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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
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QuoteOriginally posted by falconeye Quote
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
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QuoteOriginally posted by Pål Jensen Quote
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, 08:08 AM - 1 Like   #185
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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:

Name:  _IGP9818.jpg
Views: 500
Size:  126.8 KBName:  _IGP9812.jpg
Views: 517
Size:  126.9 KBName:  _IGP9824.jpg
Views: 509
Size:  116.4 KB

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

Name:  _IGP9812_crop.jpg
Views: 511
Size:  53.3 KBName:  _IGP9824_crop.jpg
Views: 521
Size:  55.8 KBName:  _IGP9818_crop.jpg
Views: 515
Size:  60.9 KB

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!
02-07-2014, 08:25 AM - 1 Like   #186
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QuoteOriginally posted by VisualDarkness Quote
Those test shots are really good.... encouraging.
02-07-2014, 08:26 AM   #187
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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
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QuoteOriginally posted by ElJamoquio Quote
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
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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
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QuoteOriginally posted by baro-nite Quote
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
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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,
02-07-2014, 01:40 PM   #192
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QuoteOriginally posted by Alizarine Quote
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
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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
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QuoteOriginally posted by Zygonyx Quote
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
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QuoteOriginally posted by audiobomber Quote
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.)
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