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02-10-2014, 07:06 PM   #241
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QuoteOriginally posted by Mistral75 Quote
Not need for telemetry. Lens ID is enough.
the complexity I was referring to is that if you have a lens and a converter attached, it is functionally 2 lenses attached and the camera
software has to be smart enough to figure out and identify both, and the converter firmware needs to be helpful so the camera isn't baffled
by the presence of 2 lenses, And we don't know yet if the converter has some ability to alter it's optics like the 1.7X adapter or not.

02-13-2014, 04:56 AM   #242
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A short remark concerning the new teleconverter, firmware updates, SDM and SR:

Up to now, most of the firmware of Pentax DSLRs is not aware of teleconverters. The cameras operate without the knowledge, how they should optimally react. This is a gamble, especially concerning SDM functionality. Therefore, the latter is limited when converters are used - even if these possess powerzoom-power contacts (which are "abused" for SDM). The processing and interpretation of signals crucially influences operativeness, e.g. the regulation of the focus via SDM. Over- or undershoots in correction values can lead to judder. In extreme cases, precise focus cannot be found. Additionally, the "correct" focal length influences the shake reduction, which then can be optimized (e.g. 300*1.4mm are stabilized instead of 300mm). The correct transferal and processing of data is imho the main advantage of the new converter. It remains to be seen, whether or not the new firmware also influences the usage of other teleconverters. In principle, an additional entry in the menu with a tag for a converter and the corresponding "extension" (1.4x/1.7x/2x) could heal most of current problems.
02-13-2014, 05:30 AM   #243
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Image of HD Pentax 1.4x Teleconverter

QuoteOriginally posted by froeschle Quote
Up to now, most of the firmware of Pentax DSLRs is not aware of teleconverters.
I basically agree but I am not sure if this is the entire story.

E.g., a lens has an associated value (K value?) of how much the focus screw has to be turned to cause a given phase shift in the AF system. So, even with a screw drive AF, somebody has to translate the K value. Maybe, the converter does so. It is certainly taken care of with the 1.7x AF converter at least. The new TC could translate all data w/o need to make the FW TC aware. Who knows.

I agree that full AF and SR support is this converter's selling point.

I am curious to see if Pentax addresses the problem of EXIF data. E.g. with Nikon at least, EXIF hides the TC (except for effective focal length and aperture) which creates problems in post processing, e.g. when selecting a proper lens profile. And as TCs add CA, that's an issue.
02-13-2014, 07:27 AM   #244
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I agree that this is probably not the entire story. It is an interesting question, how the "K value" is determined.

Extension rings for PAF with powerzoom-power contacts exist. AFAIK, no problems with AF (screw and SDM) are known. These are rare and currently sell at relatively high prices (more expensive than some converters). In principle, one could obtain an extension ring from a teleconverter by removal of the lens elements. It would be revealing if and how such a modified converter would work. Autofocus should at least hunt, if the "K value" would be changed by teleconverters (and not by extension rings).

The 1.7x AF converter is another story, as autofocus is solely provided by the converter. What happens, if you mount an "M" lens (i.e. [nearly] no data from the lens is provided) and the focal length is not correctly set? The 1.7x AF converter also correctly worked e.g. with the Z-1P. This camera did not know anything about the focal length of a mounted "M" lens.

02-13-2014, 07:39 AM - 1 Like   #245
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You guys are way over-thinking this... if the converter gives me good pictures then I'll be happy. I get the right focal length from my 1.7 TC, the camera doesn't know anything, but it asks me to input the focal length. That's enough to let me know when I look back through my pictures what lens I was using... what else do you need? Anything above that is bonus. Is there some great benefit to totally accurate exif that I'm missing? Funny, when I shot film the exif was what you wrote down yourself in a notebook you carried with you... I don't remember my photography ever suffering, when I forgot to bring the notebook.
02-13-2014, 08:45 AM   #246
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QuoteQuote:
I get the right focal length from my 1.7 TC, the camera doesn't know anything, but it asks me to input the focal length.
So, what happens, if you dial in a totally wrong focal length? Is AF performance still as good as before (turn off SR to eliminate its possible influence)?
02-13-2014, 09:04 AM   #247
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QuoteOriginally posted by froeschle Quote
So, what happens, if you dial in a totally wrong focal length? Is AF performance still as good as before (turn off SR to eliminate its possible influence)?
The only downside is in the exif.. the camera doesn't seem to care. I've many times had the wrong focal length dialed in, 400 when it should have been 700 etc. , I don't know how it would affect the SR, but it doesn't otherwise impact IQ.
02-13-2014, 10:04 AM   #248
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QuoteQuote:
You guys are way over-thinking this... if the converter gives me good pictures then I'll be happy.
Sometimes, we want to know, how and why something works .
QuoteQuote:
Is there some great benefit to totally accurate exif that I'm missing?
As an example:
QuoteQuote:
E.g. with Nikon at least, EXIF hides the TC (except for effective focal length and aperture) which creates problems in post processing, e.g. when selecting a proper lens profile. And as TCs add CA, that's an issue.
This was the "problem" under investigation:
QuoteQuote:
a lens has an associated value (K value?) of how much the focus screw has to be turned to cause a given phase shift in the AF system. So, even with a screw drive AF, somebody has to translate the K value. Maybe, the converter does so. It is certainly taken care of with the 1.7x AF converter at least.
QuoteQuote:
the camera doesn't seem to care. [...] I don't know how it would affect the SR
The camera should know, how much to turn the focus screw due to different "magnifications" (due to a teleconverter and the attached lens). Shake reduction is optimized for the corresponding focal length. This is the main reason why the body asks you to input this value.
QuoteQuote:
The new TC could translate all data w/o need to make the FW TC aware. Who knows.
Firmware updates are necessary according to Pentax/Ricoh:
QuoteQuote:
The camera's firmware must be updated to the latest version before using the autofocus function. Compatible camera bodies are: K-3, K-50, K-30, K-5 II, K-5 II s, K-5, K-01, K-7, and K-r.


02-25-2014, 11:39 AM   #249
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Bring it on Pentax! It is a shame that Tamron made the only SDMcompatible tele converter.
That said, I will keep the Tamron converter for now since there is no lens in Pentax-land that would really benefit from such a converter. With the decision for a 5.6/560 a 2.8/300 which is THE lens for converters is badly missing.
02-25-2014, 12:25 PM   #250
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QuoteOriginally posted by zapp Quote
Bring it on Pentax! It is a shame that Tamron made the only SDMcompatible tele converter.
The Tamron convertor has very limited SDM compatibility. AF is compromised. Often you need to press up to four times to get it to the focal point and even then it's random whether it is spot on or not.


QuoteOriginally posted by zapp Quote
That said, I will keep the Tamron converter for now since there is no lens in Pentax-land that would really benefit from such a converter.
How you can say that when there are obvious candidates like the 50-135mm, 60-250, 200mm f2.8 and 300mm f4?
02-25-2014, 02:29 PM   #251
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This new converter appears to be a re-badged Tamron. The external casing has a different ribbed texture but everything else appears identical.
02-25-2014, 02:34 PM   #252
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QuoteOriginally posted by bossa Quote
This new converter appears to be a re-badged Tamron. The external casing has a different ribbed texture but everything else appears identical.

Uh oh, hopefully you put on your flame proof. Some folks (cheerleaders) are not going to like that statement.
02-25-2014, 02:39 PM   #253
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Pentax don't seem to have had issues in the past by "remaking" other manufacturers lenses in their own image so I don't see why a TC is any different.
02-25-2014, 02:53 PM   #254
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QuoteOriginally posted by bossa Quote
This new converter appears to be a re-badged Tamron. The external casing has a different ribbed texture but everything else appears identical.
No, it doesn't. And some folks are not going to like this statement.
02-25-2014, 03:00 PM   #255
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QuoteOriginally posted by Kunzite Quote
No, it doesn't. And some folks are not going to like this statement.
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