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01-25-2014, 10:18 AM   #1
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Setting the focal length

If I do not use DA lenses on my K-3, K-3 requires the focal length!
I know it's for Shake Reducktion (SR).

Operating manual on page 84 it is written, how should I proceed?!

My question to you:

1) Should I enter the focal length, which is written on the lens?

2) Should I convert the focal length to full frame format?

3) What focal length should I enter when I use the new DA 1.4 X adapter?

4) What focal length should I enter when I use my lenses on the Pentax Q7?

Has anyone experience with this? Or does it even matter?

01-25-2014, 10:37 AM   #2
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Hi,
In all cases, just input the focal length that is printed on the lens. All cases except 3, that is, because that one I haven't tried. I'm sure it is/will be in the manual.
01-25-2014, 11:13 AM   #3
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For case 3, enter the lens x converter value. The camera doesn't know there is a teleconverter attached so you have to make the multiplication for it.

Note: for AF lenses, the camera will ignore the teleconverter because the focal length is transmitted from lens to camera without modification from the TC. The SR, therefore, will be undercompensated.

Cheers,
Lou
01-25-2014, 11:21 AM   #4
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QuoteOriginally posted by jeanpierre Quote
1) Should I enter the focal length, which is written on the lens?

2) Should I convert the focal length to full frame format?
4) What focal length should I enter when I use my lenses on the Pentax Q7?
The two posters above are absolutely right.

Do yourself a really big favor by completely wiping from your mind the concept of crop factor, FF equivalent, etc. Life will be a lot easier once you do.

01-25-2014, 11:41 AM   #5
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QuoteOriginally posted by lm4187 Quote
For case 3, enter the lens x converter value. The camera doesn't know there is a teleconverter attached so you have to make the multiplication for it.

Note: for AF lenses, the camera will ignore the teleconverter because the focal length is transmitted from lens to camera without modification from the TC. The SR, therefore, will be undercompensated.

Cheers,
Lou
I'm not sure that is the case when using a recent Pentax teleconverter. I would expect that unlike cheap third party teleconverters the real Pentax one would have a chip in it that reinterprets the messages from the lens to pass on the correct focal length and aperture to the camera.

Does anyone have one and maybe can confirm (from the EXIF) whether the TC does this reinterpretation?
01-25-2014, 12:37 PM   #6
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Thanks all.
But nobody can tell me real which focal length I have to take!!!!

Which one is written on the lens, or to convert to FF? And when using Teleconverter to add 1.4 or more? And what about with the Pentax Q7?

I am confused now!

Sorry, but I was hoping for more usefully answers.

I do think there a lot of people, who tested it!
01-25-2014, 12:55 PM   #7
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QuoteOriginally posted by jeanpierre Quote
But nobody can tell me real which focal length I have to take!!!
Which one is written on the lens, or to convert to FF?
And when using Teleconverter to add 1.4 or more? And what about with the Pentax Q7?
Did you even read the replies????
The very first response told you which to input.
QuoteOriginally posted by OJGoreng Quote
In all cases, just input the focal length that is printed on the lens. All cases except 3, that is,.
The second reply answers case #3.
QuoteOriginally posted by lm4187 Quote
For case 3, enter the lens x converter value.
I don't know how much more clear or useful an answer could be.
01-25-2014, 12:58 PM   #8
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The number written on the lens reflects a physical property of the optical lens. That it what you should use.

If you put another piece of glass in there, you have changed that property. There are no telecoverters that helps you with that. And there are no recent teleconverters available from Pentax, chip or not.

The camera (Q7 or any other) doesnt affect any properties of the lens, it is just using less of the available picture circle.

01-25-2014, 01:13 PM   #9
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Many thanks Parralax
Now I have checked it! Sorry for my "missunderstanding". I am not so littered in English.
01-25-2014, 03:40 PM   #10
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QuoteOriginally posted by lister6520 Quote
Does anyone have one and maybe can confirm (from the EXIF) whether the TC does this reinterpretation?
TBH, it didn't even know it was out yet. At any rate, from the "shooting information" window in DCU5, which seems to be ready for the thing coming out, I'm guessing it will do the re-interpretation; so may other TCs with a gate array chip. I can't predict if it will also do that if you mount a lens w/o a data contact, but I'm sure that will be in the manual.



Don't worry, Jeanpierre. Things tend to get lost in translation.
01-01-2016, 07:16 AM   #11
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Old thread, just checking...200mm non-auto lens, 2x teleconverter...I should enter 400mm?
01-01-2016, 07:33 AM   #12
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QuoteOriginally posted by Grey Area Quote
Old thread, just checking...200mm non-auto lens, 2x teleconverter...I should enter 400mm?
Correct.
01-02-2016, 01:04 PM   #13
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And - out of curiosity - if I forgot and set it to 200mm by mistake, what would the effect be?
01-02-2016, 01:10 PM   #14
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QuoteOriginally posted by lm4187 Quote
Note: for AF lenses, the camera will ignore the teleconverter because the focal length is transmitted from lens to camera without modification from the TC. The SR, therefore, will be undercompensated.
In the case of the DA teleconverter, the focal lens for AF lenses is actually automatically multiplied for you

See: Pentax-DA 1.4x AW AF Rear Converter Review - Operation | PentaxForums.com Reviews

QuoteOriginally posted by Grey Area Quote
And - out of curiosity - if I forgot and set it to 200mm by mistake, what would the effect be?
If you select a focal length greater than the actual focal length, the camera may overcompensate and potentially introduce blur. If you go under, on the other hand, you'll get sub-optimal (but possibly still satisfactory) stabilization.

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01-03-2016, 06:47 AM   #15
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Ha, I wish this was DA* gear... these are old inherited lenses...all manual; a 80-200mm "Formula 5" zoom lens and an "APK Teleplus MC4" teleconverter.

As I'm doing astrophotography I've turned off the image stabilisation (which is what most seem to reommend). Are there any other side effects?
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