Setting proper focal lenght with K-1 and manual lenses

Sylwester · 06-23-2016, 12:21 AM

I have a Zenitar 16mm. Is there any way to set focal lenght to 16mm when using manual lenses? The nearest available are: 12, 15, 18, 20 mm etc. I went through all options but found nothing helpful. Any idea?

repaap · 06-23-2016, 12:26 AM

I have gone previously with little wider, and it had worked better that tighter. For example my Samyang 14 works better with 12 mm than 15 mm.for unknown reason to me. So I'd suggest that you use 15 mm.

Adam · 06-23-2016, 12:48 AM

Originally posted by Sylwester

I have a Zenitar 16mm. Is there any way to set focal lenght to 16mm when using manual lenses? The nearest available are: 12, 15, 18, 20 mm etc. I went through all options but found nothing helpful. Any idea?

You should be OK to use any focal length close to 16, such as 15 or 18. With wide-angle lenses there isn't much of a gain/loss if the focal length is a bit off.

Sylwester · 06-23-2016, 01:05 AM

I used 15mm option, and it was good. I wonder if this has to do sth with astrotracer feature. Will K-1 make proper calculations? 1mm is not that much difference.

**Tas** · 06-23-2016, 01:17 AM

Originally posted by Sylwester

I wonder if this has to do sth with astrotracer feature.

It's to do with the shake reduction (SR). I have lenses that don't align perfectly with the SR options so for my 21mm lens I use 20mm and for the 25mm lens I use 24mm. I've seen no problems with it, but remember to turn off SR if you're mounting to a tripod.

Note too, if you forget to set the right FL for the SR the camera will record your images with the wrong focal length so try and set it when you mount a new lens so the metadata is also correct.

Tas

Na Horuk · 06-23-2016, 03:46 AM

You want to input the same number as is written on the lens, regardless of whether your camera is FF or APSC, whether the lens is FF or APSC.
Problem is with some lenses that have a focal length that is not in the table. It is too bad Pentax did not fix this (wasn't this already fixed on the Q??). In those cases, it is best to input the nearest wider focal length. This means the SR will slightly undercompensate, be slightly less effective than it could be. If you input a higher number, it will overcompensate and might actually introduce blur.
Now, a small difference might not be problematic.

Another problem are manual zoom lenses, where focal length changes. In those cases you can input the widest, or the average, or just the one that you will be using the most.

Feel free to write to Pentax that they should add more focal length choices, or change the menu so you can choose each digit separately.

06-23-2016, 12:21 AM	#1
Sylwester Inactive Account Join Date: Jul 2014 Photos: Albums Posts: 17	Setting proper focal lenght with K-1 and manual lenses I have a Zenitar 16mm. Is there any way to set focal lenght to 16mm when using manual lenses? The nearest available are: 12, 15, 18, 20 mm etc. I went through all options but found nothing helpful. Any idea?

06-23-2016, 12:48 AM	#3
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,594	Originally posted by Sylwester I have a Zenitar 16mm. Is there any way to set focal lenght to 16mm when using manual lenses? The nearest available are: 12, 15, 18, 20 mm etc. I went through all options but found nothing helpful. Any idea? You should be OK to use any focal length close to 16, such as 15 or 18. With wide-angle lenses there isn't much of a gain/loss if the focal length is a bit off. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

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06-23-2016, 12:26 AM	#2
repaap Pentaxian Join Date: Oct 2010 Photos: Gallery \| Albums Posts: 6,242	I have gone previously with little wider, and it had worked better that tighter. For example my Samyang 14 works better with 12 mm than 15 mm.for unknown reason to me. So I'd suggest that you use 15 mm.

06-23-2016, 01:05 AM	#4
Sylwester Inactive Account Join Date: Jul 2014 Photos: Albums Posts: 17 Original Poster	I used 15mm option, and it was good. I wonder if this has to do sth with astrotracer feature. Will K-1 make proper calculations? 1mm is not that much difference.

06-23-2016, 01:17 AM	#5
Tas Site Supporter Join Date: Aug 2013 Location: Brisbane, QLD Photos: Gallery \| Albums Posts: 2,202	Originally posted by Sylwester I wonder if this has to do sth with astrotracer feature. It's to do with the shake reduction (SR). I have lenses that don't align perfectly with the SR options so for my 21mm lens I use 20mm and for the 25mm lens I use 24mm. I've seen no problems with it, but remember to turn off SR if you're mounting to a tripod. Note too, if you forget to set the right FL for the SR the camera will record your images with the wrong focal length so try and set it when you mount a new lens so the metadata is also correct. Tas

06-23-2016, 03:46 AM	#6
Na Horuk Veteran Member Join Date: Feb 2012 Location: Slovenia, probably Photos: Gallery \| Albums Posts: 11,186	You want to input the same number as is written on the lens, regardless of whether your camera is FF or APSC, whether the lens is FF or APSC. Problem is with some lenses that have a focal length that is not in the table. It is too bad Pentax did not fix this (wasn't this already fixed on the Q??). In those cases, it is best to input the nearest wider focal length. This means the SR will slightly undercompensate, be slightly less effective than it could be. If you input a higher number, it will overcompensate and might actually introduce blur. Now, a small difference might not be problematic. Another problem are manual zoom lenses, where focal length changes. In those cases you can input the widest, or the average, or just the one that you will be using the most. Feel free to write to Pentax that they should add more focal length choices, or change the menu so you can choose each digit separately.

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