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Author Topic: K mount lens for wide landscapes  (Read 2886 times)

Huffie

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K mount lens for wide landscapes
« on: October 11, 2016, 08:00:14 pm »

I (hopefully) will soon be picking up a Pentax K-1. I was planning to include the  Pentax 31MM f 1.8 limited as the lens I would primarily use for my artwork. However, when reading up the lens on the website photozone.com, it said that the 31 mm number is based on the smaller sensor, that the full frame equivalent number makes this lens more of a normal lens at 47mm.
Does this sound correct?
Photozone seems like a pretty good source for lens reviews - is it truely a reliable source?
Back in the days of chemical photography, I used my Nikon F 1 with a 28mm..this is the approx view I was hoping for.
Given this, does anyone have a suggestion on a suitable lens for this camera?
The Pentax SMC-DA 21mm f/3.2 AL seemed good at first... but since it is not a full frame lens will it take full advantage of the entire sensor? I don't see the point in shelling out the $2K for that 36mp sensor if it is not being used.
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Paul2660

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Re: K mount lens for wide landscapes
« Reply #1 on: October 11, 2016, 08:32:18 pm »

The 31mm 1.8 is a full frame lens, older design, but still a very nice lens.  I have the 77mm, which is also excellent.   Both the 77mm and 31mm are the limited lenses, and FA.  Full frame.

Other wides to consider:

35mm Sigma Art, much heavier but IMO a bit better than the 31mm Pentax and a bit cheaper.

14mm Rokinon, hard to beat this lens, very inexpensive and still is the champ of all 14mm F 2.8 lenses, (nikon, canon, Sony etc).  No AF, however.

15-30 Pentax, beast, but again, an excellent optic, I would rate as good as the Nikon 14-24 and Canon 16-35mmII lenses, both of which I have used.  Pentax 15-30 is much heavier than anything else, has a curved front element and is not filter friendly.  Also mine is not tack from 24mm to 30mm, but the area I really use 15-21mm is excellent.

Samyang 20mm 1.8, still not shipping but still should be a great lens if it follows the footsteps of the 14mm.  Remember Rokinon, Samyang and Bower are all the same.

Older Pentax film lenses, mainly the 28mm that are found on ebay can be good depending on lens and condition.

Paul C


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Paul Caldwell
Little Rock, Arkansas U.S.
www.photosofarkansas.com

Huffie

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Re: K mount lens for wide landscapes
« Reply #2 on: October 12, 2016, 01:32:33 am »

Which of these would approximate the view from my old 28mm?
Is this 31MM on a full frame camera considered a true wide angle lens?
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viewfinder

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Re: K mount lens for wide landscapes
« Reply #3 on: October 12, 2016, 03:19:20 am »

The pentax K1 is a "full frame" camera...ie the sensor is the same size as a frame of 35mm film used to be....thus, a 28mm lens will behave like, well,..a 28mm.....
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NancyP

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Re: K mount lens for wide landscapes
« Reply #4 on: October 12, 2016, 11:49:46 am »

Are you planning on using f/5.6 to f/11 for most landscapes? Your needs might be answered by many options. BTW, Pentax Forums website is pretty active.  Would the Voigtlander Color Skopar 20mm f/3.5 manual focus pancake lens be of interest? I don't know how this performs at f/5.6 to f/11 near-infinity. If I were an alpinist looking for a lens, this would be a must-look-at due to the low weight.
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Huffie

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Re: K mount lens for wide landscapes
« Reply #5 on: October 12, 2016, 03:45:56 pm »

Thanks for the suggestions, Nancy.
Do you know if there is an adapter to a K mount for this Canon lens? Is the lens still in production?
The website Photozone.com states that the Pentax 31mm actually is a normal lens on a full frame camera - that the 31mm designation is for the smaller sensors.
I always thought that the lens manufacturers kept the old standard, meaning that if you have say a Canon Rebel and you wanted to buy lenses for such a camera (with the smaller sensor) then you would have to figure out the mm equivlent for each lens you wanted because the 35mm film format is larger than those sensors.
Now it seems that in these Pentax lenses they use the smaller sensor as the standard and you have to figure out the equivalent mm for each lens for full frame cameras!?
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Telecaster

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Re: K mount lens for wide landscapes
« Reply #6 on: October 12, 2016, 04:45:35 pm »

The website Photozone.com states that the Pentax 31mm actually is a normal lens on a full frame camera - that the 31mm designation is for the smaller sensors.

This is not the case. Focal length is focal length. It's a lens property, format independent. If you're using a camera with an APS-C sensor the 31mm will function like a ~45mm lens does on a "full frame" camera. But it's a 31mm lens regardless.

Quote
Now it seems that in these Pentax lenses they use the smaller sensor as the standard and you have to figure out the equivalent mm for each lens for full frame cameras!?

No. See above.

-Dave-
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Paul2660

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Re: K mount lens for wide landscapes
« Reply #7 on: October 12, 2016, 05:14:43 pm »

Thanks for the suggestions, Nancy.
Do you know if there is an adapter to a K mount for this Canon lens? Is the lens still in production?
The website Photozone.com states that the Pentax 31mm actually is a normal lens on a full frame camera - that the 31mm designation is for the smaller sensors.
I always thought that the lens manufacturers kept the old standard, meaning that if you have say a Canon Rebel and you wanted to buy lenses for such a camera (with the smaller sensor) then you would have to figure out the mm equivlent for each lens you wanted because the 35mm film format is larger than those sensors.
Now it seems that in these Pentax lenses they use the smaller sensor as the standard and you have to figure out the equivalent mm for each lens for full frame cameras!?

It's not that hard.

Pentax DA = APS-C image circle
Pentax FA  = 35mm full frame

The 31mm is a FA lens and will seen as a 31mm lens on the K1. 3mm less than 28mm which means it is very close.

Note also most Canon or Nikon lenses will not adapt to Pentax as the focal flange distance is basically the same thus you lose infinity focus.

More on the 31mm.

http://www.pentaxforums.com/lensreviews/SMC-Pentax-FA-31mm-F1.8-Limited-Lens.html

Paul C
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Paul Caldwell
Little Rock, Arkansas U.S.
www.photosofarkansas.com

NancyP

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Re: K mount lens for wide landscapes
« Reply #8 on: October 12, 2016, 08:29:52 pm »

Voigtlander lenses on Pentax mounts are no longer being sold new, but you might find them on ebay.
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Paulo Bizarro

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Re: K mount lens for wide landscapes
« Reply #9 on: October 13, 2016, 04:33:16 am »

I would also consider the Zeiss SLR lenses for K mount. Today, they only make them for Canon EF (ZE) and Nikon F (ZF) mounts, but in the past, they made them for Pentax.

This means searching in the used market, but a good set of Zeiss primes for landscapes seems the way to go. 21, 35, 50, 85 focal lengths.
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