Pentax 20mm F2.8 A

Lens-a-do · 02-08-2017, 01:59 PM

Hi all,
Well I finally found one on the auction site a 20mm f2.8 A lens, it looks to be in good shape but! the aperture blades don't close which I think I could fix myself, the Pentax lenses are pretty
easy to work on. Does anyone here use it on a K5ii?. I think it goes to a 30mm which is a ideal angle for me.

**UncleVanya** · 02-08-2017, 03:24 PM

It is a 20mm always. But it will give you a similar field of view as a 30mm does on a 35mm film camera.

However if you like using a DA 18-55 zoom set at 30mm this will not be at all similar. All lenses will display a similar field of view at a given focal length on a specific size sensor (as long as they cover the entire sensor or larger) so a 6x7 35mm lens and a DA 35mm lens will give a similar image on the k5 series.

DagT · 02-09-2017, 09:26 AM

I´ve tried A20mm on a K-3, K-5 as well as some older cameras (and also K-1). It is a great lens, but with a little distortion. As UncleVanya say the field of view will be the same as when you is you chose 20mm on your 18-55mm lens.

Lens-a-do · 02-09-2017, 04:22 PM

It will be about a 30mm on a C size sensor which should be a nice angle of view, when I get it I have to do a repair on the aperture it seems it's a bit stuck
but I'll figure it out.

DagT · 02-14-2017, 05:25 AM

Originally posted by Lens-a-do

It will be about a 30mm on a C size sensor which should be a nice angle of view, when I get it I have to do a repair on the aperture it seems it's a bit stuck
but I'll figure it out.

Just in case:
If you compare the field of view with a FA31 mounted on K-1, then yes, the A20 will give you approximately the same if you use it on an APS-C sensor. However, the field of view you get with the A20 on an APS-C sensor will be identical to the field of view you get with a DA18-55 at 20mm on an APS-C sensor, and almost the same field of view that you get with the DA21 lens on that sensor.

:-)

Lens-a-do · 02-18-2017, 03:08 PM

Sweet!

Lens-a-do · 02-28-2017, 10:24 AM

I received the lens and it needs a little help so I opened it up. First the aperture blades were getting stuck for some reason at the opened position, so I cleaned them with a bit of lighter fluid that seems to make them work
much smoother. Next there is a bracket with a spring attached that spring was really loose so with a quick bend outward on both sides made it much tighter and with that done and the index ring put back in the aperture
opens and closes normally now. I did clean the inner glass and put it all back together and so far the pictures are looking good.

02-08-2017, 01:59 PM	#1
Lens-a-do Junior Member Join Date: Oct 2015 Posts: 35	Pentax 20mm F2.8 A Hi all, Well I finally found one on the auction site a 20mm f2.8 A lens, it looks to be in good shape but! the aperture blades don't close which I think I could fix myself, the Pentax lenses are pretty easy to work on. Does anyone here use it on a K5ii?. I think it goes to a 30mm which is a ideal angle for me.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
For Sale - Sold: SMC Pentax-A 20mm f2.8	matsoberg	Sold Items	10	12-05-2016 11:24 AM
K1 and performance with 20mm A f2.8, 24mm f2.8 A, and 20-35 FA F4	stemked	Pentax Full Frame	17	11-22-2016 11:53 AM
Issues with SMC Pentax-A 20mm F2.8	vinni	Pentax SLR Lens Discussion	10	04-18-2015 01:18 AM
For Sale - Sold: SMC Pentax-A 20mm F2.8 lens	jmb	Sold Items	6	10-18-2012 06:51 PM

02-08-2017, 03:24 PM	#2
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,397	It is a 20mm always. But it will give you a similar field of view as a 30mm does on a 35mm film camera. However if you like using a DA 18-55 zoom set at 30mm this will not be at all similar. All lenses will display a similar field of view at a given focal length on a specific size sensor (as long as they cover the entire sensor or larger) so a 6x7 35mm lens and a DA 35mm lens will give a similar image on the k5 series.

02-09-2017, 09:26 AM	#3
DagT Senior Member Join Date: Sep 2012 Location: Oslo Posts: 110	I´ve tried A20mm on a K-3, K-5 as well as some older cameras (and also K-1). It is a great lens, but with a little distortion. As UncleVanya say the field of view will be the same as when you is you chose 20mm on your 18-55mm lens.

02-09-2017, 04:22 PM	#4
Lens-a-do Junior Member Join Date: Oct 2015 Posts: 35 Original Poster	It will be about a 30mm on a C size sensor which should be a nice angle of view, when I get it I have to do a repair on the aperture it seems it's a bit stuck but I'll figure it out.

02-14-2017, 05:25 AM	#5
DagT Senior Member Join Date: Sep 2012 Location: Oslo Posts: 110	Originally posted by Lens-a-do It will be about a 30mm on a C size sensor which should be a nice angle of view, when I get it I have to do a repair on the aperture it seems it's a bit stuck but I'll figure it out. Just in case: If you compare the field of view with a FA31 mounted on K-1, then yes, the A20 will give you approximately the same if you use it on an APS-C sensor. However, the field of view you get with the A20 on an APS-C sensor will be identical to the field of view you get with a DA18-55 at 20mm on an APS-C sensor, and almost the same field of view that you get with the DA21 lens on that sensor. :-)

02-18-2017, 03:08 PM	#6
Lens-a-do Junior Member Join Date: Oct 2015 Posts: 35 Original Poster	Sweet!

02-28-2017, 10:24 AM	#7
Lens-a-do Junior Member Join Date: Oct 2015 Posts: 35 Original Poster	I received the lens and it needs a little help so I opened it up. First the aperture blades were getting stuck for some reason at the opened position, so I cleaned them with a bit of lighter fluid that seems to make them work much smoother. Next there is a bracket with a spring attached that spring was really loose so with a quick bend outward on both sides made it much tighter and with that done and the index ring put back in the aperture opens and closes normally now. I did clean the inner glass and put it all back together and so far the pictures are looking good.

Thread Tools	Search this Thread
	Search this Thread: Advanced Search