Using 645 FA and A lenses on K20D

davidb-g · 12-17-2011, 04:21 PM

Has anybody had experience using FA and A 645 lenses with the 645 K mount to a K20D. I find the instruction manual for the K20D very difficult to follow on this topic.

How should the K20D be set up to make best use of these lenses?

Presumably the camera has to be set for manual focus?

Can through the lens metering be used, if so how does this work?

Any other pointers on this subject, other than buy a 645D, will be much appreciated?

David.

Adam · 12-17-2011, 04:31 PM

Assuming you have the adapter, these lenses will work just like M42 lenses. The procedure for shooting and metering is found here: https://www.pentaxforums.com/forums/pentax-lens-articles/110657-how-use-meter...k-x-k-7-a.html

As long as you're willing to walk around with an oversized manual lens on your camera, you'll enjoy good image quality from 645 lenses.

excanonfd · 12-17-2011, 10:04 PM

Originally posted by davidb-g

Has anybody had experience using FA and A 645 lenses with the 645 K mount to a K20D. I find the instruction manual for the K20D very difficult to follow on this topic.

How should the K20D be set up to make best use of these lenses?

Presumably the camera has to be set for manual focus?

Can through the lens metering be used, if so how does this work?

Any other pointers on this subject, other than buy a 645D, will be much appreciated?

David.

I shoot with Pentax 645 A lenses (don't have any FA) with a 645K to PK adapter. The adapter do not pass along any information to and from the lens to the body therefore, it's all completely manual. Centre weighted average metering and spot metering are possible but the lens has to be closed down via the aperture ring. Set your camera to Av mode, stop the lens down to the desired aperture setting and press the shutter to capture image. On the K20D stop down metering isn't always linear, you will have to compensate for the metering error. IQ with 645 lenses are excellent because you are shooting through the centre of the lens - no need to worry about sharpness dropping in the corner of the frame. Downside is the lenses are generally heavier and larger than the 135 format counterparts. If you intend to shoot a 645 camera (film , I assume) some time in the future, buying 645 lenses can make sense but if not, it would be better to stick to current generation or 135 format lenses. It can get tiring to look through dim viewfinder while carrying heavy camera set up, for any lengths of time.

davidb-g · 12-18-2011, 11:25 AM

Adam,

Thank you for your prompt reply. I will go through the information provided and try the lenses again on my K20D. I have the Pentax adapter and quite a few 645 lenses which I used with my 645 cameras and it seemed a shame not to be able to utilize these excelant lenses with the digital camera, particularly since Pentax make a point of saying that these lenses can be used with the K20D in there sales lit.

I may have more questions as time goes by thank you again for your prompt help.

David.

davidb-g · 12-18-2011, 11:32 AM

Thank you for your prompt reply to my question, I will now try the lenses again with K20D after reading information provided.

David.

12-17-2011, 04:21 PM	#1
davidb-g New Member Join Date: Mar 2011 Location: Prineville, Oregon Posts: 6	Using 645 FA and A lenses on K20D Has anybody had experience using FA and A 645 lenses with the 645 K mount to a K20D. I find the instruction manual for the K20D very difficult to follow on this topic. How should the K20D be set up to make best use of these lenses? Presumably the camera has to be set for manual focus? Can through the lens metering be used, if so how does this work? Any other pointers on this subject, other than buy a 645D, will be much appreciated? David.

12-17-2011, 04:31 PM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	Assuming you have the adapter, these lenses will work just like M42 lenses. The procedure for shooting and metering is found here: https://www.pentaxforums.com/forums/pentax-lens-articles/110657-how-use-meter...k-x-k-7-a.html As long as you're willing to walk around with an oversized manual lens on your camera, you'll enjoy good image quality from 645 lenses. Last edited by Ole; 12-17-2011 at 04:56 PM.

12-18-2011, 11:25 AM	#4
davidb-g New Member Join Date: Mar 2011 Location: Prineville, Oregon Posts: 6 Original Poster	Monual Lens use with K20D Adam, Thank you for your prompt reply. I will go through the information provided and try the lenses again on my K20D. I have the Pentax adapter and quite a few 645 lenses which I used with my 645 cameras and it seemed a shame not to be able to utilize these excelant lenses with the digital camera, particularly since Pentax make a point of saying that these lenses can be used with the K20D in there sales lit. I may have more questions as time goes by thank you again for your prompt help. David.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Pentax Medium Format Resources: 645 & 6x7 Cameras and Lenses, 645 & 6x7 Accessories	Adam	Pentax Medium Format	9	02-12-2017 03:38 AM
People 645 on K20D-Raj	Rupert	Post Your Photos!	5	01-25-2012 06:58 PM
Nature 645/k20d	Rupert	Photo Critique	4	09-26-2010 01:27 PM
My K20D takes terrible images with my 645 lenses, why?	drougge	Pentax DSLR Discussion	23	06-01-2010 10:19 AM

12-17-2011, 10:04 PM	#3
excanonfd Veteran Member Join Date: Jan 2010 Location: Vancouver, BC Posts: 1,421	Originally posted by davidb-g Has anybody had experience using FA and A 645 lenses with the 645 K mount to a K20D. I find the instruction manual for the K20D very difficult to follow on this topic. How should the K20D be set up to make best use of these lenses? Presumably the camera has to be set for manual focus? Can through the lens metering be used, if so how does this work? Any other pointers on this subject, other than buy a 645D, will be much appreciated? David. I shoot with Pentax 645 A lenses (don't have any FA) with a 645K to PK adapter. The adapter do not pass along any information to and from the lens to the body therefore, it's all completely manual. Centre weighted average metering and spot metering are possible but the lens has to be closed down via the aperture ring. Set your camera to Av mode, stop the lens down to the desired aperture setting and press the shutter to capture image. On the K20D stop down metering isn't always linear, you will have to compensate for the metering error. IQ with 645 lenses are excellent because you are shooting through the centre of the lens - no need to worry about sharpness dropping in the corner of the frame. Downside is the lenses are generally heavier and larger than the 135 format counterparts. If you intend to shoot a 645 camera (film , I assume) some time in the future, buying 645 lenses can make sense but if not, it would be better to stick to current generation or 135 format lenses. It can get tiring to look through dim viewfinder while carrying heavy camera set up, for any lengths of time.

12-18-2011, 11:32 AM	#5
davidb-g New Member Join Date: Mar 2011 Location: Prineville, Oregon Posts: 6 Original Poster	Thank you for your prompt reply to my question, I will now try the lenses again with K20D after reading information provided. David.