Exposure accuracy of "A" lenses on older film bodies ("K" series)

tromboads · 05-24-2015, 11:54 PM

So did we work out if older K bodies play nice with the A lenses? (in that as accurate as M and K's)

Thinking about it.. When the K1000se came out, they were released with A 50mm lenses...

**Lowell Goudge** · 05-25-2015, 04:38 AM

Originally posted by tromboads

So did we work out if older K bodies play nice with the A lenses? (in that as accurate as M and K's)

Thinking about it.. When the K1000se came out, they were released with A 50mm lenses...

Yes they play nice I responded to this point in my first post.

The issues of metering are related to the focusing screens and meter housings on Pentax DSLRs not anything else. The A series lenses still have the aperture coupling to permit open aperture metering like the K and M series lenses, and as I said earlier, the aperture activation lever is used as a switch, open stopped down, so no issue there either

tromboads · 05-25-2015, 03:03 PM

Yes but as we all know the aperture levers are measured differently from the A and the M lenses? Or maybe this is the source of confusion.

I think we all thought the ratio of the movement from the A lever and the M lever was different, therefore how could the M and K bodies know how to compensate for the A lever.

**Lowell Goudge** · 05-25-2015, 04:41 PM

Originally posted by tromboads

Yes but as we all know the aperture levers are measured differently from the A and the M lenses? Or maybe this is the source of confusion.

I think we all thought the ratio of the movement from the A lever and the M lever was different, therefore how could the M and K bodies know how to compensate for the A lever.

But since the K&M bodies stop down by letting the aperture lever go completely to the point where the aperture stop in the lens limits the stopping down, there is no issue. Same with A series bodies with M lenses. In AV mode, setting the aperture manually the camera leve works like a switch. It lets the lens stop down to the lent's limit. The body stays out of the way

tromboads · 05-26-2015, 01:20 AM

I thought the ratio,well the distance between f stops was different on M and A lenses however, hence why we cant reverse engineer M lenses to act as A lenses in modern bodies.?

**Kerrowdown** · 05-26-2015, 01:59 AM

Originally posted by vonBaloney

Some of the K10Ds actually had a unlevel horizon

I always blamed the whisky... unfairly perhaps after all.

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05-24-2015, 11:54 PM	#16
tromboads Veteran Member Join Date: Apr 2012 Location: Melbs Photos: Gallery Posts: 1,240	So did we work out if older K bodies play nice with the A lenses? (in that as accurate as M and K's) Thinking about it.. When the K1000se came out, they were released with A 50mm lenses...

05-25-2015, 04:38 AM	#17
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,891	Originally posted by tromboads So did we work out if older K bodies play nice with the A lenses? (in that as accurate as M and K's) Thinking about it.. When the K1000se came out, they were released with A 50mm lenses... Yes they play nice I responded to this point in my first post. The issues of metering are related to the focusing screens and meter housings on Pentax DSLRs not anything else. The A series lenses still have the aperture coupling to permit open aperture metering like the K and M series lenses, and as I said earlier, the aperture activation lever is used as a switch, open stopped down, so no issue there either

05-25-2015, 03:03 PM	#18
tromboads Veteran Member Join Date: Apr 2012 Location: Melbs Photos: Gallery Posts: 1,240	Yes but as we all know the aperture levers are measured differently from the A and the M lenses? Or maybe this is the source of confusion. I think we all thought the ratio of the movement from the A lever and the M lever was different, therefore how could the M and K bodies know how to compensate for the A lever.

05-25-2015, 04:41 PM	#19
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,891	Originally posted by tromboads Yes but as we all know the aperture levers are measured differently from the A and the M lenses? Or maybe this is the source of confusion. I think we all thought the ratio of the movement from the A lever and the M lever was different, therefore how could the M and K bodies know how to compensate for the A lever. But since the K&M bodies stop down by letting the aperture lever go completely to the point where the aperture stop in the lens limits the stopping down, there is no issue. Same with A series bodies with M lenses. In AV mode, setting the aperture manually the camera leve works like a switch. It lets the lens stop down to the lent's limit. The body stays out of the way

05-26-2015, 01:20 AM	#20
tromboads Veteran Member Join Date: Apr 2012 Location: Melbs Photos: Gallery Posts: 1,240	I thought the ratio,well the distance between f stops was different on M and A lenses however, hence why we cant reverse engineer M lenses to act as A lenses in modern bodies.?

05-26-2015, 01:59 AM	#21
Kerrowdown PEG Moderator Join Date: Aug 2008 Location: Highlands of Scotland... "Hold Infinity in the palm of your hand" - William Blake Photos: Gallery Posts: 57,863	Originally posted by vonBaloney Some of the K10Ds actually had a unlevel horizon I always blamed the whisky... unfairly perhaps after all.