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07-07-2020, 06:15 AM - 1 Like   #1
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My old P/K lenses are dumb in every respect, is that normal?

I finally got around to unpacking some boxes after my move (almost 4 yrs ago but that's a story for another day ) and lo and behold were Pentax primes from the 80's when I had my ME Super & Mx.

I have the 135/3.5, the 28/2.8 and the 50/1.7. Having read my K-50 will take any Pentax lens ever made I mounted the 135mm first. It didn't matter what setting I chose on the PASM dial, the camera reported it was in the aperture priority mode, except when in Bulb and Manual. Anyhow, the display never showed me the aperture and the exposure didn't appear correct. It didn't matter what setting my aperture ring was set to.

What am I missing here? If I can't get any more functionality from my old lenses this Pentax system is no more convenient than using old Pentax lenses on my m43 bodies with dumb adapters.

I'm sorry if this is such an obvious noob issue, especially if it's been covered many times before.

07-07-2020, 06:19 AM - 1 Like   #2
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Hopefully this will be helpful (section 2):
Pentax Green Button Guide - Articles and Tips | PentaxForums.com

And this one has more details:
https://www.pentaxforums.com/forums/54-pentax-lens-articles/110657-how-use-m...-k-30-etc.html
07-07-2020, 06:33 AM - 1 Like   #3
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Remember to tell your camera that it is OK to use old lenses:
Select [Enable] in [22. Using Aperture Ring] of the [C Custom Setting 4] menu

The following video may also be helpful:
07-07-2020, 06:56 AM - 1 Like   #4
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QuoteOriginally posted by wallythacker Quote
It didn't matter what setting I chose on the PASM dial, the camera reported it was in the aperture priority mode, except when in Bulb and Manual
That is correct behaviour. You can use Av mode but the capture will be wide open only. Any other auto mode will revert to Av.

QuoteOriginally posted by wallythacker Quote
Anyhow, the display never showed me the aperture
It wont. It has no way of reading the aperture.

Use M mode and press green button for the camera to take a stopped down meter reading and select a shutter speed. Then take your shot.

Or use Av mode (wide open only)

07-07-2020, 07:28 AM - 1 Like   #5
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It’s been covered many times before because it is not immediately intuitive and lots of folks have had the same question...

I use old K-Mount lenses all the time, almost always in manual mode with the green button metering.

It’s only a tiny bit less convenient than using them on a K1000, and I get aperture priority auto if I need it...

-Eric
07-07-2020, 09:46 AM   #6
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Another way to see at a glance what works in what mode:

The Pentax Camera Lens Compatibility Chart
07-07-2020, 12:17 PM   #7
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QuoteOriginally posted by wallythacker Quote
It didn't matter what setting I chose on the PASM dial, the camera reported it was in the aperture priority mode, except when in Bulb and Manual.
Be prepared for another small "gotcha" when using the aperture ring. Auto-ISO in M mode will result in an unexpected boot out to TAv mode which will then fail over to Av mode. I suggest a User mode configured as M mode with fixed ISO set to 200 or some other value you like.


Steve

07-07-2020, 12:45 PM - 1 Like   #8
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People, thank you so much for such detailed help. Now it's really easy to use an older lens and get proper exposures!

I also changed my RAW/Fx button to "Optical Preview" and lo and behold, it stops the lens down to let you see you DOF and how your composition will appear.

So my process is to: set my aperture, focus the lens, press the RAW/Fx button to check my composition, press my Green button to see/set the shutter speed, finally press the shutter to take the image! So it's not as bad a process as I was imaging.

But....It's actually easier and more accurate to use my Pentax vintage prime lenses with a $10 adapter on an Olympus Em1 Mark1 ! I'm not kidding about that one.
07-07-2020, 01:58 PM - 2 Likes   #9
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QuoteOriginally posted by wallythacker Quote
But....It's actually easier and more accurate to use my Pentax vintage prime lenses with a $10 adapter on an Olympus Em1 Mark1 ! I'm not kidding about that one.
Sure, if you don't mind that 75% of the image circle is cropped out...

It's also easy to use with a Sony A7/A9 kind of camera and you will get the image that it is meant to give (24x36mm). Or the A6x00 family which will give you a bit less than half the image circle (1.5x crop).

But I prefer the build and interface of Pentax cameras and their affordability, too.
07-07-2020, 02:05 PM   #10
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QuoteOriginally posted by wallythacker Quote
So my process is to: set my aperture, focus the lens, press the RAW/Fx button to check my composition, press my Green button to see/set the shutter speed, finally press the shutter to take the image! So it's not as bad a process as I was imaging.
The next thing to try is to simply keep that shutter setting until either the light or the subject changes. That is how stop-down metering was done with the Spotmatic and similar cameras; meter once and shoot at will.

QuoteOriginally posted by wallythacker Quote
But....It's actually easier and more accurate to use my Pentax vintage prime lenses with a $10 adapter on an Olympus Em1 Mark1 ! I'm not kidding about that one.
For more accurate metering with your K-50, take the green-button reading in live view and then switch back. As far as ease is concerned, I am not a fan of full-manual aperture. The stopping down manually after focusing gets old fast as does the manual opening for the next shot. An adapter with a preset ring helps, but those are more money (~$22).


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07-08-2020, 06:10 AM   #11
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QuoteOriginally posted by ChristianRock Quote
Sure, if you don't mind that 75% of the image circle is cropped out...

It's also easy to use with a Sony A7/A9 kind of camera and you will get the image that it is meant to give (24x36mm). Or the A6x00 family which will give you a bit less than half the image circle (1.5x crop).

But I prefer the build and interface of Pentax cameras and their affordability, too.
But I am cropping out using my FF vintage lenses on my K-50 which is APC-S,isn't it? So my 135mm crops to a ~200mm equivalent FOV? Doesn't bother me as the 135mm crops to 270mm EQ on my Olympus or the 50mm crops to 100mm so either way I'll get my desired composition in post.

I do agree the Olympus interface is brutal in the field, many shots get missed fiddling with settings. In the studio who cares? I like my Pentax for the field, simple and pretty rugged from what I see so far.

Too bad there's no service out there that will retrofit vintage Pentax lenses with weather resistant seals. I'd happily pay the current value of the lens to get it waterproofed.
07-08-2020, 06:15 AM   #12
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QuoteOriginally posted by ChristianRock Quote
It's also easy to use with a Sony A7/A9 kind of camera and you will get the image that it is meant to give (24x36mm). Or the A6x00 family which will give you a bit less than half the image circle (1.5x crop).

But I prefer the build and interface of Pentax cameras and their affordability, too.
I’ve been using a base A7 with adapters as a digital solution for my manual Pentax (and other) lenses since the A7 became available. I don’t mess with settings, so the menus, etc don’t bother me. Spot meter, lock exposure and reframe. The EVF focuses well without aids even at moderate apertures, so I don’t bother opening up to focus. The EVF stays bright in dim light or with lens stopped down, so I find dim light focusing easier than with an LX or MX. The M lenses are a good size for this camera. I haven’t used my K5 since getting it.
07-08-2020, 06:37 AM   #13
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QuoteOriginally posted by TomB_tx Quote
I The EVF stays bright in dim light or with lens stopped down, so I find dim light focusing easier than with an LX or MX. The M lenses are a good size for this camera. I haven’t used my K5 since getting it.
Yes, that's how my Olympus, all I guess all cameras with EVF perform. It was bizarre at first stopping down with a manual lens and watching the EVF brighten so everything was still easily visible. I assigned a F button to provide a stopped down view so I can still check on my DOF. It's not nearly as accurate as a mirror system but it's pretty darn good.
07-08-2020, 06:40 AM   #14
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QuoteOriginally posted by wallythacker Quote
But I am cropping out using my FF vintage lenses on my K-50 which is APC-S,isn't it? So my 135mm crops to a ~200mm equivalent FOV? Doesn't bother me as the 135mm crops to 270mm EQ on my Olympus or the 50mm crops to 100mm so either way I'll get my desired composition in post.
Sure, for tele work that works well.

Pentax has FF and APS-C options, so you can pick whether you get a crop of the vintage lens image, or the whole image (or for some of us we get what you can afford...)

As Norm says, there's tradeoffs whichever way you pick, so you pick whichever tradeoffs you are comfortable with... but that doesn't make other options less valid for other people.
07-08-2020, 11:28 AM   #15
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QuoteOriginally posted by wallythacker Quote
Too bad there's no service out there that will retrofit vintage Pentax lenses with weather resistant seals. I'd happily pay the current value of the lens to get it waterproofed.
While I admire your expectations, this is an impossible dream

---------- Post added 07-08-20 at 07:39 PM ----------

QuoteOriginally posted by wallythacker Quote
But I am cropping out using my FF vintage lenses on my K-50 which is APC-S,isn't it? So my 135mm crops to a ~200mm equivalent FOV? Doesn't bother me as the 135mm crops to 270mm EQ on my Olympus or the 50mm crops to 100mm so either way I'll get my desired composition in post.
The question I would pose is....."but are you getting the best IQ for your chosed FL and camera sensor"?

Sure you can plonk any lens on a smaller format and claim to have "longer reach, or "narrower field of view". But the smaller format needs to have a higher pixel pitch or improved tech, or you are achieving nothing that a crop of a larger format could do. Magnification "at the sensor" is identical across all formats.
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