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4 Days Ago   #1
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Using aperture ring on DSLR: why not same as on Super Program?

Hi, I have been reading up on using manual lenses on a Pentax DSLR, and I apologize if this "newbie" question has been asked and answered many times, but I couldn't find it on a quick search.

Say you have an A lens mounted on a DSLR, and you turn the aperture ring away from "A" to, say, f/8. Then this does not give you aperture priority metering. If you want the camera to meter, with the ring set this way, you have to use stop-down metering, the "green button" (although my *ist DS2 does not seem to have a green button), etc.

But if I recall correctly, on the Super Program, turning the ring to the desired aperture was precisely the way you got aperture priority mode. Moreover, from what I read, though I never had an M lens, this would work with an M lens too.

So what is different on the DSLR? Why does it not function in just the way my camera from 1983 would?


I ask this because I was thinking about getting an M lens, but I see that there is some rigamarole involved with the metering, and it seems like it would have been so much easier on my old Super Program. Could, in principle, the DSLR be programmed to do it, in the firmware or via some change in the settings? Or is there a difference in the construction?

Thanks!

Mark

4 Days Ago - 1 Like   #2
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Pentax DSLR and some late SLR use a "crippled" K-mount which lack the mechanical parts for sensing the aperture position when aperture ring is out of A-position.

In Pentax K-3III Ricoh have added software functionality to solve this limitation, but it is not as straightforward as using aperture ring on an older SLR.
http://kmp.pentaxians.eu/technology/k-mount/crippled_af/
4 Days Ago   #3
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All you have to do is press the green button after setting your aperture and ISO. I've wished to be able to set aperture and shutter speed, and have the green button select ISO but alas it doesn't work in my K-1 mII. I really would like to use auto-iso in my camera.
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https://www.ricoh-imaging.co.jp/english/support/man-pdf/istds2.pdf


Page 182:

"When depth of field is checked (Preview), AE Metering is switched on."

For the *ist DS2 - Instead of the Green Button, you use the Depth of Field preview to activate the AE meter.

4 Days Ago   #5
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QuoteOriginally posted by Mark DeB Quote
Say you have an A lens mounted on a DSLR, and you turn the aperture ring away from "A" to, say, f/8. Then this does not give you aperture priority metering. If you want the camera to meter, with the ring set this way, you have to use stop-down metering, the "green button" (although my *ist DS2 does not seem to have a green button), etc.
As advised above the change in the K-mount occurred before DSLRs were even a thing for Pentax. Your Super Program and even the later Z-1 would allow M or "K" lenses to be used in aperture priority, but that all changed over 20 years ago.

Your DS2 will work similar to my first DSLR the DS. First, you must enable aperture ring use in the menu. Then put the camera into Manual exposure mode. Turn the DOF lever, and use the displayed meter to select a shutter speed to give you a correct exposure. Take your shot.

Later models use a green button to stop the lens down and take a meter reading and set a shutter speed (which you are free to adjust), again in M mode.

You can actually use your M or K lens in Av mode, but the lens will always remain wide open.

Sorry, no software fix for this. As advised above the K3III has automated the process, but I cannot see that ever happening for older cameras.
4 Days Ago   #6
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QuoteOriginally posted by Mark DeB Quote
Hi, I have been reading up on using manual lenses on a Pentax DSLR, and I apologize if this "newbie" question has been asked and answered many times, but I couldn't find it on a quick search.

Say you have an A lens mounted on a DSLR, and you turn the aperture ring away from "A" to, say, f/8. Then this does not give you aperture priority metering. If you want the camera to meter, with the ring set this way, you have to use stop-down metering, the "green button" (although my *ist DS2 does not seem to have a green button), etc.


Mark
For an A lens, you leave better the lens in A position, and set the aperture on the body ( use P mode or Av mode..., these modes accept a user defined Aperture and will set then accordingly the shutter speed and ISO to the correct exposure when you take picture). On DSLR’s the aperture is typically set by the rear dial wheel.
As explained higher, the dslr’s do not sense the lens manual setting anymore, but body can ”set/control” the aperture on the lens in A-position. The process is much more like with modern lenses/bodies, except you have to focus manually. And if you come from vintage manual lenses, it feels indeed odd to shift lens aperture control into the camera.

For the older pentax K and M lenses (and M42 or other lenses with dumb adapter without Acontrol) without this A position, you have to trigger manually metering with green button or preview
Because camera can’t read the aperture, but also not set the aperture without ”modern” A setting.... hence you set the aperture on lens. When you push green button , the camera will trigger aperture in lens ”blindly&mechanically”, read light conditions and calculate/set shutter/ISO correct. Then push button to take picture with the calculated settings. The small inconvenience is that it becomes a two step process to take pictures.
4 Days Ago - 1 Like   #7
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QuoteOriginally posted by Mark DeB Quote
Say you have an A lens mounted on a DSLR, and you turn the aperture ring away from "A" to, say, f/8. Then this does not give you aperture priority metering. If you want the camera to meter, with the ring set this way, you have to use stop-down metering, the "green button" (although my *ist DS2 does not seem to have a green button), etc.
The whole point of having an "A" setting on the lens is so you don't need to rotate the aperture ring ... just use the e-dial on the back of the camera
QuoteQuote:
I ask this because I was thinking about getting an M lens, but I see that there is some rigamarole involved with the metering, and it seems like it would have been so much easier on my old Super Program. Could, in principle, the DSLR be programmed to do it, in the firmware or via some change in the settings? Or is there a difference in the construction?
There's no "rigmarole", just a slightly different procedure ...
With the mode dial set to "M" and an appropriate ISO selected, also Using Aperture Ring set in the Custom Menu :-
Focus the lens
Set the Aperture ring,
Set the Shutter speed by pressing the AE-L button (the "green button" procedure as used on the later cameras) see Item 11 on p93 and p141 of the User Manual.
Take the picture

FAST

... been using it for years
Enjoy!

4 Days Ago   #8
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QuoteOriginally posted by jcdoss Quote
All you have to do is press the green button after setting your aperture and ISO
Unfortunately this quickly sets your shutter speed but doesn't show a viewfinder reading of the metering to allow for a more slr like workflow. I find it useful to see the meter and immediately deviate from the reading by over or under exposing. That's how I always work with manual slr's. The automatic mode is not very useful imho even if it's all we have.

If I'm wrong about this and just have my cameras set up wrong I'd be very happy to find out.
4 Days Ago - 2 Likes   #9
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QuoteOriginally posted by house Quote
Unfortunately this quickly sets your shutter speed but doesn't show a viewfinder reading of the metering to allow for a more slr like workflow
Then you use the DOF preview button after. Normal Av mode with a modern lens does not show the meter either

QuoteOriginally posted by house Quote
I find it useful to see the meter and immediately deviate from the reading by over or under exposing
Then you should use the DOF preview metering method from the start.

QuoteOriginally posted by house Quote
The automatic mode is not very useful imho even if it's all we have.
The method outlined will give you the same exposure as using a modern lens on the camera....what is "not useful" about that.

QuoteOriginally posted by house Quote
If I'm wrong about this and just have my cameras set up wrong I'd be very happy to find out.
I think you just need to learn about how the process works.

Pentax have tried hard to maintain backward compatibility with their lenses manufactured up to over 40 years ago. It works.

Last edited by pschlute; 4 Days Ago at 01:24 PM.
4 Days Ago - 1 Like   #10
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QuoteOriginally posted by house Quote
Unfortunately this quickly sets your shutter speed but doesn't show a viewfinder reading of the metering to allow for a more slr like workflow. I find it useful to see the meter and immediately deviate from the reading by over or under exposing. That's how I always work with manual slr's. The automatic mode is not very useful imho even if it's all we have.

If I'm wrong about this and just have my cameras set up wrong I'd be very happy to find out.
I'm not sure what the hangup is. I deviate from a neutral exposure by changing shutter speed after pressing the green button all the time. Sometimes I change ISO but almost never do I change aperture, but I could change any of the three to override the meter reading if I think the scene calls for it. If you know you're going to want, for example, to overexpose by one stop, you can set the exposure compensation to +1 before hitting the green button.
4 Days Ago - 1 Like   #11
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QuoteOriginally posted by jcdoss Quote
I'm not sure what the hangup is.
You are right. There is no difference. Using green button with a manual lens in M mode gives the same exposure parameters as using a modern DFA lens in Av mode. if the photographer wants to adjust this, they need to use their brains.
4 Days Ago   #12
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QuoteOriginally posted by pschlute Quote
they need to use their brains.
.... ahk crap it all then.
4 Days Ago - 1 Like   #13
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QuoteOriginally posted by Fogel70 Quote
Pentax DSLR and some late SLR use a "crippled" K-mount which lack the mechanical parts for sensing the aperture position when aperture ring is out of A-position.

In Pentax K-3III Ricoh have added software functionality to solve this limitation, but it is not as straightforward as using aperture ring on an older SLR.
Features and Operation of the “crippled” KAF Mount | The K-Mount Page
Ah, so that is the “crippled” K-mount! Thank you for explaining, and thanks to all for your kind replies!

Mark
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QuoteOriginally posted by house Quote
Unfortunately this quickly sets your shutter speed but doesn't show a viewfinder reading of the metering to allow for a more slr like workflow. I find it useful to see the meter and immediately deviate from the reading by over or under exposing. That's how I always work with manual slr's. The automatic mode is not very useful imho even if it's all we have.
If I'm wrong about this and just have my cameras set up wrong I'd be very happy to find out.
I've just checked with my *istDS and my K-5 and they both show the shutter speed in the viewfinder after pressing the AE-L button on the *istDS or the green button on the K-5 when in Manual mode.
Without knowing which camera you're using or how you've got it set up there's no point in trying to guess why it doesn't work for you.
Do note that this functionality is only available in Manual mode for lenses not set to "A" on the aperture ring … things can get a bit more sophisticated with the K-3iii, but as the OP has a *istDS2 we can ignore that for the moment
For M42 lenses the aperture needs to be closed down manually before taking the meter reading as no K-mount cameras have the capability to control the aperture in an M42 lens.
4 Days Ago   #15
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QuoteOriginally posted by kypfer Quote
The whole point of having an "A" setting on the lens is so you don't need to rotate the aperture ring ... just use the e-dial on the back of the camera
There's no "rigmarole", just a slightly different procedure ...
With the mode dial set to "M" and an appropriate ISO selected, also Using Aperture Ring set in the Custom Menu :-
Focus the lens
Set the Aperture ring,
Set the Shutter speed by pressing the AE-L button (the "green button" procedure as used on the later cameras) see Item 11 on p93 and p141 of the User Manual.
Take the picture

FAST

... been using it for years
Enjoy!
Thank you, that explains it very well and is very clear! I appreciate it. I see now that it actually adds just one button push to the procedure, not complicated at all. Thank you for those references to the User Manual. I had seen the information contained on p. 182, but there it refers to the DOF preview and it is not explicit about what happens when you do it. Just curious, does DOF preview do the same thing as AE-L (in this context), or something different?
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