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04-14-2009, 04:25 AM   #1
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Need some help: K-m/K2000 and manual lens

Ok, Here is my question:

I followed this guide "http://forums.dpreview.com/forums/readflat.asp?forum=1036&thread=24921509&page=1" but there is a slight difference when using Pentax K-m with manual lens. I've managed to take some great shoots, but still I don't understand the "step down metering" thing...

Here are my steps, when I am using manual lens

1. "Using aperture ring" - enabled
2. I assigned AF-LOCK to AF button
3. Entered correct value for Shake Reduction
4. Set my mode dial to M

now, after I focused and got the confirmation sound, I set the right exposure and aperture (on the lens) and ready to shoot! so it's simple, I did not use metering and all setting were set manually.
Now, what I have noticed is this:
When camera set to "M" and I am trying to press AF (which is assigned to AF-LOCK) nothing happens! But if I press EV button - I can hear strange noise coming from camera, and.... the exposure is set automatically to the closest correct value! I checked it with different apertures and it works!!!! Very strange!!!!

Now, if I will switch to Av mode, the AF-LOCK works fine, and I see "*" which means exposure was locked! when I press the EV button I can set exposure compensation +/-. But the exposure value is wrong! Or it's too fast, or it's too slow and it's too hard to get the right exposure
I have tried different setting, like using wide open F-stop and locking the exposure or using f2, f4 but still the metering is completely wrong!!!

Please help and tell me what I am doing wrong?

thanks.

Greg.

04-14-2009, 08:16 AM   #2
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QuoteOriginally posted by grishazzz Quote
2. I assigned AF-LOCK to AF button
Do you perhaps mean AE Lock? I can't see that anything called AF lock would have any relevance at all when using a manual lens.

QuoteQuote:
Now, what I have noticed is this:
When camera set to "M" and I am trying to press AF (which is assigned to AF-LOCK) nothing happens! But if I press EV button - I can hear strange noise coming from camera, and.... the exposure is set automatically to the closest correct value!
Yes, that's exactly how it is supposed to work. The sound is the aperture temporarily stopping down to allow the camera to meter. On other models, the same function is performed by the Green button or the AE-L button. That should be explained in the thread you referenced.

QuoteQuote:
Now, if I will switch to Av mode
In Av mode, the aperture ring is ignored entirely. The camera always meters and shoots with the aperture wide open. Exposure should be correct (eg, same shutter speed you'd get in M mode using the Green button metering with aperture ring at largest setting), but it responds to EV compensation normally.
04-14-2009, 10:40 AM   #3
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QuoteOriginally posted by Marc Sabatella Quote
Do you perhaps mean AE Lock? I can't see that anything called AF lock would have any relevance at all when using a manual lens.
Oppps, sorry - my mistake, you are right AE-LOCK.

QuoteOriginally posted by Marc Sabatella Quote
Yes, that's exactly how it is supposed to work. The sound is the aperture temporarily stopping down to allow the camera to meter. On other models, the same function is performed by the Green button or the AE-L button. That should be explained in the thread you referenced.
Thank you!!! Now finally I've realized what was wrong. After I read that thread explaining how to use manual lenses, I did not understand which button does the trick! Mistakenly I though about AE-LOCK assigned to AF button in my case (K-M )

QuoteOriginally posted by Marc Sabatella Quote
In Av mode, the aperture ring is ignored entirely. The camera always meters and shoots with the aperture wide open. Exposure should be correct (eg, same shutter speed you'd get in M mode using the Green button metering with aperture ring at largest setting), but it responds to EV compensation normally.
thank you, now finally I am going the right direction! I would like to make it clear, Please advise or correct me:

Let's say I want to meter the exposure using the EV button in "M" mode:
1. Aperture wide open (in my case this is Helios 44-m4: F2)
2. Focus.
3. I press the EV/AV button (In K-m it's the same button)
4. I hear noise coming from camera - it means the camera is trying to meter the exposure by stopping down the aperture.
5. Take the picture, or correct the exposure by using the command dial, right?
--- In "M" mode EV compensation is not available same goes for AE-LOCK - not availabe.

In order to do this I will switch to AV? right?
or let's say if I want to get more objects in focus, I will have to use different F-stops, like 4, 5, 8. So I will have to meter exposure again? This is the step where I completely lost!
Please advice.

Thank you!

Greg.

BTW:

Helios 44-M-4 at infinity/50mm
Shutter 1/350 sec
ISO 200
EV - 0
F4??? (Dont remember)
I resized it in PS
Look sharp, right?
Israel, Haifa's Industrial Zone

Last edited by grishazzz; 04-14-2009 at 10:58 AM.
04-14-2009, 11:27 AM   #4
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QuoteOriginally posted by grishazzz Quote
Let's say I want to meter the exposure using the EV button in "M" mode:
1. Aperture wide open (in my case this is Helios 44-m4: F2)
Is that by any chance a screw mount lens? If so, the rules are different - I was talking about K-mount lenses.

QuoteQuote:
--- In "M" mode EV compensation is not available same goes for AE-LOCK - not availabe.
Correct. The whole concept of AE Lock is meaningless in M mode - exposure is *always* locked. As for EV compensation, all it does in other mdoes is change the shutter speed or aperture for you. In M mode, you just change shutter speed or aperture yourself toi get exactly the same effect.

QuoteQuote:
In order to do this I will switch to AV? right?
See above. Exposure is *always* locked in M mode; no need to switch to Av mode and hit the AE-L button to get that effect. And if you want a brighter or darker exposure, just change shutter speed or aperture yourself. No reason to change to Av mode and then ask the camera to change it for you!

QuoteQuote:
let's say if I want to get more objects in focus, I will have to use different F-stops, like 4, 5, 8. So I will have to meter exposure again?
Yes. Same exact story as when using M mode with non-manual lenses, so maybe things would become clearer for you if you first got accustomed to M mode with modern lenses. Then the slight adjustment to the differences between manual and automatic lenses with seem trivial.

QuoteQuote:
Look sharp, right?
Does to me at the posted size, sure!

04-14-2009, 12:01 PM   #5
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QuoteOriginally posted by Marc Sabatella Quote
Is that by any chance a screw mount lens? If so, the rules are different - I was talking about K-mount lenses.
Yes, it's a screw mount m42 manual lens: Helios 44-M-4

QuoteOriginally posted by Marc Sabatella Quote
Correct. The whole concept of AE Lock is meaningless in M mode - exposure is *always* locked. As for EV compensation, all it does in other modes is change the shutter speed or aperture for you. In M mode, you just change shutter speed or aperture yourself toi get exactly the same effect.
Got it, thank you!!! Now I feel confident.

QuoteOriginally posted by Marc Sabatella Quote
See above. Exposure is *always* locked in M mode; no need to switch to Av mode and hit the AE-L button to get that effect. And if you want a brighter or darker exposure, just change shutter speed or aperture yourself. No reason to change to Av mode and then ask the camera to change it for you!
Yep, like I thought. AE-L is good for taking panoramic pictures... to set&lock the same exposure for all pictures...

QuoteOriginally posted by Marc Sabatella Quote
Yes. Same exact story as when using M mode with non-manual lenses, so maybe things would become clearer for you if you first got accustomed to M mode with modern lenses. Then the slight adjustment to the differences between manual and automatic lenses with seem trivial.
Thanks for advice! I thought vise versa, to start playing with manual lens first anyway, I will switch to DA L kit lens to get things right.

QuoteOriginally posted by Marc Sabatella Quote
Does to me at the posted size, sure!
[/QUOTE]

at highest resolution it looks sharp too, but more noise is visible. The sky was dirty, when I took this picture. Usually it happens when hot wind from desert brings dust mixed with tiny pieces of sand.

Thank you, again for clear and simple instructions!
So far, all I can say - I like Pentax! every time I use it, I like it more and more....
04-14-2009, 05:29 PM   #6
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QuoteOriginally posted by grishazzz Quote
Yep, like I thought. AE-L is good for taking panoramic pictures... to set&lock the same exposure for all pictures...
But just to be clear - again, completely unnecessary in M mode. By definition, exposure is locked in M mode until you *manually* (that's the "M" part) change it.

Like I said, the rules for using M42 lenses is different, so hopefully you'll find a different guide to explain that.
04-14-2009, 06:20 PM   #7
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QuoteOriginally posted by Marc Sabatella Quote
But just to be clear - again, completely unnecessary in M mode. By definition, exposure is locked in M mode until you *manually* (that's the "M" part) change it.

Like I said, the rules for using M42 lenses is different, so hopefully you'll find a different guide to explain that.
Got my adapter and dusted off my 55 f1.8 Super Tak. You say the rules are different?

After playing with it for a while I think I know what you mean.

I don't need the green button, because the automatic apeture function does not work with this adapter.

The lens has a manual mode for stopping down the apeture.

I can use any of the AE modes and the meter will function and constantly change if I move the camera around.

In M mode, I have to use the green button to get a reading.

When I shoot wide open, however, the pics come out underexposed if I use the AE modes.

I can use EV compensate and get a better exposure if I increase by two stops.

If I have it stopped down all the way, it tends to overexpose at that same EV setting. I get a better exposure at 0 EV.

Is this what you are talking about and or is there more to know?

I want to join the SUPER TAK Club!

Thanks
04-15-2009, 04:19 AM   #8
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grishazzz, may I suggest that you read "Notes on [19. Using Aperture Ring]" and "Restrictions on using lenses with aperture ring set to a position other than A" sections on page 241, 242 of operating manual of the camera...

04-16-2009, 12:56 AM   #9
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QuoteOriginally posted by simico Quote
grishazzz, may I suggest that you read "Notes on [19. Using Aperture Ring]" and "Restrictions on using lenses with aperture ring set to a position other than A" sections on page 241, 242 of operating manual of the camera...
Simico, thank you for your advise.
I have already read the whole manual including this section, but still the manual looks dry and it doesn't provide the detailed info I was looking for. Thank's again.

Marc Sabatella

QuoteOriginally posted by Marc Sabatella;:
Like I said, the rules for using M42 lenses is different, so hopefully you'll find a different guide to explain that.
Thank you Marc. Maybe you know, where can I find this guide?
04-16-2009, 01:23 PM   #10
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Unfortunately, I don't have any experience with M42 lenses nor do I know where there might be a good writeup. I understand that unlike K-mount lenses, they may stop down as soon as you turn the aperture ring. But I gather that depends on wheter the lens has an "auto" switch, and also some M42 lenses have two aperture rings and I don't totally understand how they relate.
04-16-2009, 01:45 PM   #11
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Marc,

I see. Anyway thank you for your explanations.
Now I feel more confident with manual settings. I'll find this info later.
I've tried using different aperture combinations and finally I got it right I guess. (i.e: step down metering was activated at F8, than manually I am switching to f 5.6 (approximately 2 stops down) and the result comes out way better, maybe I am wrong, but after playing with the settings, I am getting way better results!!! or I set shutter speed manually, like I was doing before )
04-16-2009, 04:32 PM   #12
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grishazzz,

I am new to dslrs, have a k2000, too, and was curious about using m42 lenses about a week ago. I tried to research this online and this is the only article I could find about it:

LINK

My understanding of that article is that with m42 lenses on Pentax dslrs, when you set the aperture to f/22, for example, it will actually close down to that f-stop, which makes it hard to focus since there's not enough light. So you have to set the aperture wide open in order to be able to focus, then set the aperture to the one you actually want, press the Av button to take a reading and have the shutter speed set for you, and then finally take the shot.

Other manual focus lenses, like the Pentax M series, will keep the aperture wide open the whole time, even when you set it to f/22, so there's no problem focusing. When you press the Av button, the camera will quickly stop down to f/22, take the reading, and set the shutter speed for you, then go back to wide open aperture. When you take the shot, it will again stop down to f/22.

I really wanted to buy m42 lenses because I've read they're cheap but excellent, but if my understanding is correct, it's only practical if you have a lot of time to set up the shot. I like to take quick snaps, so I only want to set the aperture once.
04-18-2009, 11:10 PM   #13
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QuoteOriginally posted by grishazzz Quote
Marc,

I see. Anyway thank you for your explanations.
Now I feel more confident with manual settings. I'll find this info later.
I've tried using different aperture combinations and finally I got it right I guess. (i.e: step down metering was activated at F8, than manually I am switching to f 5.6 (approximately 2 stops down) and the result comes out way better, maybe I am wrong, but after playing with the settings, I am getting way better results!!! or I set shutter speed manually, like I was doing before )
What mode are you using?

On the km/k2000, automatic stop down metering does not work on m42 mount (screwmount), or for any Pentax DSLR afaik. This is due to the fact that the body cannot communicate or control the lens.

You can use screwmount lenses in two different modes, M or Av. Any mode other than M works, but the camera is actually in Av mode.

M mode:

Set Aperture
Press Ev to meter
shoot

Av mode:

My Km was always 2 stops off in Av mode. However, Av mode works, but you'll either have to short the data pin (it's the pin at the bottom near the screw onthe body) or use Ev compensation to get correct metering. Once you've either shorted the pin or set Ev compensation you simply:

Adjust aperture
Shoot

QuoteOriginally posted by greentea3 Quote
grishazzz,

I am new to dslrs, have a k2000, too, and was curious about using m42 lenses about a week ago. I tried to research this online and this is the only article I could find about it:

LINK
I really wanted to buy m42 lenses because I've read they're cheap but excellent, but if my understanding is correct, it's only practical if you have a lot of time to set up the shot. I like to take quick snaps, so I only want to set the aperture once.
Although it isn't always necessary to open it wide to focus, it does become increasingly difficult with lower light; however, with Takumars that have a Manual/Auto switch on the side you could manually stop down using the switch. This switch sits next to the aperture ring. In "manual" mode the aperture physically moves as you move the aperture ring. In "auto" mode the lens is always wide open (at least for DSLRs). So, with Takumars with this switch you can just use it to toggle between wide and your desired fstop.

Personally, the greatest challenge for me isn't the metering, it's the focus. Focusing with my old film body is quick and easy. Doing so with my DSLR can be a challenge, but there are ways to make this easier. You can trap focus, use a different focusing screen to assist focusing, or prefocus.

Manual lenses certainly take more work and forethought than do others, but if you are prepared, then it's possible to be fairly quick.
04-19-2009, 12:19 AM   #14
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M42 lenses on a Pentax DSLR? Easiest thing in the world.

1. Set Av mode
2. Set the auto/manual switch on your lens to "M"

Confirm that the switch is in the correct position by looking through the viewfinder and turning the aperture ring. Does the brightness of the scene change? If so, good. If not, move the switch.

Now you're ready to take pictures. Set your aperture to f4 or larger (2.8 or 2 or 1.8 etc etc) to make focusing easier.

1. Focus
2. Adjust to desired shooting aperture
3. Press the shutter button

I've done around 20,000 shots with the K100D and K20D using M42 lenses. There's nothing complicated about it.
04-19-2009, 09:14 AM   #15
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QuoteOriginally posted by Mike Cash Quote
M42 lenses on a Pentax DSLR? Easiest thing in the world.

1. Set Av mode
2. Set the auto/manual switch on your lens to "M"

Confirm that the switch is in the correct position by looking through the viewfinder and turning the aperture ring. Does the brightness of the scene change? If so, good. If not, move the switch.
That's only true if your lens has a switch. Some, like grishazzz's Helios, don't and need the stop-down pin to be jammed in some way.
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