M lens on K20D..bracket, meter?

*janosh* · 08-07-2008, 11:20 AM

...auto-bracket (3 exposures) doesn't seem to work with my new 85/2 M....what am I missing?

Also...how can I meter with M lens? Green button doesn't seem to do that...

Are there any useful M settings other than M and Av?

IF you were mixing an M with DA primes in the field, with rapidly changing action, what mode would you prefer? Av? User? M? Why?

*Michaelina2* · 08-07-2008, 12:06 PM

This works for me using an SMC-M lens...

1. Install lens.
2. Turn on camera
3. Confirm focal length of lens (85)
4. Go to pp 129 of Manual. Get description of the various settings available and procedures for selection.
5. Set "M" mode
6. Determine appropriate DOF and set aperture of lens
7. Manually focus on subject
8. Press green button to set shutter speed to fit lens setting.
9. Press shutter button to take photo(s)

Easy... eh?

augustmoon · 08-07-2008, 12:33 PM

Originally Posted by janosh

...auto-bracket (3 exposures) doesn't seem to work with my new 85/2 M....what am I missing?

Also...how can I meter with M lens? Green button doesn't seem to do that...

Are there any useful M settings other than M and Av?

IF you were mixing an M with DA primes in the field, with rapidly changing action, what mode would you prefer? Av? User? M? Why?

Use M mode for M lenses. Green button should stop down and select proper shutter speed if you are in M mode and you have set up your menu to allow the use of the len's aperture ring.

If you are using a mix of M and Auto lenses. Use M mode... why? because if you use M mode for all that's easier than switching modes as well as switching lenses.

Set up your menu properly depending upon you camera model.

Set aperture on lens to desired f/stop.

Set camera to M mode.

Press the green button, the cam will select the correct shutter speed. If you have exposure compensation dialed in, this will affect the metering.

Press shutter button.

if you want to bracket, select a different shutter speed or aperture, then press shutter button again without pressing green button.

Auto bracketing will not work in M mode.

*janosh* · 08-07-2008, 01:51 PM

Auto bracketing will not work in M mode.[/quote]

Thanks...I was afraid of that. I doubt auto-bracketing is that useful anyway, but
I've been exploring it in other modes.

*Michaelina2* · 08-07-2008, 03:53 PM

Originally Posted by augustmoon

Auto bracketing will not work in M mode.

Hmmm... I must be doing something wrong, 'cause it sure works for me.

*janosh* · 08-07-2008, 07:46 PM

Originally Posted by Michaelina2

Hmmm... I must be doing something wrong, 'cause it sure works for me.

We were talking about "M" mode with prime M lens....

...are YOU talking about success in M with an M prime?

*Michaelina2* · 08-08-2008, 04:58 AM

Originally Posted by janosh

We were talking about "M" mode with prime M lens....

...are YOU talking about success in M with an M prime?

Ah, Yes... M & M success

(Like you, I have an SMC Pentax-M 1:2 85mm lens)

Again, refer to pp. 129-132 in the K20D Manual.

Note that the the bracketed images are not the result of the camera manipulating the lens aperture mechanically (if it did that - in addition to exposure - the DOF of each image would differ). Instead, exposure variation is created electronically via the camera's EV setting.

*janosh* · 08-08-2008, 09:40 AM

Originally Posted by Michaelina2

Ah, Yes... M & M success (Like you, I have an SMC Pentax-M 1:2 85mm lens)

Again, refer to pp. 129-132 in the K20D Manual.

Note that the the bracketed images are not the result of the camera manipulating the lens aperture mechanically (if it did that - in addition to exposure - the DOF of each image would differ). Instead, exposure variation is created electronically via the camera's EV setting.

I probably have something set in a way that conflicts with the bracketing setting (which I've confirmed)...I wonder what it is...any ideas?

code4code5 · 08-08-2008, 12:25 PM

If you shoot in Av mode, Bracket drive should change your shutter speed accordingly, IIRC.

JohnV3 · 08-08-2008, 04:12 PM

If you shoot in AV mode with an M lens, you will get mixed results but you may get lucky depending on the lighting conditions. As I previously stated, the camera gets confused because, without the elctrical connection, it does not know where the lens is set.

I just finished testing my M50 1.4 on the K20 using both AV mode and manual mode with the green button. It is a very bright day. This is all in the back yard BTW. On some subjects in the bright sun, using M mode and green button, the image was way overexposed. The same subject in AV mode at the same aperture gave a better exposure. I think it was just the luck of the exact conditions because overall with different subjects, the M mode and green button gave better more consistant results.

The farther I go, the more confused I am getting. I would like to see some more comments from the experts here, or anyone actually, about using an M lens (no A setting) in the AV mode and maybe this discussion can be put to rest for a while and I can clear my head.

I've read the manuals, the Magic Lantern book, and Yvon's K10 book and I don't think the M lens issue has been adequately adressed in any. Yvon's K10 book came the closest.

John

Edit: As I said in the second paragraph above, I was getting mixed results when using the green button with an M lens. I just discovered that the reason I was getting mixed results was because I did not have the camera set to TV Shift in the custom menu #26 "Green button in TAV & M" which adjusts the shutter speed for correct exposure when using an M lens and pressing the green button. Further testing gave consistant results using the green button.

I don't use the M lens very often so I overlooked this when setting custom values for the new K20. I suppose I could just delete most of the nonsense above but OTOH, it may help in understanding what's going on. Using any mode other than manual and green button with an M lens will give mixed results or wrong exposures or you may get lucky (i.e. your mileage may vary).

code4code5 · 08-08-2008, 04:55 PM

My K100D tends to underexpose M lenses regularly. I love to shoot wide open, so I work in Av mode and dial in +.7 to +1.0 EV compensation

JohnV3 · 08-08-2008, 05:19 PM

I guess that will work because the camera should adjust the speed for the wide open lens. However, how does the camera know if wide open is 1.4, 3.5 or 5.6? It seems it should make a difference or am I missing something.

John

*janosh* · 08-09-2008, 07:26 AM

SUCCESS!

Thanks for the advice on bracketing. I had thought it was set only in the dropdown menu, but that's secondary...the primary adjustment is made with a button and the front wheel. Convenient when I want it!

It seems as if the aperture setting of my M lens (85/2) is irrelevant except with the "M" setting. That may be the only setting in which an M lens's aperture setting works at all...I think that in Av, for example, it always works at f/2, no matter what I've set with the aperture ring.

*Michaelina2* · 08-09-2008, 07:34 AM

Congrats... I knew you could figure it out!

Manual (as in "Operating") can be a truly marvelous thing... eh?

JohnV3 · 08-11-2008, 11:15 AM

Pressing the green button when using a M lens to get a proper exposure will work only if item #26 in the Custom menu, "Green button in TAV & M" is set to TV shift. With this setting, the shutter speed is adjusted automatically (see p. 95 in the K20 operating manual) according to the aperture setting. Unless you have this setting, the green button does not work proerly when using M lenses.

Also, the exposure setting will remain the same until the green button is pressed again. This means that for bracketing or continuous shooting, the exposure determined by the first pressing of the green button will remain for the remainder of the shots.

I hope this helps to clarify things.

John