Stopping down from max aperture takes two clicks of e-dial


WaypointCharlie

Link Posted 29/04/2013 - 08:32
These days I make some adjustments on the K-5 more by touch than sight. Often I count clicks of the e-dial when making aperture adjustments. However, in some cases it takes two clicks to the right on the e-dial to start stopping down from max aperture, not one. This somewhat throws my system! What's that about? I think it may depend upon lens and zoom level, so perhaps a rounding thing. Is there an option somwhere to enable/disable it? Is it a bug? Does the K-5II/IIs do it too? Non of the other exposure adjustments have this stickiness and this doesn't happen when opening up from min aperture.

(I've configured for 3 clicks per stop)
Last Edited by WaypointCharlie on 29/04/2013 - 08:38

johnriley

Link Posted 29/04/2013 - 08:37
Possibly the first click is just reawakening the camera, or alternatively you are makining the first click before the camera has completed some other action.

It's the sort of question better answered whilst handling the camera. If it's repeatable though, then use two clicks by feel and you'll have a repeatable result.
Best regards, John

WaypointCharlie

Link Posted 29/04/2013 - 08:43
No it's not a reawakening thing and, whilst it's repeatable, it only happens on some lenses at some zoom levels.

The point is, I don't always have in my head that I'm stopping down from max aperture for a given lens and may therefore need two clicks rather than one. I'm even less likely to have in my head that the zoom level I've set is one that will need one click or two clicks! This means I always have to check the screen when stopping down and keep a careful look if the first click takes effect.

Try it for yourself. I'm just testing it on a 18-250mm. At 18mm it takes two clicks to get it off f/3.5. At 35mm it only takes one click to get off f/4.0.
Last Edited by WaypointCharlie on 29/04/2013 - 08:50

johnwhit

Link Posted 29/04/2013 - 08:59
I'm not sure about the K5 but my K20D stops down in 1/3 stops, maybe it's one of the options I've set in the Custom menu.

John
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WaypointCharlie

Link Posted 29/04/2013 - 09:18
johnwhit, I've also set for 1/3rd stops. My query is why in some circumstances it takes one click to start stopping down from wide open, other times it takes two. Eg, it takes two clicks to stop down 1/3rd from f/3.5 to f/4.0 with my 18-250mm set to 18mm.

johnriley

Link Posted 29/04/2013 - 09:48
The difference seems to be what the aperture is when you first turn the camera on. With the 18-250mm and the 18-135mm if set to f/3.5 then the first click does nothing, the second goes to f/4. If the camera is already on then the first click goes straight to f/4.

It does seem to be related to first operation of the camera and waking the system.

Don't forget that the aperture value changes with zooming with many zoom lenses.

I'm not sure why you have your camera set to wide open all the time? Mine is set to whatever aperture was set when last used - usually between f/8 and f/16. As a consequence, this particular behaviour has never become apparent.
Best regards, John

WaypointCharlie

Link Posted 29/04/2013 - 09:59
No John, it's not a case of what the aperture is when I first turn on (I too store the aperture value in memory).

With my 18-250mm at 18mm set to f/4.0 it takes one click to the left to open up to f/3.5. It then takes two clicks to the right to move it back to f/4.0. What's more, if I make just one click to the right from f/3.5 then turn off that click is memorised because it then only takes one more to click the right after turning back on the stop down to f/4.0. That does sound like a rounding thing.

Perhaps when you next use your camera you could try it for yourself. Or are you saying that with the 18-250mm on your camera you can get a one click stop down from f/3.5 to f/4.0 when it is already on?
Last Edited by WaypointCharlie on 29/04/2013 - 10:10

johnriley

Link Posted 29/04/2013 - 10:08
That's what I'm saying. I tried it with the two lenses mentioned and both behave the same.

Hope that helps.
Best regards, John

WaypointCharlie

Link Posted 29/04/2013 - 10:11
Are you using 1/3 stops or 1/2 stops? I'm using 1/3 stops. Perhaps it's a rounding effect of using 1/3 stops. However, the max aperture of the 18-250mm is f/3.5 which is a 1/3 stop not a 1/2 stop, so if anything I might expect rounding to affect a camera setup for 1/2 stops, not 1/3 stops.
Last Edited by WaypointCharlie on 29/04/2013 - 10:15

johnriley

Link Posted 29/04/2013 - 10:14
I have recently adapted half stops. I routinely use a minus adjustment on the K-5 and found -0.3EV too little and -0.7EV too much, and -0.5EV just right.

It may be so, and if you change to half steps and find the problem disappears we've found the answer.
Best regards, John

WaypointCharlie

Link Posted 29/04/2013 - 10:22
Ah yes, it seems it may be a quirk (dare I say bug!) with 1/3 EV steps. It's rare I'll shoot wide open and I've only noticed it through doing lens focus checks (watch this space for a posting about that!)
Last Edited by WaypointCharlie on 29/04/2013 - 10:25

johnriley

Link Posted 29/04/2013 - 10:36
You can say bug if you want to, but probably more of an inevitable consequence.

At least pentax use proper in-between aperture values that photographers can recognise. Some makes don't do that and a "f/5.6 and a half" I find quite quite irritating. It doesn't cost any time to say "f/6.3"!
Best regards, John

gartmore

Link Posted 29/04/2013 - 15:08
i find that 1/3 doesnt make enough difference to be worthwhile
Ken
“We must avoid however, snapping away, shooting quickly and without thought, overloading ourselves with unnecessary images that clutter our memory and diminish the clarity of the whole.” - Henri Cartier-Bresson -

Algernon

Link Posted 29/04/2013 - 18:11
Pentax must have thought +/- 1/3 stop internally on each lens was
useful...... because that's all they've allowed for

'
Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi

johnha

Link Posted 29/04/2013 - 19:01
Algernon wrote:
Pentax must have thought +/- 1/3 stop internally on each lens was
useful...... because that's all they've allowed for

'

It was useful in the days of film, where your ISO was limited by the film you had loaded (particularly slide - where your latitude of error is very limited). It still is useful if you need specific shutter speeds (capturing spinning propellor blades for example). Depending on the speed of the prop, the ability to fine tune the shutter speed for the right effect is very useful.

I set mine at 0.5 because it's faster to scroll from one end to the other, and any minor corrections can be done easily in post.

John.
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