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Comment by Mongoose posted on K10 manual metering question. at 15/02/2007 - 10:12
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This thread discusses some of the problems with stop-down metering with pre-A lenses:
Mongoose posted on K10 manual metering question. at 14/02/2007 - 19:31
viewfinder wrote:
Presumably when using older lenses one can still use a simple metering mode without use of any 'stop down' control
If only. The problem is that without stopping hte lens down, the camera has no way of knowing what the aperture ring has been set to.Presumably when using older lenses one can still use a simple metering mode without use of any 'stop down' control
This thread discusses some of the problems with stop-down metering with pre-A lenses:
Mongoose posted on K10 manual metering question. at 14/02/2007 - 19:31
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normal lines of text will auto wrap, it only becomes an issue if you try a really really long string of characters with no spaces (such as a URL). The auto wrap has nowhere to break the line so it leaves it all on one and you get an ultra wide page.old timer wrote:
Not a photographic issue but a PC one related to this site
Why do some posts stretch right off the screen? Most of the time there is no problem, but recently it seems to have become worse.
Graham
Try writing shorter lines of text, hit return now and again when typing, try it in preview mode if you don't believe me Not a photographic issue but a PC one related to this site
Why do some posts stretch right off the screen? Most of the time there is no problem, but recently it seems to have become worse.
Graham
Comment by Mongoose posted on Too wide to see at 13/02/2007 - 20:46
sometimes its a very wide picture, sometimes a very long URL
It's annoying.
It's annoying.
Comment by Mongoose posted on Too wide to see at 13/02/2007 - 17:25
there's no point saving them as RGB unless you are adding some sort of colour tone to them. A greyscale image will just have all three channels exactly the same if saved as RGB so its a total waste of space.
Comment by Mongoose posted on Scanning Mono 35mm Negs at 13/02/2007 - 17:20
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yes, that is exactly it, and is the reason why I'm right, though I prefer to think of cutting down a 35mm negative to APS size.Mongoose wrote:
yes but you will have the same depth of field as a 50mm lens. This is more DOF than you would have had if you were using the 75mm lens which you would need to get the same field of view on film.
To imagine the crop factor you could take a print and a scissors. Just cut four stripes from sides of the print off. yes but you will have the same depth of field as a 50mm lens. This is more DOF than you would have had if you were using the 75mm lens which you would need to get the same field of view on film.
Reuben, thanks for the link, I knew that but couldn't prove it so decided to leave it out for the sake of clarity.
Comment by Mongoose posted on In the move from film to digital ... at 14/02/2007 - 14:46
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yes but you will have the same depth of field as a 50mm lens. This is more DOF than you would have had if you were using the 75mm lens which you would need to get the same field of view on film.blende8 wrote:
It's more a 75/1.7 in terms of DOF.
It's impossible to change DOF using a crop. If you have 10cm of DOF you WILL have the same depth in crop. The only change is you see only a part of full frame area with full resolution.It's more a 75/1.7 in terms of DOF.
Comment by Mongoose posted on In the move from film to digital ... at 14/02/2007 - 12:02
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I don't see the point in struggling when the right kit for the job is readily available.
given unlimited cash, I couldn't agree more. If I had the money all my M series and equivalent glass would be out the window tomorrow to be replaced by nice shiney new lenses. Saddly this is not an option for me, so I am slowly learning the ideosyncrasies of the K10D's meter.I don't see the point in struggling when the right kit for the job is readily available.
It's really no different than learning to guess if it was a 1 stop evening or a 2 stop evening with my KR5 (always underexposed in low light), it's just not something one expects to have to do with a new DSLR. Especially not when the previous version worked fine.
I think on the whole I'm just going to use my M series and earlier lenses on the *istDL2.
Comment by Mongoose posted on K10D Stop down metering exposure problem at 20/03/2007 - 01:29
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Conclusions:
1. As a means of quickly setting the shutter speed the camera thinks is correct given an aperture selected on the lens using the aperture ring, the green button is clearly superior.
only in the same way as Av mode is "clearly superior" to M modeConclusions:
1. As a means of quickly setting the shutter speed the camera thinks is correct given an aperture selected on the lens using the aperture ring, the green button is clearly superior.
Don't get me wrong, I use the green button probably more often than DOF preview. The green button method is faster and on my *istDL2 it's more or less allways what I use. On my K10D where I know that the exposure will be off a bit the more I stop down I tend to use DOF preview and set my exposure accordingly. I'm slowly getting a feel for what will work out well.
Comment by Mongoose posted on K10D Stop down metering exposure problem at 20/03/2007 - 01:22
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Thanks for the replies to my posting, there are however a few points Iwould like to point out.
As I understand the point of having an A setting on the A-type lens is that it is possible, provided there is some kind of predictability in the relationship between the aperture actuator and the actual aperture, to let the processor in the camera decide the aperture when shooting in Auto or Shutter priority.
correctThanks for the replies to my posting, there are however a few points Iwould like to point out.
As I understand the point of having an A setting on the A-type lens is that it is possible, provided there is some kind of predictability in the relationship between the aperture actuator and the actual aperture, to let the processor in the camera decide the aperture when shooting in Auto or Shutter priority.
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The way it usually is realised is by having the aperture set at the smallest setting of the lens.
The "A" setting on pentax A lenses, is (as far as I know) an example of this,
The way it usually is realised is by having the aperture set at the smallest setting of the lens.
The "A" setting on pentax A lenses, is (as far as I know) an example of this,
again correct, you understand perfectly (or at least we are both wrong the same way lol)
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therefore the actuator from the body has to stop down differently, given different chosen apertures by the camera program, if it didn't, the aperture would have to be controlled by some other means (electric contacts?) in order to change the aperture.
yes, but this only happens when the camera is operating an A series lens.therefore the actuator from the body has to stop down differently, given different chosen apertures by the camera program, if it didn't, the aperture would have to be controlled by some other means (electric contacts?) in order to change the aperture.
The camera is able to tell that the lens is not in A setting because the contacts don't engage (if you look at the back of an A series lens and move the aperture ring into/out of A, you will notice that one of the contacts moves in and out as you do so), or else everything is shorted if it's an M series or earlier lens.
unless an A series lens is detected, the actuator moves the whole way down (or doesn't move at all if the camera is in Av mode).
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That the function is as described is how I understand the explanation on the k-mount homepage (see link in my previous posting).
Another aspect is that the lack of the coding contacts in the mount also gives problems for the camera body - in order to function corectly the camera needs 3 informations from the lens: the minimum and maximum apertures and whether or not the aperture ring is set to the minimum
For non A type lenses none of these informations are given, or rather the information given are:
minimum aperture: 22 maximum
aperture: 1.2
since all of the lens contacts are "on".
the camera only needs this information if it is trying to set the aperture itself or use multi segment metering. All it actually needs for stopped down centre weighted or spot metering is a light reading. For open aperture metering it would need a relative aperture value, but in stop down mode the light falling on the meter is exactly what will fall on the sensor and no other information is (should be) needed.That the function is as described is how I understand the explanation on the k-mount homepage (see link in my previous posting).
Another aspect is that the lack of the coding contacts in the mount also gives problems for the camera body - in order to function corectly the camera needs 3 informations from the lens: the minimum and maximum apertures and whether or not the aperture ring is set to the minimum
For non A type lenses none of these informations are given, or rather the information given are:
minimum aperture: 22 maximum
aperture: 1.2
since all of the lens contacts are "on".
Comment by Mongoose posted on K10D Stop down metering exposure problem at 19/03/2007 - 16:20
The cameras meter takes a reading of the light coming through the lens and assigns a shutter speed accordingly. Since we have an open aperture metering system, this light does not correspond to the amount of light which will hit the sensor when you trip the shutter, unless the lens is being used wide open.
In older cameras, there was a cam on the side of the K mount which engaged with another cam on the lens allowing the camera to determine the position of the aperture ring. This information allows the camera to adjust its selected shutter speed by the correct amount to compensate for the lens stopping down.
Unfortunately in recent years (starting with the budget MZ-50) Pentax have seen fit to remove this cam, presumably to save on manufacturing costs since it is only required for lenses at least 25 years old. I believe the MZ-6 was the last camera to be introduced with the cam, the entire *ist and KD series lack the ability to read the aperture ring.
Without the cam, the camera cannot tell how much to compensate exposure to get from wide open to the shooting aperture. The *istD and KD series have the option of circumnavigating this problem by stopping down the lens to shooting aperture to take the light reading. This works wonderfully on the *ist series, but for some reason it completely messes everything up on the K10D as discussed in another thread. This is the only serious flaw in an otherwise dangerously close to perfect camera.
Why Pentax cannot follow Nikon's lead in this and at least restore aperture ring support on the top of the range models I fail to understand. It's a feature which I for one would pay extra for.