Re: Help! *istD problems (repost)
I think focusing screen misalignment is most likely. I would do some more tests and then visit Pentax. I'm an LX user and when I handle digital SLRs I'm struck at how poor and small the viewfinder images are. They are not like the glorious optical instruments of the past and I reckon it's quite likely they don't build the screens and viewfinders that hold them any where near as accurately, assuming folk will be using autofocus and re-touching/cropping in Photoshop. Cornelius Nuzzlemuff III -- Whatever you Wanadoo: http://www.wanadoo.co.uk/time/ This email has been checked for most known viruses - find out more at: http://www.wanadoo.co.uk/help/id/7098.htm
Re: Help! *istD problems (repost): rewind, play again
(That's an analogy from a quaint analog device called a tape recorder. When everything is digital, will we use digalogies instead of analogies?) Anyway... My recollection was that the autofocused and manually focused images were sharp in the finder but blurry on film. Thus, the focusing screen and the AF sensor agree with each other, but disagree with the imaging sensor. This would indicate that the imaging sensor needs shimming, not the focusing screen. Or, to do it the hard way, one could shim both the AF sensor and the focusing screen to get them to agree with the imaging sensor. In any case, it would seem that the camera needs to take a trip to a Pentax facility. Rick --- Godfrey DiGiorgi [EMAIL PROTECTED] wrote: A friend of mine had a similar issue with his Canon 10D. His manually focused exposures were never quite on the money, but AF exposures were bang on target. After a suitable and similar round of measurebating, he concluded that the focusing screen was in need of shimming ... It was representing a focus plane some small fraction of a millimeter off from where the sensor was. Autofocus worked fine because it evaluates focusing distance through a completely different set of optics and parameters than manual focus. He had his camera adjusted by Canon and now it focuses precisely, both in MF and AF. I believe they shimmed the focusing screen. Godfrey --- Gonz wrote: I need some help with my *istD. For the longest time, I've been having problems with my pics being quite soft wide open. I thought that it was just because the lens was wide open. I have alot of manual focus lenses, which I use often. The problem showed up mainly with them, so I went back to look at some of the pics more carefully, and I noticed a pretty consistent pattern. There were areas of sharpness alright, but not where I wanted them to be. I was consistently back-focusing. So I did some tests. I mounted my FA* 85 1.4 on the camera, set it on a tripod, and proceded to make some careful experiments to see if I could put the blame where it belonged, on me or the camera. The setup was your typical measurebating focus test setup. I had a ruler at an angle with a target off to the side of it where I focused. I took pictures with and without autofocus. The result: no matter how carefully I manually focused, the autofocus was always right on the money, and I always back focused. I adjusted the diopter after autofocusing to see if I could match the camera's focus point, took my glasses off, put my glasses on, danced around the camera, but no matter, I always back-focused. What is going on here? Doesnt the autofocus see the same thing I do? Or is something mal-adjusted somewhere? When I look through the viewfinder after I auto focus, it seems to be in decent focus, but it looks pretty much the same as when I focus manually. If I then switch to manual focus and get it out of focus and back in and take the pic, it is back-focused! Am I going blind? ... __ Do you Yahoo!? Yahoo! Sports - Sign up for Fantasy Baseball. http://baseball.fantasysports.yahoo.com/ __ Do you Yahoo!? Yahoo! Mail - now with 250MB free storage. Learn more. http://info.mail.yahoo.com/mail_250
Re: Help! *istD problems (repost)
Maybe there is a different path from lens to AF and to MF? There is, but they both have to go through the focusing screen don't they? So I'm thinking I must be having vision issues. I blurred up several nice shots the other day in a theatre production that had to use MF because AF would hunt too much in the dark. rg [EMAIL PROTECTED] wrote: I'm not sure if there could be a technical reason for the discrepancy between focus and autofocus. Perhaps it could be the result of an incorrect diopter adjustment and a near-sighted or far-sighted eye? In regard to exposure, I generally set my *istD to overexpose by half a stop. That yields a pretty nice exposure under most circumstances. Finally, there's no such thing as a correct histogram. If you're shooging a scene with no highlights, the histogram may not extend all the way to the right, yet your exposure might be perfect. Similarily, blown highlights aren't always wrong. For example, a strong backlight on water can create attractive specular highlights that are out of range. A photo with no dark shadows would have a histogram that doesn't extend all the way to the left. One with deep blacks might have out-or-range blacks. You have to judge with your eye. The histogram is only a guide. Paul Reposting, since the first didnt seem to make it. I need some help with my *istD. For the longest time, I've been having problems with my pics being quite soft wide open. I thought that it was just because the lens was wide open. I have alot of manual focus lenses, which I use often. The problem showed up mainly with them, so I went back to look at some of the pics more carefully, and I noticed a pretty consistent pattern. There were areas of sharpness alright, but not where I wanted them to be. I was consistently back-focusing. So I did some tests. I mounted my FA* 85 1.4 on the camera, set it on a tripod, and proceded to make some careful experiments to see if I could put the blame where it belonged, on me or the camera. The setup was your typical measurebating focus test setup. I had a ruler at an angle with a target off to the side of it where I focused. I took pictures with and without autofocus. The result: no matter how carefully I manually focused, the autofocus was always right on the money, and I always back focused. I adjusted the diopter after autofocusing to see if I could match the camera's focus point, took my glasses off, put my glasses on, danced around the camera, but no matter, I always back-focused. What is going on here? Doesnt the autofocus see the same thing I do? Or is something mal-adjusted somewhere? When I look through the viewfinder after I auto focus, it seems to be in decent focus, but it looks pretty much the same as when I focus manually. If I then switch to manual focus and get it out of focus and back in and take the pic, it is back-focused! Am I going blind? The second problem is that I seem to always be adjusting exposure upwards in the PS raw program, usually between .5 and 1.0 stops. What should a good histogram look like? My camera seems to like to underexpose, in my opinion. Is this normal because of the blown hilites problem? When I bring in the raw pics into PS raw, the histogram usually shows no pixel values above the halfway point, yet if I look at the histogram using the *istD lcd panel, it seems to show some luminance values, although very few of them, up to the max luminance value. Why is there a discrepancy? I am going to try the same thing with Pentax raw and see if the histogram matches PS raw to some degree. I know that PS camera raw breaks up the values into RGB components, while Pentax combines them into a single histogram, so there might be an apples-oranges thing going on here. Anyhow, I would love to tap the collective PDML brains to see what I need to do here to solve some of these technical issues. Thanks ahead of time for any help you can give me. rg
Re: Help! *istD problems (repost)
Quoting Gonz [EMAIL PROTECTED]: Maybe there is a different path from lens to AF and to MF? There is, but they both have to go through the focusing screen don't they? So I'm thinking I must be having vision issues. I blurred up several nice shots the other day in a theatre production that had to use MF because AF would hunt too much in the dark. I, too, manually focus my *ist D most of the time because AF hunts too much, and find that many of my manually-focused shots have the plane of focus behind where I want it. I haven't run a precise test, but I've been seeing the tendency all along in my pictures. In my case, I *know* I'm having vision issues. The new glasses are on order. I'll see what happens after I get them. ERNR
Re: Help! *istD problems (repost)
Af has nothing to do with the focusing screen, except for the display of which sensor is being used. Gonz wrote: Maybe there is a different path from lens to AF and to MF? There is, but they both have to go through the focusing screen don't they? So I'm thinking I must be having vision issues. I blurred up several nice shots the other day in a theatre production that had to use MF because AF would hunt too much in the dark. rg [EMAIL PROTECTED] wrote: I'm not sure if there could be a technical reason for the discrepancy between focus and autofocus. Perhaps it could be the result of an incorrect diopter adjustment and a near-sighted or far-sighted eye? In regard to exposure, I generally set my *istD to overexpose by half a stop. That yields a pretty nice exposure under most circumstances. Finally, there's no such thing as a correct histogram. If you're shooging a scene with no highlights, the histogram may not extend all the way to the right, yet your exposure might be perfect. Similarily, blown highlights aren't always wrong. For example, a strong backlight on water can create attractive specular highlights that are out of range. A photo with no dark shadows would have a histogram that doesn't extend all the way to the left. One with deep blacks might have out-or-range blacks. You have to judge with your eye. The histogram is only a guide. Paul Reposting, since the first didnt seem to make it. I need some help with my *istD. For the longest time, I've been having problems with my pics being quite soft wide open. I thought that it was just because the lens was wide open. I have alot of manual focus lenses, which I use often. The problem showed up mainly with them, so I went back to look at some of the pics more carefully, and I noticed a pretty consistent pattern. There were areas of sharpness alright, but not where I wanted them to be. I was consistently back-focusing. So I did some tests. I mounted my FA* 85 1.4 on the camera, set it on a tripod, and proceded to make some careful experiments to see if I could put the blame where it belonged, on me or the camera. The setup was your typical measurebating focus test setup. I had a ruler at an angle with a target off to the side of it where I focused. I took pictures with and without autofocus. The result: no matter how carefully I manually focused, the autofocus was always right on the money, and I always back focused. I adjusted the diopter after autofocusing to see if I could match the camera's focus point, took my glasses off, put my glasses on, danced around the camera, but no matter, I always back-focused. What is going on here? Doesnt the autofocus see the same thing I do? Or is something mal-adjusted somewhere? When I look through the viewfinder after I auto focus, it seems to be in decent focus, but it looks pretty much the same as when I focus manually. If I then switch to manual focus and get it out of focus and back in and take the pic, it is back-focused! Am I going blind? The second problem is that I seem to always be adjusting exposure upwards in the PS raw program, usually between .5 and 1.0 stops. What should a good histogram look like? My camera seems to like to underexpose, in my opinion. Is this normal because of the blown hilites problem? When I bring in the raw pics into PS raw, the histogram usually shows no pixel values above the halfway point, yet if I look at the histogram using the *istD lcd panel, it seems to show some luminance values, although very few of them, up to the max luminance value. Why is there a discrepancy? I am going to try the same thing with Pentax raw and see if the histogram matches PS raw to some degree. I know that PS camera raw breaks up the values into RGB components, while Pentax combines them into a single histogram, so there might be an apples-oranges thing going on here. Anyhow, I would love to tap the collective PDML brains to see what I need to do here to solve some of these technical issues. Thanks ahead of time for any help you can give me. rg -- I can understand why mankind hasn't given up war. During a war you get to drive tanks through the sides of buildings and shoot foreigners - two things that are usually frowned on during peacetime. --P.J. O'Rourke
Re: Help! *istD problems (repost): rewind, play again
--- Rick Womer [EMAIL PROTECTED] wrote: ... In any case, it would seem that the camera needs to take a trip to a Pentax facility. Indeed, whatever the cause of the problem, this is likely the best course of action. Godfrey __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
Help! *istD problems (repost)
Reposting, since the first didnt seem to make it. I need some help with my *istD. For the longest time, I've been having problems with my pics being quite soft wide open. I thought that it was just because the lens was wide open. I have alot of manual focus lenses, which I use often. The problem showed up mainly with them, so I went back to look at some of the pics more carefully, and I noticed a pretty consistent pattern. There were areas of sharpness alright, but not where I wanted them to be. I was consistently back-focusing. So I did some tests. I mounted my FA* 85 1.4 on the camera, set it on a tripod, and proceded to make some careful experiments to see if I could put the blame where it belonged, on me or the camera. The setup was your typical measurebating focus test setup. I had a ruler at an angle with a target off to the side of it where I focused. I took pictures with and without autofocus. The result: no matter how carefully I manually focused, the autofocus was always right on the money, and I always back focused. I adjusted the diopter after autofocusing to see if I could match the camera's focus point, took my glasses off, put my glasses on, danced around the camera, but no matter, I always back-focused. What is going on here? Doesnt the autofocus see the same thing I do? Or is something mal-adjusted somewhere? When I look through the viewfinder after I auto focus, it seems to be in decent focus, but it looks pretty much the same as when I focus manually. If I then switch to manual focus and get it out of focus and back in and take the pic, it is back-focused! Am I going blind? The second problem is that I seem to always be adjusting exposure upwards in the PS raw program, usually between .5 and 1.0 stops. What should a good histogram look like? My camera seems to like to underexpose, in my opinion. Is this normal because of the blown hilites problem? When I bring in the raw pics into PS raw, the histogram usually shows no pixel values above the halfway point, yet if I look at the histogram using the *istD lcd panel, it seems to show some luminance values, although very few of them, up to the max luminance value. Why is there a discrepancy? I am going to try the same thing with Pentax raw and see if the histogram matches PS raw to some degree. I know that PS camera raw breaks up the values into RGB components, while Pentax combines them into a single histogram, so there might be an apples-oranges thing going on here. Anyhow, I would love to tap the collective PDML brains to see what I need to do here to solve some of these technical issues. Thanks ahead of time for any help you can give me. rg
Re: Help! *istD problems (repost)
I'm not sure if there could be a technical reason for the discrepancy between focus and autofocus. Perhaps it could be the result of an incorrect diopter adjustment and a near-sighted or far-sighted eye? In regard to exposure, I generally set my *istD to overexpose by half a stop. That yields a pretty nice exposure under most circumstances. Finally, there's no such thing as a correct histogram. If you're shooging a scene with no highlights, the histogram may not extend all the way to the right, yet your exposure might be perfect. Similarily, blown highlights aren't always wrong. For example, a strong backlight on water can create attractive specular highlights that are out of range. A photo with no dark shadows would have a histogram that doesn't extend all the way to the left. One with deep blacks might have out-or-range blacks. You have to judge with your eye. The histogram is only a guide. Paul Reposting, since the first didnt seem to make it. I need some help with my *istD. For the longest time, I've been having problems with my pics being quite soft wide open. I thought that it was just because the lens was wide open. I have alot of manual focus lenses, which I use often. The problem showed up mainly with them, so I went back to look at some of the pics more carefully, and I noticed a pretty consistent pattern. There were areas of sharpness alright, but not where I wanted them to be. I was consistently back-focusing. So I did some tests. I mounted my FA* 85 1.4 on the camera, set it on a tripod, and proceded to make some careful experiments to see if I could put the blame where it belonged, on me or the camera. The setup was your typical measurebating focus test setup. I had a ruler at an angle with a target off to the side of it where I focused. I took pictures with and without autofocus. The result: no matter how carefully I manually focused, the autofocus was always right on the money, and I always back focused. I adjusted the diopter after autofocusing to see if I could match the camera's focus point, took my glasses off, put my glasses on, danced around the camera, but no matter, I always back-focused. What is going on here? Doesnt the autofocus see the same thing I do? Or is something mal-adjusted somewhere? When I look through the viewfinder after I auto focus, it seems to be in decent focus, but it looks pretty much the same as when I focus manually. If I then switch to manual focus and get it out of focus and back in and take the pic, it is back-focused! Am I going blind? The second problem is that I seem to always be adjusting exposure upwards in the PS raw program, usually between .5 and 1.0 stops. What should a good histogram look like? My camera seems to like to underexpose, in my opinion. Is this normal because of the blown hilites problem? When I bring in the raw pics into PS raw, the histogram usually shows no pixel values above the halfway point, yet if I look at the histogram using the *istD lcd panel, it seems to show some luminance values, although very few of them, up to the max luminance value. Why is there a discrepancy? I am going to try the same thing with Pentax raw and see if the histogram matches PS raw to some degree. I know that PS camera raw breaks up the values into RGB components, while Pentax combines them into a single histogram, so there might be an apples-oranges thing going on here. Anyhow, I would love to tap the collective PDML brains to see what I need to do here to solve some of these technical issues. Thanks ahead of time for any help you can give me. rg
Re: Help! *istD problems (repost)
Paul, I'm not quite sure if near or farsightedness neither diopter adjustment plays a role. I made up a thread with a very similar problem, and my thoughts led me to the idea that focussing is always done on the viewfinder screen, and diopter adjustment just makes me see the screen better or worth, but doesn't influence focussing. I think it's two different systems. Please correct me if I'm wrong, I'm thankful for any advice. Gonz, did you try different lenses as I did, or just the 85? Pancho [EMAIL PROTECTED] wrote: I'm not sure if there could be a technical reason for the discrepancy between focus and autofocus. Perhaps it could be the result of an incorrect diopter adjustment and a near-sighted or far-sighted eye? In regard to exposure, I generally set my *istD to overexpose by half a stop. That yields a pretty nice exposure under most circumstances. Finally, there's no such thing as a correct histogram. If you're shooging a scene with no highlights, the histogram may not extend all the way to the right, yet your exposure might be perfect. Similarily, blown highlights aren't always wrong. For example, a strong backlight on water can create attractive specular highlights that are out of range. A photo with no dark shadows would have a histogram that doesn't extend all the way to the left. One with deep blacks might have out-or-range blacks. You have to judge with your eye. The histogram is only a guide. Paul
Re: Help! *istD problems (repost)
Gonz [EMAIL PROTECTED] wrote: Reposting, since the first didnt seem to make it. Since the subject of list reliability has come up lately I'd like to note that I received both you first post and this one. -- Mark Roberts Photography and writing www.robertstech.com
Re: Help! *istD problems (repost)
I'm not quite sure if near or farsightedness neither diopter adjustment plays a role. I made up a thread with a very similar problem, and my thoughts led me to the idea that focussing is always done on the viewfinder screen, and diopter adjustment just makes me see the screen better or worth, but doesn't influence focussing. I think it's two different systems. I do believe that this is true. Nearsightedness and farsightedness (and, in fact, presbyopia, astigmatism, etc.) only hinder one's ability to see the focus screen, and do not actually affect the focus, at least in the sense of somehow skewing focusing direction toward too close or too far. The only negative effect (and I'm not really making light of this) of these eye conditions is merely to make focusing more difficult because seeing the focus screen becomes more difficult. Fred
Re: Help! *istD problems (repost)
Probably not a very helpful post, but I experienced the opposite when I had an ist D. With a Sigma 28-70 2.8 EX, AF would constantly backfocus, MF was tack sharp. With the F 50 1.4, and FA 28 2.8 AF MF worked perfectly. Sounds like a rather bizarre problem. Hope you get it sorted out soon. Cheers, Ryan - Original Message - From: Gonz [EMAIL PROTECTED] To: pentax-discuss@pdml.net Sent: Thursday, February 24, 2005 7:26 AM Subject: Help! *istD problems (repost) Reposting, since the first didnt seem to make it. I need some help with my *istD. For the longest time, I've been having problems with my pics being quite soft wide open. I thought that it was just because the lens was wide open. I have alot of manual focus lenses, which I use often. The problem showed up mainly with them, so I went back to look at some of the pics more carefully, and I noticed a pretty consistent pattern. There were areas of sharpness alright, but not where I wanted them to be. I was consistently back-focusing. So I did some tests. I mounted my FA* 85 1.4 on the camera, set it on a tripod, and proceded to make some careful experiments to see if I could put the blame where it belonged, on me or the camera. The setup was your typical measurebating focus test setup. I had a ruler at an angle with a target off to the side of it where I focused. I took pictures with and without autofocus. The result: no matter how carefully I manually focused, the autofocus was always right on the money, and I always back focused. I adjusted the diopter after autofocusing to see if I could match the camera's focus point, took my glasses off, put my glasses on, danced around the camera, but no matter, I always back-focused. What is going on here? Doesnt the autofocus see the same thing I do? Or is something mal-adjusted somewhere? When I look through the viewfinder after I auto focus, it seems to be in decent focus, but it looks pretty much the same as when I focus manually. If I then switch to manual focus and get it out of focus and back in and take the pic, it is back-focused! Am I going blind? The second problem is that I seem to always be adjusting exposure upwards in the PS raw program, usually between .5 and 1.0 stops. What should a good histogram look like? My camera seems to like to underexpose, in my opinion. Is this normal because of the blown hilites problem? When I bring in the raw pics into PS raw, the histogram usually shows no pixel values above the halfway point, yet if I look at the histogram using the *istD lcd panel, it seems to show some luminance values, although very few of them, up to the max luminance value. Why is there a discrepancy? I am going to try the same thing with Pentax raw and see if the histogram matches PS raw to some degree. I know that PS camera raw breaks up the values into RGB components, while Pentax combines them into a single histogram, so there might be an apples-oranges thing going on here. Anyhow, I would love to tap the collective PDML brains to see what I need to do here to solve some of these technical issues. Thanks ahead of time for any help you can give me. rg
Re: Help! *istD problems (repost)
A friend of mine had a similar issue with his Canon 10D. His manually focused exposures were never quite on the money, but AF exposures were bang on target. After a suitable and similar round of measurebating, he concluded that the focusing screen was in need of shimming ... It was representing a focus plane some small fraction of a millimeter off from where the sensor was. Autofocus worked fine because it evaluates focusing distance through a completely different set of optics and parameters than manual focus. He had his camera adjusted by Canon and now it focuses precisely, both in MF and AF. I believe they shimmed the focusing screen. Godfrey --- Gonz wrote: I need some help with my *istD. For the longest time, I've been having problems with my pics being quite soft wide open. I thought that it was just because the lens was wide open. I have alot of manual focus lenses, which I use often. The problem showed up mainly with them, so I went back to look at some of the pics more carefully, and I noticed a pretty consistent pattern. There were areas of sharpness alright, but not where I wanted them to be. I was consistently back-focusing. So I did some tests. I mounted my FA* 85 1.4 on the camera, set it on a tripod, and proceded to make some careful experiments to see if I could put the blame where it belonged, on me or the camera. The setup was your typical measurebating focus test setup. I had a ruler at an angle with a target off to the side of it where I focused. I took pictures with and without autofocus. The result: no matter how carefully I manually focused, the autofocus was always right on the money, and I always back focused. I adjusted the diopter after autofocusing to see if I could match the camera's focus point, took my glasses off, put my glasses on, danced around the camera, but no matter, I always back-focused. What is going on here? Doesnt the autofocus see the same thing I do? Or is something mal-adjusted somewhere? When I look through the viewfinder after I auto focus, it seems to be in decent focus, but it looks pretty much the same as when I focus manually. If I then switch to manual focus and get it out of focus and back in and take the pic, it is back-focused! Am I going blind? ... __ Do you Yahoo!? Yahoo! Sports - Sign up for Fantasy Baseball. http://baseball.fantasysports.yahoo.com/
Re: Help! *istD problems (repost)
Can't help on the back focusing, but on the histogram I do think that the *ist-D is programmed to under-expose a bit. I typically see a need to adjust the exposure up 1/2 stop or so. Personally, I find that to be OK. At a low ISO the increase in noise is minimal. before the *ist-D I routinely shot with my old CP990 set to -1/3 exposure comp in order to prevent blown out highlights - the conversion process in that camera routinely put a good chunk of the pixels to full white. If something was lost in one of those bright areas, it was just lost. Far better (IMO) to have to pump up the brightness, even if that introduces a little noise, and not loose a critical detail. That's not to say there should be no pure whites or blacks in an image. It's just that I prefer to make the decision about how the histogram gets clipped. and not have to live with the camera's decision. - MCC - - - - - - - - - - - - - - - - - - - - Mark Cassino Photography Kalamazoo, MI www.markcassino.com - - - - - - - - - - - - - - - - - - - - - Original Message - From: Gonz [EMAIL PROTECTED] To: pentax-discuss@pdml.net Sent: Wednesday, February 23, 2005 4:26 PM Subject: Help! *istD problems (repost) The second problem is that I seem to always be adjusting exposure upwards in the PS raw program, usually between .5 and 1.0 stops. What should a good histogram look like? My camera seems to like to underexpose, in my opinion. Is this normal because of the blown hilites problem? When I bring in the raw pics into PS raw, the histogram usually shows no pixel values above the halfway point, yet if I look at the histogram using the *istD lcd panel, it seems to show some luminance values, although very few of them, up to the max luminance value. Why is there a discrepancy? I am going to try the same thing with Pentax raw and see if the histogram matches PS raw to some degree. I know that PS camera raw breaks up the values into RGB components, while Pentax combines them into a single histogram, so there might be an apples-oranges thing going on here. Anyhow, I would love to tap the collective PDML brains to see what I need to do here to solve some of these technical issues. Thanks ahead of time for any help you can give me. rg
