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02-16-2011, 04:59 PM   #616
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QuoteOriginally posted by Christine Tham Quote
Well, this diagram illustrates the size of the centre sensor (and all the other sensors) - courtesy of Falk I think:
So now we superimpose. I'm not sure what this tells us.

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02-16-2011, 05:06 PM   #617
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QuoteOriginally posted by GregK8 Quote
So now we superimpose. I'm not sure what this tells us.
I think it tells us that if jolepp had originally pointed the camera at the eyes, it is just conceivable that the camera could have focused on the spoon (edit: or, much more likely, the hair on the forehead, since that would have yielded the greatest contrast pattern).

Remember the camera could have focused anywhere along the horizontal or vertical line, not just where they cross.

Note: I am not claiming that this is what the camera actually did, merely that it could have happened.

Nor am I claiming that jolepp's camera does not have a problem. We know from jolepp's battery tests that there is indeed a problem.

I'm simply saying the image is not conclusive of a problem under actual shooting conditions.

I am sorry that jolepp missed out on what could have been a perfect shot of the kid.

I am also sorry that I missed out on hundreds of shots where I am certain I pointed my K10D at where I wanted it to focus, only to have the camera focus on something completely different. But I'm not blaming the K10D for those shots.
02-16-2011, 05:36 PM   #618
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Actually, I'm now thinking that the grid is scaled too large for that picture. If I look at that picture through my viewfinder so it fills the whole focus screen, the AF points are probably more like this.
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02-16-2011, 05:54 PM   #619
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Whatever...you can find all sorts of crutches and excuses but the bottom line is that the K5 does not focus to specifications for a good number of users. How many? No one knows, but it is reported that Pentax is anxiously and furiously working on a solution. If there is no problem and just simply User Error or standard AF failure common on all cameras......why would Pentax be working on that solution?
It can't be both ways........No problem and Pentax is working hard to fix it? Does that make a lick of sense?

Look at these again, shot by Al, a longtime Pentax shooter going back to film days and fully experienced and qualified to know that he sent back three cameras with good reason.

His old K100D
[IMG] [/IMG]

His last K5
[IMG] [/IMG]

Personally, and no, I don't have a K5, but tons of Pentax gear, and I do want a working K5......Personally, I would like to stop seeing excuses being manufactured and see some answers and a fix for these very real problems. I'm looking to stay with Pentax not leave, but some here are trying to convince me and others that a faulty camera is somehow acceptable.....and it just isn't.
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02-16-2011, 06:04 PM   #620
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Rupert, no one is trying to convince you that a faulty camera is acceptable. I think we can all agree on that. What we are saying, is, stop shouting that the sky is falling, when it clearly isn't. For the 1 billionth time, if you don't like the K-5, don't buy it. Simple. Going on a crusade here is not helping anyone, and the repeated posts are extremely annoying. All consumer products have issues, there are few perfect cameras from any manufacturer (that is a fact). You have a warranty, and a liberal return policy...you can use it if you have any issues. Many here have returned 2 or 3 cameras, and they are not as upset over it as you are.

Why don't you take the same amount of time you spend on PF, writing the same posts over and over, and write Pentax USA (or Hoya Corp)? I bet if you bombarded them with the same drivel that us PF-ers are subjected to on a daily basis, they'd have no choice but to fix all of the issues and send you a free camera for your tireless effort to end the dreadful camera injustice we've all had to endure for too long!
02-16-2011, 06:21 PM   #621
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And the Sky Isn't Falling

Many folks all over the world are enjoying this great camera. My bet is that FF effects less than 1% of all pictures taken and that's probably a stretch, That's why the professional reviewers haven't picked up on it. The reviewers focus on parameters most of us deal with on a daily basis not the parmeters expressed in this thread.
02-16-2011, 06:22 PM   #622
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QuoteOriginally posted by Christine Tham Quote
Well, this diagram illustrates the size of the centre sensor (and all the other sensors) - courtesy of Falk I think:
Thanks for the quote. If I posted it than it must have been in citation of somebody else.

The drawing is basically correct. However, we'll have to recalibrate it for the K-5 camera before we can draw conclusions.

A transparent PNG in original K-5 size one can overlay in Photoshop may be a good tool in discussions like these.

For the calibration, I found one can do the following:

Put the camera on a tripod, point it to a sheet of paper with a long vertical line (in a second step with a horizontal line for the other direction). Then move the paper left-right until you reach a point where 6 focus indicators are triggered (in AUTO-AF selection mode). You may only be able to reach a point where the indicators toggle but thats good enough. Take a photo in that postion. Continue until you reached all 6 sensitivity crossings in the horizontal direction. Then repeat with the four positions using a long horizontal line. After you overlay all ten resulting images, you obtain a checkerboard image where the fields mark each AF point's sensitivity area.

It would be particularly interesting to check for any change between K-7 and K-5.
02-16-2011, 07:32 PM   #623
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QuoteOriginally posted by falconeye Quote
The drawing is basically correct. However, we'll have to recalibrate it for the K-5 camera before we can draw conclusions.
Agree.

If I recall correctly, that diagram was for the *ist D, and we know that one of the "improvements" in the K-5 is Pentax changed the size of the AF sensors.

However, the bottom line is that we still don't know what exactly the camera focused on, and maybe we will never know.

I do know from personal experience that if I aim my camera at the eyes, it's likely the camera won't focus on the eyes.

The eyes are typically low contrast with no well defined sharp edges, so the AF sensor will probably focus on something else - I only mentioned the spoon because in the photo that object is brighter than the face and has sharp edges so would register very strongly on the phase detect.

I once wasted an entire shoot capturing cyclists and the camera kept focusing on the grass in the background which were sunlit. This was on the K10D. And despite the cyclist taking up a large proportion of the frame, and the camera on centre focus.

I think we keep forgetting and imagine the AF sensor is seeing what we are seeing, but at the end of the day it is just registering voltage changes.

02-16-2011, 07:36 PM   #624
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QuoteOriginally posted by qtopplings Quote
Rupert, no one is trying to convince you that a faulty camera is acceptable.
I don't think I'm trying to convince anyone of that, I'm trying to sort out fact from fiction.
02-16-2011, 07:41 PM   #625
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QuoteOriginally posted by mgm2 Quote
Many folks all over the world are enjoying this great camera. My bet is that FF effects less than 1% of all pictures taken and that's probably a stretch, That's why the professional reviewers haven't picked up on it. The reviewers focus on parameters most of us deal with on a daily basis not the parmeters expressed in this thread.
Taking pictures below EV4 and expecting the AF to work is not an unusual photographic scenario.

Your post is unrealistic and not based upon any reasonable assumption of people's photographic habits.

Why not just accept that a significant amount of people are reporting a low light FF issue instead of trying to minimise this issue?

Do you even own a K-5?


02-16-2011, 07:50 PM   #626
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QuoteOriginally posted by qtopplings Quote
Rupert, no one is trying to convince you that a faulty camera is acceptable. I think we can all agree on that. What we are saying, is, stop shouting that the sky is falling, when it clearly isn't. For the 1 billionth time, if you don't like the K-5, don't buy it. Simple. Going on a crusade here is not helping anyone, and the repeated posts are extremely annoying. All consumer products have issues, there are few perfect cameras from any manufacturer (that is a fact). You have a warranty, and a liberal return policy...you can use it if you have any issues. Many here have returned 2 or 3 cameras, and they are not as upset over it as you are.

Why don't you take the same amount of time you spend on PF, writing the same posts over and over, and write Pentax USA (or Hoya Corp)? I bet if you bombarded them with the same drivel that us PF-ers are subjected to on a daily basis, they'd have no choice but to fix all of the issues and send you a free camera for your tireless effort to end the dreadful camera injustice we've all had to endure for too long!
If you find these posts annoying then don't open the damn thread FFS, no one is forcing you to.

By making noise about Rupert's posts you are simply contributing to what you are complaining about and thus making yourself look foolish.

I support Rupert's crusade. I actually own a K-5 and it does actually have a FF problem in low light. OK Rupert hasnt bought a K-5 yet, but if he's in the market to shekk out over a a thousand shekels for one he has a right to make a noise about a serious issue this camera has


QuoteQuote:
your tireless effort to end the dreadful camera injustice we've all had to endure for too long!

Complete and utter bullsh1t.

You haven't had to endure anything so stop crying you have. If you are that bothered about people discussing the FF issue why even open the damn threads. Truly pathetic.
02-16-2011, 07:54 PM   #627
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QuoteOriginally posted by Christine Tham Quote
Agree.

If I recall correctly, that diagram was for the *ist D, and we know that one of the "improvements" in the K-5 is Pentax changed the size of the AF sensors.

However, the bottom line is that we still don't know what exactly the camera focused on, and maybe we will never know.

I do know from personal experience that if I aim my camera at the eyes, it's likely the camera won't focus on the eyes.

The eyes are typically low contrast with no well defined sharp edges, so the AF sensor will probably focus on something else - I only mentioned the spoon because in the photo that object is brighter than the face and has sharp edges so would register very strongly on the phase detect.

I once wasted an entire shoot capturing cyclists and the camera kept focusing on the grass in the background which were sunlit. This was on the K10D. And despite the cyclist taking up a large proportion of the frame, and the camera on centre focus.

I think we keep forgetting and imagine the AF sensor is seeing what we are seeing, but at the end of the day it is just registering voltage changes.

Hi there Christine T.


You made claim earlier. just asking again where you got his info from ....



QuoteOriginally posted by Christine Tham Quote

Remember the K-5 will prefer to focus on the closest object within the sensor hairlines, not necessarily the object at the notional "point" as depicted on the screen.

Will it? Where is this reliably documented?


And in any case given the same subject with two different light levels the distance of various objects in the scene is irrelevant.

IOW, if your questionable statement above is true then the "K-5 will prefer to focus on the closest object within the sensor hairlines, not necessarily the object at the notional "point" as depicted on the screen." at normal light levels too, and seems to focus on what is at the centre of the red square.
02-16-2011, 08:16 PM   #628
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QuoteOriginally posted by Smeggypants Quote
If you find these posts annoying then don't open the damn thread FFS, no one is forcing you to.

By making noise about Rupert's posts you are simply contributing to what you are complaining about and thus making yourself look foolish.

I support Rupert's crusade. I actually own a K-5 and it does actually have a FF problem in low light. OK Rupert hasnt bought a K-5 yet, but if he's in the market to shekk out over a a thousand shekels for one he has a right to make a noise about a serious issue this camera has





Complete and utter bullsh1t.

You haven't had to endure anything so stop crying you have. If you are that bothered about people discussing the FF issue why even open the damn threads. Truly pathetic.
Actually, you're the one that's crying. It figures you'd chime in here. I'm not bothered by the discussion of FF, I am interested in it, which is why I'm reading the thread. What I am bothered by is the constant repetitive crap that's being posted by a few people here, like Rupert. People are trying to troubleshoot the "issue", and not convince people the camera is perfect.

Quote:
your tireless effort to end the dreadful camera injustice we've all had to endure for too long!

PS. That last bit was me being saracstic.
02-16-2011, 08:30 PM   #629
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Your thought to send some of complaints Pentax's way is actually a good one.Maybe they will give some more info to those of you that are so concerned about the state of affairs. I am not being sarcastic. I'm thinking they (Pentax) are more likely to read mails sent to them rather than complaints on forum that they have nothing to do with. I may send one myself.
02-16-2011, 09:09 PM   #630
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I think I've come up with an excel "spreadsheet", actually a form, where you can plug in any aperture, any shutter speed and any ISO and it will give you the EV for the picture. At least, I think it works - Excel's format for logarithms is different than how you usually see it written. If someone could tell me what EV a picture would be that was taken with f5.6, a shutter speed of 1/25, and Ev of -.3 and an ISO of 16,000 (2.5 something, like 2.59278175) I could verify if I have the formula working right. My days of doing math like this are long gone (and I never went all that much beyond this even when I was in school too many years ago).

I've been wondering about this whole issue and if what I sometimes see is the low-light front focus or just a lens that isn't adjusted right (I've been struggling with that and what's possibly a faulty lens issue also). And I've taken pictures with other lenses, in what I consider low light where I haven't had the issue so I wanted something where I could just put in all the figures, rather than trying to figure out from a chart and trying to compute how many stops different ISO (fill in the blank) was from ISO 100.

If someone can verify whether my example is correct, I'd appreciate it. By the way, the picture in my example was, in fact, front focused. But it was also taken with one of my problem lenses so at this point I'm not convinced either way. If I know my formula is correct, I'll be able to figure out if the ones that are not front focused are really low enough light or if I have simply a lens problem.

If anyone is interested, the formula I am working with is: =LOG(((Av*Av)/Tv),2)-LOG((ISO/100),2)-Ev . Excel's format for logs is to put the number then a comma and then the base, so I would assume that would be an appropriate formula for log2(aperture squared/shutter speed)-log2(ISO/100)-Ev. That is, assuming I managed to understand the formula for EV correctly, as I said, my math skills are very, very rusty.
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