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02-08-2011, 05:17 PM   #451
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The problem with proving the AF operation one way or another with pictures of regular subjects is that there is usually no way of knowing what the camera used for focus; even when using center AF there is quite a bit of leeway (could be anything in the area roughly equal to the center circle of the viewfinder). The remedy for this is using a target which has high contrast detail in a limited range of depth: the AF can only focus on something it "sees".

02-08-2011, 05:53 PM   #452
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QuoteOriginally posted by jrforman Quote
Rupert,

I don't have the 43 mm limited but I do have a FA 50mm 1.4. I wanted to try to see what I got with my K-5 at those settings. So here is what I got at ISO 400, 1/15th of a second, f1.8 at about a foot and a half. Tungsten (halogen light on dimmer - really orange, auto WB). I had done fine tuning yesterday in natural light. No other changes. Did I do what you wanted? Or was I missing the boat in some way?
Your pic is shot at about EV4


My K-5 focusses OK at EV4.


You should try the same test at EV2 and below where people are reporting the FF problem

This chart will help you convert exposure settings to EV


Ultimate Exposure Computer
02-08-2011, 06:12 PM   #453
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QuoteOriginally posted by jrforman Quote
Rupert,

I don't have the 43 mm limited but I do have a FA 50mm 1.4. I wanted to try to see what I got with my K-5 at those settings. So here is what I got at ISO 400, 1/15th of a second, f1.8 at about a foot and a half. Tungsten (halogen light on dimmer - really orange, auto WB). I had done fine tuning yesterday in natural light. No other changes. Did I do what you wanted? Or was I missing the boat in some way?
i could not get that shot, mine will ff at ev5 ... what's the build date and serial of your k5 please
02-08-2011, 06:35 PM   #454
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QuoteOriginally posted by jrforman Quote
Rupert,

I don't have the 43 mm limited but I do have a FA 50mm 1.4. I wanted to try to see what I got with my K-5 at those settings. So here is what I got at ISO 400, 1/15th of a second, f1.8 at about a foot and a half. Tungsten (halogen light on dimmer - really orange, auto WB). I had done fine tuning yesterday in natural light. No other changes. Did I do what you wanted? Or was I missing the boat in some way?
Looks fine to me, I would be satisfied with that, no doubt about it. For you guys that have good working models, I envy you and so do many others.

jthommo advised me to look at the "Post your K5 Shots" thread and I had already been following it....some of the shots there are simply amazing and have nothing to do with low light, just fantastic shooting and superb results. I'm still in the game with Pentax, they just need to get me a camera ready and get it right. That is all I have ever wanted...and still do. I can buy most any camera made, but the K5 if right, will be perfect for me and my damned Squirrels.
Best Regards

02-08-2011, 07:07 PM   #455
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QuoteOriginally posted by Smeggypants Quote
Your pic is shot at about EV4


My K-5 focusses OK at EV4.


You should try the same test at EV2 and below where people are reporting the FF problem

This chart will help you convert exposure settings to EV


Ultimate Exposure Computer
I was duplicating Rupert's shot that he posted with the K20D, with the same settings. I wasn't attempting a lower EV shot.

BUT I did three EV 2.6 shots just now (Separate focusing, reading from light meter). SLIGHT forward focusing. Some variability. Did three shots to show the variability of focus. f2.0 this time with higher ISO. This is a detail crop of the photo.
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02-08-2011, 07:29 PM   #456
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QuoteOriginally posted by jrforman Quote
I was duplicating Rupert's shot that he posted with the K20D, with the same settings. I wasn't attempting a lower EV shot.

BUT I did three EV 2.6 shots just now (Separate focusing, reading from light meter). SLIGHT forward focusing. Some variability. Did three shots to show the variability of focus. f2.0 this time with higher ISO. This is a detail crop of the photo.
if you focussed on the centre of the coin then that's definite front focussing. You should have slightly for DOF behind the coin.
02-08-2011, 07:37 PM   #457
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Whats the best way to do a quick and dirty FF test shot with my new k-5?
02-08-2011, 08:00 PM   #458
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-Set camera to AF-C
-Set Aperture to f/2, shutter time 1/25s and sensitivity ISO3200 (in manual mode)
-Take a photo in a dimly tungsten light lit room (use a dimmer or put the light further away) with contrasty objects (such as a book case)
-it is nice to have some objects closer at the bottom edge of the picture to see if that ends up being sharp due to the FF

Take a few shots (and look which AF spots are in focus) and if your shots look slightly dim, it should be around the 2EV

This is how I do this practical quick and dirty test to see if the FF issue is present or not.

02-08-2011, 08:20 PM   #459
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QuoteOriginally posted by Smeggypants Quote
if you focussed on the centre of the coin then that's definite front focussing. You should have slightly for DOF behind the coin.
I agree. I need to go to 2.8 to get the entire coin in focus (still slight forward focus there but both sides of coin is in focus).

I also have to qualify this by type of lens. It seems my FA50 is my best. In subsequent testing I learned my DA40 is significant FF at low EV. Same with my DA*50-135. The FA 100 macro is somewhere in the middle.

When I do the test with florescent light I get the same results as tungsten.

My K20D, if it can find focus, provides better focus results.

But for me (flame off, I'm just talking about my experience here) I don't shoot in this low of light that often so its not as much an issue as it is for others. And of course I think it should be corrected. I also learned that if I do, I'm going to do it with my FA50 which gives me the best focus. Perhaps helpful if you know which lens is going to do what if you shoot in low light.
02-08-2011, 08:22 PM   #460
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QuoteOriginally posted by jrforman Quote
I agree. I need to go to 2.8 to get the entire coin in focus (still slight forward focus there but both sides of coin is in focus).

I also have to qualify this by type of lens. It seems my FA50 is my best. In subsequent testing I learned my DA40 is significant FF at low EV. Same with my DA*50-135. The FA 100 macro is somewhere in the middle.

When I do the test with florescent light I get the same results as tungsten.

My K20D, if it can find focus, provides better focus results.

But for me (flame off, I'm just talking about my experience here) I don't shoot in this low of light that often so its not as much an issue as it is for others. And of course I think it should be corrected. I also learned that if I do, I'm going to do it with my FA50 which gives me the best focus. Perhaps helpful if you know which lens is going to do what if you shoot in low light.

could I have the build date of your K5 please ??
02-08-2011, 08:42 PM   #461
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QuoteOriginally posted by Tommot1965 Quote
could I have the build date of your K5 please ??
Yep. Took me a while to find windows machine with PhotoME, but here it is.

Firmware: 1.02.21.10
mgf date: 12-20-10
model: 0x12e76
02-08-2011, 08:46 PM   #462
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To me, this isn't really a valid FF test because there is enough variability in where the actual focus sensor is in relation to the led representation of where it is that you could be focusing anywhere on that coin, which is borne out by the variable results you attained.

In order to really do it right, you need a focus chart with a large, high contrast area that is used for focus so there is absolutely no doubt where the camera is focusing on, since it won't be able to lock on if you are off the edge.
02-08-2011, 09:15 PM   #463
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OT: Exiftool

Off topic but don't forget about ExifTool ....
And for Lightroom users, Friedl's Metadata Viewer Plugin (which uses Exiftool)

QuoteOriginally posted by jrforman Quote
Yep. Took me a while to find windows machine with PhotoME, but here it is.

Firmware: 1.02.21.10
mgf date: 12-20-10
model: 0x12e76
02-08-2011, 09:52 PM   #464
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QuoteOriginally posted by GregK8 Quote
To me, this isn't really a valid FF test because there is enough variability in where the actual focus sensor is in relation to the led representation of where it is that you could be focusing anywhere on that coin, which is borne out by the variable results you attained.

In order to really do it right, you need a focus chart with a large, high contrast area that is used for focus so there is absolutely no doubt where the camera is focusing on, since it won't be able to lock on if you are off the edge.
You're right. It isn't. I just started this to respond to Rupert's desire to duplicate the K20D shot and then started checking my lens due to a comment from someone who indicated it should be lower light and so on. I got what I needed for my shooting and learned something about the capabilities of my camera/lenses in low light. I hope someone, perhaps yourself, perhaps not, could design and execute a valid test. For me right now, I'll stick to a little more light and slightly higher apertures until a fix is there.
02-08-2011, 10:18 PM   #465
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QuoteOriginally posted by jrforman Quote
I hope someone, perhaps yourself, perhaps not, could design and execute a valid test.
I am due to receive my replacement on Friday, and I plan on setting up something in my basement studio this weekend.
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