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03-30-2011, 11:15 AM   #166
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Here's the LensAlign I made .... thanks to xbow for the graphics.








Now I've noticed a strange behaviour with my replacement K-5. I put my sigma 30/1.4 on it and it focussed spot on in daylight without any AF fine tuning. Cool! - it also focussed spot on at EV2 ( most of the time ) - Also cool.

today, after making the SmegAlign I decided to calibrate my lenses. I put my FA50/1.4 on and that needed no adjustment either. Cool!

I then put another lens on which did need some adjustment. so after turning on AF adjustment and calibrating this lens, I then put the Sigma 30/1.4 back on and it was really back focussing. It needed a +5 to calibrated it again. The same happened with the FA50/1.4 which needed -10 to calibrate it.

A bit flabbergasted by this I reset the AF fine tuning and turned it off. Both the Sigma 30/1.4 and the FA 50/1.5 showed back focus and front focus respectively and the need the +5 and -10 to correct them


So it seems that simply turning the AF Fine tuning on does something permanent to the AF system, which even a reset won't cure.

I'm taking delivery of my 2nd K-5 tomorrow so I'll be sure to test this again with the new camera.

note: this was all in daylight and was nothing to do with any front focussing in low light. In fact the front focussing behaviour with the replacement K-5 is working fine ( most of the time ) with the sigma in daylight and EV2. AFing with 103 in low light is still inconsistent.

03-30-2011, 12:24 PM   #167
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QuoteOriginally posted by Smeggypants Quote
So it seems that simply turning the AF Fine tuning on does something permanent to the AF system, which even a reset won't cure.
I have seen something very similar; erratic behavior. After testing with my 1.4 in various light conditions and finding it dead on the money (with my second K-5 body and firmware 1.03 ) in nearly all conditions, I put my 100 f2.8 on. It was fine. I put on my Sigma 18-50 f2.8, and it front-focused, so I enabled fine adjust and gave it about 5 in adjustment. It was right on the money; I chose "adjust one", not adjust all. Afterwards, my two tested primes were ff in low light, badly. The AF of this camera is an enigma to me; sometimes it's right on the dime, other times it reports a lock when there's nothing in focus (visibly in the viewfinder). I observed the same behavior on my other k-5.

That said, if I just walk around and take pictures, I find most of them are well focused in most circumstances; it "feels" like a similar ratio to what I got from my K20D, but focus is generally faster.
03-30-2011, 12:55 PM   #168
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Hey, Smeg. Did you do a camera reset as well as an AF reset?

Jack
03-30-2011, 01:07 PM   #169
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QuoteOriginally posted by jbinpg Quote
Hey, Smeg. Did you do a camera reset as well as an AF reset?

Jack
If you mean reset all the non AF parameters? No I didn't. I spent ages setting them up including the User Slots. I can't see that reseetting the non AF parameters would affect the AF.

rebooting the camera ( switching on and off ) made no difference.

03-30-2011, 01:14 PM   #170
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QuoteOriginally posted by jstevewhite Quote
I have seen something very similar; erratic behavior. After testing with my 1.4 in various light conditions and finding it dead on the money (with my second K-5 body and firmware 1.03 ) in nearly all conditions, I put my 100 f2.8 on. It was fine. I put on my Sigma 18-50 f2.8, and it front-focused, so I enabled fine adjust and gave it about 5 in adjustment. It was right on the money; I chose "adjust one", not adjust all. Afterwards, my two tested primes were ff in low light, badly. The AF of this camera is an enigma to me; sometimes it's right on the dime, other times it reports a lock when there's nothing in focus (visibly in the viewfinder). I observed the same behavior on my other k-5.

That said, if I just walk around and take pictures, I find most of them are well focused in most circumstances; it "feels" like a similar ratio to what I got from my K20D, but focus is generally faster.
It certainly is an enigma. The inconsistent focussing in low light is definitely something that 1.03 introduces. I've confirmed this with two K-5s now.

During valibration today I snapped whole bunch of real world stuff and most of them were in focus, including down to EV2. So I can safely say my previous K-5 was a dud regarding AF.

I think Pentax needs to do some more work on the firmware.
03-30-2011, 01:45 PM   #171
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I see you both have somthing in comon

"I put on my Sigma"

Have you checked the lens ID the Sigma you own is reporting to the camera?

As its possible you may be unlucky and have a duplicate ID from your Penax lena and Sigmas Reverse engineered cloned ID.

This could confuse the camera.
03-30-2011, 01:52 PM   #172
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I did a camera reset and my USER modes remained intact.
03-30-2011, 02:23 PM   #173
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Smeggy it would be great if your experiences were relayed to Pentax Support.
There should be a good resolution to all the issues you're going through with the K-5.

03-30-2011, 02:35 PM   #174
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QuoteOriginally posted by awaldram Quote
I see you both have somthing in comon

"I put on my Sigma"

Have you checked the lens ID the Sigma you own is reporting to the camera?

As its possible you may be unlucky and have a duplicate ID from your Penax lena and Sigmas Reverse engineered cloned ID.

This could confuse the camera.
My Sigma 30 is reporting to the camera. the FA50 and it are both having their settings remembered.
03-30-2011, 03:19 PM   #175
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1.04, here we come!

Sigh.
03-30-2011, 03:34 PM   #176
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QuoteOriginally posted by Quicksand Quote
1.04, here we come!

Sigh.
Yup, there's more work to do.
03-30-2011, 04:07 PM   #177
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QuoteOriginally posted by Tommot1965 Quote
I must admit Im not too happy with this 17-50, my other was replaced as it had a faulty lens hood holder on the lens..
What was the issue with the lens hood holder? Was the lens hood loose or not locking at all? A loose lens hood seems to be a common issue with this lens, and I think the notch to lock in the lens hood was designed a bit too small.
03-30-2011, 05:12 PM   #178
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These tests at 1.4 or whatever are crazy. I use a 2.8 lens everyday. The AF algorithems have some <= or >= for acuracy for sure. I am sure.
Also rounded off to the nearest whole number if i had to guess. I get results like this daily.

Also i shoot with nikon and canon shooters daily. And i see the same thing. I shoot with guys daily that shoot 400mm f2.8, 500 f4, 600 f4 even 800 f5.6. These guys if not really seasoned get very poor results. The K-5 and professional glass demands respect for sure.

I am slowely changing to canon but only for the lack of comment from HOYA . No Telephotos?? Showes me they are not commeted to Pentax. Just bidding time.

If you shoot one lens alot you will see the difference in the viewfinder verrrry fast and refocus. Also very fast. Then pull the triger.

The Af in artificial light is another story. But I am just amazed at the people who run teset like this... The K-5 is very good camera. The best i have ever used.

Amazing.

Last edited by garyk; 03-30-2011 at 05:41 PM.
03-30-2011, 05:40 PM   #179
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QuoteOriginally posted by Smeggypants Quote
So it seems that simply turning the AF Fine tuning on does something permanent to the AF system, which even a reset won't cure.
A potential explanation is that the camera has default correction values that are overridden the first time an AF adjust is made. A reset seems to set everything to "0", not to the default values.

Are you planning to make a low-light comparison to the K20D with your new K-5s? It would be interesting to see when the K20D stops locking focus and how the FFing compares.

Also, it would be super cool if you could compare your SmegAlign (looks good) to a standard flat focus chart.

An improvement to the SmegAlign would be an alignment aid because the "parallel target and angled ruler" approach requires that the target plane and the sensor plane are perfectly aligned to each other. Otherwise you get incorrect readings. A mirror temporarily attached to the target area is probably the easiest way to achieve alignment.
03-30-2011, 08:06 PM   #180
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QuoteOriginally posted by Class A Quote
A potential explanation is that the camera has default correction values that are overridden the first time an AF adjust is made. A reset seems to set everything to "0", not to the default values.
Possibly. But if so it would be a behaviour that flies against common sense.


QuoteQuote:
Are you planning to make a low-light comparison to the K20D with your new K-5s? It would be interesting to see when the K20D stops locking focus and how the FFing compares.
I will try, but my priority is taking real life photographs rather than exact scientific study

Once I've received my 2nd K-5 in afew hours and proved it's working fine, I shall be sticking my K20D up on ebay shortly afterwards.



QuoteQuote:
Also, it would be super cool if you could compare your SmegAlign (looks good) to a standard flat focus chart.

An improvement to the SmegAlign would be an alignment aid because the "parallel target and angled ruler" approach requires that the target plane and the sensor plane are perfectly aligned to each other. Otherwise you get incorrect readings. A mirror temporarily attached to the target area is probably the easiest way to achieve alignment.
Frankly for real life analysis such accuracy isn't needed. For example my original tests in this thread, although not scientifically accurate by any means were more than enough to show the issues I was testing for.

Aligning the SmegAlign by eye is more than enough to calibrate a lens for real world snapping success.
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