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06-28-2009, 11:11 PM   #1
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Is it somewhat normal for a 77mm Limited to be, well, a bit schitzo?

HEY, I can hear you laughing already...STOP THAT...I'm serious...REALLY...hehehe...

It all began with a product shot that came out like crap taken on a tripod, SR off, focus tracking off, AF on. It was AWFUL and completely out of focus. And even though it's a HUGE crop given the size and distance thing, my 24-60mm Siggy took the same shot spot on first try when I got it. Soooo, that is when the "testing" started tonight.

Overall the lens is consistently back focusing when it is off. The shot is never front focused. The amount of back focus can be > 1" at 30"...but that is as close to consistent as it has gotten today.

The thing is all over them map from shot to shot. Been testing in my usual methodical fashion, stopping down and comparing shots. And other such testing using various settings. And of course I tried AF micro-adjustment...which worked but only at +10 which to me seems kinda sorta a sign something weird is happening. Then did not work, then it worked then not, then turning it off the focus was even worse. All the while not ever adjustment had the same effect.

I would post samples BUT, since nothing is consistent it comes down to if the lens is just in need to some 'dawggie downers' or something else to 'even it out'...

I have never owned a lens or body with focus issues, and I have owned some lenses known to have these issues, like, well, the 24-60mm which is actually spot on every time at all FL's and apertures. You can see it's consistent and typical performance in the mini-gallery using the link below. I have already found a copy with a Pentax mount I can buy tomorrow if need be...

Speaking of apertures, I did find the focus was better as stopped down simply because the DOF improves. Mind I am NOT describing a soft focus thing, the missed focus can be at f/8 and when it misses it misses completely. It even biffs in green box mode.

Anyway, if this is normal or maybe it needs sending in...I did get it from a seller in Canookia and it wasn't packed well at all. Just the lens in it's box inside another box about 1/2" taller than the lens box...no padding. So, my thought is the bump & grind of the trip might have buggered something....or, as with the women from my life, it's NUTS!! hahahaha....

Anyway, any suggestions or info on the history of this lens and any, ummm, interesting behavior.

OK, I decided to upload a bunch of shots here:

BreckLundin's Place

And here is the shot which started all the confusion:


here is basically the same shot with the 24-60mm:

that shot is, of course processed but the first shot could never turn into this one. There isa tigher crop in the gallery for the 24-60mm.

The first 11 shots were from the other day and are fine for what they were...the remain shots are the new test shots showing the weird focus thing.

Oh, last, I tried under different lighting too and received the same insistent results...so all are AF, have not tried MF but will tomorrow when it's not so late. And the EXIF (INFO) will show the modes...and the back focus pretty obvious.

Otherwise, HELP? And remember I am not pissing and moaning, k? Just trying to figure out what's up...new gear, new system really different lens that seems to take AWESOME shots...but I am not used to a keeper rate using stabilization and AF of probably under 20% taken as a whole. I had hoped to use this lens for product shots as well as for fun, but maybe that is not it's strong suit?

Thanks all!!

The pics of the med bottle with the Kindle box as a background were tonight and are direct from the camera into LR2.4 then uploaded, not editing, not even basic adjustments...I mean exposure is not the issue but rather the focus all over the map.

Oh, one last thing, I have upgraded the firmware to 1.03 from day one so that is prolly not the issue, unless the fix to the AF really fixed this body...hehehe...am I cranky, ya sure youbetcha, is it the end of my life, ya, probably...tomorrow the 35mm Limited lands anywhere between 4PM-6PM, so if that lens is also off I'll know it's likely the body and will get Amazon to just swap on for me, probably have a replacement by Wednesday...I spend more than enough with them (we buy EVERYTHING on Amazon anymore) and it would be my first ever return beyond one book on macro I sent back like the day after it landed. I think that would be the fastest first pass at a fix.


Last edited by brecklundin; 06-28-2009 at 11:31 PM.
06-28-2009, 11:20 PM   #2
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ugly piece of glass. send it to me !
06-28-2009, 11:21 PM   #3
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What was the question?

Seriously, have you checked to see if it has a screw loose or anything like that? That's a serious question BTW but it would fit in with your schizo theory.
06-28-2009, 11:48 PM   #4
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you know...that is a good suggestion. I will double check what i can see...it seems odd though that once mounted there would be issues with a loose screw. But, I like it...in case not...where does one drop in the Xanax and other meds?

BTW, my cousin is actually schizophrenic and I hope nobody with the condition or someone who matters takes my comment as more than a lighthearted look at the issue. Even my cousin can joke about it now that we have hit well controlled for him. So, I often forget others are not so lucky to find a good control over it.

06-29-2009, 12:31 AM   #5
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Ok...maybe it;s ME who is full goose bozo here...but I took the lens off the body, gave the screws a quick check on the body and the lens, nothing loose except the one "screw" that should be which is part of the focus mechanism. Even though I could not see anything on the surface of the front and rear elements, I went ahead and cleaned them...and now no more back focusing or mis-focusing. Everything to spot on right as it should look in camera...even at 20x-ish zoom during replay...

Soooo, I dunno, the results are there and it was happening...why I dunno, I did everything I knew of to track it down and nothing worked, consistently...not sure of a smudge on the front element would be enough to throw off the focus by that much or not, well not one that I could not see eye my naked eyeball.

OK, all is fine...we'll see which Sybil I wake up with in the AM.
06-29-2009, 12:56 AM   #6
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QuoteOriginally posted by Pentaxor Quote
ugly piece of glass. send it to me !
have you no shame?....or does the 'will pander for gear' work?

If I do give it away...your name will be on the list!! how is that?
06-29-2009, 01:25 AM   #7
Damn Brit
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In my younger days I had a habit of saying "I'm not schizo, are we?".
06-29-2009, 01:45 AM   #8
emr
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Even though the problem seems to be resolved now, I have to ask whether you're sure which focus point you're actually using in the camera? Don't be offended if this sounds a silly question. I usually use center focus, but the dial had once accidentally turned to select point and most of the photos from that occasion were out of focus.

06-29-2009, 04:01 AM   #9
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Never offended by a question, especially as it was a key thing I left out....of course i might be a PITA and SA in a reply but only in jest...

But I almost exclusively use the center FP and in this case I was using it. I tried the two modes for selecting the CFP using SEL or the[*] (specifically set to the CFP only) setting one whatever that dial is called (NOTE: I just looked in the manual and it is called AF Switch Point Switching Dial ---gee who know it would be that simple?...). In fact one of the first things I checked as to be sure I was not letting the danged camera select the FP...for me that never works well. Took me about 2-months with the 40D before I realized it flat was useless on that body...it would miss just enough to look OK on the LCD then during post, I learned I really stunk on ice...now that was the camera setting for sure!

Excellent question...thanks for helping...if nothing else it's a good reminder for other folks who run into a similar issue.

I really am thinking either some bit was stuck inside the system even if it was showing as set right within the menu...or there was some thin bit of something on the front element preventing a consistent focus. Dunno...still tomorrow I plan on spending most of the afternoon working on really putting the lens into use for eBay things. And I really would not be disappointed if it's not the best product lens on the planet because I KNOW it's great in the field from everything I have found. I did find it interesting there were not more people using to for product shots as I assumed there would be...

I did learn enough to know for certain items the minor bit of softness that can show-up from the DOF at f/1.8 could be very interesting for certain items. This is my first lens since an OLD 50mm from the 70s with a sub-f/2.8 aperture...it's gonna be fun for sure!
06-29-2009, 04:21 AM   #10
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Could there have possibly been grit/dirt/grease in the focus screw interface? It doesn't take a lot of foreign material to screw up a sensitive mechanical interface. Otherwise you can do what we do when we're unable to find whatever a train operator was complaining about in his subway car "No defect found, no repair required, will monitor train"

NaCl(intermittent defect is the worst kind)H2O
06-29-2009, 08:03 AM   #11
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QuoteOriginally posted by brecklundin Quote
Even though I could not see anything on the surface of the front and rear elements, I went ahead and cleaned them...and now no more back focusing or mis-focusing. Everything to spot on right as it should look in camera...even at 20x-ish zoom during replay...
you know what. this kind of "magic" wipe worked for me once too.
I love my DA40 but there was a time when it was consistently BFing inconsistently (if that makes sense. in other words exactly as you described with your 77). Despite not seeing anything on the glass I gave it a good wipe and since then this little beauty is giving my 31ltd very good run for the money in both, usage and IQ.

BR
06-29-2009, 08:42 AM   #12
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QuoteOriginally posted by brecklundin Quote
have you no shame?....or does the 'will pander for gear' work?

If I do give it away...your name will be on the list!! how is that?
sure SANTA. I'd be a good boy !
06-29-2009, 02:56 PM   #13
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QuoteOriginally posted by axl Quote
you know what. this kind of "magic" wipe worked for me once too.
I love my DA40 but there was a time when it was consistently BFing inconsistently (if that makes sense. in other words exactly as you described with your 77). Despite not seeing anything on the glass I gave it a good wipe and since then this little beauty is giving my 31ltd very good run for the money in both, usage and IQ.

BR
Interesting...I will see how it goes today. Unfortunately I am IDIOT, left the danged camera powered on all night with SR running...battery dead, auto-off was probably the first setting I changed...note to self....BUY MORE BATTERIES!! Adorama here I come.

I went so far last night as to look at the front and rear (I suspect the rear element btw) under a 10x loupe just to see what might be on the surface. I was surprised to see there was a fine layer of mottled residue...I am thinking given the petite size of the lens itself, anything on the rear element, and maybe even the front, will have the potential to induce weird behaviors such as this random back focusing.

I appreciate that you mentioned you also has something similar!! Helps to know I might not have yet gone completely 'round the bend...

Soooo, soon as I have a charged battery, probably an hour yet, time for more testing to ensure all is well. Have genuine lens pens handy as well as some ROR (Residual Oil Remover...great stuff!) and a couple silk MF cloths. Somewhere I still have some of the old paper lens tissues, in my opinion nothing has cleaned lenses as well since those were the norm, but I suppose the paper might eventually take a toll on the coatings(?).
06-29-2009, 02:57 PM   #14
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QuoteOriginally posted by Pentaxor Quote
sure SANTA. I'd be a good boy !
Why do I have a sense that will never happen!!
06-29-2009, 03:47 PM   #15
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I'd say, spend some time reading the hundreds of other threads on focus over the years, come to good understanding of how the autofocus system works and the common user errors in using it - most common being failure to adequately control what the camera is actually focusing on. Then download one of the good focus test charts referenced in those other threads, read the isntructions carefully, follow them carefully, test in good light (not incandescent), and post the results.
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