The 40 Ltd...Brutally Sharp lens. Who else is using it?

Tommy · 03-20-2009, 12:34 AM

It's threads like this that makes me love and hate this forum at the same time. For a (too) long time I've had the DA 12-24 at the top of my wish list. A series of many fortunate and a few unfortunate events has led me to postpone the next lens purchase and during this time I've become increasingly interested in the DA*55. I also promised myself to not get a flash until I master available light photography. Well, I don't master it yet, but I really want a flash now. On top of that I need a new monitor, a calibrator and maybe a new laptop.

And now you've convinced me that I really need the DA 40.

I'm starting to understand what you all mean when you talk about LBA

schmik · 03-20-2009, 12:34 AM

Here is another series. Same conditions. Camera is on a tripod and focused. Then AF is turned off.

images start at f2.8 and go to f/8.

cheers
mike

schmik · 03-20-2009, 12:36 AM

The remainder of the shots.

And Marc, no it's not a DOF thing.

cheers
mike

fearview · 03-20-2009, 01:03 AM

@schmik

my shot always sharp at wide open. you have to check yours soon as possible, i dont think the result is correct, something wrong.

axl · 03-20-2009, 01:12 AM

sorry to say schmik but your lens is backfocusing quite badly. So Marc was kind of correct. You don't see lens that isn't sharp but you see the effect of thin DOF combined with BF.

PS: what camera are you using? I was seeing something very similar with my DA40 combined with K10D until I tweaked the focusing adjustment

schmik · 03-20-2009, 01:15 AM

here are two of the images uncropped. F2.8 and F8.

Any more opinions. If this is not correct then what do i do about it?

schmik · 03-20-2009, 01:18 AM

It's on the K100d.... does this require a lens adjustment or camera adjustment?

Some of the other shots i have taken at F4.5 are stunningly sharp.

cheers
mike

axl · 03-20-2009, 01:19 AM

it's hard to say from the last set of images, but I really do think your DA40 is backfocusing

schmik · 03-20-2009, 01:19 AM

oops... double post.

So, if i adjust the camera via the whole debug menu. Which way do i go? left or right (see below).
Is this a camera problem or a lens problem?

If i adjust the AF this will affect all of my lens...right?

STEP
1. Power OFF
While pressing [AE-L]+[INFO], turn the camera on.
Firmware is desplayed on LCD.
Press [MENU]->[MENU]->[INFO] within 5 seconds.
You can see DEBUG mode screen.
By pressing [Right key],Make [DEBUG MODE DIS] to [DEBUG MODE EN].
Then, Press [OK].

2. Press [MENU], you can see setup menu.
By pressing [Up key], select AF TEST.
By pressing [Right key], go into AF TEST menu.
By pressing [Down key], select FOCUS CORR.
now you can adjust shift amount by pressing [right key] or [left key].
(*Don't touch AF Area Test.)
after changing the value, Press [OK] to save.
3. Test your camera that Focus is corrected.
(repeat step 2. till you satisfy the result.)
4. Power OFF
While pressing [AE-L]+[INFO], turn the camera on.
Firmware is desplayed on LCD.
Press [MENU]->[MENU]->[INFO] within 5 seconds.
You can see DEBUG mode screen.
By pressing [Right key],Make [DEBUG MODE EN] to [DEBUG MODE DIS].
Then, Press [OK].
5. Go out and enjoy!!

axl · 03-20-2009, 01:21 AM

Originally posted by schmik

It's on the K100d.... does this require a lens adjustment or camera adjustment?

Some of the other shots i have taken at F4.5 are stunningly sharp.

cheers
mike

I don't know if you can adjust AF on K100D. BTW can you pinpoint where was AF point?

BR

schmik · 03-20-2009, 01:33 AM

I believe AF was on the card. But I can't be 100% sure.

The instructions above are apparently for the k100d. I'll try it later.... if time allows. Batteries are charging now

Am i correct to assume that it is a camera problem. I just double checked my shots with the fisheye (only other decent auto focus lens i own). They are soft soft soft wide open too. I just allways assumed it was the lens.

Why can't this stuff just work straight from the box? Seriously.

mike

axl · 03-20-2009, 01:37 AM

good luck sorting it out, it's hard to judge anything with FE since because of it's FOV the DOF will be huge at any given apperture (at least that's how it works for corrected lenses) unless you're not focusing very very close.
Anyway, retest with DA40, choose less busy scene (f.e. put one of your AA cells in front of white wall) and have a go, or put 3 or more AA cells staggered but spread wide enough so central AF point will catch only one. Let us know then...
BR

benjikan · 03-20-2009, 02:18 AM

Originally posted by schmik

OK... sorry for the attachments but couldn't bothered with flickr right now.

These area ll crops, these were taken off a tripod all focused on the card (and then AF turned off, so the same focus for all shots).

card1 = f2.8
card2 = f3.5
and so on until f/8.

Is this normal. I'm just checking due to the reputation of this lens.

cheers
mike

There is a problem. This is NOT normal. Either it is your auto focus alignment or you have a lemon. I use this lens professionally and if these results you have posted were what I was getting, I would most definitely not be using this lens and send it back to Pentax.

Marc Sabatella · 03-20-2009, 10:30 AM

Originally posted by schmik

I believe AF was on the card. But I can't be 100% sure.

I don't think it's *possible* to be 100% sure based on the full size image you posted - the post/pipe the card was mounted to might have been the actual focus target chosen by the camera even if you specifically chose center point. That is, the card does not appear to cover the entire center AF sensor.

I agree that what you are seeing is definitely a matter of the f/2.8 shots being out of focus, but I certainly would not be leaping to any conclusions that there is a malfunction here. You need to repeat your test using a setup in which the camera cannot possibly choose any focus point other than the intended one (do that by choosing a larger target, or by shooting from a shorter distance).

Quote:

I just double checked my shots with the fisheye (only other decent auto focus lens i own). They are soft soft soft wide open too. I just allways assumed it was the lens.

With an extreme wide angle lens, it's next to impossible to force the camera to focus on any single object, since most objects will be rendered much smaller than any of the AF sensors. Plus DOF is pretty darned wide. Which is to say, it wouldn't seem to likely to me that this is what is going on. But again, you'd have to do a controlled focus test (discussions of this topic are pretty much a weekly event here; also jus browse around the net) to be able to say for sure.

**sinus007** · 03-20-2009, 12:48 PM

Hi Ben,
The only disagreement I have is the word brutally. Why not use beautifully or marvelously?

Just a note on the side.....

03-20-2009, 01:12 AM	#35
axl Veteran Member Join Date: Mar 2007 Location: Nove Zamky, Slovakia Photos: Gallery \| Albums Posts: 7,183	sorry to say schmik but your lens is backfocusing quite badly. So Marc was kind of correct. You don't see lens that isn't sharp but you see the effect of thin DOF combined with BF. PS: what camera are you using? I was seeing something very similar with my DA40 combined with K10D until I tweaked the focusing adjustment Last edited by axl; 03-20-2009 at 01:15 AM. Reason: PS added

03-20-2009, 12:48 PM	#45
sinus007 Site Supporter Join Date: Jul 2008 Location: Cleveland, OH, USA Photos: Gallery Posts: 292	Brutally Sharp? Hi Ben, The only disagreement I have is the word brutally. Why not use beautifully or marvelously? Just a note on the side.....

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03-20-2009, 12:34 AM	#31
Tommy Senior Member Join Date: May 2008 Location: Stockholm, Sweden Photos: Gallery Posts: 195	It's threads like this that makes me love and hate this forum at the same time. For a (too) long time I've had the DA 12-24 at the top of my wish list. A series of many fortunate and a few unfortunate events has led me to postpone the next lens purchase and during this time I've become increasingly interested in the DA*55. I also promised myself to not get a flash until I master available light photography. Well, I don't master it yet, but I really want a flash now. On top of that I need a new monitor, a calibrator and maybe a new laptop. And now you've convinced me that I really need the DA 40. I'm starting to understand what you all mean when you talk about LBA

03-20-2009, 01:03 AM	#34
fearview Veteran Member Join Date: Apr 2008 Location: Jakarta Photos: Gallery Posts: 1,067	@schmik my shot always sharp at wide open. you have to check yours soon as possible, i dont think the result is correct, something wrong.

03-20-2009, 01:18 AM	#37
schmik Veteran Member Join Date: May 2008 Location: Sydney Aus Photos: Gallery Posts: 527	It's on the K100d.... does this require a lens adjustment or camera adjustment? Some of the other shots i have taken at F4.5 are stunningly sharp. cheers mike

03-20-2009, 01:19 AM	#38
axl Veteran Member Join Date: Mar 2007 Location: Nove Zamky, Slovakia Photos: Gallery \| Albums Posts: 7,183	it's hard to say from the last set of images, but I really do think your DA40 is backfocusing

03-20-2009, 01:19 AM	#39
schmik Veteran Member Join Date: May 2008 Location: Sydney Aus Photos: Gallery Posts: 527	oops... double post. So, if i adjust the camera via the whole debug menu. Which way do i go? left or right (see below). Is this a camera problem or a lens problem? If i adjust the AF this will affect all of my lens...right? STEP 1. Power OFF While pressing [AE-L]+[INFO], turn the camera on. Firmware is desplayed on LCD. Press [MENU]->[MENU]->[INFO] within 5 seconds. You can see DEBUG mode screen. By pressing [Right key],Make [DEBUG MODE DIS] to [DEBUG MODE EN]. Then, Press [OK]. 2. Press [MENU], you can see setup menu. By pressing [Up key], select AF TEST. By pressing [Right key], go into AF TEST menu. By pressing [Down key], select FOCUS CORR. now you can adjust shift amount by pressing [right key] or [left key]. (*Don't touch AF Area Test.) after changing the value, Press [OK] to save. 3. Test your camera that Focus is corrected. (repeat step 2. till you satisfy the result.) 4. Power OFF While pressing [AE-L]+[INFO], turn the camera on. Firmware is desplayed on LCD. Press [MENU]->[MENU]->[INFO] within 5 seconds. You can see DEBUG mode screen. By pressing [Right key],Make [DEBUG MODE EN] to [DEBUG MODE DIS]. Then, Press [OK]. 5. Go out and enjoy!!

03-20-2009, 01:21 AM	#40
axl Veteran Member Join Date: Mar 2007 Location: Nove Zamky, Slovakia Photos: Gallery \| Albums Posts: 7,183	Originally posted by schmik It's on the K100d.... does this require a lens adjustment or camera adjustment? Some of the other shots i have taken at F4.5 are stunningly sharp. cheers mike I don't know if you can adjust AF on K100D. BTW can you pinpoint where was AF point? BR

03-20-2009, 01:33 AM	#41
schmik Veteran Member Join Date: May 2008 Location: Sydney Aus Photos: Gallery Posts: 527	I believe AF was on the card. But I can't be 100% sure. The instructions above are apparently for the k100d. I'll try it later.... if time allows. Batteries are charging now Am i correct to assume that it is a camera problem. I just double checked my shots with the fisheye (only other decent auto focus lens i own). They are soft soft soft wide open too. I just allways assumed it was the lens. Why can't this stuff just work straight from the box? Seriously. mike

03-20-2009, 01:37 AM	#42
axl Veteran Member Join Date: Mar 2007 Location: Nove Zamky, Slovakia Photos: Gallery \| Albums Posts: 7,183	good luck sorting it out, it's hard to judge anything with FE since because of it's FOV the DOF will be huge at any given apperture (at least that's how it works for corrected lenses) unless you're not focusing very very close. Anyway, retest with DA40, choose less busy scene (f.e. put one of your AA cells in front of white wall) and have a go, or put 3 or more AA cells staggered but spread wide enough so central AF point will catch only one. Let us know then... BR

03-20-2009, 02:18 AM	#43
benjikan Veteran Member Join Date: Jan 2007 Location: Paris, France Photos: Gallery Posts: 4,308 Original Poster	Originally posted by schmik OK... sorry for the attachments but couldn't bothered with flickr right now. These area ll crops, these were taken off a tripod all focused on the card (and then AF turned off, so the same focus for all shots). card1 = f2.8 card2 = f3.5 and so on until f/8. Is this normal. I'm just checking due to the reputation of this lens. cheers mike There is a problem. This is NOT normal. Either it is your auto focus alignment or you have a lemon. I use this lens professionally and if these results you have posted were what I was getting, I would most definitely not be using this lens and send it back to Pentax.

03-20-2009, 10:30 AM	#44
Marc Sabatella Veteran Member Join Date: Sep 2006 Location: Denver, CO Photos: Gallery Posts: 10,685	Originally posted by schmik I believe AF was on the card. But I can't be 100% sure. I don't think it's possible to be 100% sure based on the full size image you posted - the post/pipe the card was mounted to might have been the actual focus target chosen by the camera even if you specifically chose center point. That is, the card does not appear to cover the entire center AF sensor. I agree that what you are seeing is definitely a matter of the f/2.8 shots being out of focus, but I certainly would not be leaping to any conclusions that there is a malfunction here. You need to repeat your test using a setup in which the camera cannot possibly choose any focus point other than the intended one (do that by choosing a larger target, or by shooting from a shorter distance). Quote: I just double checked my shots with the fisheye (only other decent auto focus lens i own). They are soft soft soft wide open too. I just allways assumed it was the lens. With an extreme wide angle lens, it's next to impossible to force the camera to focus on any single object, since most objects will be rendered much smaller than any of the AF sensors. Plus DOF is pretty darned wide. Which is to say, it wouldn't seem to likely to me that this is what is going on. But again, you'd have to do a controlled focus test (discussions of this topic are pretty much a weekly event here; also jus browse around the net) to be able to say for sure.

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