Backfocus problems need to be fixed by Nikon?

Started Sep 11, 2012 | Discussions
BijouStGuy
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Re: Said it wrong
In reply to Mako2011, Sep 11, 2012

Hi Mako,
Thank you for the clarification.
Richard

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Nikon D80 Nikon D7000 Nikon D610 Nikon AF-S DX Nikkor 35mm f/1.8G Nikon AF-S Nikkor 70-300mm f/4.5-5.6G VR +6 more
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Reilly Diefenbach
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Re: 35mm/F1.8 lens is bad?
In reply to David Lal, Sep 11, 2012

It seems to me that everyone who gets this lens runs out and shoots everything in sight at 1.8, searching for instant photgraphic meaningfullness at the cost of a thoroughly difficult task beyond the brief of a consumer camera of focusing on the eye or other intended target with a depth of field of a few centimeters. Forgetting the twin facts that it takes years of practice and better equipment to get consistently good at this, and that wafer-thin DOF is a dreadful cliche by now. The fact that this lens is pretty sharp wide open but can only hit focus 2 out of 3 times at best doesn't help the newbies at all. The best I could advise with that lens at that setting is the Ray Soares nostrum of keep tapping that focus button and take enough shots that there will be keepers in the batch.

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hrogersiii
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Re: Backfocus problems need to be fixed by Nikon?
In reply to shutterbud, Sep 11, 2012

I recommend that you purchase a Lensalign kit and follow the instructions to calibrate the lens inquestion.

With my D7000, I discovered that several of my lenses were not as crisp as they should have been. My brother, a professional, discovered the same thing with his array of lenses and his D4 and D800 configurations.

If you follow that process, it should correct the issues you are having.

Iny my humble opinion, it is important to remember that these lenses are mass produced and these types of variances in the process are not always caught in the QA/QC process due to the amount of time it would take for each lens.

Hope this helps.

Harry Rogers

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sshoihet
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Re: 35mm/F1.8 lens is bad?
In reply to Reilly Diefenbach, Sep 11, 2012

Ah, just wait until the D600 starts rolling out and the DOF is even shallower

Groups and children, i rarely shoot under f4, individuals f2.8.

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nfpotter
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Re: Backfocus problems need to be fixed by Nikon?
In reply to hrogersiii, Sep 11, 2012

hrogersiii wrote:

I recommend that you purchase a Lensalign kit and follow the instructions to calibrate the lens inquestion.

With my D7000, I discovered that several of my lenses were not as crisp as they should have been. My brother, a professional, discovered the same thing with his array of lenses and his D4 and D800 configurations.

If you follow that process, it should correct the issues you are having.

Iny my humble opinion, it is important to remember that these lenses are mass produced and these types of variances in the process are not always caught in the QA/QC process due to the amount of time it would take for each lens.

Hope this helps.

Harry Rogers

Unfortunately, Harry, it doesn't. The OP owns a camera with no AF Fine Tune ability.

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Mako2011
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Re: Said it wrong
In reply to mosswings, Sep 11, 2012

mosswings wrote:

Mako2011 wrote:

BijouStGuy wrote:

Hi Mako,

Could you explain what you mean by "...the 35mm plane of focus falls outside the DOF consistently at f/1.8..". Thanks for your time.
Richard

I actually said it wrong. I should have said if the POINT OF FOCUS falls outside the DOF consistently. The plane of focus is the point directly between the farthest point that starts to show focus blur and the nearest point that shows focus blur (center of DOF). DOF is that range between closest in focus point and farthest in focus point. Ideally we want the point we focus on to coincide with the center of DOF or focus plain (with some minor caveats).

I think it's unacceptable if the Point of Focus consistently falls outside the DOF (and it can not be corrected by AF fine tune if the camera has that).....Nikon should fix that.

Thank you for correcting me. Hope I haven't confused more.

Mako, sorry to be persnickety, but technically it isn't possible for the point of focus to fall outside of the DOF. Depth of field is a derived phenomenon; it's the zone AROUND the point of focus that displays less than a certain amount of blur. I think that what you may be trying to say is that the positioning accuracy of the focus plane will be less than some fraction of the depth of field expected for that combination of FL, aperture, and subject distance.

Thanks, got to get my terms in order Point of Focus is how I'm referring to the point/subject/place you are trying to focus on. Point the camera at a flat target in the distance (that target is now the Point of Focus) with the focus box on it and af confirmed....the if the target (POF) falls outside the DOF of the actual resulting picture...and can not be corrected with AF-Fine tune....then Nikon should fix it.

I need a diagram....that somebody labels correctly for me

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shutterbud
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Re: Said it wrong
In reply to Mako2011, Sep 12, 2012

Thanks everyone for all the constructive comments. [and thanks DPR for the "ignore user" function :-)]

I plan to spend some time using the kit lens to see if the same problem manifests itself, though obviously with much smaller aperture comes less room for error. I too have noticed very few q.c. issues with the D5100 body coming up on fora and found the comments on the limitations of the 35mm lens helpful. I've definitely been given food for thought.

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jjlad
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Re: Said it wrong
In reply to shutterbud, Sep 12, 2012

shutterbud wrote:

Thanks everyone for all the constructive comments. [and thanks DPR for the "ignore user" function :-)]

I plan to spend some time using the kit lens to see if the same problem manifests itself, though obviously with much smaller aperture comes less room for error. I too have noticed very few q.c. issues with the D5100 body coming up on fora and found the comments on the limitations of the 35mm lens helpful. I've definitely been given food for thought.

Here's a simple way to see where your lens is focusing.
Find a lawn with nice medium height grass.
Stick a golf tee in the grass.

Walk back to what you'd think is a normal shooting distance for the lens you want to check.
Shoot the tee.
Examine the photo.

The grass right around it should be clearly and crisply in focus. If the grass behind is in focus its back focusing and vice versa.

Repeat with your other lenses and if zooms, try them at different focal lengths to see if the error is consistent.

If you have to send the gear in to be calibrated send along the images on a disk or an sd card clearly labelled as yours and request it be returned.

Hope that helps.
--
http://www.flickr.com/photos/jjlad/sets/

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shutterbud
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Re: Said it wrong
In reply to jjlad, Sep 12, 2012

As I have said several times, I am certain I am experiencing backfocus with this lens at wider apertures. I just need to determine why and by how much. I will update this thread as more info becomes available.

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Deleted1929
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Re: Said it wrong
In reply to shutterbud, Sep 12, 2012

Hope it works out for you.

I'd suggest starting a new thread when or if you need to. If you re-enter this one you'll just get bogged down with people who only read some of the early posts and then start the original discussion all over again.

-- hide signature --

StephenG

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shutterbud
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Re: Said it wrong
In reply to Deleted1929, Sep 12, 2012

Fair comment.

I must admit to being nonplussed by the strength of feeling this seemingly innocent thread generated. I don't know if it's the complex nature of photography itself or simply the consequence-free nature of internet forums.

Nevertheless, happy snapping to you all.

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nfpotter
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Re: Said it wrong
In reply to jjlad, Sep 12, 2012

jjlad wrote:

shutterbud wrote:

Thanks everyone for all the constructive comments. [and thanks DPR for the "ignore user" function :-)]

I plan to spend some time using the kit lens to see if the same problem manifests itself, though obviously with much smaller aperture comes less room for error. I too have noticed very few q.c. issues with the D5100 body coming up on fora and found the comments on the limitations of the 35mm lens helpful. I've definitely been given food for thought.

Here's a simple way to see where your lens is focusing.
Find a lawn with nice medium height grass.
Stick a golf tee in the grass.

Walk back to what you'd think is a normal shooting distance for the lens you want to check.
Shoot the tee.
Examine the photo.

The grass right around it should be clearly and crisply in focus. If the grass behind is in focus its back focusing and vice versa.

Repeat with your other lenses and if zooms, try them at different focal lengths to see if the error is consistent.

If you have to send the gear in to be calibrated send along the images on a disk or an sd card clearly labelled as yours and request it be returned.

Hope that helps.
--
http://www.flickr.com/photos/jjlad/sets/

That is NOT a good test, at all.

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pavi1
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Re: Backfocus problems need to be fixed by Nikon?
In reply to nfpotter, Sep 12, 2012

Does the D5100 allow you to lock the selected focus point? I do not see a locking switch on the back of the camera is why I ask. I had a D40 for a short time and it would focus on my intended subject and before I could complete pushing the shutter, the focus would jump to something behind the subject as your camera appears to have done. Only rarely would it change to something in front, of course there is rarely anything in front of the subject.

Harry Rogers

Unfortunately, Harry, it doesn't. The OP owns a camera with no AF Fine Tune ability.

-- hide signature --

Everything happens for a reason. #1 reason: poor planning
WSSA #44

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Mako2011
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Great tool
In reply to nfpotter, Sep 12, 2012

nfpotter wrote:

jjlad wrote:

shutterbud wrote:

Thanks everyone for all the constructive comments. [and thanks DPR for the "ignore user" function :-)]

I plan to spend some time using the kit lens to see if the same problem manifests itself, though obviously with much smaller aperture comes less room for error. I too have noticed very few q.c. issues with the D5100 body coming up on fora and found the comments on the limitations of the 35mm lens helpful. I've definitely been given food for thought.

Here's a simple way to see where your lens is focusing.
Find a lawn with nice medium height grass.
Stick a golf tee in the grass.

Walk back to what you'd think is a normal shooting distance for the lens you want to check.
Shoot the tee.
Examine the photo.

The grass right around it should be clearly and crisply in focus. If the grass behind is in focus its back focusing and vice versa.

Repeat with your other lenses and if zooms, try them at different focal lengths to see if the error is consistent.

If you have to send the gear in to be calibrated send along the images on a disk or an sd card clearly labelled as yours and request it be returned.

Hope that helps.
--
http://www.flickr.com/photos/jjlad/sets/

That is NOT a good test, at all.

I've actually been doing it and am surprised and how accurate it is regards getting a quick check if things might be off. I was surprised, but it is very useful. Almost as good as a quick LiveView vs PDAF comparison....not a replacement for a proper fine tune...but a great tool in the old bag.

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Reilly Diefenbach
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Re: Said it wrong
In reply to nfpotter, Sep 12, 2012

Potter is correct. The shooting of tiny slanted targets is a one way ticket to the funny farm. Don't go where so many have slid down the slippery slope into terminal tweakery. This is a consumer camera with a good basic lens, not an artificial intelligence machine.

Print out the test chart here:
http://www.graphics.cornell.edu/~westin/misc/ISO_12233-reschart.pdf

and tape it to the fridge and put the camera on a tripod with remote, using autofocus. Compare manually focused with magnified live view to autofocus at 200% in ViewNX. Try it handheld with a high enough shutter speed. If the camera passes this test, then go out and take photos, lots of them. If the lens isn't consistent, then get a better one.

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nfpotter
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Re: Backfocus problems need to be fixed by Nikon?
In reply to pavi1, Sep 12, 2012

pavi1 wrote:

Does the D5100 allow you to lock the selected focus point? I do not see a locking switch on the back of the camera is why I ask. I had a D40 for a short time and it would focus on my intended subject and before I could complete pushing the shutter, the focus would jump to something behind the subject as your camera appears to have done. Only rarely would it change to something in front, of course there is rarely anything in front of the subject.

Harry Rogers

Unfortunately, Harry, it doesn't. The OP owns a camera with no AF Fine Tune ability.

-- hide signature --

Everything happens for a reason. #1 reason: poor planning
WSSA #44

If your focus point is "jumping" ANYWHERE, you have some sort of automatic focus mode on. NOT recommended.

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pavi1
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Re: Backfocus problems need to be fixed by Nikon?
In reply to nfpotter, Sep 12, 2012

D40 had no way to lock the focus point, none. I have not used a D5100 or read the manual, that is why I asked about the ability to select and lock a focus point.

nfpotter wrote:

pavi1 wrote:

Does the D5100 allow you to lock the selected focus point? I do not see a locking switch on the back of the camera is why I ask. I had a D40 for a short time and it would focus on my intended subject and before I could complete pushing the shutter, the focus would jump to something behind the subject as your camera appears to have done. Only rarely would it change to something in front, of course there is rarely anything in front of the subject.

Harry Rogers

Unfortunately, Harry, it doesn't. The OP owns a camera with no AF Fine Tune ability.

-- hide signature --

Everything happens for a reason. #1 reason: poor planning
WSSA #44

If your focus point is "jumping" ANYWHERE, you have some sort of automatic focus mode on. NOT recommended.

-- hide signature --

Everything happens for a reason. #1 reason: poor planning
WSSA #44

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pavi1
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Re: Backfocus problems need to be fixed by Nikon?
In reply to pavi1, Sep 12, 2012

Just to be sure we are on the same page, I always shoot single point or whatever it is called on D40.

pavi1 wrote:

D40 had no way to lock the focus point, none. I have not used a D5100 or read the manual, that is why I asked about the ability to select and lock a focus point.

nfpotter wrote:

pavi1 wrote:

Does the D5100 allow you to lock the selected focus point? I do not see a locking switch on the back of the camera is why I ask. I had a D40 for a short time and it would focus on my intended subject and before I could complete pushing the shutter, the focus would jump to something behind the subject as your camera appears to have done. Only rarely would it change to something in front, of course there is rarely anything in front of the subject.

Harry Rogers

Unfortunately, Harry, it doesn't. The OP owns a camera with no AF Fine Tune ability.

-- hide signature --

Everything happens for a reason. #1 reason: poor planning
WSSA #44

If your focus point is "jumping" ANYWHERE, you have some sort of automatic focus mode on. NOT recommended.

-- hide signature --

Everything happens for a reason. #1 reason: poor planning
WSSA #44

-- hide signature --

Everything happens for a reason. #1 reason: poor planning
WSSA #44

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Mako2011
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Re: Said it wrong
In reply to Reilly Diefenbach, Sep 12, 2012

Reilly Diefenbach wrote:

Potter is correct. The shooting of tiny slanted targets is a one way ticket to the funny farm. Don't go where so many have slid down the slippery slope into terminal tweakery. This is a consumer camera with a good basic lens, not an artificial intelligence machine.

Agreed but, note what was indicated

" Walk back to what you'd think is a normal shooting distance for the lens you want to check. "

I've gone out and given it a go...it really is a quick and easy way to get a feel for if more focus investigation is required. Distance is large, light is usually good, and lock-on has been easy. Just a quick check...not a method to a final AF tune.

Print out the test chart here:
http://www.graphics.cornell.edu/~westin/misc/ISO_12233-reschart.pdf

and tape it to the fridge and put the camera on a tripod with remote, using autofocus. Compare manually focused with magnified live view to autofocus at 200% in ViewNX. Try it handheld with a high enough shutter speed. If the camera passes this test, then go out and take photos, lots of them. If the lens isn't consistent, then get a better one.

AGREED!!!

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Reilly Diefenbach
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Re: Said it wrong
In reply to Mako2011, Sep 12, 2012

Mako, how many focus threads would you guess we've seen with the 351.8?

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