D80 Backfocus

Wouldn't you know it, the first D80 I got my hands on in the local store had a slight backfocus problem. Having had this problem in the past, I am wary of this problem so a took my pocket backfocus target with me and took a test shot right on the counter of the store.



Since I help a lot of other people who have this problem I need for someone who has a D80 to lift the mirror and tell me what the rear mirror stop looks like. Someone has already discovered that the D2Hs has a different stop from the D70 and D50. The D70 only requires a 2 mm hex wrench shown below.



The D2Hs requires a special bent socket wrench designed especially for this adjustment. There is a concentric pin on top of a hex bolt for the autofocus mirror as seen here.



I would appreciate it if someone could peek into his new D80 and tell me which method Nikon chose for the two adjustments. The store that let me take these pictures would not let me touch the mirror to see for myself.

Thank you

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http://www.leongoodman.com/d70focusnew.html
http://www.pbase.com/photoleon
http://www.leongoodman.com

You could have tried another lens or two at the store just to make sure it's the body and not the lens.

I have adjusted my D70s to be right on for my 18-70mm lens, the 55-200mm lens is also right on, my 50mm 1.8 is slightly off but I normall manual focus this lens so that doesn't bother me.

This was my own 50 mm lens I brought with me. I know that some very wide lenses shift focus from their wide open to stopped down which was in this case f4. I cover that in my web page below. What I need to know to pass on to others is what kind of tool they are going to need to make an adjustment if they need to. The guy I am working with on his D2Hs works for a newspaper and has three bodies with the problem. He is going to make a tool for his adjustments. I just need to know if it is going to be a problem finding a tool for the D80.

Thanks

--
http://www.leongoodman.com/d70focusnew.html
http://www.pbase.com/photoleon
http://www.leongoodman.com

First, I personally appreciate your web site and instuctions as it made my D70s and 18-70mm focus right on as it was way off originally. One must realize that there are tons of front and back focusing Nikons out there with the owners really not knowing it and disgusted why their photos are not sharply focused. Nikon could have given us an external hex screw to turn to make the focus adjustment easier but I guess they figured most owners would really get the focus out of alignment and contantly send the camera back overloding their repair facilities.

That's great that you tried your own 50mm lens on the D80 so that eliminated that variable.

I am also interested in the D80 adjustment system as I may buy one depending on the reviews and I'm sure the D80 focus will need to be optimized again!

Leon,

You probably know the answer already, but I thought I'd post here anyway.

I too bought a D80 today and tested for backfocus. It has it! I had one lens (180mm AF-D) that has front focus on several bodies where all my other lenses are fine. This one lene focused fine on the D80 and 18-200, 50mm and a 18-55 focused back (the 50 being pretty much spot one, where the AF-S lenses very slightly back, even after the adjustment).

My D70s has been adjusted for the rest of my lenses and front focuses with the 180mm.

Focus chart or flat target - same thing.

I adjusted the D80 EXACTLY the same way I did the D70s - 2mm hex wrench, rear socket. Backfocus is now mostly eliminated.

Faster than a trip to the store, I would say.

I need to retest in daylight at distant objects before final verdict, and to possibly adjust focus more precisely...

Am I unlucky, or too critical or just plain wrong???? My first D80 backfocused with all but one of my lenses (bad one, needs repair anyway).

I got my second D80 today with the 18-135 kit lens. I also have the 18-200 VR (currently trying to decide which one to keep). Both these lenses seem to show backfocus with the D80. Similarly my 50mm AF-D F/1.4 backfocuses too.

I only had time to do a quick test today and will be testing more rigorously tonight, but what I see is not very encouraging. Here are two center crops at 135mm with both lenses as well as the full image to get an idea of the focus target. Look at the stamp book edge to see how the DOF is entirely behind the target.

I think I can adjust the camera and will do it once I confirm this is indeed an issue, but two out of two...

The "test setup" - full image. Focus is with narrow center sensor. No reframing was done.



All below are 100% crops:

18-200 VR at 135mm:



18-135 at 135mm (see how much sharper it is than the VR at this length? At 50mm it is reversed - the VR is sharper)



18-135 at 135mm (the white threads on the right are sharper (they are about 1/4 inch to the rear from the front ones). the focus line should have been near the middle or slightly infront of it on the paper clip - instead it is towards the back of it)



18-200 VR at 200mm:

Same problem with 18-70 AF-S under 50mm, and 28-80G under 35mm for real life targets.

The focus test confused me:

28-80G fails only on 28mm, 18-70 fails on 18mm, 25mm and 70mm.

My previous test:

70-300G:

Front focus on 300mm, good at 180mm, backfocus on 70mm

I think it could be the body

My original post asked the question whether the D80 is exactly the same inside the image box. Does it look like two 2 mm hex wrench pegs?

I will volunteer that unless you use a target that will only focus in one spot, you cannot tell a thing about focus. The camera may also be assembled so that the actual sensor is not squarely in the center of the focus rectangle. This is a critical thing to know. Sometimes the sensor is like the red cross shown below.



Here is how to frame a focus point with nothing but white space around the focus point. When the target is framed like this, only the center line will activate focus in the proper plane.



This target can be downloaded at the link below.

--
http://www.leongoodman.com/d70focusnew.html
http://www.pbase.com/photoleon
http://www.leongoodman.com

PhotoLeon1935 said:

My original post asked the question whether the D80 is exactly the
same inside the image box. Does it look like two 2 mm hex wrench
pegs?

Click to expand...

seems YES

I made Tim's test.

Not the "grouch" thing but to the question about the 2mm hex wrench. It is the same as in the D70/D70s (I may have burried this info in my original response to you).

I did the 45 degree test as well as parallel target tests with nothing to focus on outside of the focus plane (be it a black line on a 45 degree test, or just nothing else close enough to a parallel 2-dimensional target). And yes, I tested to make sure if I move outside of these areas, then I get no focus lock).

By the way, I think your new focus chart with the fat center line seems to be more prone to error than the old one with the thinner line - the center line is too wide and I have observed that I can focus on its top or bottom part depending on whether I "approach" from the top white space or the bottom one. With 180mm AF-D F/2.8 lens at 2.8 this makes noticeable difference as there can be as much as 3-5mm focus shift due to the thickness of the line and the 45 degree position. Single thinner line or no line at all but a parallel target in the middle works better IMO to eliminate this type of error.

Tim and I worked together to agree that the horizontal line on a white field is accurate as long as the sensor sees the line. If the sensor is very low compared to the focus rectangle the camera is capable of focusing on the texture of the paper and can give false back focus results.

People who use a newspaper and/or yardstick haven't got a clue what the camera focused on.

Mapping the sensor position not only prevents false backfocus results but puts the photographer on guard when he has to focus in a busy environment such as a bird in a tree. Most of the early D70s had the sensor positioned like this:



--
http://www.leongoodman.com/d70focusnew.html
http://www.pbase.com/photoleon
http://www.leongoodman.com

how would i know I have this problem w/o testing for it?

kocho said:

Not the "grouch" thing but to the question about the 2mm hex
wrench. It is the same as in the D70/D70s (I may have burried this
info in my original response to you).

I did the 45 degree test as well as parallel target tests with
nothing to focus on outside of the focus plane (be it a black line
on a 45 degree test, or just nothing else close enough to a
parallel 2-dimensional target). And yes, I tested to make sure if I
move outside of these areas, then I get no focus lock).

By the way, I think your new focus chart with the fat center line
seems to be more prone to error than the old one with the thinner
line - the center line is too wide and I have observed that I can
focus on its top or bottom part depending on whether I "approach"
from the top white space or the bottom one. With 180mm AF-D F/2.8
lens at 2.8 this makes noticeable difference as there can be as
much as 3-5mm focus shift due to the thickness of the line and the
45 degree position. Single thinner line or no line at all but a
parallel target in the middle works better IMO to eliminate this
type of error.

Click to expand...

Kocho,

Are you using the large target or the pocket target for the long lens?

What do you think about setting up 3 to 5 pocket targets vertically in a stairstep fashion for long lenses? Similar to batteries on a table at different distances.

--
http://www.leongoodman.com/d70focusnew.html
http://www.pbase.com/photoleon
http://www.leongoodman.com

It is pretty easy to map the sensor, if that is what you are talking about. Put the camera in AF-C mode and half press the shutter. Swing the camera left and right and watch the lamp post go in an out of focus. Remember where it pops in from each direction. rotate the camera vertically and do the same watching the point the camera sees the post. It is not all that accurate but you can see the results immediately.

I used the horizontal handle on my tripod for my first test.

I used a painted match stick and printed background for my next test and the 50 mm lens which is gear driven so I could hear it shift focus.

I just did it with a square post and discovered the shadow side did not grab focus at the edge like the bright side.

You will find something that works!

--
http://www.leongoodman.com/d70focusnew.html
http://www.pbase.com/photoleon
http://www.leongoodman.com

I've been testing focussing of my D80 and D200 yesterday and got mixed results. Testing this accurately is really hard and is very dependent on the focus target. I noticed with batteries that the roundness and size has influence. I shot with a 50mm f/1.4 and found 'backfocus', until I realized that if the AF system had focussed on the edges of the centre battery focus is perfect. The front of the centre battery was off, the front of the second battery was in focus, but this was in the same plane as the edge of the centre batteries. hmmm.

As a sidenote to adjusting the focus yourself with a wrench: by doing that you change the alignment of the mirror(s), so the top and bottom focus points will be out of sync after adjustment.

PhotoLeon1935 said:

Kocho,

Are you using the large target or the pocket target for the long lens?

What do you think about setting up 3 to 5 pocket targets vertically
in a stairstep fashion for long lenses? Similar to batteries on a
table at different distances.

--
http://www.leongoodman.com/d70focusnew.html
http://www.pbase.com/photoleon
http://www.leongoodman.com

Click to expand...

--
Philip

Flashlight said:

I've been testing focussing of my D80 and D200 yesterday and got
mixed results. Testing this accurately is really hard and is very
dependent on the focus target. I noticed with batteries that the
roundness and size has influence. I shot with a 50mm f/1.4 and
found 'backfocus', until I realized that if the AF system had
focussed on the edges of the centre battery focus is perfect. The
front of the centre battery was off, the front of the second
battery was in focus, but this was in the same plane as the edge of
the centre batteries. hmmm.

Click to expand...

Use 9 volt batteries. They have flat sides. Ha!

Flashlight said:

As a sidenote to adjusting the focus yourself with a wrench: by
doing that you change the alignment of the mirror(s), so the top
and bottom focus points will be out of sync after adjustment.

Click to expand...

Theoretically the top and bottom are closer to proper focus when the mirror is 45 degrees at the same focus as the center sensor. Remember the front mirror is for Manual focus. The back is for electronic focus. Manufacturing tolerances should put everything in the proper plane, but if something needs to be adjusted it is the mirrors, no matter what.

Flashlight said:

PhotoLeon1935 said:

Kocho,

Click to expand...

Click to expand...

--
http://www.leongoodman.com/d70focusnew.html
http://www.pbase.com/photoleon
http://www.leongoodman.com

PhotoLeon1935 said:

Kocho,

Are you using the large target or the pocket target for the long lens?

Click to expand...

Large one. I have one printed at 11x14 sheet that I find has enough room above and under the center line to accomodate the 180mm AF-D with its approximately 5-6 feet minimum focusing distance.

PhotoLeon1935 said:

What do you think about setting up 3 to 5 pocket targets vertically
in a stairstep fashion for long lenses? Similar to batteries on a
table at different distances.

Click to expand...

I only use one and move the camera or target back and fourth - I find this "safer" so that the "wrong" target does not accidentally get in focus.

PhotoLeon1935 said:

--
http://www.leongoodman.com/d70focusnew.html
http://www.pbase.com/photoleon
http://www.leongoodman.com

Click to expand...

Flashlight said:

As a sidenote to adjusting the focus yourself with a wrench: by
doing that you change the alignment of the mirror(s), so the top
and bottom focus points will be out of sync after adjustment.

Click to expand...

I have stayed away from this forum for ages.

Your statement is likely based on a certain "expert" who posts his expert rubbish on every forum, makes me wonder how such an imminent expert has so much free time on his hands.

The statement is simply NOT correct!!

My D70 after I adjuetsed using the 2 cam screws to correct backfocus has all the sensors correctly matching the LCD markings.

It may well be that some don't match but they arae most likley like that BEFORE any adjuetment is made.

I any case it DOESN'T MATTER so long as YOU KNOW how the sensors are aligned relative to the LCD markings for that once in a lifetime bird shot or whatever.

Leon thanks for asking the question, good to know the D80 can also be adjusted. Good to see you are ignoring that "expert" I mentioned earlier, by the way it's not anyone that has posted in this thread, so far, but I am sure he will add his expertise soon.

I think you guy should try this back focus test chart before making a conclusion about your camera.

I found this off from some other camera site. This chart is very well made. And very accurate too.

http://rapidshare.com/files/5112197/FocusTestBoard.pdf

I always believe that back focus is cause by the lens moreless the camera body itself.

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You are seeing from my eyes!!!
Derek....
Nikon D80,
Olympus SP350 w/0.7x / FL-40 Flash Gun
Panasonic FZ 2 w/Wcon~07, FX-7
Sony DSC_P1~717
Fujifilm F601