Back Focus Revised - New Info...

Started Dec 29, 2005 | Discussions
PhotoLeon1935 Senior Member • Posts: 2,305
Back Focus Revised - New Info...

Thanks to Wally OZ and several other contributors, I have made some changes in my D70 Backfocus web page. Wally pointed out that the Number 2 adjustment in the mirror assembly is for manual focus instead of what I described as sensor position adjustment. If you are one of the people who used my procedure to correct backfoucus you should read the new instructions. It may be that you have given up trying to use manual focus once you got auto focus to work properly.

Although many people were kind enough to thank me for helping solve their problem they are all still at risk for having faulty manual focus adjustment. Please help me to identify those who need to read the new procedure by keeping this thread alive until all have been warned.

As Wally has pointed out, there are still some recent cameras being delivered with this fault. If you have not been satisfied with your image sharpness, you owe it to yourself to at least look. Most cameras are Ok, but a few need to be tweaked.

Here is the page:

http://www.leongoodman.com/d70focus.html

After you have seen the new page, please comment in this thread to help others who might need this.

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TANSTAAFL - There aint no such thing as a free lunch.
If it sounds too good to be true it just might be so.
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OP PhotoLeon1935 Senior Member • Posts: 2,305
Re: Back Focus Revised - New Info...

Boy, it doesn't take long to slip off of page one. Maybe you should add a comment and then go to the web page.

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TANSTAAFL - There aint no such thing as a free lunch.
If it sounds too good to be true it just might be so.
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http://www.leongoodman.com

Wally OZ Veteran Member • Posts: 5,194
Canon AF works better

Hi Leon,

Just helping it a long, the subject is not controversial enough

A bit more.

Only sepia ducks stay on the front page here for days on end.

There, now that should get some attention.

Seriously, I did have a look at your current page and cannot fault it, thanks.

fishcatcher Senior Member • Posts: 2,511
BF in a brand new D200

That ought to get more attention than sepia ducks, kitty cats, and Aunt Tessie visiting for Xmas.

Masa_K Regular Member • Posts: 300
Re: Back Focus Revised - New Info...

Thanks for the info. I did the test, and I got different results, depending on the lens. One lens did back focus, but the other did front focus.

I thought maybe, I messed up the focus, so I tried twice per each lens, and got the same results both time.

What does this mean?

Thanks
Masa

Hal Fisher Senior Member • Posts: 2,005
Re: Back Focus Revised - New Info...

I had the same problem were one lens front focused badly (35/2) while a 18-70 backed focused. I adjusted it the old way with the front most screw (supposedly just for manual focusing) and turning it clockwise about 1/2 turn correct both problems. Weird huh?

Hal

OP PhotoLeon1935 Senior Member • Posts: 2,305
Re: Back Focus Revised - New Info...

Wallly suggests to close each lens 1/2 to 1 stop and try again. Some lenses are compromised at their outer edge and cause faulty focus shift. Sometimes a mechanical coupled focus will be different from the electrical wave motor focus. Example 50mm f1.4 is mechanical, kit lense is wave motor. There are a couple of theories about this. I now have an IR/UV cut filter on my kit lens and it blocks IR totally and may focus differently now.

Summary: I don't know.
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TANSTAAFL - There aint no such thing as a free lunch.
If it sounds too good to be true it just might be so.
http://www.pbase.com/photoleon
http://www.leongoodman.com

Jan De Smet Regular Member • Posts: 353
Re: Back Focus Revised - Step 2

Hi Leon,

why do you think adjustment in step 2 (manual focus) might misalign the focus sensor and sensor box in viewfinder? Is that because tilting the mirror (your drawing) tilts the image in the viewfinder a bit?

Jan
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¡Nikon! ¡Por supuesto!

mszerg Regular Member • Posts: 175
Canon AF depends on light source

and focuses on different places under daylight and fluorescent

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Jan De Smet Regular Member • Posts: 353
Re: Leon G: Back Focus Revised - Step 2

Hi Leon - could you have a last look at this?
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Hal Fisher Senior Member • Posts: 2,005
You'll have to contact him directly...

I think he expects people to respond to this thread just to keep it on top so your request might get ignored by him. Go to the original post under "Posted by" and send him a direct email if you want a question answered.

Hal

Petison Regular Member • Posts: 136
You Cannon be serious...

You perfectly know that the one that really shines out is... Pentax!
Regards

 Petison's gear list:Petison's gear list
Sony RX100 III Nikon D750 Sony a6500 Nikon D850 Nikon AF-S Nikkor 300mm f/4D ED-IF +6 more
OP PhotoLeon1935 Senior Member • Posts: 2,305
Re: You'll have to contact him directly...

Thanks, Hal

Wally is in Australia, Jan is in Belgium and I am in Idaho, USA. Finding us all awake at the same time is a real trick. I slept late this morning.

And now Jan:

Yes, the little mirror fulcrum point is part way down the edge of the large mirror. Change the large mirror and the small one needs to be adjusted again. Hmmm... I am thinking about whether it is wise to start with cam 1.......

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TANSTAAFL - There aint no such thing as a free lunch.
If it sounds too good to be true it just might be so.
http://www.pbase.com/photoleon
http://www.leongoodman.com

OP PhotoLeon1935 Senior Member • Posts: 2,305
Re: Canon AF depends on light source

I thought you might be Sergei Khizhiy by your id but I see you are not. Do you know if he is still active in Russian speaking photo galleries. He is the one who started all this. I saw you gallery and like what you do.
--
TANSTAAFL - There aint no such thing as a free lunch.
If it sounds too good to be true it just might be so.
http://www.pbase.com/photoleon
http://www.leongoodman.com

Jan De Smet Regular Member • Posts: 353
Re: well Leon...

now you got me excited to start testing and if necessary adjust, and now you back off....
I'll test the focus first
--
¡Nikon! ¡Por supuesto!

OP PhotoLeon1935 Senior Member • Posts: 2,305
Re: well Leon...

But you have no sunlight at this time of day. Remember what Wally said.
--
TANSTAAFL - There aint no such thing as a free lunch.
If it sounds too good to be true it just might be so.
http://www.pbase.com/photoleon
http://www.leongoodman.com

Wally OZ Veteran Member • Posts: 5,194
Jan it is NOT that difficult

Jan,

There is NO RISK involved at all, you can put the cams back exactly where they had been, you do know to remember the starting position of the cams, that is not difficult to do as you will see if you do try it.

You need to thoroughly test FIRST, doing this accurately is possibly more important than the adjustment as your camera body may require no adjustment at all, you may have one lens that requires service.

You only adjust your camera body if testing with more than 2 lenses reveals a problem i.e a TEST CONFIRMED NEED to make adjustments to the camera body.

Which cam you start with will not make much of a difference as we already knew the 2 cams interact, and we already knew you have to go back and re test both auto focus and manual focus.

Other than trying to perhaps arrive at a quicker method, nothing has changed.

The other thing that hasn't changed is that adjustment works the more picky you are and the more effort you put in the better the results, it sure beats arguing with service people and waiting.

All your questions make this sound so complicated, when in fact it is NOT complicated at all as anyone who has actually done it will confirm.

On The 2 cams issue, here is my 2 cents.

I adjusted auto focus then used the camera for a while, till I found that manual focus wasn't spot on.

I then adjusted manual focus using my Sigma 50-500 at 500mm and the rough bark on a tree 60 feet away.

The adjustment to the front cam was very little.

Re testing auto focus on all lenses I found no need to re adjust auto focus [the rear cam] at all it was still spot on.

The lenses I tested on my D70 purchased January 2005;

25 year old Nikkor 50 mm f2 [manual focus only].
Nikkor 18-70 Kit lens,
Sigma 18-50 2.8.
Sigma 150 2.8 macro,
Sigma 70-200 2.8,
Sigma 80-400 OS,
Sigma 50-500 Bigma.

On the D70 that I purchased in August 2004 [subsequently stolen] I tested

25 year old Nikkor 35mm f1.4 [manual focus only]
25 year old Nikkor 50mm f2 [manual focus only]
Nikkor 18-70 kit lens.

That body did NOT require any fcous adjustment.

mszerg Regular Member • Posts: 175
I'm not, but... :-)

asked google what does he knows about Sergei and he told me th following

http://www.pbase.com/khizhiy/root&view=tree
http://dvdhelp.narod.ru/D70_back_focus.html

also found Sergei's e-mail: khizhiy@online.ru

so you can try to contact him

PS:
Thanks for visiting my gallery

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Jan De Smet Regular Member • Posts: 353
Re: I hope I'm NOT that difficult

Leon, Wally, I was just kidding. of course I'm not afraid to test. I will find a way to mark the initial marking positions.

And as Leon correctly put: when I wrote previous reply it was pitch dark here. This afternoon I'm going to get me a decent tripod that can support well the D70 with the 70-200VR, current one doesn't, is too cheap.

And yes...wait for a clear and sunny day before doing the testing. Now it's freezing, snowing and very grey.
If I run into trouble then, I'll find you guys...(LOL)
Thnaks a lot
--
¡Nikon! ¡Por supuesto!

Wally OZ Veteran Member • Posts: 5,194
Re: I hope I'm NOT that difficult

Hey Jan,

I am certain I would have mentioned this, come down under for instant sunny results, we a total fire ban for the new year wekend, it's hot and sunny.

Jan De Smet wrote:

Leon, Wally, I was just kidding. of course I'm not afraid to test.
I will find a way to mark the initial marking positions.
And as Leon correctly put: when I wrote previous reply it was pitch
dark here. This afternoon I'm going to get me a decent tripod that
can support well the D70 with the 70-200VR, current one doesn't, is
too cheap.
And yes...wait for a clear and sunny day before doing the testing.
Now it's freezing, snowing and very grey.
If I run into trouble then, I'll find you guys...(LOL)
Thnaks a lot
--
¡Nikon! ¡Por supuesto!

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