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BF not fixed... please help a desperate d70 newbie!

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Paul Tatterson

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Hi everyone,

I bought my new D70 about a month ago and sent it back after a week because of BF (I'm in the UK). I got it back yesterday, but I don't think anything has changed. I only have the 18-70, and the problem is most noticable (to me) at wide angle, and (obviously) with the lens wide open. I'm pretty gutted about the whole thing... this was by no means a small investment for me!

I don't have a printer at the moment and and no way of printing a a focus test chart. Unfortunately I don't have any web host set up so can't post pics.

First question:

A change in focal length (zoom) after focus lock has been acheived should not affect focus, right? i.e if I focus on a point at full tele, then zoom out to full wide, the the lens should remain in focus right? Well it doesn't... if I re-depress the shutter after zooming out (or in) it very clearly adjusts it's focus. Please correct me if I'm wrong here (I'd like to be wrong).

Second question:

Regarding the focus points in the viewfinder: does an object need to completely cover the whole focus point in order for it to detect it properly? Or is a object dead in the centre of the focus area but filling only half of it ok?

I've come from using a G3 most recently and have been craving for more control over focus (and everything else!), but I think I need some tips on this one.

I have used SLRs in the past, but I wasn't so 'in to it' back then.

I really want this to work out... don't want to have to swap it for another one (that will takes weeks anyway), only to find the same problem. And there aren't any other suitable options for my needs/budget other than the d70.

Many thanks for any help!
Paul
 
1. Go to http://www.photobucket.com and you can a free account that can link pics to this site. You need to copy & paste the URl once you have uploaded the photo to their site. The images will be limited to 250k so you will need to crop and downgrade quality of jpegs.

2. Focus will change with focal length - half-press shutter again after zooming and you should see it focus.

3. You need to focus on something that has a distinct contrast WITHIN the focus box.
Paul Tatterson said:
Hi everyone,

I bought my new D70 about a month ago and sent it back after a week
because of BF (I'm in the UK). I got it back yesterday, but I
don't think anything has changed. I only have the 18-70, and the
problem is most noticable (to me) at wide angle, and (obviously)
with the lens wide open. I'm pretty gutted about the whole
thing... this was by no means a small investment for me!

I don't have a printer at the moment and and no way of printing a a
focus test chart. Unfortunately I don't have any web host set up
so can't post pics.

First question:
A change in focal length (zoom) after focus lock has been acheived
should not affect focus, right? i.e if I focus on a point at full
tele, then zoom out to full wide, the the lens should remain in
focus right? Well it doesn't... if I re-depress the shutter after
zooming out (or in) it very clearly adjusts it's focus. Please
correct me if I'm wrong here (I'd like to be wrong).

Second question:
Regarding the focus points in the viewfinder: does an object need
to completely cover the whole focus point in order for it to detect
it properly? Or is a object dead in the centre of the focus area
but filling only half of it ok?

I've come from using a G3 most recently and have been craving for
more control over focus (and everything else!), but I think I need
some tips on this one.

I have used SLRs in the past, but I wasn't so 'in to it' back then.

I really want this to work out... don't want to have to swap it for
another one (that will takes weeks anyway), only to find the same
problem. And there aren't any other suitable options for my
needs/budget other than the d70.

Many thanks for any help!
Paul
Click to expand...
 
Also you will need a tripod or something else for stable shooting. Keep in mind that you need a shallow depth of field to spot focus errors.

With kit lens, use 70mm focal length + smallest aperture (f/4.5?) + focus distance at 40cm (NOT the minimum of 38, as anything in front will not be in focus).
Buckrogers said:
2. Focus will change with focal length - half-press shutter again
after zooming and you should see it focus.

3. You need to focus on something that has a distinct contrast
WITHIN the focus box.
Paul Tatterson said:
Hi everyone,

I bought my new D70 about a month ago and sent it back after a week
because of BF (I'm in the UK). I got it back yesterday, but I
don't think anything has changed. I only have the 18-70, and the
problem is most noticable (to me) at wide angle, and (obviously)
with the lens wide open. I'm pretty gutted about the whole
thing... this was by no means a small investment for me!

I don't have a printer at the moment and and no way of printing a a
focus test chart. Unfortunately I don't have any web host set up
so can't post pics.

First question:
A change in focal length (zoom) after focus lock has been acheived
should not affect focus, right? i.e if I focus on a point at full
tele, then zoom out to full wide, the the lens should remain in
focus right? Well it doesn't... if I re-depress the shutter after
zooming out (or in) it very clearly adjusts it's focus. Please
correct me if I'm wrong here (I'd like to be wrong).

Second question:
Regarding the focus points in the viewfinder: does an object need
to completely cover the whole focus point in order for it to detect
it properly? Or is a object dead in the centre of the focus area
but filling only half of it ok?

I've come from using a G3 most recently and have been craving for
more control over focus (and everything else!), but I think I need
some tips on this one.

I have used SLRs in the past, but I wasn't so 'in to it' back then.

I really want this to work out... don't want to have to swap it for
another one (that will takes weeks anyway), only to find the same
problem. And there aren't any other suitable options for my
needs/budget other than the d70.

Many thanks for any help!
Paul
Click to expand...
Click to expand...
 
Paul

Q1. Don't worry. You are wrong
Q2. Answer on page 73 of manual.

Backfocus should not be an issue with a new camera. Check your technique. Try "single area" focus.

Cheers

Matt
Paul Tatterson said:
Hi everyone,

I bought my new D70 about a month ago and sent it back after a week
because of BF (I'm in the UK). I got it back yesterday, but I
don't think anything has changed. I only have the 18-70, and the
problem is most noticable (to me) at wide angle, and (obviously)
with the lens wide open. I'm pretty gutted about the whole
thing... this was by no means a small investment for me!

I don't have a printer at the moment and and no way of printing a a
focus test chart. Unfortunately I don't have any web host set up
so can't post pics.

First question:
A change in focal length (zoom) after focus lock has been acheived
should not affect focus, right? i.e if I focus on a point at full
tele, then zoom out to full wide, the the lens should remain in
focus right? Well it doesn't... if I re-depress the shutter after
zooming out (or in) it very clearly adjusts it's focus. Please
correct me if I'm wrong here (I'd like to be wrong).

Second question:
Regarding the focus points in the viewfinder: does an object need
to completely cover the whole focus point in order for it to detect
it properly? Or is a object dead in the centre of the focus area
but filling only half of it ok?

I've come from using a G3 most recently and have been craving for
more control over focus (and everything else!), but I think I need
some tips on this one.

I have used SLRs in the past, but I wasn't so 'in to it' back then.

I really want this to work out... don't want to have to swap it for
another one (that will takes weeks anyway), only to find the same
problem. And there aren't any other suitable options for my
needs/budget other than the d70.

Many thanks for any help!
Paul
Click to expand...
 
Paul Tatterson said:
Hi everyone,

I bought my new D70 about a month ago and sent it back after a week
because of BF (I'm in the UK). I got it back yesterday, but I
don't think anything has changed. I only have the 18-70, and the
problem is most noticable (to me) at wide angle, and (obviously)
with the lens wide open. I'm pretty gutted about the whole
thing... this was by no means a small investment for me!

I don't have a printer at the moment and and no way of printing a a
focus test chart. Unfortunately I don't have any web host set up
so can't post pics.
Click to expand...
You can check for backfocus without printing test charts. Take 3 or 4 bottles/containers with clear sharp writing on them, and arrange them so that they are all at slightly different distances from the camera. Then experiment with that setup. Do it carefully, and don't forget to use a tripod! The kit lens isn't the sharpest lens in the universe (especially wide open) so it's easy to think you have backfocus when you actually don't.
Paul Tatterson said:
First question:
A change in focal length (zoom) after focus lock has been acheived
should not affect focus, right? i.e if I focus on a point at full
tele, then zoom out to full wide, the the lens should remain in
focus right? Well it doesn't... if I re-depress the shutter after
zooming out (or in) it very clearly adjusts it's focus. Please
correct me if I'm wrong here (I'd like to be wrong).
Click to expand...
A change in focal length absolutely will affect your focus. There are lenses (known as parfocal lenses) which will maintain focus while zooming, but the kit lens is not parfocal.
Paul Tatterson said:
Second question:
Regarding the focus points in the viewfinder: does an object need
to completely cover the whole focus point in order for it to detect
it properly? Or is a object dead in the centre of the focus area
but filling only half of it ok?
Click to expand...
No, it needs to cover the whole thing. If it's only half covering it anything could happen. Also Thom Hogan (www.bythom.com) has established that the outer focus areas don't exactly match the position/size of the markers in the viewfinder so you need to allow for that. Be sure to give the camera a nice big well-lit contrasty area to focus on, while you're testing for backfocus.
Paul Tatterson said:
I've come from using a G3 most recently and have been craving for
more control over focus (and everything else!), but I think I need
some tips on this one.

I have used SLRs in the past, but I wasn't so 'in to it' back then.

I really want this to work out... don't want to have to swap it for
another one (that will takes weeks anyway), only to find the same
problem. And there aren't any other suitable options for my
needs/budget other than the d70.
Click to expand...
I highly recommend getting a 50mm f/1.8 lens. It's a wonderful lens, great value for money, and it'll give you something to compare the kit lens to.
Paul Tatterson said:
Many thanks for any help!
Paul
Click to expand...
 
Want my honest opinion. Keep the camera, exchange the lens.

I know that might be difficult, depends on where and how you bought it.

If you bought from a shop, not the Internet you should have an option, particularly if you can demonstrate this to them, and my hunch is you will be able to.

Simple test I did in a pro shop, was place two pens in a beaker/cup, one in front of the other and focussed on the front one. With kit lens the one behind was more in focus, not with the others. All you then have to do is show them the image, from you flash card. You dont need to print stuff out.

I tried with kit lens on several bodies and always got the same problem. Have tried other lenses e.g. 24-85 AFS, and 24-120 VR, no problem. It appears that each lens can behave differently, but this BF (IMO) is particularly prevelant with that lens. This might be your quickest solution. (FYI, I got refund on my first one, and then bought body and 24-120 VR).

Other info, The focus sensor in the middle is a cross hair. In the other four areas its a horizontal line. do a search here and you will find some pics demonstrating it. They are not necessarily centred where you think they are either. Think of them as approximate, but they are not the same as the depiced rectangles.

Good luck.

Adrian.
Paul Tatterson said:
Hi everyone,

I bought my new D70 about a month ago and sent it back after a week
because of BF (I'm in the UK). I got it back yesterday, but I
don't think anything has changed. I only have the 18-70, and the
problem is most noticable (to me) at wide angle, and (obviously)
with the lens wide open. I'm pretty gutted about the whole
thing... this was by no means a small investment for me!

I don't have a printer at the moment and and no way of printing a a
focus test chart. Unfortunately I don't have any web host set up
so can't post pics.

First question:
A change in focal length (zoom) after focus lock has been acheived
should not affect focus, right? i.e if I focus on a point at full
tele, then zoom out to full wide, the the lens should remain in
focus right? Well it doesn't... if I re-depress the shutter after
zooming out (or in) it very clearly adjusts it's focus. Please
correct me if I'm wrong here (I'd like to be wrong).

Second question:
Regarding the focus points in the viewfinder: does an object need
to completely cover the whole focus point in order for it to detect
it properly? Or is a object dead in the centre of the focus area
but filling only half of it ok?

I've come from using a G3 most recently and have been craving for
more control over focus (and everything else!), but I think I need
some tips on this one.

I have used SLRs in the past, but I wasn't so 'in to it' back then.

I really want this to work out... don't want to have to swap it for
another one (that will takes weeks anyway), only to find the same
problem. And there aren't any other suitable options for my
needs/budget other than the d70.

Many thanks for any help!
Paul
Click to expand...
--
View my stuff at...
http://www.rootminus1.com/pics/index.php?cat=10031
 
Fot the first question: I think this is normal for the D70 ( I really wonder why, but it does it with all my lenses and the focus is is good)

Question2: Not really. With my 28-200 and 50mm lens it always focusses right where I intend to. With the kitlens I'm frustrated. I have the very same problem as you. Also send it in for BF...the results are still the same. I don't want to send the camera back in. The camera is fine, but with the kitlens it's frustrating.

Maybe you should swap it for this lens: 28-200 3.5-5.6G I think it's even cheaper than the kitlens. I have very good results with it. It isn't a AF-S (so it makes a little noise when focussing and is a bit slower, still fast). You'll lose the wide angle, but gain a lot more tele. And I'm pretty sure you won't have BF problems anymore.

You should be able to find one around 300 euro's, sorry don't know how much that is in pounds.
Paul Tatterson said:
Hi everyone,

I bought my new D70 about a month ago and sent it back after a week
because of BF (I'm in the UK). I got it back yesterday, but I
don't think anything has changed. I only have the 18-70, and the
problem is most noticable (to me) at wide angle, and (obviously)
with the lens wide open. I'm pretty gutted about the whole
thing... this was by no means a small investment for me!

I don't have a printer at the moment and and no way of printing a a
focus test chart. Unfortunately I don't have any web host set up
so can't post pics.

First question:
A change in focal length (zoom) after focus lock has been acheived
should not affect focus, right? i.e if I focus on a point at full
tele, then zoom out to full wide, the the lens should remain in
focus right? Well it doesn't... if I re-depress the shutter after
zooming out (or in) it very clearly adjusts it's focus. Please
correct me if I'm wrong here (I'd like to be wrong).

Second question:
Regarding the focus points in the viewfinder: does an object need
to completely cover the whole focus point in order for it to detect
it properly? Or is a object dead in the centre of the focus area
but filling only half of it ok?

I've come from using a G3 most recently and have been craving for
more control over focus (and everything else!), but I think I need
some tips on this one.

I have used SLRs in the past, but I wasn't so 'in to it' back then.

I really want this to work out... don't want to have to swap it for
another one (that will takes weeks anyway), only to find the same
problem. And there aren't any other suitable options for my
needs/budget other than the d70.

Many thanks for any help!
Paul
Click to expand...
--
gallery's @ http://www.illdesign.nl
 
Buckrogers said:
1. Go to http://www.photobucket.com and you can a free account that can
link pics to this site. You need to copy & paste the URl once you
have uploaded the photo to their site. The images will be limited
to 250k so you will need to crop and downgrade quality of jpegs.
Click to expand...
thanks - i'll have to try that one.
Buckrogers said:
2. Focus will change with focal length - half-press shutter again
after zooming and you should see it focus.
Click to expand...
from this and the other replys... it seems I was wrong (thankfully). i was sure i read that somewhere, must have been talking about those parfocal lenses another poster mentioned.
Buckrogers said:
3. You need to focus on something that has a distinct contrast
WITHIN the focus box.
Click to expand...
 
Thomas Comerford said:
You can check for backfocus without printing test charts. Take 3 or
4 bottles/containers with clear sharp writing on them, and arrange
them so that they are all at slightly different distances from the
camera. Then experiment with that setup. Do it carefully, and don't
forget to use a tripod! The kit lens isn't the sharpest lens in the
universe (especially wide open) so it's easy to think you have
backfocus when you actually don't.
Click to expand...
i've been doing a similar test with CD case spines. the bottles is another good idea... will try that later!
Thomas Comerford said:
A change in focal length absolutely will affect your focus. There
are lenses (known as parfocal lenses) which will maintain focus
while zooming, but the kit lens is not parfocal.
Click to expand...
ah ha! that must have been what i was reading about a while ago. I read so many books about slr technique over the last few months while saving up for the d70. one of those random facts that became skewed in my memory!
Thomas Comerford said:
I highly recommend getting a 50mm f/1.8 lens. It's a wonderful
lens, great value for money, and it'll give you something to
compare the kit lens to.
Click to expand...
from what i've read here in the past - that is definitely on the shopping list!

cheers!
Paul
 
Ilja said:
Fot the first question: I think this is normal for the D70 ( I
really wonder why, but it does it with all my lenses and the focus
is is good)
Click to expand...
that's been the overwhelming response - I'm happily convinced i was wrong!
Ilja said:
Maybe you should swap it for this lens: 28-200 3.5-5.6G I think
it's even cheaper than the kitlens. I have very good results with
it. It isn't a AF-S (so it makes a little noise when focussing and
is a bit slower, still fast). You'll lose the wide angle, but gain
a lot more tele. And I'm pretty sure you won't have BF problems
anymore.
You should be able to find one around 300 euro's, sorry don't know
how much that is in pounds.
Click to expand...
i really like the wide(ish) angle of the 18-70, and i don't really want to go to a slower (i.e. darker) lens. I bought it as a boxed kit - don't know if they'll swap just the lens.
 
thanks for all the very quick-off-the-mark responses.

I'm glad i was wrong about Q1.

I'll have to play around more with a few different focus tests. I'd read that the best way to test for BF was to get as close as possible to the subject matter - looks like i may have been too close. I'll try it all again.

I absolutely love the d70 in terms of ergonomics and speed - i can't wait to get out with it for real and become really familiar with it. I just need to convince myself that it's not messing me around first!

cheers
Paul
Paul Tatterson said:
Hi everyone,

I bought my new D70 about a month ago and sent it back after a week
because of BF (I'm in the UK). I got it back yesterday, but I
don't think anything has changed. I only have the 18-70, and the
problem is most noticable (to me) at wide angle, and (obviously)
with the lens wide open. I'm pretty gutted about the whole
thing... this was by no means a small investment for me!

I don't have a printer at the moment and and no way of printing a a
focus test chart. Unfortunately I don't have any web host set up
so can't post pics.

First question:
A change in focal length (zoom) after focus lock has been acheived
should not affect focus, right? i.e if I focus on a point at full
tele, then zoom out to full wide, the the lens should remain in
focus right? Well it doesn't... if I re-depress the shutter after
zooming out (or in) it very clearly adjusts it's focus. Please
correct me if I'm wrong here (I'd like to be wrong).

Second question:
Regarding the focus points in the viewfinder: does an object need
to completely cover the whole focus point in order for it to detect
it properly? Or is a object dead in the centre of the focus area
but filling only half of it ok?

I've come from using a G3 most recently and have been craving for
more control over focus (and everything else!), but I think I need
some tips on this one.

I have used SLRs in the past, but I wasn't so 'in to it' back then.

I really want this to work out... don't want to have to swap it for
another one (that will takes weeks anyway), only to find the same
problem. And there aren't any other suitable options for my
needs/budget other than the d70.

Many thanks for any help!
Paul
Click to expand...
 
I had BF but for 2-3 months questioned it because of all the different views on this forum. Probably best to do the test outside then you'll get good light. You can even use a magazine ( as I did ) and just use the centre focus square ( remember this is actually a cross in side the square ). Focus on a page of writing at about 45 degress. I did all these tests and finally realised that I definitely had about 10 to 15mm BF. Finally confirmed it with the chart that's available ( search for D70 test chart on this forum ).

Now the good news - I sent it back to Nikon and rang them everyday. It took approx 1 1/2 weeks. When I re-did test my 18-70mm was spot on.

Now I am the happiest D70 user in Basingstoke.

One further test worth trying is to go to a camera shop and try various lenses to check the focus. I took my pics home and discovered some very desirable lenses that I now have to save up for.

Good luck, don't panic. The D70 is a very capable camera
 
Thomas Comerford said:
Thomas Comerford said:
Second question:
Regarding the focus points in the viewfinder: does an object need
to completely cover the whole focus point in order for it to detect
it properly? Or is a object dead in the centre of the focus area
but filling only half of it ok?
Click to expand...
No, it needs to cover the whole thing. If it's only half covering
it anything could happen. Also Thom Hogan (www.bythom.com) has
established that the outer focus areas don't exactly match the
position/size of the markers in the viewfinder so you need to allow
for that. Be sure to give the camera a nice big well-lit contrasty
area to focus on, while you're testing for backfocus.
Click to expand...
There's also been a fair amount of anectdotal evidence floating around that if both near and far image data is present within the AF sensor area being used, the camera will tend to focus on the more distant subject. This can lead you to believe you've got a BF problem when you don't.

I haven't noticed this myself, but then I really haven't looked too hard for it. I did check my center sensor coverage area, and it closely matches the area depicted in the viewfinder. Others report their coverage area differs from the display indication, so YMMV.

I'd second the motion to try bottles with fine lettering for test subjects, shot from a tripod wide open at various focal lengths. This is what I've done to test new lenses, and it gives a nice indication of focus accuracy, as well as where the DOF falls. I also set the bottle on a rough surface (my deck rail, which is weathered wood), and the DOF range shows up very clearly in the wood grain.

Good luck,

spike
 
Paul Tatterson said:
First question:
A change in focal length (zoom) after focus lock has been acheived
should not affect focus, right? i.e if I focus on a point at full
tele, then zoom out to full wide, the the lens should remain in
focus right? Well it doesn't... if I re-depress the shutter after
zooming out (or in) it very clearly adjusts it's focus. Please
correct me if I'm wrong here (I'd like to be wrong).
Click to expand...
In theory a zoom lens shouldn't change focus when it's zoomed, especially if you initially focus with the lens at its longest focal length it should maintain the focus when you zoom to wide angle.

That's theory. In practice you can't count on that, especially with a consumer zoom lens. Refocus after zooming.
--
--Bob
 
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