Not manual v auto which has been done before.

But variations in focussing behaviour between different cameras of the same model - Nikon 8400.

My 8400s have been failing at a rate of about 1 per trip of late. They're getting stripped and cleaned between, but they're definitely showing their age.

On the last few trips I've been using my spare. This one was almost new, in good condition. But whilst it takes razor sharp closeups, it takes out of focus shots in large chambers. This is on the exact same settings as I've used for ages.

An example taken with my old 8400:

🔗Croesor-Rhosydd-Through-Trip-16-02-2008-Image-007[linkphoto]Croesor-Rhosydd-Through-Trip-16-02-2008-Image-007[/linkphoto][/link]

And an example taken with my spare, which has had almost no underground use before, but using the exact same settings:

🔗Croesor-Slate-Mine-User-Album-Image-53474[linkphoto]Croesor-Slate-Mine-User-Album-Image-53474[/linkphoto][/link]

Nothing like as sharp.

Wonder why?

---

Two questions, are the cameras identical including age and if light painting was used was the light source stationary?

Two questions, are the cameras identical including age and if light painting was used was the light source stationary?

Similar age, so firmware (I did consider this but can't see why it would be an issue when set to infinity) might not necessarily be the same. Light painting for both photos, same light source used, not stationary. But it's not just this photo, it's every chamber photo taken with the offending camera. Closeups it's fine with, above ground photos on auto focus are fine, but large chamber shots underground all come out blurred.

---

Are you using the same lens?

Yes, you can't change the lens on the 8400 😉

---

Any clues in the EXIF data?
Might it be focusing beyond infinity?

Nothing too details, and nothing telling.

Same f-stop
Same focal length
Same metring mode
BIOS version the same (E8400v1.5)

Only difference really was 2nd (blurred) photo was RAW at ISO50, 1st (sharp) photo was TIFF at ISO100.

Given this particular camera gives dodgy results every time it's used (but only in large chambers) I suspect it's just a bad one.

---

Yes, you can't change the lens on the 8400 ;)

You are in effect using two completely different cameras. They might have the same model No. but they may have been built in different factories, never mind different countries.

My suggestion would be to take some shots in a more controlled environment to try and track down the variants in the cameras.

Two questions, are the cameras identical including age and if light painting was used was the light source stationary?

Similar age, so firmware (I did consider this but can't see why it would be an issue when set to infinity) might not necessarily be the same. Light painting for both photos, same light source used, not stationary. But it's not just this photo, it's every chamber photo taken with the offending camera. Closeups it's fine with, above ground photos on auto focus are fine, but large chamber shots underground all come out blurred.

This may be irrelevant but a mate had two cameras of identical make and type, a lot of pics on the newer model were poor when using traditional light painting.
After much reading of the small print it turns out that the newer model had a facility that identified what it thought the subject was and tried to keep that area sharp electronically.
This facility operated whilst light painting and re-focused to wherever the light was!
Turned that bit off and all OK since.

Only difference really was 2nd (blurred) photo was RAW at ISO50, 1st (sharp) photo was TIFF at ISO100.

How are you processing the files once they are out of the camera?

Photoshop. Import direct from RAW.

I do promise you though the large chamber shots off this one particular 8400 are blurry 🙂

---

The fact that the camera takes razor sharp close-ups but is out of focus at infinity leads me to suspect that it's an issue with depth of focus i.e. the distance between the rear lens element and the sensor. In miniature cameras the positioning of the sensor (or film) relative to the lens is of critical importance. This will be compounded with the use of a short focal length lens and a wide aperture.

Thanks Gwyn, that would certainly explain it. The odd thing is though it did it from new (new to me, it was a 2nd hand camera) so I guess the original owner might have clonked the lens at some point.

---

What is your focus set on?
If it is a spot meter, the first photo would focus on the chap and wall behind him.
The second photo has a tunnel in the centre which could cause problems.
When doing dark church photography in the past You work to manual settings on a tripod ie 22mins at F16, (Do you have reciprocity problems with digital?). You paint the picture with light using a similar setup.
Set both cameras up together and photograph a large solid wall an various distances then compare.

---