Jump to content




The above adverts really do help Fotozones. Please click on them if they are relevant to you. Not seeing them? Just exclude Fotozones from your ad blocker. Thanks!


Photo
- - - - -

D800 in CS6, strange data


  • Please log in to reply
14 replies to this topic

#1 JohnBrew

JohnBrew

    Advanced Member

  • Life Member
  • 928 posts
  • LocationFolly Beach, SC

Posted 30 September 2012 - 21:15

In bridge if you highlight an image the EXIF data appears to the lower right in a box "Camera Data". I noticed this weird thing (to me anyway!) It says "Focal length" and underneath it says "Focal length in 35m...". What I am seeing is on a 50mm lens under the second heading is 55mm. On the 85 1.4 it states 93mm and on a 105 it says 115 and so on. Anyone know what's going on? and why?
I double checked an image from the D700 and each catagory agrees with the lens used. So that makes it even more strange since each camera is FF.

#2 nfoto

nfoto

    Fierce Bear of the North

  • Administrators
  • 16,649 posts
  • LocationOslo, Norway
  • Edit my pics?:No

Posted 30 September 2012 - 22:56

There is a specific EXIF tag named "FocalLength35mm" which here obviously is treated in a nonsensical fashion. Whether blame is due the camera maker (Nikon), software developer (Adobe), or the EXIF Committee itself, is unclear though. The tag should *never* have been there in the first place, so perhaps the EXIF regulations are the main culprit here.

Just shows the folly of the "crop factors" and the conversion of focal lengths derived from them.
Bjørn

#3 Bjørn J

Bjørn J

    Happy user of Nikon photographic tools

  • Life Member
  • 729 posts
  • LocationNorth Norway
  • Edit my pics?:Ask Me

Posted 01 October 2012 - 10:06

In my Bridge CS6 the EXIF data for real focal length and the stupid "35mm focal length" are identical, both on zoom lenses and on the prime lens I tried it on (60mm macro).
____________________________________________________________

Bjørn J

#4 JohnBrew

JohnBrew

    Advanced Member

  • Life Member
  • 928 posts
  • LocationFolly Beach, SC

Posted 01 October 2012 - 11:15

Bjorn R. is correct. I figured this out last night as I tried to find some sleep. Since I was shooting in 5:4 ratio the EXIF data is giving the crop factor focal length. We didn't need this before and we don't need it now. I'll probably switch back to 3:2 for when I use the Zeiss 21.

#5 pluton

pluton

    Advanced Member

  • Life Member
  • 700 posts
  • LocationSanta Monica, CA USA
  • Edit my pics?:Ask Me

Posted 07 October 2012 - 01:34

Aside from the folly of naming an equivalent focal length, I am even more irked when they give you an equivalent focal length for a frame which is a different aspect ratio, and to further fan the flames of uselessness, it's based on the diagonal angle of view.
Keith B.

#6 Ann

Ann

    Professional Photographer

  • Life Member
  • 10,160 posts
  • LocationNew York State
  • Edit my pics?:No

Posted 18 October 2012 - 00:26

Is it possible that the sensor in the D800 (or the area of it which you are using) is NOT actually the same size as a traditional 35mm film camera's frame size?

If the D800 sensor is physically smaller than 36 mm x 24 mm then your EXIF data is probably reporting the correct figures for the "equivalent to 35mm" FL.

#7 nfoto

nfoto

    Fierce Bear of the North

  • Administrators
  • 16,649 posts
  • LocationOslo, Norway
  • Edit my pics?:No

Posted 18 October 2012 - 00:45

The FX sensor fits the nominal 24x36 mm frame within 0.1 mm. We had less precision than that using film, for example with wide-angle lenses that actually recorded slightly outside the gate window.
Bjørn

#8 Bart Willems

Bart Willems

    Forum troglodyte

  • Life Member
  • 3,011 posts
  • LocationElmwood Park, NJ
  • Edit my pics?:Ask Me

Posted 18 October 2012 - 22:32

Aside from the folly of naming an equivalent focal length, I am even more irked when they give you an equivalent focal length for a frame which is a different aspect ratio, and to further fan the flames of uselessness, it's based on the diagonal angle of view.


Wouldn't that diagonal be the diameter of the image circle the frame fits in? Same image circle, same multiplier factor?
Bart

Too much gear, not enough common sense!
Flickr and Zenfolio, too!

#9 nfoto

nfoto

    Fierce Bear of the North

  • Administrators
  • 16,649 posts
  • LocationOslo, Norway
  • Edit my pics?:No

Posted 18 October 2012 - 22:55

The lens always projects the same image circle. The camera [format] only decides what part(s) of it to use. So the "multiplier" is constant (= unity).
Bjørn

#10 bjornthun

bjornthun

    Advanced Member

  • Life Member
  • 2,963 posts
  • LocationFredrikstad, Norway
  • Edit my pics?:Ask Me

Posted 20 October 2012 - 01:44

Instead of working with crop factors, people should learn what the normal focal length is for the camera in question and work out from that what is wide and long lenses. Just like It was done in the days of 35mm, 120 and different sizes of sheet film for LF cameras. Of course, that would require thinking on one's own...
Bjørn T

#11 nfoto

nfoto

    Fierce Bear of the North

  • Administrators
  • 16,649 posts
  • LocationOslo, Norway
  • Edit my pics?:No

Posted 20 October 2012 - 12:18

Or think in terms of field of view, which to most is even more intimidating. But the only way to get the proper picture as it were.

When I mainly dealt with view cameras, I always carried a 6x12 cm or 4x5" back to put on my 6x9 cm camera. In case I didn't get the coverage (field of view) I needed, I just swapped the back. This practice presumed of course the taking lens had sufficient angle of view (which I got by employing lenses with a large image circle). No change in "DOF" of course occurred. All these distinctions and considerations so natural to the view camera user are lost with the silly crop factors. Plus people these days really believe the cropping alters "DOF" which is even more silly.
Bjørn

#12 pluton

pluton

    Advanced Member

  • Life Member
  • 700 posts
  • LocationSanta Monica, CA USA
  • Edit my pics?:Ask Me

Posted 20 October 2012 - 18:07

And, don't forget:
The expression "Depth Of Field" now often carries a new meaning, which is:
"Lack Of Depth Of Field"
Keith B.

#13 arthurking83

arthurking83

    A royal pain in the ass

  • Life Member
  • 946 posts
  • LocationMelbourne, Australia
  • Edit my pics?:Ask Me

Posted 20 October 2012 - 18:36

My suspicions are that in the instance that the OP is having trouble with, it's almost certainly an Adobe issue.

In the very rare instances that I use LR, it sometimes convolutes the focus distance data to read as 4million klms.

eg. ApproximateFocusDistance: 4294967295

I think it must have something to do with having focused at infinity(or close too).

If that same image is saved using any other software the reported focus distance is close too, if not spot, on what the actual distance was.

#14 nfoto

nfoto

    Fierce Bear of the North

  • Administrators
  • 16,649 posts
  • LocationOslo, Norway
  • Edit my pics?:No

Posted 20 October 2012 - 18:44

4294967295=2^32-1

Largest positive integer in a double word (32 bit). Or infinity, if you so wish
Bjørn

#15 arthurking83

arthurking83

    A royal pain in the ass

  • Life Member
  • 946 posts
  • LocationMelbourne, Australia
  • Edit my pics?:Ask Me

Posted 20 October 2012 - 19:34

Aha Ok thanks for that perspective.
That part makes sense other than the fact that I know most of those images are focused at about 5m away.

actually!.. here's another version of the focused distance:

FocusDistance: 6.31 m

this info is copy and pasted from the exif viewer, and the only difference is the choice of editing/raw conversion software. The image is the same.


And then on the other hand, if it seems that they're using this double word computer speak in this one instance(of many that I've seen), then what does 0.4 mean?

There doesn't appear to be any distance metric used, so I assumed they were using cm.
The shot with 0.4 as the focused distance info was made using the 150mm Sigma macro lens, which I prefocused and then set the camera/lens to subject distance, and then tweaked the focus again.

On the image processed with LR, this exif data bit is listed as
(copy and pasted)
ApproximateFocusDistance: 0.4

yet the same info, listed slightly differently when using CaptureNX2 to save the image
(copy and pasted again)
FocusDistance: 0.40 m

This is the same raw file image processed with two different software, and the data listed under the "Other Info" or Manufacturer or Camera heading in the exif data... depending on which exif data software is used.




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users



Receive a FREE CAMERA BAG from Think Tank Photo


An appeal to all Fotozones visitors: please help me to keep this site going by starting your gear purchases using any one of the affiliate links shown below:

Amazon.com | Amazon.co.uk | Amazon.de | Adorama.com | thinkTank Photo | DigitalRev.com | OWC | B&H or Donate via PayPal

Starting your shopping here doesn't cost you anything more, but by using the links above (or any others found on the site) you are advising the affiliate that you support this website. This results in a small commission that helps with the running costs. If your preferred outlet isn't among those listed above you can also support the site by making a donation of any amount via PayPal (no PayPal account required). Any donation will be most appreciated.