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David Berry

David Berry

🇦🇺 Australia 🦘
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Far Eastern Curlew (endangered), Moreton Bay, Queensland, AU …​


Far Eastern Curlew : Numenius madagascariensis
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Far Eastern Curlew : Numenius madagascariensis
You can only see EXIF info for this image if you are logged in.


Far Eastern Curlew : Numenius madagascariensis
You can only see EXIF info for this image if you are logged in.


Far Eastern Curlew : Numenius madagascariensis
You can only see EXIF info for this image if you are logged in.

Far Eastern Curlew : Numenius madagascariensis
Endangered Species
Moreton Bay, Queensland
27°S; 153°E Zoom map as necessary.
camera—subject: 56 metres​

  • Can anyone comment on DxO's camera-to-subject calculations?
… David
 
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Whiskey Man said:
Fifty-six meters? Really? Wow! Or do you think the distance is a bit in error?
Click to expand...
Whiskey …

I'd like a second opinion — even a third or fourth as I'm not altogether convinced. If the distance is wrong, presumably too far, we'll blame DxO PureRAW 3 which provided the info in the processed files.

There's nothing unusual about my setup (R5 + RF 100–500 + 1.4 extender) and DxO has (surely!) both Canon-supplied and measured-in-house specs for this combo. Is there something in the focusing mechanism of our lenses that records the distance (in 'steps'?) that is then converted into distance?

Compare Capture Date (on the tidal flats of Moreton Bay) and Metadata Date (at home the next day when the distance info was added by DxO).

More insights and opinions, please!

… David

LrC Screenshot
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LrC Screenshot
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My assumption is that the metadata date/time is the date and time the metadata from the file is read and decoded on the computer. Since I don't have DxO-1, I can't really check how it assigns and labels the data.

As far as the distance is concerned, your initial comment/question and my ignorance of the bird and its physical size led me to question the distance. After looking it up and reading that the Far Eastern Curlew adult is typically 60-66 cm in body length, I can believe the 56 meters distance with a focal length of 700mm. Using some quick and crude measurements from the image in post #7, I calculated a ballpark range of about 60 meters; very close to 56 meters.

For that distance, the image quality is quite good, excellent even. The shots also hold up well with cropping.

Very nice images.
 
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David Berry said:
Is there something in the focusing mechanism of our lenses that records the distance (in 'steps'?) that is then converted into distance?
Click to expand...
To calculate distance you either need a laser beam, or the ability to triangulate. This software would need a database of the size of the bird and pattern recognition to calculate distance during successive shots. Frankly, I don't see how its coming up with a number. If someone knows, please share.
 
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Whiskey Man said:
My assumption is that the metadata date/time is the date and time the metadata from the file is read and decoded on the computer.
Click to expand...
Quite so: the genuine date/time (when the shutter was pressed) versus DxO time (when the metadata was altered).


Star Tracker said:
Frankly, I don't see how it's coming up with a number. If someone knows, please share.
Click to expand...
ST…

My guess is that the position of our lenses' focusing element is recorded in the image's original RAW metadata, but done so in a way that needs processing (by DxO, for example) to make it intelligible to LrC.


I checked the BCG Forum while having a late-afternoon mug of cocoa on our deck. That, of course, is a signal for the locals to fly in for their share: sunflower seed in the case of this Rainbow Lorikeet. Although the light was poor, I grabbed my R5 and RF 100–500 to check distance at close range. Focus was on the bird's eye.

Afterwards I measured from the saucer to where I had been sitting: my five-metre measuring tape was not quite long enough. Five metres and a bit, then.

Here is DxO PureRAW’s calculation. (Yes, I am embarrassed now that I note the combination of BIF shutter speed and crazy-high ISO for a bird-on-a-plate shot! Pay attention next time, David!)

dxo-distance.jpg
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Any chance of an R8/R9 shooter running a RAW file through DxO and seeing if it computes camera-to-subject distance?

… David
 
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David Berry said:
...(Yes, I am embarrassed now that I note the combination of BIF shutter speed and crazy-high ISO for a bird-on-a-plate shot! Pay attention next time, David!)

… David
Click to expand...
It seems that the "BIF shutter speed and crazy-high ISO" did just fine for the shot.

But I know exactly what you mean as I've done it myself; many times. And that works a lot better than when it's the other way around.
 
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