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Saturday, 4 April 2015

Panasonic FZ1000 Crop RAW or i-Zoom ?


Original RAW capture at E400mm focal length. This is a crop to half linear dimensions of the original, effectively a 5Mpx file at E800mm focal length.


Panasonic FZ1000 at E800mm focal length

The Panasonic FZ1000  is one of the most versatile cameras I have ever used, providing very good image quality in a wide range of conditions.

The lens ranges in focal length from E25mm at the wide end to E400mm at the long end, where E= 35mm equivalent focal length.

There are four ways to extend the effective focal length:

1. Cropped RAW

2. i-Zoom (JPG only)  Set i-Zoom ON in the Rec Menu.

3. Extra Optical Zoom (JPG only)  Set Picture Size to M = 10 Mpx  or S = 5 Mpx in the Rec Menu.

4. Digital Zoom (JPG only)  Set Digital Zoom ON in the Rec Menu.

The three JPG zooms can be combined but with severe loss of quality so I will confine this discussion to a maximum of E800mm as this is a useful zoom level which can give good results and makes the camera readily controllable handheld.

In each case this produces a file with 5 effective Megapixels. The higher Mpx counts on the Digital Zoom and i-Zoom files are just achieved by interpolation, they do not indicate any extra imaging information.

In previous and current trials I confirmed that the three digital JPG zooms give identical results once the resulting images are brought to the same total pixel count, pixels per inch and output size.

So for the comparison with cropped RAW I have used the i-Zoom frames.

Same subject and camera using i-Zoom with the focal length indicator at E800mm, original JPG capture.


The test

With the camera on a sturdy tripod I photographed Casuarina trees about 200 meters away. These trees have fine soft needles instead of leaves providing a good test of the imaging system’s ability to resolve fine detail.

For the RAW capture I zoomed to E400mm, cropped the file to half linear size (= E800mm = quarter area and therefore 5 Mpx) and sharpened the cropped file in Adobe Camera Raw.
For the i-Zoom capture I zoomed out to E800mm using the E Focal length guide in the EVF. I sharpened this file and increased contrast as I have my JPG settings at low contrast.

Then I adjusted the JPG file to the same pixels per inch and  picture size as the cropped RAW file.

I opened both files together in Photoshop and examined them side by side on screen.

This is a crop from the already cropped original RAW capture at E400mm. This picture has 0.69 Mpx.
And here is the crop from the i-Zoom image. I hope that after its voyage  through cyberspace you will be able to see this version lacks resolution of  fine details present in the photo above this one.
The difference is not simply due to sharpening which can up to a point improve either image. 


Results

The cropped RAW file showed better rendition of  fine detail.

Apart from that the color  was different but that’s about all.

Advantages of cropped RAW

* The RAW file has all the captured information so is much more tolerant of digital editing.

* Better rendition of fine subject details.

* Better highlight/shadow detail.

* Much greater capacity for highlight recovery when subject brightness range is high.

* Ability to tailor noise reduction/contrast/sharpening  to each file individually as opposed to the batch processing approach of JPG rendition.

Advantages of i-Zoom

* The crop occurs at the point of capture with possible advantage for autoexposure and autofocus.

* Suits JPG workers well.

* Able to use JPG functions such as i-Dynamic and i-Resolution. (But RAW is better).

I-Zoom, Extra Optical Zoom or Digital Zoom ?

* I Zoom can be set ON in the Rec Menu and left on all the time if desired. If RAW capture is used it is inactive. Switch to JPG quality and the zoom indicator in the viewfinder now indicates a maximum E Focal Length of 800mm.  You have full control of the size and position of the AF box.

* Extra Optical Zoom is a bit of a misnomer. No zoom beyond E400mm occurs in the lens in any zoom mode. This one is active if  Picture Size is set to [ExM 10M] or [ExS 5M] in the Rec menu.

* Digital Zoom is like i-Zoom but you have no control over the large, fixed AF box once the zoom indicator passes E400mm.

It’s all quite confusing.  I don't pretend to  understand the technology behind the digital zooms but I can view the results readily enough.

Which to use ?

RAW shooters look no further. Keep right on shooting RAW and crop.

JPG shooters have to make a decision.

I have found i-Zoom easy to use. I can leave it set to ON all the time with no effect if RAW or RAW+JPG Quality is set, but immediate effect if JPG only is set.

Some users like Extra Optical Zoom but remember you get reduced picture size with all captures, zoomed or not.

There may be some advantage for video with Digital Zoom but I have not explored this.

Comment about pixel counts

We now have DSLRs with 50 million pixels. Wow ?

The Casuarina pictures shown in this post have 5 million pixels. You can see plenty of detail even though the pixel count is very low by current standards.

In my view super high pixel counts are basically a marketing exercise. I guess a few professional photographers will be able to make good use of the potentially extreme resolution if their lenses and technique are good enough. But for the vast majority of amateur/enthusiast and I suspect most professional photographers 50Mpx is just overkill.

This morning I printed up one of my tree pictures made with a hand held Panasonic LX100 in the Australian bush. At an actual picture size of 390 x 586 mm the print looks clear and sharp, with crisp rendition of fine details. Pixel count after cropping and some perspective correction in Photoshop is 9.6 Mpx.

Viewers will like/dislike the photo on grounds of aesthetics or personal preference but I very much doubt many people will find grounds for adverse comment about technical issues.


2 comments:

  1. What was the print resolution of the 390x586mm image?

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    Replies
    1. 360 dpi if I remember correctly. That's what I usually use.
      Andrew

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