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Single frame mode: Why is there a lag between successive frames although there is a large buffer? Time to zoom?


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Hi there,

 

I am learning to handle my MP and have a couple of questions concerning the performance. If I undestand the mechanics correctly, after a picture is taken it gets first buffered and then written to the memory card. My naive assumption is, that as  long as the buffer is not full, the camera should be very responsive in taking pictures. In continuous mode this is indeed the case. Hold the shutter release and fire away. klack-klack-klack-klack-...

 

Now my question: in single frame mode I have to wait almost until the red light has stopped flashing before beeing able to take the next picture. So it is more like, klack-wait(count till 2)-klack-wait(count till 2)-... I do not understand why this is that the case. I know, that the camera can do much better, but I do not want to use the burst mode, only two or three successive pictures. Anything I can do about this? Am I naive, or ist this something that should be easily adressable software wise. After all we know what the camera can do in continuous mode.

 

Second, somehow related question: I have to wait until the picture has been written to the SD card, before beeing able to zoom in 100% for checking focus. Once again: Shouldn't that be possible with the picture in buffer? This really slows me down...

 

Thank you for your insights!

 

Bernd

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In single shot mode I take as many images as I like even while the red light is on. Even with the buffer full one can shoot an image every second and I can tell you it takes a lot of images to fill the buffer so that you get relegating to one shot per second.

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You must be in LV mode i suspect. Press the LV button and your MP should do klack-klack-klack like my modest M240. If not, remove the battery and press the LV button again if need be. 

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I just wanted to write "I am not in live mode, oh oh, there is something wrong with my camera!" Then I remembered somewhere reading about new metering methods in the 240. And yes indeed: I was in advanced. Switching to classic gives me the desired speed. Can someone confirm this? Actually this would even make sense, as the curtain has to be opended again...

 

Thx!

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I just wanted to write "I am not in live mode, oh oh, there is something wrong with my camera!" Then I remembered somewhere reading about new metering methods in the 240. And yes indeed: I was in advanced. Switching to classic gives me the desired speed. Can someone confirm this? Actually this would even make sense, as the curtain has to be opended again...

 

Thx!

 

Yes, in advanced metering mode the shutter endlessly opens and closes so the Live View image can be used by the camera, in normal centre weighted metering mode the camera simply uses the conventional reflected reading from the shutter blinds. That is what you are hearing and waiting for with your M-P. :)

 

 

Steve

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The file has to be converted to an in-camera JPG before it can be processed for zooming, so it cannot be zoomed when in the buffer.

 

Uhm... not really.

 

In order to view (and zoom) the image, the camera needs to develop the raw image. This means de-bayer, gamma, et cetera. Think about a mini-Lightroom app in the camera firmware.

 

JPEG is just a way of compressing a developed image so that it uses less space on the card.

If you think about it, Lightroom can perfectly display a raw image without converting it to JPEG first  ;)

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Uhm... not really.

 

In order to view (and zoom) the image, the camera needs to develop the raw image. This means de-bayer, gamma, et cetera. Think about a mini-Lightroom app in the camera firmware.

 

JPEG is just a way of compressing a developed image so that it uses less space on the card.

If you think about it, Lightroom can perfectly display a raw image without converting it to JPEG first  ;)

Correct me if I am wrong, but the image displayed on the LCD is the .jpg  file generated by the camera AFAIK.  (possibly the DNG embedded . jpg file if you shoot DNG only.)

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Correct me if I am wrong, but the image displayed on the LCD is the .jpg  file generated by the camera AFAIK.  (possibly the DNG embedded . jpg file if you shoot DNG only.)

In play mode the camera obviously fetches the JPEG data from the card and expands it to its uncompressed state so you may zoom in. The image preview after the shot is a different matter. Whether the camera keeps the uncompressed image data in memory or does a decompression on the fly should you choose to zoom in is an implementation detail. We would need to look at the source code to see what it really does.

 

There is a time/space trade-off: If the camera retains the uncompressed data even after compression (at least for a short while) this may be a waste of memory; on the other hand, should you choose to zoom in, access will be faster.

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I did notice onthe M8 that  it displayed a "raw" type image (for instance with all the noise at slow shutterspeeds), before jumping to a corrected image.

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Whether the camera keeps the uncompressed image data in memory or does a decompression on the fly should you choose to zoom in is an implementation detail. We would need to look at the source code to see what it really does.

 

There is a time/space trade-off: If the camera retains the uncompressed data even after compression (at least for a short while) this may be a waste of memory; on the other hand, should you choose to zoom in, access will be faster.

 

Going through JPEG would be just a waste of time and power, in any case.

All the camera needs to do is retain the full-resolution data for the last shot while it is displayed (zoomed or not).

There is no memory problem because the camera is idle showing the image, and its multi-image buffer is empty (or being flushed to card).

 

However, some cameras may decide to show on the LCD the low-resolution buffer used to develop the scaled down image which is embedded in the raw file, and will only proceed with full raw development if the user decides to zoom in the picture. This saves power in case the user shoots RAW only, at the cost of a little delay (raw development) after the zoom-in button is pressed. But if the user shoots JPEG, there should be no delay because the image must have been developed at full resolution in order to generate the full-size JPEG.

 

The M240 may use a similar approach. You may have noticed (as it is very irritating) that you can only zoom-in one level before the image is fully flushed to card. To see this, take a photo and keep rotating the wheel to zoom in. You will get the higher magnification levels only as soon as the "writing" red light turns off.

My educated guess is that the first zoom-in level you get is the embedded low-res DNG preview. If you decide to zoom-in further, then the camera has to develop the full image, and the M240 does that after the image has been flushed to disk. Good firmwares won't let you wait until the image has been saved, but hey, it's a Leica  ;)

Note that I only shoot raw, and I haven't tried with JPEG; there should be no zoom-in delay if one shoots JPEG, but I am too lazy to verify this  :)

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My cameras are also afflicted by this. And it's the most annoying thing on the whole camera, for me. Waiting for the blinkies to be able to zoom past the first level is a PITA. I also don't remember this being an issue earlier on, although it could have. I wonder whether this is a new "feature" added with the last firmware update, as is Leicas normal way of things.

 

Gordon

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Leica Mayfair told me that if you wanted to examine the performance of a lens using the display then it was important not to use RAW, or RAW + Jpeg, as the image displayed would be the embedded low resolution Jpeg of the RAW file.

 

The advice was to save the image in high resolution Jpeg only.  It's the "Quick and Dirty" method they employ and for many purposes it works more than adequately. 

 

Clearly not as good as using a RAW file displayed on a high quality monitor after processing but actually surprisingly capable. 

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Leica Mayfair told me that if you wanted to examine the performance of a lens using the display then it was important not to use RAW, or RAW + Jpeg, as the image displayed would be the embedded low resolution Jpeg of the RAW file.

 

I am afraid the guy at Leica Mayfair who told you this is wrong.

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