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Author Topic: Live view review  (Read 7498 times)
BernardLanguillier
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« Reply #20 on: January 18, 2009, 04:47:30 PM »
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Quote from: kingtutt
Why?

Because the resolution is so high that the eye has a hard time finding the real peak of focus.

What appears to be adequate focus with lower res medium, like film or a 12 MP device, just don't cut it anymore.

I am not saying that all the images will be out of focus, just that achieving repeatably critical focus without live view is very challenging.

Cheers,
Bernard
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A few images online here!
KenS
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« Reply #21 on: January 18, 2009, 06:12:51 PM »
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Quote from: BernardLanguillier
Because the resolution is so high that the eye haseq a hard time finding the real peak of focus.

What appears to be adequate focus with lower res medium, like film or a 12 MP device, just don't cut it anymore.

I am not saying that all the images will be out of focus, just that achieving repeatably critical focus without live view is very challenging.

Cheers,
Bernard

I am a landscape photographer who has been shooting a Pentax 67 for 20+ years.  I scan my (Velvia and TMax) film and work the files in Photoshop.  I've been considering an all digital approach, i.e DSLR, perhaps Sony a A900 - which does NOT have live view.  I bring up my medium format experience because I find it somewhat ironic and disappointing that the ease with which focus accuracy and DOF settings can be accurately and confidently determined (but not always achieved) with my current camera system has apparently been lost in the DSLR realm  (short throw autofocus lenses making manual adjustment imprecise, no depth of field scales - esp on zoom lenses, sparse distance markings on lens barrels, no readout in the LCD monitor indicating focused distance...)

The following discussions on focusing (especially for landscape work) have only served to confuse me enough that I have grave doubts about switching to a DSLR.
Sure I'd better be able to handle dynamic range, equipment would be lighter, I'd have instant feedback on exposure, but it's not at all clear to me that I would
be confident focus and DOF were good until I returned home to Photoshop.

http://luminous-landscape.com/forum/index....=29650&st=0
and also:
http://forums.dpreview.com/forums/readflat...eidman&qf=m

Not everyone seems to agree live view provides a good solution for focusing a DSLR.  There is no real consensus on any technique  

It occurs to me that if a DSLR did provide an accurate LCD (not a sparse barrel marking) readout  of it's focus distance (i.e. lens to target distance) one could use a table of hyperfocal distances (or a DOF calculator) and get back the imprecise/missing info and confidence my Pentax 67 provides.  I know of know  DSLR systems which provide this distance info, why?

This is not meant to be a complaint or criticism of anyones suggestions, afterall, no one is making me switch... but I just thought I'd bring it up in case anyone else is in my situation or has some advice.

Ken



 

 
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aaykay
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« Reply #22 on: January 19, 2009, 12:15:15 PM »
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One of the "Cons" from live-viewing off such large sensors, is the fact that when one is feeding LV through the main sensor, the sensor is heating up, resulting in digital noise that will make its way into the image,  that would not be present during a normal non-LV exposure.  I am assuming the newer implementations have got highly efficient Noise Reduction routines on the sensor, to take care of this.

Essentially, unlike a split-second exposure, now you are clocking the data off the sensor, dozens of times every second and feeding it to the LV screen, consuming a considerable amount of power, while also generating digital noise.  

A CCD would consume a lot more power than a CMOS and thus a CMOS is a better fit when it comes to LV, especially with a large sensor like those used in a dSLR.   The other advantage with a CMOS sensor is the ability to accomodate Noise-Reduction circuitry on the sensor, unlike a CCD that is incapable of accomodating such circuitry on the sensor.  This on-sensor NR circuitry will enable the reduction of the inevitable digital noise being generated via Live-view.

Think of LV as an extremely long exposure, prior to the actual click.  The more you delay prior to the click, by fiddling around with the settings, the more you are heating up the sensor.

Having said this, having LV as a tool is definitely a plus over not having this as an option at all - just don't assume that there are no ill effects from clocking data off such large sensors, hundreds of times, in a short period of time.  Like any other tool, use it wisely.  

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photoshutter
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« Reply #23 on: January 21, 2009, 07:53:31 AM »
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My Leica M8 has no AF too.
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NikosR
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« Reply #24 on: January 21, 2009, 08:44:17 AM »
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Quote from: KenS
It occurs to me that if a DSLR did provide an accurate LCD (not a sparse barrel marking) readout  of it's focus distance (i.e. lens to target distance) one could use a table of hyperfocal distances (or a DOF calculator) and get back the imprecise/missing info and confidence my Pentax 67 provides.  I know of know  DSLR systems which provide this distance info, why?

While I would be hesitant to rely on traditional DoF tables for calculating DoF (but this is the subject for another long discussion), I'm sure distance readout would come as handy for many uses, and of course one can build one's own DoF 'table' based on shooting experience rather than mathematical formulae and suspect CoF assumptions. I'm sure the manufacturers will come out with this feature sooner rather than later. They have to keep something for their future releases don't they?

One can imagine other features also based on facilities already existing in the dSLRs of today. For example, it has been suggested to use the accelerometers build in the VR/IS/AS functions to display vibration info helpful to the user seeking to optimise his tripod setup or shooting technique.
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Nikos
aaykay
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« Reply #25 on: January 21, 2009, 09:27:16 AM »
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Quote from: NikosR
For example, it has been suggested to use the accelerometers build in the VR/IS/AS functions to display vibration info helpful to the user seeking to optimise his tripod setup or shooting technique.

Sony already provides the vibration information in the view-finder display and allows one to optimize ones technique, to reduce the number of "vibration bars" visible on the view-finder.   We can visibly see the number of bars go down, when one employs good technique.


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fike
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« Reply #26 on: January 21, 2009, 09:39:45 AM »
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Quote from: aaykay
One of the "Cons" from live-viewing off such large sensors, is the fact that when one is feeding LV through the main sensor, the sensor is heating up, resulting in digital noise that will make its way into the image,  that would not be present during a normal non-LV exposure.  I am assuming the newer implementations have got highly efficient Noise Reduction routines on the sensor, to take care of this.

Essentially, unlike a split-second exposure, now you are clocking the data off the sensor, dozens of times every second and feeding it to the LV screen, consuming a considerable amount of power, while also generating digital noise.  

A CCD would consume a lot more power than a CMOS and thus a CMOS is a better fit when it comes to LV, especially with a large sensor like those used in a dSLR.   The other advantage with a CMOS sensor is the ability to accomodate Noise-Reduction circuitry on the sensor, unlike a CCD that is incapable of accomodating such circuitry on the sensor.  This on-sensor NR circuitry will enable the reduction of the inevitable digital noise being generated via Live-view.

Think of LV as an extremely long exposure, prior to the actual click.  The more you delay prior to the click, by fiddling around with the settings, the more you are heating up the sensor.

Having said this, having LV as a tool is definitely a plus over not having this as an option at all - just don't assume that there are no ill effects from clocking data off such large sensors, hundreds of times, in a short period of time.  Like any other tool, use it wisely.

I haven't seen any camera evaluations that have brought this up as a real-world phenomenon.  While this may be a theoretical issue, I don't know if I believe that it really produces any visible effects.   Can you point me to any review or samples that verify this issue?    
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Fike, Trailpixie, or Marc Shaffer
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I carry an M43 ILC, a couple of good lenses, and a tripod.
fike
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« Reply #27 on: January 21, 2009, 09:40:38 AM »
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Quote from: mahleu
You look like a tourist?

  Please tell me you are kidding.
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Fike, Trailpixie, or Marc Shaffer
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I carry an M43 ILC, a couple of good lenses, and a tripod.
aaykay
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« Reply #28 on: January 21, 2009, 10:56:08 AM »
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Quote from: fike
I haven't seen any camera evaluations that have brought this up as a real-world phenomenon.  While this may be a theoretical issue, I don't know if I believe that it really produces any visible effects.   Can you point me to any review or samples that verify this issue?

Exactly, there has been NO tests done, to "practically" demonstrate this "theoretical" problem.  I am assuming you do realize the validity of the "theory" behind continuously live-feeding off such huge sensors and the consequent appearance of digital noise in the images.

Someone competent needs to do a detailed RAW  analysis, with images that are live-fed for a considerable amount of time, vs another one taken without LV (with normal split-second exposure) and analyze the NR applied on the RAW files (if any) and verify the differences.   I am assuming that with NR, there might be differences observable in really fine detail in the images, like with fine hair etc.
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JeffKohn
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« Reply #29 on: January 21, 2009, 12:42:21 PM »
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Quote
One of the "Cons" from live-viewing off such large sensors, is the fact that when one is feeding LV through the main sensor, the sensor is heating up, resulting in digital noise that will make its way into the image, that would not be present during a normal non-LV exposure. I am assuming the newer implementations have got highly efficient Noise Reduction routines on the sensor, to take care of this.
Well, this isn't really a reason not to use Liveview IMHO, because you can always turn it off for a few seconds before taking the actual exposure.  In fact you don't have much choice except to do so if shooting Nikon and using MLU, since you have to switch to the MLU shooting mode.
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KenS
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« Reply #30 on: January 21, 2009, 05:13:07 PM »
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Quote from: NikosR
While I would be hesitant to rely on traditional DoF tables for calculating DoF (but this is the subject for another long discussion), I'm sure distance readout would come as handy for many uses, and of course one can build one's own DoF 'table' based on shooting experience rather than mathematical formulae and suspect CoF assumptions. I'm sure the manufacturers will come out with this feature sooner rather than later. They have to keep something for their future releases don't they?

I hope you are right and manufacturers do provide distance readout in the near future.
I agree with you completely about traditional DOF tables.  Many (all ?)  6x7 medium format DOF scales assume a Circle of Confusion of 0.055 or 0.060 mm.  For 35 mm format it is 0.030 mm.  I use a DoF table based on 0.045 mm to meet my required print size and viewing distance.  An optimum f-stop technique (tradeoff between defocus blur and diffraction) is also very useful, based on an article in PhotoTechniques Mag by Paul Hanma (1996).

For any of this to work you've got to know the distances to important objects in your field of view.
An alternative may be to carry around an optical rangefinder (Bushnell Scout, or other) used by hunters.  So now one would need both a DoF table AND
a rangefinder !   Sure would be a lot nicer if the camera provided all this info.

Not to loose track of the Live View topic... while one (debateable) benifit of LV is to aid focusing I think a useful supplement, or even replacement would be to provide the distance readout and DoF (with a user configurable CoC) info right in the camera.
« Last Edit: January 21, 2009, 05:17:53 PM by KenS » Logged
Colorado David
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« Reply #31 on: January 21, 2009, 05:23:12 PM »
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I have a video camera that gives distance information in the view finder.  The problem is that it is widely variable.  I do actually carry a laser rangefinder at times.  Mine is made by Leica and is extremely accurate.
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KenS
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« Reply #32 on: January 21, 2009, 06:24:24 PM »
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Quote from: Colorado David
I have a video camera that gives distance information in the view finder.  The problem is that it is widely variable.  I do actually carry a laser rangefinder at times.  Mine is made by Leica and is extremely accurate.

David,

Glad to get your response.  I just did a quick search, noticed there is a Leica CRF 900 that has a close range of 2 yards (anything closer than that and I can stick my foot out and guess pretty well !).
- Please tell me what model you are using
- What kind of accuracy do you get, especially at close range?
- Does it work well in both bright sunlight and pre-dawn or dusk ?
      I am particulary concerned about bright sunlight because I have difficulty using my "FAT Max" laser rangefinder in bright sunlight. It is hard to see
      what I'm pointing at and I don't always get a readout. That's why I mentioned an optical rangefinder.
      However, the Fat Max was only about 1/5 cost of the Leica, so maybe that's the difference in performance?
- Any limitations or inaccuracies you care to mention?

Interesting that your video camera has distance readout.  That would suggest that this could be built into a  DSLR.  Assuming reasonable accuracy it could supplement or replace Live View for focusing and DOF -> f-stop determination.

Ken

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Colorado David
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« Reply #33 on: January 21, 2009, 08:14:40 PM »
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The model I'm using is the LRF 900 Scan.  It is probably five years old.  There are newer models available now including the one built into the very fine Leica Binocular.  Mine is accurate +/- one yard.  It does not read at under 10 yards.  It is equally reliable in both bright sun and low light.  Sometimes this unit, as any rangefinder, will have trouble in fog/mist. Laser range finders as a product group are subject to continuous improvements and new products are introduced every year.  The current batch of rangefinders have built-in inclinometers.  This feature is valuable for a rifleman or archers as incline determines ballistic range.  That is not a feature most photographers will need or use.  The current batch of products are working on the issue with fog and mist as well as foreground obstructions, such as grasses, that interfere with accurate ranging.  Most optical instrument companies are in the sport optic or rangefinder business.  Nikon makes a very popular unit.  Swarovski makes one that is very, very nice and also doubles as a 7x30 monocular with Swarovski quality optics.
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KenS
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« Reply #34 on: January 21, 2009, 10:53:40 PM »
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Quote from: Colorado David
The model I'm using is the LRF 900 Scan. ... snip ... Nikon makes a very popular unit.  Swarovski makes one that is very, very nice and also doubles as a 7x30 monocular with Swarovski quality optics.

I found the following comparison which may be useful to someone following this:

http://www.fs.fed.us/eng/pubs/html/98241307/98241307.html
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Mark Muse
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« Reply #35 on: January 25, 2009, 11:01:52 AM »
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I purchased a 5D2 over the A900 (after agonizing for months!) for one reason: the 5d2 has live view. Otherwise for me and what I do (landscapes) the Sony is a no brainer. I expect the eventual replacement for the A900 will have live view, and I would be perfectly happy if the optical viewfinder reverted to a high quality EVF like the G1.

Live view on the 5d2 works well, but an articulated LCD would be a huge improvement. There are three focusing options in live view:
•Quick, requiring a brief blackout as the mirror comes down for focusing. This is the same focusing using the nine points or any selected one of them that is the main focus method using the viewfinder, and works just as well.  
•Contrast Detect as in P&S territory. I haven't used this so I have no comment on its implementation.
•Face Detect.

The view is the same as the final exposure (100% of the file), though interestingly Canon says "approximately". The user can zoom the actual scene to 5x and 10x by simply pushing a button once or twice. The third push returns to full frame display. Canon does not say how this relates to the zoom in a raw file processor (50% pixels? 100% pixels?) but it seems to be close to 100% at 10x. Manual focusing or focus verification is a breeze at 10x. You can use the joy stick to cruise around the frame. This LCD is really nice: great resolution and decent color management should you choose the option to have live view emulate the color/contrast that will result from the current settings. Someone mentioned batteries: yes, get a number of them if you will be using live view. A battery will last ~1/3 as long. I don't believe the inclusion of live view in the 5d2 has resulted in any compromises in any viewfinder-use functionality.

Now that I have some good L lenses I must say I am NOT overwhelmed by the image quality of this camera. Using either Aperture or Raw Developer (I only shoot RAW), color discrimination and rendering is superb. But tonal distinctions, particularly in the midtones, in a word, sucks. So does sensor sharpness/pixel contrast, the files' ability to be enlarged over the native resolution, and the files' ability to be sharpened without producing obvious artifacts.

To put this in perspective, I've been using a view camera (to shoot film) and a Sony R1. The R1 is a 10 MPx APS-C CMOS fixed lens (granted it is a good Zeiss Vario Sonnar T) that is pretty darned noisy in the shadows of longer exposures. But I can enlarge those Sony files (2x native res) to make 15 x 22 exhibition prints that are stunning. With the 5d2, a 1.5x native size is a little larger but in some ways is already pushed too far! Are Canon L lenses that inferior to Zeiss lenses? I have used the A900 with the 24-70 CZ and those results are much more what I expect going from 10 MPx APS-C to 20+ MPx full frame pro gear.

Sorry for the rant. Any 5d2 users out there? Can you provide any insights? The lenses I have are 70-200 ƒ4L with IS, 50 ƒ2.5 macro, and 17-40 ƒ4L.
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