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Author Topic: More Than Megapixels - An IQ180 Field Review  (Read 5225 times)
ternst
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« Reply #20 on: May 14, 2011, 08:47:45 AM »
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What I find interesting are yaya's comments elsewhere saying LCCs may no longer be required for the AP2 12 when using a tech camera - which if that were true I assume this would also be available for the IQs perhaps? Seems like it is a software issue to begin with so that would make sense, and would take us yet another giant leap forward especially for tech cam users.
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ternst
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« Reply #21 on: May 14, 2011, 09:47:35 AM »
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Two observations about Mark's great writeup - first, he still uses a laser rangefinder and only uses the focus mask to confirm that his rangefinder worked. I'm hoping the focus mask will make use of the rangefinder mute. And secondly he is still using a wake up cable, with a comment that having the back turned on for 5-10 minutes (depending on ambient temp) did not induce any noise - that amount of time would be just getting started for me and I frequently spend 30 minutes or more shooting an outdoor scene. I wonder how long this back can be turned on without generating noise at 72 deg. F? I don't like using a wake up cable due to the fact you have to make two connections each time you change a lens (actually four - two off the old lens and two on the new lens) vs. just having to unplug/plug in the sync cable when the back is on all the time (like a Leaf). I much prefer to keep a cable release on each lens so all I have to do it change out the sync cable - much faster and saves wear and tear on the threads. I guess the alternative is to be turning the back off and then on again frequently. Colder weather would be better of course!
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michael
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« Reply #22 on: May 14, 2011, 10:02:14 AM »
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Focus Mask and even Live View won't make the laser redundant. As good as the mask is, there is the point of critical focus and the rest is depth of field and circle of confusion toleration.

So if the subject is at nine feet, ten and three quarter inches, the laser will tell you this. Even at its most restricted setting the focus mask will show subjects at, say 8 feet, and 11 feet as also being in focus (I'm making these numbers up to make a point. Don't take them as exact).

So, Live View will be good for accurate framing, and focus mask wil confirm focus, but for the critical focus that MF digital requires a Leica Disto 5 and fine focus marks on the lens (such as those on the Alpa rings HPF rings) will still be the preferable way of working.

I was dubious about this method, but after the first time out with it I found it to be fast, simple, and deadly accurate.

Michael
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ternst
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« Reply #23 on: May 14, 2011, 10:25:14 AM »
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Thanks. I've got a disto in my bag anyway but almost never use it - I've been a zone focusser for many decades and it still seems quick and easy to estimate (with f16 or thereabouts)  - when doing macro or a longer lens I still use a ground glass.
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EricWHiss
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« Reply #24 on: May 14, 2011, 12:08:29 PM »
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The real differences aren't so much in the image quality as in the operational side of things. The Phase is hands-down the better back when it comes to features. But the Aptus provides similar image quality for many thousands less.



Michael, thanks for the info.   The one thing missing from the Phase backs for me is the rotating sensor which I find very useful with the AFi-ii 12, but I have a camera with a WLF and might not be a problem for 645 cameras. 
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dchew
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« Reply #25 on: May 14, 2011, 12:31:06 PM »
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I'm going to assume that liveview focusing will alleviate the need to shim the back? Comments
Marc

No I don't think so.  Well, maybe not.  If the back is too far away, then you can't physically focus at infinity.  Shimming is the only way to fix that.  If the back is too close, then you simply loose a bit of close focus.  So, I think:
1. IF live-view becomes the most accurate tool for checking focus, AND
2. Your back is either just right or too close...

Then you should be able to focus just fine without shimming.  We've already heard there is a need for a ND filter in bright sunlight.  We don't know yet how useful live-veiw will be.  However, my expectation is that I will use various tools to ensure accurate focus:  Focus mask, zooming to 100%, using the Alpa HPF rings, distometer, and a shimmed back.  Just like those who use a lightmeter along with the histogram, there usually is a combination of tools used.  A shimmed back that accurately reflects what the distance scale on the lens reads is another tool that can help verify what the other tools are telling you.

And of course if your back is too far away AND you want to focus at infinity, your stuck.

Dave
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ErikKaffehr
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« Reply #26 on: May 14, 2011, 12:48:52 PM »
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Hi,

There needs to be some margin for thermal expansion so there needs to be some slack in infinity.

Id suggest that LV focusing is the solution, but it may not be as easy as expected. In real world images don't snap in and out of focus and there is also some focus shift when stopping down.

Best regards
Erik


No I don't think so.  Well, maybe not.  If the back is too far away, then you can't physically focus at infinity.  Shimming is the only way to fix that.  If the back is too close, then you simply loose a bit of close focus.  So, I think:
1. IF live-view becomes the most accurate tool for checking focus, AND
2. Your back is either just right or too close...

Then you should be able to focus just fine without shimming.  We've already heard there is a need for a ND filter in bright sunlight.  We don't know yet how useful live-veiw will be.  However, my expectation is that I will use various tools to ensure accurate focus:  Focus mask, zooming to 100%, using the Alpa HPF rings, distometer, and a shimmed back.  Just like those who use a lightmeter along with the histogram, there usually is a combination of tools used.  A shimmed back that accurately reflects what the distance scale on the lens reads is another tool that can help verify what the other tools are telling you.

And of course if your back is too far away AND you want to focus at infinity, your stuck.

Dave
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dchew
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« Reply #27 on: May 14, 2011, 12:59:01 PM »
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Erik,

On a DSLR I agree with you; my Canon lenses could be focused beyond the infinity mark. However, this is not the way Schneider and Rodenstock lenses are made.  The infinity mark is the end stop, and in fact the shimming procedure is set up to make the infinity stop equal to sharp focus at infinity.  So there is no slack at infinity on these lenses.  You could of course shim it that way, but that would, um, require shimming!  And all the distance scales would be off.

Dave

Hi,

There needs to be some margin for thermal expansion so there needs to be some slack in infinity.

Id suggest that LV focusing is the solution, but it may not be as easy as expected. In real world images don't snap in and out of focus and there is also some focus shift when stopping down.

Best regards
Erik


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vjbelle
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« Reply #28 on: May 14, 2011, 01:21:26 PM »
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So, Live View will be good for accurate framing, and focus mask wil confirm focus, but for the critical focus that MF digital requires a Leica Disto 5 and fine focus marks on the lens (such as those on the Alpa rings HPF rings) will still be the preferable way of working.

I was dubious about this method, but after the first time out with it I found it to be fast, simple, and deadly accurate.

Michael
How exactly, then, did you check for critical focus?  Or, did you take numerous images at differing focus marks and pick the best one....  The whole idea of this back is to be able, somehow, to check for critical focus in the field...
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Wayne Fox
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« Reply #29 on: May 14, 2011, 02:24:21 PM »
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Focus Mask and even Live View won't make the laser redundant. As good as the mask is, there is the point of critical focus and the rest is depth of field and circle of confusion toleration.


So, Live View will be good for accurate framing, and focus mask wil confirm focus, but for the critical focus that MF digital requires a Leica Disto 5 and fine focus marks on the lens (such as those on the Alpa rings HPF rings) will still be the preferable way of working.

Michael
Guess I should reconsider waiting on the focusing rings.

Any particular reasons you feel live view focusing won't be as effective as on a dslr at 10x zoom. (may be the IQ's won't do 10x zoom ?)

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michael
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« Reply #30 on: May 14, 2011, 03:02:50 PM »
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Since no one outside of Phase's development lab has seen IQ live view yet, I think we should all wait a month or so and then judge what it can and can't do for ourselves.

Michael
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Anders_HK
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« Reply #31 on: May 14, 2011, 08:56:04 PM »
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Frankly, comparing image quality between the Aptus II 12 and Phase IQ180 is a bit like counting the hairs on the beards on the angels sitting on a pin. It would be the worst case of pixel peeping.

At this level of performance there are so many small variables that such a comparison would be fraught with difficulty.

The real differences aren't so much in the image quality as in the operational side of things. The Phase is hands-down the better back when it comes to features. But the Aptus provides similar image quality for many thousands less.

Michael

Michael,

The title of your article is rightfully "More than Megapixels" and likewise rightfully Mark points out "It is not all about megapixels!". There is much more to image quality and these backs than mere pixels and your reply of pixel peeping. Obvious one can assume that there must be more with the Aptus/Afi-II 12 and IQ80 since both have the newest generation sensor on the market. It would be interesting to read a comparison of those differences between the two backs.

The interesting thus is to find out what more than interface differs between the backs, and of what is different in the implementation of these sensors by Leaf and P1 (hardware and programming). Are the sensors the same? As I pointed out in my first post, Leaf has a longer history of working with Dalsa sensors and that could possibly mean that they may (or may not) have some extra up their sleeves.

Again it would be appreciated if you would find out through your sources.

I have also asked two times in posts above if you will update and edit these and other articles per corrections pointed out in this forum? It appears clear that for correctness the Aptus/Afi-II 12 and IQ80 are jointly at "King of Hill" in image quality of single shot devices. Without corrections it would seem that if not fan-boy label we could at very least speak of too much kool-aid on the newest toy gear segment?  Wink What digital backs are to I think most of us is mere TOOLS. What I ask for is simply info to find out how they hold up against each other and other such tools.

Regards
Anders

P.S. As compared to live view, the composition mode sounds far more interesting and simpler to use.
« Last Edit: May 14, 2011, 09:09:42 PM by Anders_HK » Logged
ErikKaffehr
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« Reply #32 on: May 15, 2011, 01:39:56 AM »
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Hi,

Thermal expansion coefficient for brass is around 20 ppm/C, so a temperature difference of 50 Celsius would cause a 0.05 mm change on a 5 cm long brass object. Aluminium is similar. So 0.01 mm of shim corresponds to about 10 degrees Celsius on a 50 mm object.

Best regards
Erik


Erik,

On a DSLR I agree with you; my Canon lenses could be focused beyond the infinity mark. However, this is not the way Schneider and Rodenstock lenses are made.  The infinity mark is the end stop, and in fact the shimming procedure is set up to make the infinity stop equal to sharp focus at infinity.  So there is no slack at infinity on these lenses.  You could of course shim it that way, but that would, um, require shimming!  And all the distance scales would be off.

Dave

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michael
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« Reply #33 on: May 15, 2011, 07:26:17 AM »
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Anders,

The only information about the sensor difference that I could get from both Phase and Leaf is that yes, it is the same sensor and no, it isn't.

My interpretation is that it is based on the same sensor die, but that Phase has some additional circuitry so that Sensor+ is supported.

What I do know is that the 80MP sensor was co-designed with Dalsa by Phase, to their specification, and that it is proprietary to them. We therefore will likely not see a competitor any time soon.

Michael
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Jack Flesher
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« Reply #34 on: May 15, 2011, 12:18:35 PM »
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So if the subject is at nine feet, ten and three quarter inches, the laser will tell you this. Even at its most restricted setting the focus mask will show subjects at, say 8 feet, and 11 feet as also being in focus (I'm making these numbers up to make a point. Don't take them as exact).


Michael,

I am not so sure this is the case.  I have not specifically measured either, but in my tests with f2.8 captures and a higher tolerance setting of near 50, the range of "mask" indicated by the back was extremely narrow and closely matched the critical pixels when brought into C1 and viewed at 100% -- I'm talking a few inches or so of mask depth and actual pixel depth from an angled, detailed subject taken at around 20 feet with the 80LS.  I agree that it doesn't render the laser moot -- at least yet -- but the range focus mask selects may be tunable to the point it's more than adequately fine at higher settings for many types of imaging. More experimentation is needed, but IMHO it shows great promise for critical focus determinations...
« Last Edit: May 15, 2011, 12:26:06 PM by Jack Flesher » Logged

michael
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« Reply #35 on: May 15, 2011, 12:26:20 PM »
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Jack,

You may be right. I haven't spent enough time testing this aspect. I will this week.

Michael
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