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05-06-2014, 07:28 AM   #166
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QuoteOriginally posted by DSims Quote
So why are these DOF calculators wrong?

Can someone help here?
Again I ask - how are DOF calculators wrong, precisely?

.

---------- Post added 05-06-14 at 08:54 AM ----------

QuoteOriginally posted by clackers Quote
Not this again!


You've cheated by moving the camera, John - you're really talking about FoV, not DoF, and changing two variables, not one.
No, he kept distance to subject the same, F-stop the same. What changed was FL - to maintain the same FOV.

QuoteQuote:
The DoF isn't the relative percentage of the frame that's in/out of focus, it's the absolute amount of the subject.
The relative % of the frame in focus does come into play when you crop. The absolute measured distance between the 'acceptable focus' borders in front and behind the subject and the distance from the sensor and the front acceptable focus area does not change, it can't change by cropping, but the % of the frame in focus changes radically by cropping.

Here's Joseph James' example demonstrating this:



People can get caught up in the tape measurements only, and miss the fact that the % of the frame (image) in 'acceptable focus' has changed quite a bit as a result of the crop, and thus falsly state that 'cropping does not change inage DOF'. It does.

This is why, while using the same lens on FF and apsc from the same distance gives aps-c less DOF, cropping the FF image to the same FOV as aps-c (1.5x) causes the DOF of the resulting image to be identical to the aps-c image.




.


Last edited by jsherman999; 05-06-2014 at 08:00 AM.
05-06-2014, 08:40 AM   #167
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Equivalence wins again. Is there anything equivalence can't do? I'm going to ask equivalence out to the junior prom.
05-06-2014, 04:53 PM   #168
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QuoteOriginally posted by jsherman999 Quote

No, he kept distance to subject the same, F-stop the same. What changed was FL - to maintain the same FOV..

Jsherman, first line of the second paragraph in that link. The gentleman used the same Sigma 105mm.


QuoteOriginally posted by jsherman999 Quote
People can get caught up in the tape measurements only, and miss the fact that the % of the frame (image) in 'acceptable focus' has changed quite a bit as a result of the crop, and thus falsly state that 'cropping does not change inage DOF'. It does.

Again, % amount of the frame in focus is not DoF.


DoF is the absolute amount of the object in focus.


They're related, but certainly not the same thing.

If my wife and I in the future stand side by side to take a picture of a friend, she with the K-30 and DA50, and me with the same lens on The Holy Grail (Pentax K-1 Full Frame), many people are of the impression that I'll be able to get the cool-looking near eye in focus, far one OoF shot, and she won't! :-)

---------- Post added 05-07-14 at 10:20 AM ----------

QuoteOriginally posted by ElJamoquio Quote
Equivalence wins again. Is there anything equivalence can't do? I'm going to ask equivalence out to the junior prom.


If you go parking with her afterwards, ElJamoquio, I hear you'll end up with a bad dose of LBA!

Last edited by clackers; 05-06-2014 at 05:19 PM.
05-06-2014, 06:56 PM   #169
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QuoteOriginally posted by jsherman999 Quote
Again I ask - how are DOF calculators wrong, precisely?
QuoteOriginally posted by jsherman999 Quote
The relative % of the frame in focus does come into play when you crop. The absolute measured distance between the 'acceptable focus' borders in front and behind the subject and the distance from the sensor and the front acceptable focus area does not change, it can't change by cropping, but the % of the frame in focus changes radically by cropping.
Thank you for pointing out the answer to the question. The absolute measured distance does not change, but the DOF calculators still say that it does!

05-07-2014, 05:49 AM   #170
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QuoteOriginally posted by clackers Quote
Jsherman, first line of the second paragraph in that link. The gentleman used the same Sigma 105mm.

No, you said John changed the distance in his response. That's what I was referring to.

.
05-07-2014, 05:51 AM   #171
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QuoteOriginally posted by jsherman999 Quote
No, you said John changed the distance in his response. That's what I was referring to.

.
Ah, with you now! (Thumbup)
07-02-2014, 01:43 PM - 1 Like   #172
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To get back to the original point of the thread …

Despite any marketing which might suggest the contrary, the pricing of the 645Z clearly leaves the door open for Pentax to release a FF at some point. The 645 is currently around seven times the price and almost double the weight of Pentax's next-in-line camera, and cannot use the same lenses. I'd say that door is wide open! Just about anyone in the market for the 645Z will already own either a FF or an existing MF. Those people aren't going to be buying a Pentax FF. The potential market for a Pentax FF is therefore unaffected by the 645 release - ie. those who have significant investment in K-mount lenses who want higher image quality/narrower DOF/better viewfinder/classic lens FOV who can't afford the money or time involved in changing systems entirely.

So I disagree with the suggestion in the opening post that the release of the 645Z in any way precludes the development and release of FF. If the 645Z sells well (and I think it will), then if anything, its release makes a FF more likely.
07-02-2014, 04:26 PM   #173
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QuoteOriginally posted by jonby Quote
its release makes a FF more likely.
With the 645Z release now out of the way, it does indeed beg the question: what will all those Ricoh engineers start working on next?

07-02-2014, 04:39 PM   #174
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QuoteOriginally posted by rawr Quote
With the 645Z release now out of the way, it does indeed beg the question: what will all those Ricoh engineers start working on next?
It was certainly hinted that it would be the full frame, but that was interpreted as Japanese executives being polite, so really, only a handful of Japanese guys know, whether they were being polite and a full frame is coming, or they were being polite and it isn't.
07-02-2014, 05:26 PM   #175
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QuoteOriginally posted by rawr Quote
With the 645Z release now out of the way, it does indeed beg the question: what will all those Ricoh engineers start working on next?
The engineers should have been done a long time ago. The 645Z shares almost all of its technology with the K-3 or the 645D. The 645z team should have been pretty small and should have been finished months ago. Production and marketing are the ones who are just now getting done with the 645z.

So what have they been working on since the K-3 was released? With a K-1 maintaining most of the K-3 tech, there really should not be a lot of new tech to design. A new shutter and OVF. New AF sensor array for the bigger VF.
07-02-2014, 05:49 PM   #176
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QuoteOriginally posted by rawr Quote
With the 645Z release now out of the way, it does indeed beg the question: what will all those Ricoh engineers start working on next?
Most of that small team will probably be doing something else.

Whoever was put on the FF team a couple of years ago or more has probably stayed there - at least a good number of them. They're the ones who've received no glory so far for all the work they've been doing behind the scenes. But they also know they're working on the most significant project - much more so than the K-3 (or its follow-ons), the 645Z, the Q line, or anything else.
07-02-2014, 06:02 PM   #177
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I think the team is now trying to resolve the mirror flap issue... and trying to find out if it's also infected the 645z. Rumour has it DRabbit has been sent two 645z cameras to field test... I made that up.... don't quote me. Y'all know how these rumours can get started.
07-02-2014, 06:07 PM   #178
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QuoteOriginally posted by normhead Quote
I think the team is now trying to resolve the mirror flap issue... and trying to find out if it's also infected the 645z. Rumour has it DRabbit has been sent two 645z cameras to field test... I made that up.... don't quote me. Y'all know how these rumours can get started.
Actually that's a special team which is visiting all the other teams to make sure they include a similar defect in their cameras But they're going to have to get more creative soon, because the mirror-flap fun is about to get old. It will be interesting to see what they come up with next!
07-02-2014, 06:07 PM   #179
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QuoteOriginally posted by rawr Quote
With the 645Z release now out of the way, it does indeed beg the question: what will all those Ricoh engineers start working on next?
Well, I think we all hope it's more like 'finishing off' than 'starting'. Either way I don't think they should start twiddling their thumbs just yet. If the 645Z sells well then there will be calls for new lenses, while a full-frame pro standard zoom would be a wise move for release with the FF camera. Finally, if you ask me most of the DA line now need a performance upgrade to avoid looking shoddy on the K-3 sensor.

Before they get back to work though, I hope they're allowed a day off to congratulate themselves on the release of the 645Z, which at the moment is looking like an absolute beauty. A deft move from Ricoh. Combining the existing technology from their small format cameras, previous MF camera and newly available CMOS sensor, they have exploited their unique position as a player in both arenas to create a highly compelling product which defines its own place in the market.
07-02-2014, 06:24 PM   #180
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QuoteOriginally posted by DSims Quote
Actually that's a special team which is visiting all the other teams to make sure they include a similar defect in their cameras But they're going to have to get more creative soon, because the mirror-flap fun is about to get old. It will be interesting to see what they come up with next!
I here its going to be the flash pops up and goes off 50 times, they are upping the irritation level. They've put condensers in there so it will go off at least two more times after you remove the battery. You heard it here first. They're sick of people like me saying it's not all that serious. They want to get people's attention.
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