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10-10-2012, 05:34 AM - 1 Like   #1
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Recipe for ultra-thin K-mount body

Hi,

Why don't pentax put the sensor up where the prism is on a dslr and fix the mirror at 45 degrees in place?

You could take up to 20 mm of thickness off the body with just this one move.

Matt

10-10-2012, 08:14 AM - 1 Like   #2
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If you think you can one-up the engineers of Pentax, Canon, and Nikon, then put your money where your mouth is. Start a camera company and produce this miracle compact DSLR.
10-10-2012, 11:53 AM   #3
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And why wouldn't it work?

If you're so sure this idea will fail, please explain why.

Matt
10-10-2012, 12:09 PM   #4
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Most of the greatest discoveries in humankind were doubted by the rest of the scientific community and of course the rest of the population. Einstein was ridiculed at first for his theory of relativity.

Then again, there are plenty of "inventors" who think they have the plans for cold fusion reactors, for time travel, etc.

I'm just saying that usually an idea as simple as yours has already been tested. There are probably many problems that you haven't thought of that the thousands of engineers who are paid on a daily basis to solve these problems have. Then again, maybe your suggestion is a genius idea that has been overlooked. If you're so confident that it WILL work, why tell everyone on a forum about it? Why not invest in this idea, refine it, and sell it to a camera company? Or double down and start your own compact DSLR company and make the big bucks. Steve Jobs didn't make millions by proposing his Ipod idea on a forum for everyone to see.

10-10-2012, 12:23 PM   #5
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I've seen this idea floated before, so I would hope that Pentax (and others) have at least considered it. I don't recall reading anything that conclusively ruled it out so I'll guess at reasons why it hasn't been done:
  1. Mirrorless cameras with newer mounts can already be made more compact (due to less back focus distance) than any DSLR mount.
  2. How much does the sensor assembly weigh? Maybe relocating it to the top of the camera might make the camera top-heavy and ruin ergonomics?
  3. A non-reflex mirror might confuse typical consumers because such a camera doesn't fit into either the mirrorless or DSLR category.
  4. This design would be limited to an LCD-only design much like the K-01. With the sensor up in the prism area there's little room left for a viewfinder, whether EVF or OVF.
  5. In a typical DSLR, a dirty mirror only affects the viewfinder image. With this new design mirror dirt would affect images. The mirror would have to be cleaned occasionally and cleaning scratches would accumulate over time, permanently decreasing image quality.
10-10-2012, 01:42 PM - 1 Like   #6
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So you've got nothing, you just felt like criticizing?

Gee, thanks for your contribution to the thread. Please read my original post, I merely asked "why Pentax don't do x."

It was an honest question, and if anyone has any technical insights as to why this is not possible (I am not stupid and would assume there are reasons it has not been done yet, no one having ever thought of it being the least likely of all) and is able to communicate with somewhat less sarcasm, I would enjoy a civilized conversation.

Matt
10-10-2012, 01:49 PM   #7
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  1. Mirrorless cameras with newer mounts can already be made more compact (due to less back focus distance) than any DSLR mount.

    But they don't accept all of my K-mount lenses!
  2. This design would be limited to an LCD-only design much like the K-01. With the sensor up in the prism area there's little room left for a viewfinder, whether EVF or OVF.

    I know that's the drawback, but if they can market a clunker like the K-01 with even a slight amount of success, imagine how successful what a very svelt and improved K-mount body with good ergonomics would be.

    QuoteQuote:
  3. In a typical DSLR, a dirty mirror only affects the viewfinder image. With this new design mirror dirt would affect images. The mirror would have to be cleaned occasionally and cleaning scratches would accumulate over time, permanently decreasing image quality.
I don't see why the mirror would scratch when you clean it. And I've had my k10d for 6 years now and shot 10's of thousands of images with it, changing lenses all over the place, never cleaned the mirror once, it looks just like brand new. And in the worst case, replacing the mirror should be neither difficult nor expensive. It's not a moving part.

Matt
10-10-2012, 01:53 PM   #8
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Its an interesting idea. The only problems I see is that it removes the possibility of OVF (but that's okay for some camera designs) and it is no longer a "DSLR."
The other problem is that the mirror might degrade quality too much or introduce other optical imperfections.

10-10-2012, 02:06 PM   #9
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It is an interesting idea, but I think the mirror would degrade quality, reduce light, and make SR much harder to implement. I have said so before but I think Pentax should get in the e-mount game and create a more functional adapter than currently available (AE and exif functionality). E mount is a lens system waiting to be exploited.

Last edited by ihasa; 10-10-2012 at 02:48 PM.
10-10-2012, 02:11 PM   #10
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If you want a conversation about the technical barriers to your proposed solution, you should have said so. Naming your post "Recipe for ultra-thin K-mount Body" is a little bold. Maybe point out some potential problems, solutions, etc, instead of making a statement that suggests Pentax, Nikon, Canon have been doing it wrong for 50 years.
10-10-2012, 02:30 PM   #11
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I'm a little lost here - why would that be any thinner than a camera without a mirror? Or are you trying to keep the OVF? In that case, how are you getting the image to the OVF and to the sensor?

If you remove the prism and replace it with the sensor, you'd only save on height. The sensor will take the width and length of the prism.

And if you reflect the image to the sensor - does that affect registration distance in any way?

Am I missing something?
10-10-2012, 02:38 PM   #12
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QuoteOriginally posted by ironlionzion Quote
If you want a conversation about the technical barriers to your proposed solution, you should have said so. Naming your post "Recipe for ultra-thin K-mount Body" is a little bold. Maybe point out some potential problems, solutions, etc, instead of making a statement that suggests Pentax, Nikon, Canon have been doing it wrong for 50 years.
That's not the impression I got from his post. Equally perhaps the first person to respond could have shot him down in flames less harshly.
10-10-2012, 02:43 PM   #13
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QuoteOriginally posted by JinDesu Quote
I'm a little lost here - why would that be any thinner than a camera without a mirror? Or are you trying to keep the OVF? In that case, how are you getting the image to the OVF and to the sensor?

If you remove the prism and replace it with the sensor, you'd only save on height. The sensor will take the width and length of the prism.

And if you reflect the image to the sensor - does that affect registration distance in any way?

Am I missing something?
You could move the rear lcd closer to the mirror, having vacated the space taken up by the sensor/SR mechanism. But now you have the problem of putting the SR mechanism in the roof of the camera, and you've only saved a few mm in depth.
10-10-2012, 02:49 PM   #14
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QuoteOriginally posted by ihasa Quote
You could move the rear lcd closer to the mirror, having vacated the space taken up by the sensor/SR mechanism. But now you have the problem of putting the SR mechanism in the roof of the camera, and you've only saved a few mm in depth.
Is there a dimension for the prism? Is it wider/longer than the sensor AND output electronics by much? I can't imagine that to be true - my focusing screen isn't so much bigger than my sensor.

Again - it could save on height (height of prism vs thickness of sensor & output electronics), but I don't see it saving much more than that... you could move the rear closer to the mirror (no more mirror flip mechanism), but there is also the degradation of image from the mirror (unless you have a seriously awesome mirror that doesn't cause chromatic distortions, which mirrors will do).
10-10-2012, 03:43 PM   #15
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QuoteOriginally posted by KL Matt Quote
Gee, thanks for your contribution to the thread.
QuoteOriginally posted by KL Matt Quote
and is able to communicate with somewhat less sarcasm
read my post. please, point out where I was being sarcastic? My first post poked a little fun at your idea, but it was in good nature. I responded to your next post saying "why would it fail" with a semi serious response. Clearly you took it as a huge insult.

QuoteOriginally posted by ihasa Quote
Equally perhaps the first person to respond could have shot him down in flames less harshly.
I didn't add to the conversation by my first post, but it was my second post that pissed him off, and I'm not sure why. I always hear revolutionary "solutions" that weren't thought out or researched. So when he posted a "recipe for a thing K-mount body" without any previous research presented, my cynical side kicked in.
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