Should Pentax make a digital TLR ?

ppohja · 03-11-2018, 07:40 AM

Many phones nowadays are improving the image quality by actually having dual lenses on the main camera.

Could this idea be carried up to the SLR world? Business-wise, it would allow selling a second copy of every lens that people have already bought.

There was a patent describing some kind of film TLR, but maybe more traditional bird nest design would make more sense?

Should this happen, would it be Q mount or K mount?

HarisF1 · 03-11-2018, 07:45 AM

I wouldn't buy it. What's the benefit?

ppohja · 03-11-2018, 08:04 AM

Improved image quality.

Double the resolution or 8x resolution with pixel shift
Double the FPS (like gatling machine gun)
Improved dynamic range
New kind of bokeh effects

There's a reason why cell phone makers do it.

victormeldrew · 03-11-2018, 08:14 AM - **1 Like**

Originally posted by ppohja

There's a reason why cell phone makers do it.

Yes, to attempt to overcome some of the limitations of microscopic sensors and lenses, to try to close the gap to a full size camera.

pathdoc · 03-11-2018, 08:42 AM

TLR historically = at least 6 x 4.5, a size which is already covered (albeit at a slightly smaller aspect ratio) by the 645D and Z.

As for duplicating lens purchases, no. Just no. Let one copy be optically "off" from the other and the results would not be pretty, nor would the compensation be easy.

thazooo · 03-11-2018, 08:45 AM - **2 Likes**

I shoot with a TLR regularly. It's called a Rollei 3'5 e. It's the Real Full Frame, none of that 35mm crop stuff

DeadJohn · 03-11-2018, 09:12 AM - **5 Likes**

Originally posted by ppohja

..Could this idea be carried up to the SLR world?...

It could be done but is a bad product idea. The complexity of synchronizing 2 lenses and sensors would be unnecessarily complex. Parallax errors would affect any scenes that had depth to them. Yes, it's theoretically possible to fix some of that with software processing, but you won't get noticeably improved results over a single camera and lens.

Film TLR cameras use one lens to look through and the other to capture the image, and don't provide the same lens change versatility we get from SLR, DSLR, and mirrorless.

The concept, though, is being successfully used for astronomy. Lots of image processing is required, and it only works at infinity focus where there are no parallax issues. Here's one project:
Dragonfly - Dunlap Institute

**ChrisPlatt** · 03-11-2018, 09:58 AM - **1 Like**

No doubt they'd sell dozens, perhaps hundreds...

Chris

stevebrot · 03-11-2018, 11:07 AM - **3 Likes**

Originally posted by ppohja

digital TLR ?

I think perhaps there is a problem of definition. The camera you describe is not a TLR. This is a TLR (mine):

Hint: Only the bottom lens takes a picture.

Steve

leekil · 03-11-2018, 11:33 AM

Originally posted by DeadJohn

The concept, though, is being successfully used for astronomy. Lots of image processing is required, and it only works at infinity focus where there are no parallax issues. Here's one project:

Is this basically doing image stacking to reduce noise, but by taking multiple photos at once to avoid movement during longer exposures?

---------- Post added 03-11-18 at 11:35 AM ----------

There's also this camera, with *16* lenses:

Light Camera | Light

Not a Number · 03-11-2018, 12:26 PM

Right, TLR stands for "Twin Lens Reflex" camera. Reflex because it uses a mirror to the viewfinder. The mirror is fixed and the image in the viewfinder is reversed and upside down. SLR ("Single Lens Reflex") cameras have a roof prism to orient the image the proper way in the viewfinder. The mirror will move on SLRs (except in case on some Sonys). Even though the image was reversed on TLRs the idea was - what-you-see-is-what-you-get.

**TedH42** · 03-11-2018, 12:34 PM

Originally posted by stevebrot

I think perhaps there is a problem of definition. The camera you describe is not a TLR. This is a TLR (mine):

Hint: Only the bottom lens takes a picture.

Steve

My Yashica-635 agrees with Steve's Yashica-44. You are describing a "dual sensor" camera, not a TLR.

ppohja · 03-11-2018, 01:38 PM

Originally posted by DeadJohn

It could be done but is a bad product idea. The complexity of synchronizing 2 lenses and sensors would be unnecessarily complex. Parallax errors would affect any scenes that had depth to them. Yes, it's theoretically possible to fix some of that with software processing, but you won't get noticeably improved results over a single camera and lens.

Why these problems are not affecting phone makers?

Parallax errors can also be a benefit. In the old days, camera makers spent extra effort to design and manufacture beam splitters on front of the lens. Nowadays such Steritar seems to ask for close to 300$ on eBay.

It isn't that long time ago when the idea of taking 4 pictures and combining them in software was said to be a bad product idea, unnecessarily complex and anyways impossible because of moving targets changing location between shots would anyways ruin the picture.

Originally posted by DeadJohn

Film TLR cameras use one lens to look through and the other to capture the image, and don't provide the same lens change versatility we get from SLR, DSLR, and mirrorless.

Obvious. Just using the TLR name to give a connection of how could the thing look alike. A digital reincarnation clearly wouldn't just 1:1 copy the old concept.

Other usages could be e.g. sliding focusing - other lens takes the pic at f1.4 and the other f11 and then give a slider for defining the depth of field. Simplified light field.

Originally posted by Not a Number

Right, TLR stands for "Twin Lens Reflex" camera. Reflex because it uses a mirror to the viewfinder. The mirror is fixed and the image in the viewfinder is reversed and upside down. SLR ("Single Lens Reflex") cameras have a roof prism to orient the image the proper way in the viewfinder. The mirror will move on SLRs (except in case on some Sonys). Even though the image was reversed on TLRs the idea was - what-you-see-is-what-you-get.

SLR's got mirror moving, TLR's -- in the old times -- didn't.

A TLR with a swinging mirror to give both lenses light path to their corresponding sensors. Nobody has implemented this, but it still would be a TLR.

leekil · 03-11-2018, 02:02 PM

With phones, the dual lenses are primarily there because the small form factor prohibits a larger lens -- like a zoom lens. Two small flat lenses make more sense than a larger lens that would just out from the phone.

On a DSLR, they are already kind of big & heavy, but a second lens would just make them more big and heavy. And....they already have the zoom functionality that the two lenses give a phone camera, by putting a zoom lens on it.

**AstroDave** · 03-11-2018, 02:21 PM

Originally posted by leekil

Is this basically doing image stacking to reduce noise, but by taking multiple photos at once to avoid movement during longer exposures?

Yes - to reduce noise, but most importantly for astronomers using the dragonfly array, the (Canon 400 mm f/2.8 L IS II USM) telephoto lenses do not have any internal obstructions in the optical path. Virtually ALL other astronomical telescopes have stuff in the light path (typically struts that hold up parts of the telescope, like secondary mirrors and the detectors) that scatter light. The scattered light limits how faint you can see low surface brightness structure near brighter emission like the central parts of galaxies. Movement (of either the tracking mount or objects in the sky) is not a problem.

http://iopscience.iop.org/article/10.1086/674875/pdf discusses the dragonfly array(s). Quoting from the abstract: "The lenses are mounted on a common framework and are coaligned to simultaneously image the same position on the sky. .... The system has no obstructions in the light path, optimized baffling, and internal optical surfaces coated with a new generation of antireflection coatings based on subwave-length nanostructures. As a result, the array’s point-spread function has a factor of ∼10 less scattered light at large radii than well-baffled reflecting telescopes."

03-11-2018, 07:40 AM	#1
ppohja Senior Member Join Date: Jan 2013 Photos: Gallery \| Albums Posts: 194	Should Pentax make a digital TLR ? Many phones nowadays are improving the image quality by actually having dual lenses on the main camera. Could this idea be carried up to the SLR world? Business-wise, it would allow selling a second copy of every lens that people have already bought. There was a patent describing some kind of film TLR, but maybe more traditional bird nest design would make more sense? Should this happen, would it be Q mount or K mount?

03-11-2018, 01:38 PM	#13
ppohja Senior Member Join Date: Jan 2013 Photos: Gallery \| Albums Posts: 194 Original Poster	Originally posted by DeadJohn It could be done but is a bad product idea. The complexity of synchronizing 2 lenses and sensors would be unnecessarily complex. Parallax errors would affect any scenes that had depth to them. Yes, it's theoretically possible to fix some of that with software processing, but you won't get noticeably improved results over a single camera and lens. Why these problems are not affecting phone makers? Parallax errors can also be a benefit. In the old days, camera makers spent extra effort to design and manufacture beam splitters on front of the lens. Nowadays such Steritar seems to ask for close to 300$ on eBay. It isn't that long time ago when the idea of taking 4 pictures and combining them in software was said to be a bad product idea, unnecessarily complex and anyways impossible because of moving targets changing location between shots would anyways ruin the picture. Originally posted by DeadJohn Film TLR cameras use one lens to look through and the other to capture the image, and don't provide the same lens change versatility we get from SLR, DSLR, and mirrorless. Obvious. Just using the TLR name to give a connection of how could the thing look alike. A digital reincarnation clearly wouldn't just 1:1 copy the old concept. Other usages could be e.g. sliding focusing - other lens takes the pic at f1.4 and the other f11 and then give a slider for defining the depth of field. Simplified light field. Originally posted by Not a Number Right, TLR stands for "Twin Lens Reflex" camera. Reflex because it uses a mirror to the viewfinder. The mirror is fixed and the image in the viewfinder is reversed and upside down. SLR ("Single Lens Reflex") cameras have a roof prism to orient the image the proper way in the viewfinder. The mirror will move on SLRs (except in case on some Sonys). Even though the image was reversed on TLRs the idea was - what-you-see-is-what-you-get. SLR's got mirror moving, TLR's -- in the old times -- didn't. A TLR with a swinging mirror to give both lenses light path to their corresponding sensors. Nobody has implemented this, but it still would be a TLR. Last edited by ppohja; 03-11-2018 at 01:44 PM.

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03-11-2018, 07:45 AM	#2
HarisF1 Veteran Member Join Date: Apr 2016 Posts: 543	I wouldn't buy it. What's the benefit?

03-11-2018, 08:04 AM	#3
ppohja Senior Member Join Date: Jan 2013 Photos: Gallery \| Albums Posts: 194 Original Poster	Improved image quality. Double the resolution or 8x resolution with pixel shift Double the FPS (like gatling machine gun) Improved dynamic range New kind of bokeh effects There's a reason why cell phone makers do it.

03-11-2018, 08:14 AM - 1 Like	#4
victormeldrew Veteran Member Join Date: Jun 2015 Location: South West UK Photos: Albums Posts: 1,493	Originally posted by ppohja There's a reason why cell phone makers do it. Yes, to attempt to overcome some of the limitations of microscopic sensors and lenses, to try to close the gap to a full size camera.

03-11-2018, 08:42 AM	#5
pathdoc Pentaxian Join Date: Mar 2015 Photos: Gallery \| Albums Posts: 6,381	TLR historically = at least 6 x 4.5, a size which is already covered (albeit at a slightly smaller aspect ratio) by the 645D and Z. As for duplicating lens purchases, no. Just no. Let one copy be optically "off" from the other and the results would not be pretty, nor would the compensation be easy.

03-11-2018, 08:45 AM - 2 Likes	#6
thazooo Pentaxian Join Date: Sep 2006 Location: Mississippi, USA Photos: Gallery Posts: 854	I shoot with a TLR regularly. It's called a Rollei 3'5 e. It's the Real Full Frame, none of that 35mm crop stuff

03-11-2018, 09:12 AM - 5 Likes	#7
DeadJohn Pentaxian Join Date: Jan 2011 Location: New York Posts: 4,834	Originally posted by ppohja ..Could this idea be carried up to the SLR world?... It could be done but is a bad product idea. The complexity of synchronizing 2 lenses and sensors would be unnecessarily complex. Parallax errors would affect any scenes that had depth to them. Yes, it's theoretically possible to fix some of that with software processing, but you won't get noticeably improved results over a single camera and lens. Film TLR cameras use one lens to look through and the other to capture the image, and don't provide the same lens change versatility we get from SLR, DSLR, and mirrorless. The concept, though, is being successfully used for astronomy. Lots of image processing is required, and it only works at infinity focus where there are no parallax issues. Here's one project: Dragonfly - Dunlap Institute

03-11-2018, 09:58 AM - 1 Like	#8
ChrisPlatt Site Supporter Join Date: Nov 2007 Location: Rockaway Beach NYC Posts: 7,694	No doubt they'd sell dozens, perhaps hundreds... Chris

03-11-2018, 11:07 AM - 3 Likes	#9
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by ppohja digital TLR ? I think perhaps there is a problem of definition. The camera you describe is not a TLR. This is a TLR (mine): Hint: Only the bottom lens takes a picture. Steve

03-11-2018, 11:33 AM	#10
leekil Pentaxian Join Date: May 2016 Photos: Albums Posts: 2,003	Originally posted by DeadJohn The concept, though, is being successfully used for astronomy. Lots of image processing is required, and it only works at infinity focus where there are no parallax issues. Here's one project: Is this basically doing image stacking to reduce noise, but by taking multiple photos at once to avoid movement during longer exposures? ---------- Post added 03-11-18 at 11:35 AM ---------- There's also this camera, with 16 lenses: Light Camera \| Light

03-11-2018, 12:26 PM	#11
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	Right, TLR stands for "Twin Lens Reflex" camera. Reflex because it uses a mirror to the viewfinder. The mirror is fixed and the image in the viewfinder is reversed and upside down. SLR ("Single Lens Reflex") cameras have a roof prism to orient the image the proper way in the viewfinder. The mirror will move on SLRs (except in case on some Sonys). Even though the image was reversed on TLRs the idea was - what-you-see-is-what-you-get.

03-11-2018, 12:34 PM	#12
TedH42 F/8 & Somewhere Join Date: Dec 2011 Location: Colorado Photos: Gallery Posts: 1,412	Originally posted by stevebrot I think perhaps there is a problem of definition. The camera you describe is not a TLR. This is a TLR (mine): Hint: Only the bottom lens takes a picture. Steve My Yashica-635 agrees with Steve's Yashica-44. You are describing a "dual sensor" camera, not a TLR.

03-11-2018, 02:02 PM	#14
leekil Pentaxian Join Date: May 2016 Photos: Albums Posts: 2,003	With phones, the dual lenses are primarily there because the small form factor prohibits a larger lens -- like a zoom lens. Two small flat lenses make more sense than a larger lens that would just out from the phone. On a DSLR, they are already kind of big & heavy, but a second lens would just make them more big and heavy. And....they already have the zoom functionality that the two lenses give a phone camera, by putting a zoom lens on it.

03-11-2018, 02:21 PM	#15
AstroDave Loyal Site Supporter Join Date: May 2007 Location: Flagstaff, Arizona Posts: 1,637	Originally posted by leekil Is this basically doing image stacking to reduce noise, but by taking multiple photos at once to avoid movement during longer exposures? Yes - to reduce noise, but most importantly for astronomers using the dragonfly array, the (Canon 400 mm f/2.8 L IS II USM) telephoto lenses do not have any internal obstructions in the optical path. Virtually ALL other astronomical telescopes have stuff in the light path (typically struts that hold up parts of the telescope, like secondary mirrors and the detectors) that scatter light. The scattered light limits how faint you can see low surface brightness structure near brighter emission like the central parts of galaxies. Movement (of either the tracking mount or objects in the sky) is not a problem. http://iopscience.iop.org/article/10.1086/674875/pdf discusses the dragonfly array(s). Quoting from the abstract: "The lenses are mounted on a common framework and are coaligned to simultaneously image the same position on the sky. .... The system has no obstructions in the light path, optimized baffling, and internal optical surfaces coated with a new generation of antireflection coatings based on subwave-length nanostructures. As a result, the array’s point-spread function has a factor of ∼10 less scattered light at large radii than well-baffled reflecting telescopes."