Date   

T2 adapter equivalent for mirrorless cameras #cameras-issues #macro

Jeroen de Wijs
 

Someone wants me to prepare an old macro lens for DSLRs for a Sony with e-mount (NEX). For all the analogue camera's it was easy; when you know the brand and model, you can find a T2 adapterring for it and you were sure you got the right focus distance of 55 mm. to the film. 
Now with mirrorless camera's, I can find T2 adapter rings for all kinds of mirrorless camera's. Still with the standard distance of 55 mm. to the sensor.
But when I would design an alternative lens, intend to be used on mirrorless camera's, with a shorter focal distanceI, have to choose a contra coupling system. T2 is made for 55 mm. distance. What is the mirrorless camera equivalent for the shorter distances, say 30 mm. to sensor? I cannot find a general mount with screw ring. Or should I adopt a known brand as counter coupling system?
A thread is the easiest coupling system to make, or just plain straight, without any thread or bajonet.
I wonder what our groups opinion would be.
thanks,
Jeroen. 


Re: Panasonic Lumix 3d lens with Close-up Lenses vs Spacers Test

George Themelis
 

I have a couple of comments:

 

As Linda said, one of the biggest advantages of using close-up lenses vs. extension is that you need less cropping to set the stereo window. This is due to a prismatic effect of the lenses and it was first noticed and reported by Ken Burgess. When he tried using close-up lenses in 3D video cameras, he noticed that he did not need to adjust the stereo window as much or at all. He reported his findings here:

http://www.cyclopital3d.com/3D_Camera_Convergence_Adjustments.pdf

 

The higher the magnification, the more pronounced is this effect. One of the main issues at high magnifications is the amount of cropping required to set the stereo window. This is not (as much of) a problem when using close-up lenses.

 

In my standard setup, I have a 0.5mm extension which gives me the minimum magnification / close-focusing distance I can live with (anything less than that is nearly flat for me). From there, I use achromatic lenses to increase the magnification to take advantage of this effect.

 

Considering that the cost of the achromatic lenses is $20-$25 (according to the information here) why would anyone use a single lens? I would think that people would like the best image quality for a reasonable cost. If you start at a certain extension, as I do, then you only need one or two achromatic lenses.

 

Finally, I am surprised to hear that adding close-up lenses changes the exposure. If the lens is coated, the light loss should be minimal/negligible. I have never heard of exposure adjustments for using UV filters for example, even though these are an extra piece of glass too. Even if there was some minimal light loss, the achromatic lenses should not have more light loss. Adding glass does not steal light. It is the reflections on the surface that steal the light, but, with good coatings the light loss should be negligible. (In the achromatic lenses the two elements are cemented so there is no extra surface to reflect light).

 

George

 

 

=====

 

Results:

As expected, the simple singlet Vivitar lens resulted in a less sharp image compared to the other two options. There was a little blue fringing on the edges of the wings, although not as noticeable as I had expected. The black of the butterfly was noticeably not as black as with the other two options.

 

The achromatic lens and the Lumix lens with 1mm spacers installed resulted in images that were practically equal in quality. The lens with spacers installed had a bit of a cheat advantage in my test though because its focusing distance was significantly closer at 6.5” vs the achromat which focused at 8.5”.

 

Other observation: Both the singlet and the doublet (achromat) close-up lenses resulted in exposures that were around 1/8 to 1/4 stop darker than the lens with spacers. This was expected as adding glass steals a little light, and the doublet was slightly darker than the singlet.

 

I’ve attached a comparison image with 4x and 10 blow-ups so you can easily compare the shots, along with stereo pairs from all three options.

 

My Conclusion:

While the simple singlet Vivitar lens resulted in a bit lower image quality than the other two, I regularly use them with my adapter because they are cheap and provide a really easy and quick method to change magnification when shooting in the field. I’ve gotten very nice images using them. After all, the great thing about the Panasonic 3d lens is its convenience. For really sharp close-up and macro shots there are much better options. After these tests however, I will mainly use the lower magnification +1 and +2 Vivitars with the Pany lens because I think the image sharpness of the lower magnifications will be better, and their greater focusing distance will also help that. I will certainly not stack them (i.e. use both +1 and +2 stacked to get +3). I will use the +5 achromat and a +10 achromat that I have for the greater magnifications (it’s a +10 Optima achromat lens, available on Amazon for $24.95). For those of you using spacers, that is a good option with quality on a par with the achromat lens. To easily change magnifications in the field, either using close-up lenses with an adapter to fit onto the Lumix lens, or having multiple Lumix 3d lenses set up with different spacers are both good options.
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Re: Panasonic Lumix 3d lens with Close-up Lenses vs Spacers Test

 
Edited

 
 
Thanks for posting the test shots and info, Chuck.
 
One thing I thought I remembered as a potential advantage of using closeup lenses (rather than washer spacers) was that there may be benefit from a  prismatic effect making the subject more similarly aligned in left and right images. Is that correct? Since you can only see one side while shooting, I have had problems on occasion where I thought the subject was framed properly but the non-visualized side had bad framing.
 
If anyone wants to experiment with closeup lenses before ordering one of these  spiffy 3D-printed filter holders for their panasonic 3D lens , it is pretty easy to use gaffers tape around the barrel of the 3d lens and the add-on, to secure it temporarily.
 
I do indeed have several of these 3D lenses with different washer spacings, since the lenses were pretty inexpensive at one point, and changing washers in the field obviously is not practical.  I tend to use the lens with 0.8mm washer spacing for most of my closeup subjects, mainly butterflies and flowers. But I also have lenses with  0.5 and  1.6 spacers that I use occasionally.  Many people  like the 1.0 spacing. These are achieved with various combinations of 0.5mm and 0.8 mm thick washers. I have not measured exactly what focusing distance these correlate to, and I do use the "focus peaking" feature on the GX7 (or GX8) to help tell when I am in focus, although it cannot always be seen well. 
 
I do have some achromatic closeups, and some wide angle add-on lenses, that I would like to experiment with sometime soon. Linda

On Sun, Sep 13, 2020 at 10:05 PM Chuck <3dpdinc@...> wrote:

As promised last Sunday, I did comparison testing for the Panasonic Lumix 3d Lens using close-up lenses vs spacers in the lens. To keep things simple, I used components that I had on hand. They were not all exact apples to apples, but close enough to get a good sense of how image qualities from each of them compare to each other. Here are the three groups compared:

Lumix 3d Lens with +4 Singlet Close-up Lens (Vivitar - $9.99 for set on Amazon that includes: +1, +2,+4,+10)

Lumix 3d Lens with a +5 Achromat Close-up Lens (Kenko – $19.90 on Amazon)

Lumix 3d Lens with 1mm Spacers Installed

 

The test set-up details:

-         Panasonic GX7 Camera

-         Lumix 3d Close-up Adapter (any adapter can be used, this is the one I will be selling)

-         Focus distance was 8 and 8.5 inches respectively for the +4 and +5 lenses, but 6.5 inches for the lens with 1.0mm spacers. I only have .5mm washers, so I stacked two.

-         On-board flash used

-         Subject was a black butterfly. I selected it due to its limited depth of about 3/8” (wanted everything in focus) and dark edges wings and antenna (good for sharp defined edges, and dark edges where fringing can be prominent).  

 

Results:

As expected, the simple singlet Vivitar lens resulted in a less sharp image compared to the other two options. There was a little blue fringing on the edges of the wings, although not as noticeable as I had expected. The black of the butterfly was noticeably not as black as with the other two options.

 

The achromatic lens and the Lumix lens with 1mm spacers installed resulted in images that were practically equal in quality. The lens with spacers installed had a bit of a cheat advantage in my test though because its focusing distance was significantly closer at 6.5” vs the achromat which focused at 8.5”.

 

Other observation: Both the singlet and the doublet (achromat) close-up lenses resulted in exposures that were around 1/8 to 1/4 stop darker than the lens with spacers. This was expected as adding glass steals a little light, and the doublet was slightly darker than the singlet.

 

I’ve attached a comparison image with 4x and 10 blow-ups so you can easily compare the shots, along with stereo pairs from all three options.

 

My Conclusion:

While the simple singlet Vivitar lens resulted in a bit lower image quality than the other two, I regularly use them with my adapter because they are cheap and provide a really easy and quick method to change magnification when shooting in the field. I’ve gotten very nice images using them. After all, the great thing about the Panasonic 3d lens is its convenience. For really sharp close-up and macro shots there are much better options. After these tests however, I will mainly use the lower magnification +1 and +2 Vivitars with the Pany lens because I think the image sharpness of the lower magnifications will be better, and their greater focusing distance will also help that. I will certainly not stack them (i.e. use both +1 and +2 stacked to get +3). I will use the +5 achromat and a +10 achromat that I have for the greater magnifications (it’s a +10 Optima achromat lens, available on Amazon for $24.95). For those of you using spacers, that is a good option with quality on a par with the achromat lens. To easily change magnifications in the field, either using close-up lenses with an adapter to fit onto the Lumix lens, or having multiple Lumix 3d lenses set up with different spacers are both good options.

Within a day or two I will post photos of the adapter ready for sale.

-Chuck (I'll post this to the Lumix3d group also, but could not find a way to post to both at the same time).


+4 Vivitar


+5 Achromat Kenko


1.0mm Total Height Spacers installed in Lumix 3d lens

 

 


Panasonic Lumix 3d lens with Close-up Lenses vs Spacers Test

Chuck
 

As promised last Sunday, I did comparison testing for the Panasonic Lumix 3d Lens using close-up lenses vs spacers in the lens. To keep things simple, I used components that I had on hand. They were not all exact apples to apples, but close enough to get a good sense of how image qualities from each of them compare to each other. Here are the three groups compared:

Lumix 3d Lens with +4 Singlet Close-up Lens (Vivitar - $9.99 for set on Amazon that includes: +1, +2,+4,+10)

Lumix 3d Lens with a +5 Achromat Close-up Lens (Kenko – $19.90 on Amazon)

Lumix 3d Lens with 1mm Spacers Installed

 

The test set-up details:

-         Panasonic GX7 Camera

-         Lumix 3d Close-up Adapter (any adapter can be used, this is the one I will be selling)

-         Focus distance was 8 and 8.5 inches respectively for the +4 and +5 lenses, but 6.5 inches for the lens with 1.0mm spacers. I only have .5mm washers, so I stacked two.

-         On-board flash used

-         Subject was a black butterfly. I selected it due to its limited depth of about 3/8” (wanted everything in focus) and dark edges wings and antenna (good for sharp defined edges, and dark edges where fringing can be prominent).  

 

Results:

As expected, the simple singlet Vivitar lens resulted in a less sharp image compared to the other two options. There was a little blue fringing on the edges of the wings, although not as noticeable as I had expected. The black of the butterfly was noticeably not as black as with the other two options.

 

The achromatic lens and the Lumix lens with 1mm spacers installed resulted in images that were practically equal in quality. The lens with spacers installed had a bit of a cheat advantage in my test though because its focusing distance was significantly closer at 6.5” vs the achromat which focused at 8.5”.

 

Other observation: Both the singlet and the doublet (achromat) close-up lenses resulted in exposures that were around 1/8 to 1/4 stop darker than the lens with spacers. This was expected as adding glass steals a little light, and the doublet was slightly darker than the singlet.

 

I’ve attached a comparison image with 4x and 10 blow-ups so you can easily compare the shots, along with stereo pairs from all three options.

 

My Conclusion:

While the simple singlet Vivitar lens resulted in a bit lower image quality than the other two, I regularly use them with my adapter because they are cheap and provide a really easy and quick method to change magnification when shooting in the field. I’ve gotten very nice images using them. After all, the great thing about the Panasonic 3d lens is its convenience. For really sharp close-up and macro shots there are much better options. After these tests however, I will mainly use the lower magnification +1 and +2 Vivitars with the Pany lens because I think the image sharpness of the lower magnifications will be better, and their greater focusing distance will also help that. I will certainly not stack them (i.e. use both +1 and +2 stacked to get +3). I will use the +5 achromat and a +10 achromat that I have for the greater magnifications (it’s a +10 Optima achromat lens, available on Amazon for $24.95). For those of you using spacers, that is a good option with quality on a par with the achromat lens. To easily change magnifications in the field, either using close-up lenses with an adapter to fit onto the Lumix lens, or having multiple Lumix 3d lenses set up with different spacers are both good options.

Within a day or two I will post photos of the adapter ready for sale.

-Chuck (I'll post this to the Lumix3d group also, but could not find a way to post to both at the same time).


+4 Vivitar


+5 Achromat Kenko


1.0mm Total Height Spacers installed in Lumix 3d lens


Facebook's 2d to 3d AI project

Philip Heggie
 

 

 

Sent from Mail for Windows 10

 


Re: RED Hydrogen review #hydrogen

Andy Modla
 


Re: RED Hydrogen review #hydrogen

JackDesBwa|3D
 

KenK extracted 15 images from the Holopix50k dataset:

Dataset (or more precisely info to get it): [you need gsutil to download the images from the Google Cloud Storage nodes]

JackDesBwa


Re: RED Hydrogen review #hydrogen

Gordon Au
 

Can anyone share a link to an online gallery of *SBS stereopairs or anaglyphs* taken on the H1? I have yet to see (m)any stereos from it not locked behind the H1-exclusive app… Thanks.


Re: Double vision: Canon registers patent for stereoscopic lens for mirrorless cameras

John Rupkalvis
 

I just received an email from my partner Lenny Lipton.  Lenny mentioned that Canon may have filed that patent because they might have had a patent quota, similar to the quota that RealD has.  Lenny and I have partnered on several optical projects, and have been granted a U.S. patent on a stereoscopic lens design as co-inventors.  

John A. Rupkalvis
stereoscope3d@...

Picture


On Sun, Sep 13, 2020 at 9:31 AM John Rupkalvis via groups.io <stereoscope3d=gmail.com@groups.io> wrote:
This is a fairly common configuration.  It is very similar to the configuration of the StereoVision refracting elements.  The prime lens, or main group of elements, are the four elements closest to the sensor.  The first three elements are all negative, and serve to shorten the effective focal length.  The next two elements are positive, and probably serve several purposes including at least partial aberration correction.  The elements adjacent to the irises that are at 90 degrees to the others are relay elements that serve primarily to control the diameter of the "light tunnel" to get the rays past the mirrors without vignetting.  

John A. Rupkalvis
stereoscope3d@...

Picture


On Sun, Sep 13, 2020 at 6:55 AM akdens2 via groups.io <akdens2=yahoo.com@groups.io> wrote:
You have been talking about placing  add-on lenses like wide conversion lenses in front of camera lenses tho shorten their focal length.

Whereas this 7 element group is the main and integral part of the proposed camera lens.

Oktay


Re: Double vision: Canon registers patent for stereoscopic lens for mirrorless cameras

John Rupkalvis
 

This is a fairly common configuration.  It is very similar to the configuration of the StereoVision refracting elements.  The prime lens, or main group of elements, are the four elements closest to the sensor.  The first three elements are all negative, and serve to shorten the effective focal length.  The next two elements are positive, and probably serve several purposes including at least partial aberration correction.  The elements adjacent to the irises that are at 90 degrees to the others are relay elements that serve primarily to control the diameter of the "light tunnel" to get the rays past the mirrors without vignetting.  

John A. Rupkalvis
stereoscope3d@...

Picture


On Sun, Sep 13, 2020 at 6:55 AM akdens2 via groups.io <akdens2=yahoo.com@groups.io> wrote:
You have been talking about placing  add-on lenses like wide conversion lenses in front of camera lenses tho shorten their focal length.

Whereas this 7 element group is the main and integral part of the proposed camera lens.

Oktay


Re: 3D Macro & Panasonic FT-012 3D lens

George Themelis
 

I too have tried the combination of macro and wide angle lens.

 

One problem with the Panasonic 3D lens is that the field of view is quite narrow. The lens itself is listed as having a FL of 12.5mm. For the M4/3 format with a crop ratio of 2x this gives an equivalent FL of 25mm, which is very wide.

 

But since two pictures share one frame, the equivalent FL is twice that, so 50mm. With further cropping this is reduced to something like maybe 75mm, not wide after all.

 

I often have the desire to include more in one frame, hence the idea of using a wide angle lens.

 

But now I wonder if the combination of macro and a wide angle lens is self-defeating. By reducing the FL, you reduce the deviation achieved by the macro lens (from the same distance). So maybe moving back will have the same depth (deviation) as coming closer and using the WA lens?

 

I guess the difference is in the perspective: Even if the deviation is the same, you have a different perspective if you get closer vs. staying back.

 

George

 

From: Chuck
Sent: Friday, September 11, 2020 9:33 PM
To: main@photo-3d.groups.io
Subject: Re: [Photo-3d] 3D Macro & Panasonic FT-012 3D lens

 

Looks like that worked out very nicely Barry. So it sounds like you are using the Sony wide angle lens in combination with a macro lens ["Sony Wide angle with Macro lens..."]; did I understand that correctly? If so, were you looking to achieve a shorter focal length of the wide angle? I can understand using either independently on the Pany 3d lens, but never considered using those in combination. Thanks, Chuck

 


Re: 3D Macro & Panasonic FT-012 3D lens

George Themelis
 

Interesting…

 

Question about the two pictures with and without the WA attachment: These were taken with the unmodified Panasonic 3D lens?

 

George

 

From: Barry Aldous
Sent: Saturday, September 12, 2020 5:45 PM
To: main@Photo-3d.groups.io
Subject: Re: [Photo-3d] 3D Macro & Panasonic FT-012 3D lens

 

Yes, it did work out nicely – by chance.  The intention was to add a simple close-up but amongst my collection, I came across the Sony two portion wide-angle lens whereby removing the front segment, the remaining close-up portion provided the magnification I was looking for.  The Sony lens will be hard to find nowadays, but Neewer produce a similar lens.   

 

Neewer 58mm 0.43x Professional HD Wide Angle Lens with Macro Portion, available on eBay or from Amazon for around $30 to $40.  I use a couple of these lenses of a smaller size on my Fuji W3 camera.  The Macro FOV is around 1” (25mm). 

 

The attached images are representative of the Sony lens performance; the Neewer lens should be similar!

 

Barry

 

From: Chuck
Sent: 12 September 2020 02:33
To: main@Photo-3d.groups.io
Subject: Re: [Photo-3d] 3D Macro & Panasonic FT-012 3D lens

 

Looks like that worked out very nicely Barry. So it sounds like you are using the Sony wide angle lens in combination with a macro lens ["Sony Wide angle with Macro lens..."]; did I understand that correctly? If so, were you looking to achieve a shorter focal length of the wide angle? I can understand using either independently on the Pany 3d lens, but never considered using those in combination. Thanks, Chuck

 

Attachments:

 


Re: Double vision: Canon registers patent for stereoscopic lens for mirrorless cameras

Oktay
 

You have been talking about placing  add-on lenses like wide conversion lenses in front of camera lenses tho shorten their focal length.

Whereas this 7 element group is the main and integral part of the proposed camera lens.

Oktay


Re: 3D Macro & Panasonic FT-012 3D lens

Barry Aldous
 

Yes, it did work out nicely – by chance.  The intention was to add a simple close-up but amongst my collection, I came across the Sony two portion wide-angle lens whereby removing the front segment, the remaining close-up portion provided the magnification I was looking for.  The Sony lens will be hard to find nowadays, but Neewer produce a similar lens.   

 

Neewer 58mm 0.43x Professional HD Wide Angle Lens with Macro Portion, available on eBay or from Amazon for around $30 to $40.  I use a couple of these lenses of a smaller size on my Fuji W3 camera.  The Macro FOV is around 1” (25mm). 

 

The attached images are representative of the Sony lens performance; the Neewer lens should be similar!

 

Barry

 

From: Chuck
Sent: 12 September 2020 02:33
To: main@Photo-3d.groups.io
Subject: Re: [Photo-3d] 3D Macro & Panasonic FT-012 3D lens

 

Looks like that worked out very nicely Barry. So it sounds like you are using the Sony wide angle lens in combination with a macro lens ["Sony Wide angle with Macro lens..."]; did I understand that correctly? If so, were you looking to achieve a shorter focal length of the wide angle? I can understand using either independently on the Pany 3d lens, but never considered using those in combination. Thanks, Chuck

 


Re: Double vision: Canon registers patent for stereoscopic lens for mirrorless cameras

John Rupkalvis
 

These drawings both show exactly what I was saying.  The first elements are negative meniscus, and the rear elements of the prime lenses, closest to the sensor, are positive, as I have been saying all along. 

John A. Rupkalvis
stereoscope3d@...

Picture


On Fri, Sep 11, 2020 at 8:15 PM Depthcam via groups.io <depthcam=yahoo.ca@groups.io> wrote:
Very interesting discussion on optics.  Again I agree with Bill that the Canon design for this stereo lens is surprisingly advanced and I have to believe they would not have put that much research into it just for the exercise.  But I still find it hard to believe they will actually manufacture such a lens.

One thing I wanted to bring up that I wonder if anyone else has noticed:  There are actually two versions of the stereo lens in the patent.  One of them is symmetrical with the outermost front lens groups an equal distance from the center while the second design shows an asymmetrical version.  In the first design, all lens arrangements in the left and the right side are identical but in the second version they are different lens designs which apparently have the purpose of maintaining the same focal length while having a longer optical path on one side than on the other.

The only logical reason for this is to increase the interaxial to one side - perhaps because the symmetrical model has too small an interaxial - but not the other, since any increase in width in that side would impede upon the space required for a hand to hold the camera by the hand grip.  They put a lot of effort in optical design just to accommodate a hand !

Francois


Re: Double vision: Canon registers patent for stereoscopic lens for mirrorless cameras

Bill G
 

>  I still find it hard to believe they will actually manufacture such a lens.

            I do too... not because of marketing reasons, but technical and cost reasons.  What if they determine in the end, the lens will retail for $6K, is the market big enough to ramp up production methodologies, testing apparatus for each of the components to determine tolerance, QC, etc.?   These Giants need to build things in relatively high volume.  But Canon is a bit unique vs. other Giants, as they do build some highly sophisticated optics in volume that is considered low volume to electronic Giants.  Canons line up of high end sports (long) lenses, are prob. very low volume.  With prices in the $3K to $12K price range, some of the costlier lenses prob. sell under 400 a year.   Quite often, they are rented by pros.  But having the right lenses will sell camera bodies as well, a unique marketing marriage that Canon has capitalized on well through the years.

Unless they have built working prototypes of this stereo lens, and are convinced tolerancing will not crash the economics, there is still a long way to go.   I doubt there is a working prototype...but if there is, surely there is a MUCH better chance of Canon bringing the product to market. 

I doubt they will extend the interoc.  The handle is still a restriction... Not sure if you were suggesting they would only extend the left side to achieve greater Interoc?  I doubt it... and I think that would create viewing issues?  Never thought about how that would effect viewing... hmmm, interesting premise.   If the ray pattern is parallel, it's feasible with an extension tube.  But remember, there are tolerances also in this ray bundle as well.  The further you extend the tube, the parallelism errors magnify.  We do see this successfully implemented with marco, but often these are fixed tube lengths.

This is why I suggested in a previous post... interoc adjustment can more easily be achieved with a rotating the two outer lenses in a radius.  But this will only allow a smaller interoc for close work.  I doubt v1.0 of such a lens would include any of this...just getting a base unit to market will be a remarkable achievement....at least for the VR crowd, which I assume what this is designed for.  With a lucky break, maybe these VR units will soon have very high resolution screens with better optics for those of us pursuing fine art 3d.  In which case, the Plug n Play 3d solution will be here!   And if so....when?  3yrs, 5yrs 10 yrs?

I am hoping Canon is also working on a matching VR headsets, they are the perfect maker to develop a complete working system.  They have extreme knowledge of high resolution small screens as these are  used in their viewfinders and rear displays.  They also have extreme knowledge of visual optics unlike other camera makers.  They were the FIRST to make a 65 deg AFOV EP (Eye Piece) in their 10x42L binocs.  AFOV in astronomy and binocs =  Apparent Field of View, which designates the image end vs. the subject end, which is called TFOV, (True Field of View)   That was 15 years ago...still today, I have not seen this matched by other binoc makers, it is quite the visual experience, as most binocs have 25 - 40 deg FOV with a few higher end makers near 50 deg AFOV.  3D users can appreciate the added Wow factor with every 5 deg gain in AFOV.   To put 65 deg AFOV in perspective, the avg. IMAX seat experiences about 70 - 75 deg AFOV.   The average cinema seat experiences 50-55 deg AFOV. 

hoping for the best!
Bill



           


On Fri, Sep 11, 2020 at 8:15 PM Depthcam via groups.io <depthcam=yahoo.ca@groups.io> wrote:
Very interesting discussion on optics.  Again I agree with Bill that the Canon design for this stereo lens is surprisingly advanced and I have to believe they would not have put that much research into it just for the exercise.  But I still find it hard to believe they will actually manufacture such a lens.

One thing I wanted to bring up that I wonder if anyone else has noticed:  There are actually two versions of the stereo lens in the patent.  One of them is symmetrical with the outermost front lens groups an equal distance from the center while the second design shows an asymmetrical version.  In the first design, all lens arrangements in the left and the right side are identical but in the second version they are different lens designs which apparently have the purpose of maintaining the same focal length while having a longer optical path on one side than on the other.

The only logical reason for this is to increase the interaxial to one side - perhaps because the symmetrical model has too small an interaxial - but not the other, since any increase in width in that side would impede upon the space required for a hand to hold the camera by the hand grip.  They put a lot of effort in optical design just to accommodate a hand !

Francois


Re: Scanning Nimslo Negatives

Mike Brown
 

Hi Francois,

I will be a making a video on the process of making a 3D lenticular from those scans. But that will be for another day. About once a week I stream live as I'm printing lenticulars in my studio. I know you don't use Facebook but I also live stream it to my YouTube channel. You can view my printing session from yesterday there.

Michael


Double Trouble

 

I've already hit a snag with Blender VR scene inspection, and I'm hoping a Blender expert can help me out.
 
You can view this presentation in 2D or in stereoscopic 3D:


Re: Measuring Multi-Camera Shutter Sync #3d-cameras #homebrew #twinrig

Antonio F.G.
 

On Thu, Sep 10, 2020 at 10:06 AM, Bill Costa wrote:
I've got a large CRT and old Windows tower salted away just for this
one and only reason. But I will need to get rid of them at some
point. In fact the longer I keep them, the more they will cost to
dispose of.
If you are a bit familiar with the oscilloscope and solder iron, I would suggest
you trash the CRT and Windoze tower and replace them with an oscilloscope:-)

For timing measurements (as stereo synch is) the oscilloscope is THE TOOL (full stop)

Moreover: with an oscilloscope you can asses the synch error of an stereo rig using
only ONE CAMERA. Most of my measurements I show below are done with one
camera (because I only have one:-)


There has been recent discussion about the laser/pendulum approach.
But I had forgotten about the flash shoe idea.
Yes, I have measured the synch of all cameras I have at hand that have a hot-shoe.
The hot-shoe pulse can be taken as a proxy of the actual photo shot. It would be
better to measure the synch error in the actual photo but this can not be done with
a digital scope, which is the one I used for the tests.
Hot-shoe measurement also limits the maximum shutter speed, because most cameras
do not trigger the flash above some speed.

I have recently bought a very old analog scope and hope I could make synch tests
from the photos proper instead of the hot-shoe. I hope the analog scope can be used
in a similar way as the CRT test, only with way better precision and capability of control.
I have two test projects for this analog scope: testing my A720 SDM rig (that has no
hot-shoe), of which I only made a few CRT-like tests using an old TV. But the photos I got
on the (interlaced) TV screen are pretty blurred and confusing.


Following are reports of the synch tests I did using a digital scope. All of them looking at the hot-shoe:

Canon 350D: http://afgalaz.es/stereo/synch_canon_350d/

Fuji X-M1, X-E2: http://afgalaz.es/stereo/synch_fuji_x/

Samsung NX1000: http://afgalaz.es/stereo/synch_nx1000/



So, I'll ask the question again, is the output of a hot shoe
sufficient to provide enough precision for useful measurement of
shutter sync?
I hope so because the flash trigger should be carefully timed respect the shutter opening,
to ensure the lighting always happens with the curtains open.

Regards
   Antonio


A Classic 3d Clip True3d in 3d Deanaglyph Auto AI Colorized

Philip Heggie
 

A Classic 3d Clip True3d in 3d Deanaglyph Auto AI Colorized

 

https://www.youtube.com/watch?v=2o3C6---oTY

 

 

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