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'Cornelius Varley's Patent Graphic Telescope'

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#1 CounterWeight

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Posted 26 August 2017 - 05:20 PM

No idea where to place this, I came upon it while doing some reading up on the "camera lucida" wrt Stephens and Catherwood... which has nothing to do with astronomy.

 

It is rare I come upon something that I've not encountered in my reading about astronomy, though I don't consider myself all that 'well read' on our favorite topic.

 

Anyone out there encountered either one of these or a book where it is a topic?  Yes I've done a 'goog' and there are many hits, more just curious - was this just for daytime use?



#2 CounterWeight

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Posted 26 August 2017 - 05:23 PM

here is a link that I found useful...



#3 BrooksObs

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Posted 26 August 2017 - 06:12 PM

The "camera lucida", or "camera obscura" for our parictular purposes, has a long history that can, I suppose, be measured in centuries. Although often applied to art in one form or another, modern versions of them have been applied to viewing terrestrial scenes rather than for astronomical purposes, but they can be used to a degree either way. These "instruments" were most commonly seen used visually during the late 19th century at beachside resorts in Europe on the beach itself. Situated within a darkened tent, patrons would pay to enter a few at a time and view their entire surroundings in a most novel way. It is said that the colors seen by the eye in full daylight are pale compared to their real hues and intensities revealed only in the semi-darkness of the camera obscura tent!

 

The principle is very much akin to how a regular camera works, except that the image is directed into the objective lens via a movable 45-degree mirror. The objective is mounted vertically and its beam projects downward onto a viewing table 6' or 8' below. The observer is literally within the camera itself!

 

One of the Amateur Telescope Making volumes discusses the construction of camera obscura-type instruments and both their terrestrial and astronomical applications. Situated in a darkened attic, the image appears on a round white table before the observer to view. Additional magnification can be produced by using a microscope-like arrangement placed on the viewing table using an attached small secondary mirror to intercept small portions of the incoming light beam from the long-focus objective. The whole arrangement is quite amazing to see and I've often thought about building one into the attic of my own home.

 

BrooksObs


Edited by BrooksObs, 26 August 2017 - 07:02 PM.


#4 Cotts

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Posted 26 August 2017 - 06:13 PM

Fascinating stuff.  I have been aware of the 'camera obscura' since I was a child. An aunt of mine used one to draw landscapes.  Picture a trailer about 6'x6'x6' with a hole in the roof.  Mount a small telescope pointing straight up in the hole.  Mount a flat mirror in a small rotatable cupola above the telescope at a 45 degree angle. The mirror collects light from the 'horizontal' more or less and then  the telescope, via eyepiece projection, focuses the light on a table and, in the darkened trailer, you can clearly see the landscape in great detail.  Just put paper down and trace the hills, buildings etc...   As I recall the lens of my Aunt's Camera Obscura was about 2 to 3 inches in diameter and must have been about 36 inches focal length..  Downside of the design - it was very, very hot in that little trailer...  I have no idea where her 'camera trailer', as she called it, ended up.  I last saw it in the late '50's when I was 7-9 years old.  Somewhere in a box I have one or two of her paintings made in it...

 

A quick Wiki check shows only the 'camera obscura' as a room with a pinhole in one wall which projected on the opposite wall...  Nothing with a telescope or lens....

 

Varley's 'Graphic Telescope' seems to be a similar idea - project a scene onto paper with a telescope and trace the outlines...  I would imagine the Varley version would be much more difficult to use as the writing/projection surface would be out in the daylight as well as losing a sizeable fraction of the light to the beam-splitter.....

 

From the design of the Varley instrument I would think it would be relatively easy to take a small, modern day refractor and eyepiece-project a scene onto paper for sketching...  No beam-splitting eyepiece, though.  Just aim with the eyepiece and diagonal by viewing through it and then rotate the diagonal to point down at the paper...  You'd need to have some shade, though, to see the image.... Perhaps project into a darkened room through the window....

 

Fascinating.   

 

Edit. BrooksObs, what you describe as the 'camera lucida' is precisely what my aunt had but hers was in a trailer which she towed behind the car to her 'targets'...  She never called it anything but 'camera trailer'....  A google search for 'camera lucida' turns up this sort of device http://www.leevalley...2,40725&p=72293 but no reference to what you and I are talking about.....

 

Dave



#5 mountain monk

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Posted 26 August 2017 - 06:56 PM

Varley was a famous watercolorist. Simple chroma, lots of sketches of, I recall, Wales. 

 

Darm skies.

 

Jack


Edited by mountain monk, 26 August 2017 - 06:57 PM.


#6 BrooksObs

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Posted 26 August 2017 - 07:14 PM

Here is a  link to a page that contains a number of illustrations of classic camera obscuras, together with the more common camera lucida-type devices typically employed by artists. Several of the illustrations show examples of the 19th century resort amusement facilities that I mentioned previously, along with their more modern incarnations. Enjoy! grin.gif

 

https://www.pinteres...33868107695724/

 

BrooksObs


Edited by BrooksObs, 26 August 2017 - 07:14 PM.


#7 EJN

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Posted 26 August 2017 - 07:15 PM

One of the Amateur Telescope Making volumes discusses the construction of camera obscura-type instruments and both their terrestrial and astronomical applications. Situated in a darkened attic, the image appears on a round white table before the observer to view.

 

That was ATM Book II (I just checked) and the article was by Horace Dall, co-inventor

of the Dall-Kirkham Cassegrain.



#8 BrooksObs

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Posted 27 August 2017 - 10:25 AM

Fascinating stuff.  I have been aware of the 'camera obscura' since I was a child. An aunt of mine used one to draw landscapes.  Picture a trailer about 6'x6'x6' with a hole in the roof.  Mount a small telescope pointing straight up in the hole.  Mount a flat mirror in a small rotatable cupola above the telescope at a 45 degree angle. The mirror collects light from the 'horizontal' more or less and then  the telescope, via eyepiece projection, focuses the light on a table and, in the darkened trailer, you can clearly see the landscape in great detail.  Just put paper down and trace the hills, buildings etc...   As I recall the lens of my Aunt's Camera Obscura was about 2 to 3 inches in diameter and must have been about 36 inches focal length..  Downside of the design - it was very, very hot in that little trailer...  I have no idea where her 'camera trailer', as she called it, ended up.  I last saw it in the late '50's when I was 7-9 years old.  Somewhere in a box I have one or two of her paintings made in it...

 

(snip)

 

Fascinating.   

 

Edit. BrooksObs, what you describe as the 'camera lucida' is precisely what my aunt had but hers was in a trailer which she towed behind the car to her 'targets'...  She never called it anything but 'camera trailer'....  A google search for 'camera lucida' turns up this sort of device http://www.leevalley...2,40725&p=72293 but no reference to what you and I are talking about.....

 

Dave

 

Brother Dave, the "camera lucida" you offer the link to is the device in perhaps its simplest , but most modern, form in using only a prism. Having dabbled in landscape oils myself off and on for many years I've often considered building, or purchasing, one of these prism-only designs. They have a distinct advantage over the optical projection type, like your aunt's camera obscura. This is because you can view 100% of the scene's ghost image 100% of the time while sketching it. With the true camera obscura, like your aunt's, the artist's hand shadows a portion of the scene while he sketches it.

 

Incidentally, I would have just loved to have seen your aunt's camera obscura in operation!

 

BrooksObs 


Edited by BrooksObs, 27 August 2017 - 10:26 AM.


#9 BrooksObs

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Posted 27 August 2017 - 10:36 AM

 

One of the Amateur Telescope Making volumes discusses the construction of camera obscura-type instruments and both their terrestrial and astronomical applications. Situated in a darkened attic, the image appears on a round white table before the observer to view.

 

That was ATM Book II (I just checked) and the article was by Horace Dall, co-inventor

of the Dall-Kirkham Cassegrain.

 

Thanks for the passage's citation, EJN. I recall loving reading Dall's account of his camera obscura in ATM II, reading it several times over and especially enjoying his comments on what he could see both terrestrially and astronomically with it.

 

Incidentally, having talked about these marvelous instruments with noted ATM and optician George East of upstate NY, I learned that he had built and installed at least one for himself in his home (it appeared in S&T I think) and several complete home camera obscura systems for clients years back. As I recall, he wasn't sure that any were still in operation as of a few years back.

 

BrooksObs


Edited by BrooksObs, 27 August 2017 - 10:38 AM.


#10 CounterWeight

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Posted 04 September 2017 - 12:33 PM

I was/am intrigued by one article that mentioned using a darker paper with light color drawing colors.  I've done some very crude sketching, I have a disability from brain stroke that makes very short term memory extraordinarily difficult if not impossible to rely on.  Looking from the ep to my sketchpad is almost torture. Not looking for sympathy, I look for solutions. I do the crude sketching to help exercise my brain and also to call out something about the object view worth noting.  It seemed to me that an apparatus like this would possibly be a game changer.

 

I often tell anyone that will listen to NOT look at pictures taken through a telescope to decide anything other than very narrowly defined things about imaging.  "Look at sketches" people make I always advocate... you may not see the same but it will be much more representative of what is possible through the eyepiece.



#11 KLWalsh

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Posted 05 September 2017 - 07:53 PM

This is sort-of related to the camera obscura. It's an amazing movie about the painter Vermeer. His technique was phenomenal - and it may have been aided by optical technology.
The movie is 'Tim's Vermeer'.

http://m.imdb.com/title/tt3089388/


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