Renaissance painters lens making technology

[Mustafa Umut Sarac]

As you know Hockney and others claim that renaissance painters used concave mirrors and lenses to paint their own photorealistic pictures.
And many scientist found :
A - Nobody could not produce precise concave mirrors at 1400s . And they say nobody could not produce precise lenses at that time.
B - These mirrors produce extreme dark images and it is impossible to see the picture on paper.
I think scientists find problem at mechanically producing precise shapes from solid glass.
My idea :
A - These painters could use big pinholes.
B - If you want to build a precise shaped glass , you have 3 selections
I - You can carve two pieces of wood , make a mold out of it , and blow glass in it , you get a lens , you can fill it with water or mineral oil or vegetable oil. Wood dont burn with blowed glass.
II - You can build a mold with powder and pour glass in it.
III - You can still blow a precise lens with the help of air pressure , create sphere without need of mold , and fill it with liquid or hot glass.

Best ,

Mustafa Umut Sarac

 

[Sparky]

Actually they could make a far more precise curved glass surface than that using a fairly simple method. Take two glass blanks (flat) and rub them together in a circular motion. One of them will become concave - the other convex. But, that's just an old wive's tale perhaps.

 

[Mustafa Umut Sarac]

You are right , but every lens and mirror in the museums are far from the precision - this is what scientist say - but may be they build it few good ones and they broken in time. Italy is glass blowing center of europe and they could produce good lenses without inventing a technology.
And they say vikings carved aspherical lenses from the rock crystal !

 

[bjorke]

People have been using wooden mirrors for a long, long, time.

It's a mistake to think that if optical tracing was possible, that it then subsequently become the mode for ALL image-making. Wrong wrong wrong. But for an artist to experience optical tracing, esp an artist of the late 1400's, would be a major revelation in HOW TO THINK ABOUT PICTURES. It takes a very limited amount of this experience to have a huge mental effect.

The various "scientific" detractors of Hockney's thesis are pretty much blind to this notion.

 

[Mustafa Umut Sarac]

Wooden mirrors !? , very intelligently.
I watched at bbc that hockney was defending his theory in front of cameras. If they have a lens , if they have a darkroom , they would have clear , bright images on painting paper. Thats very clear.
Do they need it , do da vinci need a lens for photorealistic paint ? I dont think so . They are like bach , extremelly talented.
Experiencing a new dimension on painting ? Yes , it can be true.

 

[paul ron]

And are we forgetting that the pin hole has been around long before the lens? Painter would get into a large box with a pin hole and trace out their images.

 

[Akki14]

Pinhole idea is fine. Glass making, as I understand it anyway, wasn't very refined in those days so it's all fine and good saying You just make a mould and pour in some glass. There's more to it than that. Air bubbles were in a lot of glass in those days which would be faults in a lens. It's only fairly recently that technology has perfected glass (to the chemical composition to the manufacturing stages) to a lens quality.
The camera obscura idea for painters has been around for quite a while and in some cases it appears to be correct due to how certain paintings look.

Just my opinion on it. The best blown glass examples I've seen in museums from Rome still were full of tiny air bubble flaws.

 

[Bob F.]

Eyeglasses were first produced towards the end of the 13th century so it is quite reasonable to assume that lens technology was sufficiently advanced by the 15th century to produce adequate lenses for this purpose. You do not need perfect lenses, just ones that are good enough. Newton did not need Zeiss quality glass to write Optiks in 1704...

Cheers, Bob.

 

[David A. Goldfarb]

I think it's a good bet that Vermeer used a box with a lens. Some of his works have what seems to be a clear plane of focus, which one wouldn't otherwise expect in a realistic painting produced before the invention of photography.