Reversed image upside down?

Jon Laing · April 15th, 2005, 08:30 PM

Wait wait, im confused, doesnt a normal convex lens (i.e. a 35mm SLR lens) rotate the image 180 degrees? and then you're filming the back of the image, so its flipped horizontally again. Hence, my logic says its only flipped vertically... some one please explain how it all works out to a final 180 degree rotation.

Mark Kubat · April 15th, 2005, 09:44 PM

hey, you got a 35mm lens sitting around the house? take it off your camera and hold it up to a light bulb and adjust a piece of wax paper behind it in otherwise darkened room to see the focal plane - you'll see for yourself and sleep better tonight...

I'm not being a wise-ass - seriously - see for yourself to see how it works... and all the more appreciate the hard work someone's had to put in to get image like THAT to be usable for filming, etc.

a real eye-opener for me was trying to build the system agus/mediachance system about a month and a half ago... I never would have thought that it would be possible to get something as impressive as the footage that's been presented thus far - plus, it gave me a real insight as to the principle behind the micro35...

I know some people here are excited about static systems, but let me tell you, the "spinning" system carries some very important inherent advantages...

Kevin Richard · April 15th, 2005, 10:04 PM

Yeah but your still hitting the CCD chip with the same image... you are filming the back of the image but left is left and right is right as far as the ccd chip sees it.

Mark Kubat · April 15th, 2005, 10:16 PM

Kevin... you're replying to my post?

if yes, then keep in mind - the camera is filming off a screen (ie. ground glass). It is just like filming off anything. What hits the CCD doesn't really matter - if you know what's coming onto the focal plane after the image is "resolved" by the 35mm lens, you'll know what the camera is filming...

oh, for goodness sake...

1)the image is upside down...
2)the image is also "backwards" - left is right, right is left...

make of that what you will...

3) it's REALLY easy to correct in post production using NLE software - it's not a worry.

4) there are countless workarounds like magnets on LCD pull out screens to flipping monitors upside down to solve the conundrum while shooting...

have fun!

so, in other words, if you want to see properly while shooting and don't like magnets...

get external lcd/tft monitor - that feeds in via cam's "video out"...

turn it upside down
place a mirror like a door hinge so that montor is facing "away" from you... and mirror, like inside cover of a book, is facing you...

pretend upside down monitor is page 3.
mirror is page 2 - you have book open just a crack. the back of the monitor is facing you like looking at the back cover of your book - but you just see enough of page 2 inside to see it clearly...

no sweat...

you're rockin' and rollin'

Keith Kline · April 15th, 2005, 11:15 PM

<<<-- Originally posted by Mark Kubat : get external lcd/tft monitor - that feeds in via cam's "video out"...

turn it upside down
place a mirror like a door hinge so that montor is facing "away" from you... and mirror, like inside cover of a book, is facing you...

pretend upside down monitor is page 3.
mirror is page 2 - you have book open just a crack. the back of the monitor is facing you like looking at the back cover of your book - but you just see enough of page 2 inside to see it clearly...

no sweat...

you're rockin' and rollin' -->>>

you don't have to go through all that trouble. All you need to do is take a lcd monitor and turn it upside down. This basically rotates the image 180 degrees, which is the same a flipping the image up and down and left and right. This will correct the problems. the only reason you would need to go the route of using mirrors is if you were using an lcd that was attached to the camera and could not be flip upside down (rotated 180).

Check out the example I put up the other night to explain visually...

www.twistedinsomniac.com/180/

Brian Valente · April 15th, 2005, 11:35 PM

Ketih - thanks for putting that together. I think it helps illustrate it well.

Kevin Richard · April 16th, 2005, 11:18 AM

Mark, actually know I was replying to the post above yours... I had a phone call while I was replying so it ended up posting below yours ;)

I was basically saying the same as you...

But yeah, just take a monitor and put it upside down... no mirrors needed (take that david copperfield ;) )

April 15th, 2005, 08:30 PM	#46
Jon Laing Regular Crew Join Date: Mar 2005 Location: Wall, NJ Posts: 31	Wait wait, im confused, doesnt a normal convex lens (i.e. a 35mm SLR lens) rotate the image 180 degrees? and then you're filming the back of the image, so its flipped horizontally again. Hence, my logic says its only flipped vertically... some one please explain how it all works out to a final 180 degree rotation. __________________ --Devereaux ]:-( ---> http://geocities.com/anarchist_lb

April 15th, 2005, 09:44 PM	#47
Mark Kubat Major Player Join Date: Jan 2003 Location: Toronto, Canada Posts: 375	dude, try it yourself...no, really! hey, you got a 35mm lens sitting around the house? take it off your camera and hold it up to a light bulb and adjust a piece of wax paper behind it in otherwise darkened room to see the focal plane - you'll see for yourself and sleep better tonight... I'm not being a wise-ass - seriously - see for yourself to see how it works... and all the more appreciate the hard work someone's had to put in to get image like THAT to be usable for filming, etc. a real eye-opener for me was trying to build the system agus/mediachance system about a month and a half ago... I never would have thought that it would be possible to get something as impressive as the footage that's been presented thus far - plus, it gave me a real insight as to the principle behind the micro35... I know some people here are excited about static systems, but let me tell you, the "spinning" system carries some very important inherent advantages...

April 15th, 2005, 10:16 PM	#49
Mark Kubat Major Player Join Date: Jan 2003 Location: Toronto, Canada Posts: 375	what you see if you look through 35mm lens is the same... Kevin... you're replying to my post? if yes, then keep in mind - the camera is filming off a screen (ie. ground glass). It is just like filming off anything. What hits the CCD doesn't really matter - if you know what's coming onto the focal plane after the image is "resolved" by the 35mm lens, you'll know what the camera is filming... oh, for goodness sake... 1)the image is upside down... 2)the image is also "backwards" - left is right, right is left... make of that what you will... 3) it's REALLY easy to correct in post production using NLE software - it's not a worry. 4) there are countless workarounds like magnets on LCD pull out screens to flipping monitors upside down to solve the conundrum while shooting... have fun! so, in other words, if you want to see properly while shooting and don't like magnets... get external lcd/tft monitor - that feeds in via cam's "video out"... turn it upside down place a mirror like a door hinge so that montor is facing "away" from you... and mirror, like inside cover of a book, is facing you... pretend upside down monitor is page 3. mirror is page 2 - you have book open just a crack. the back of the monitor is facing you like looking at the back cover of your book - but you just see enough of page 2 inside to see it clearly... no sweat... you're rockin' and rollin'

April 15th, 2005, 11:15 PM	#50
Keith Kline Regular Crew Join Date: Aug 2004 Location: Akron, Ohio Posts: 153	Re: what you see if you look through 35mm lens is the same... <<<-- Originally posted by Mark Kubat : get external lcd/tft monitor - that feeds in via cam's "video out"... turn it upside down place a mirror like a door hinge so that montor is facing "away" from you... and mirror, like inside cover of a book, is facing you... pretend upside down monitor is page 3. mirror is page 2 - you have book open just a crack. the back of the monitor is facing you like looking at the back cover of your book - but you just see enough of page 2 inside to see it clearly... no sweat... you're rockin' and rollin' -->>> you don't have to go through all that trouble. All you need to do is take a lcd monitor and turn it upside down. This basically rotates the image 180 degrees, which is the same a flipping the image up and down and left and right. This will correct the problems. the only reason you would need to go the route of using mirrors is if you were using an lcd that was attached to the camera and could not be flip upside down (rotated 180). Check out the example I put up the other night to explain visually... www.twistedinsomniac.com/180/

April 15th, 2005, 11:35 PM	#51
Brian Valente Major Player Join Date: Jan 2005 Location: Hollywood, CA Posts: 293	Ketih - thanks for putting that together. I think it helps illustrate it well. __________________ ========================== Brian Valente Redrock Microsystems

April 15th, 2005, 10:04 PM	#48
Kevin Richard Major Player Join Date: Mar 2005 Location: Lafayette, LA Posts: 270	Yeah but your still hitting the CCD chip with the same image... you are filming the back of the image but left is left and right is right as far as the ccd chip sees it.

April 16th, 2005, 11:18 AM	#52
Kevin Richard Major Player Join Date: Mar 2005 Location: Lafayette, LA Posts: 270	Mark, actually know I was replying to the post above yours... I had a phone call while I was replying so it ended up posting below yours ;) I was basically saying the same as you... But yeah, just take a monitor and put it upside down... no mirrors needed (take that david copperfield ;) )