Letus flip footage, film of grain

Bob Hart · October 19th, 2006, 11:33 AM

Blue Peter. That is something I know absolutely nothing about. Have I missed anything?

As for the adaptor, my first experiments consisted of a Pringles can with a slot cut in it, a 600 grit groundglassed microscope slide which I scrounged from our local path lab, an X-Fujinon f1.8 50mm lens, a heel-less sock rolled up around the lens and stuffed inside the can to hold the lens there, the other sock rolled up to hold the front of the PD150 in the can.

The concoction of course, was called the pringlecam. There are one or two frame grabs from it at www.dvinfo.net/media/hart which is a very unstructured archive of images from my experiments. The filenames are titled "fixed groundglass.JPG" or similar.

Phil Bloom · October 19th, 2006, 01:35 PM

BLue Peter is an institution in the UK. It's a kid's show that has been running since the dawn of time.

They do a spot where they make things out of nothing. Like when Thunderbirds tracy island was sold out a few christmas ago they showed how to make you own one!

Phil Bloom · October 19th, 2006, 01:36 PM

Bob, I can't quite work out what you meant by your description on page 1...

Oleg Kalyan · October 19th, 2006, 02:04 PM

Dear Phil, could you post the picture of your A1 setup, and maybe couple of seconds of original 1080 footage, from compressed video, hard to tell how is the quality, from your POV is it close to non adapter video? I also have A1 Sony, usually shoot with portrait mode, the camera keeps F Stop at 1.8... is it suitable for Letus, what is you F Stop on the lens?

Phil Bloom · October 19th, 2006, 02:15 PM

Quote:

Originally Posted by Oleg Kalyan

Dear Phil, could you post the picture of your A1 setup, and maybe couple of seconds of original 1080 footage, from compressed video, hard to tell how is the quality, from your POV is it close to non adapter video? I also have A1 Sony, usually shoot with portrait mode, the camera keeps F Stop at 1.8... is it suitable for Letus, what is you F Stop on the lens?

Hi oleg,

I wil have to post a photo later, it's not set up at moment and it's so damn fiddly! I havent seen any of my footage on my proper hd tv yet as I am still away. Will find out at the weekend. it looks great as far as I can tell, it looks different, but I think that is the point. You won't get the same detail I am sure though, so if you want non adaptor stuff to match might be worth turning down the detail in the camera when shooting now letus stuff.

I have never used the AE presets. I have always shot full manual on my cameras.

You need to keep the shutter at 50 or 60 depending on ntsc or pal, if you use a preset it will probably start changing the shutter speed. So keep shutter to that setting and keep your iris open on film lens and control exposure on the sony, if it gets too dark sony will start putting in grain unfortunately!

i have posted on the same link a file called 1080 or something like that for you!

Bob Hart · October 20th, 2006, 12:05 AM

Phil.

My technical descriptions are not always the best.

The sleeve I refer to might best be described as a tubular spacer.

I cut a short 5mm length off a piece of white plastic pipe which is 44mm internal diameter and 2mm wall thickness. You end up with a ring of plastic pipe and this is now called the tubular spacer.

This ring is too wide in diameter to fit in the hole behind the lens mount so I then cut a piece out of the ring and squeezed the ends together to make it fit in the hole in the Letus body where the mount goes.

5mm is a bit too short so I cut two washers from cereal packet. This cardboard is about 0.5mm thick. I found that one washer was enough to bring the face of the mount to the correct position. The washer fits between the rear of the tubular spacer and the end of the hole in the Letus where the glass panel is.

All up, the length of the spacing btween the back of the lens mount and the rear of the hole the lens mount sits in is 5.5mm. A single tubular spacer 5.5mm long would do it.

You might have to rub a bit more off with sandpaper on a flat surface if it is too thick.

The wall thickness has to be 2mm or more as the front end comes up against the end face of the Canon mount machining and not the wider area in front of the groove for the Canon mount. (as viewed when the mount is reversed for Nikon.)

A very thin wall thickness will allow the tubular spacer to slip over the edge of the Canon mount machining and the spacing will be wrong.

Quyen's reversable mount seems to be almost perfect for backfocus for the Canon lenses when it is pushed fully home in the Letus body before tightening the thumbscrew. I get this from another description on this site.

A much shorter precisely machined metal tubular spacer would work better but the Canon mount machining on back of the dual mount makes the precise fit difficult beyond my crude engineering capabilities, which is why so far have gone with plastic pipe and cardboard until I can get the dimensions just right then make something better out of metal.

It is only a quick fix until I can get the design for a Nikon mount with adjustable backfocus sorted. The problem with this is the space available between the back of the Nikon lenses and the front of the Letus body.

It is difficult to fit a backfocus lever, lock and button released pin lock to retain the the Nikon lens, all in the same confined area.

I'll hunt down a .jpg of my cude mod to the Nikon end of the mount to secure the lenses. The lug the radial hole is drilled through and filed back is the longer one of the three.

Feel free to post these .jpgs somewhere to help others. I have not been able to get them to take here at dvinfo because I cannot resize them.

I cannot get a .jpg of the tubular spacer arrangement presently as the Letus is back with the owner.

Phil Bloom · October 22nd, 2006, 05:09 PM

http://homepage.mac.com/philip.bloom...eb.mov-zip.zip

this is a short video I have made highlighting the letus and my steadicam merlin

Phil Bloom · October 26th, 2006, 10:32 AM

moved to another thread

October 19th, 2006, 01:35 PM	#17
Phil Bloom Trustee Join Date: Aug 2006 Location: London UK Posts: 1,939	BLue Peter is an institution in the UK. It's a kid's show that has been running since the dawn of time. They do a spot where they make things out of nothing. Like when Thunderbirds tracy island was sold out a few christmas ago they showed how to make you own one! __________________ Philip Bloom Cinematographer, Director, Filmmaker www.philipbloom.net

October 19th, 2006, 01:36 PM	#18
Phil Bloom Trustee Join Date: Aug 2006 Location: London UK Posts: 1,939	Bob, I can't quite work out what you meant by your description on page 1... __________________ Philip Bloom Cinematographer, Director, Filmmaker www.philipbloom.net

October 22nd, 2006, 05:09 PM	#22
Phil Bloom Trustee Join Date: Aug 2006 Location: London UK Posts: 1,939	http://homepage.mac.com/philip.bloom...eb.mov-zip.zip this is a short video I have made highlighting the letus and my steadicam merlin __________________ Philip Bloom Cinematographer, Director, Filmmaker www.philipbloom.net

October 26th, 2006, 10:32 AM	#23
Phil Bloom Trustee Join Date: Aug 2006 Location: London UK Posts: 1,939	moved to another thread __________________ Philip Bloom Cinematographer, Director, Filmmaker www.philipbloom.net Last edited by Phil Bloom; October 26th, 2006 at 12:28 PM.

October 19th, 2006, 11:33 AM	#16
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,476	Blue Peter. That is something I know absolutely nothing about. Have I missed anything? As for the adaptor, my first experiments consisted of a Pringles can with a slot cut in it, a 600 grit groundglassed microscope slide which I scrounged from our local path lab, an X-Fujinon f1.8 50mm lens, a heel-less sock rolled up around the lens and stuffed inside the can to hold the lens there, the other sock rolled up to hold the front of the PD150 in the can. The concoction of course, was called the pringlecam. There are one or two frame grabs from it at www.dvinfo.net/media/hart which is a very unstructured archive of images from my experiments. The filenames are titled "fixed groundglass.JPG" or similar.

October 19th, 2006, 02:04 PM	#19
Oleg Kalyan Major Player Join Date: Apr 2006 Location: MOSCOW Posts: 860	Dear Phil, could you post the picture of your A1 setup, and maybe couple of seconds of original 1080 footage, from compressed video, hard to tell how is the quality, from your POV is it close to non adapter video? I also have A1 Sony, usually shoot with portrait mode, the camera keeps F Stop at 1.8... is it suitable for Letus, what is you F Stop on the lens?

October 20th, 2006, 12:05 AM	#21
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,476	Phil. My technical descriptions are not always the best. The sleeve I refer to might best be described as a tubular spacer. I cut a short 5mm length off a piece of white plastic pipe which is 44mm internal diameter and 2mm wall thickness. You end up with a ring of plastic pipe and this is now called the tubular spacer. This ring is too wide in diameter to fit in the hole behind the lens mount so I then cut a piece out of the ring and squeezed the ends together to make it fit in the hole in the Letus body where the mount goes. 5mm is a bit too short so I cut two washers from cereal packet. This cardboard is about 0.5mm thick. I found that one washer was enough to bring the face of the mount to the correct position. The washer fits between the rear of the tubular spacer and the end of the hole in the Letus where the glass panel is. All up, the length of the spacing btween the back of the lens mount and the rear of the hole the lens mount sits in is 5.5mm. A single tubular spacer 5.5mm long would do it. You might have to rub a bit more off with sandpaper on a flat surface if it is too thick. The wall thickness has to be 2mm or more as the front end comes up against the end face of the Canon mount machining and not the wider area in front of the groove for the Canon mount. (as viewed when the mount is reversed for Nikon.) A very thin wall thickness will allow the tubular spacer to slip over the edge of the Canon mount machining and the spacing will be wrong. Quyen's reversable mount seems to be almost perfect for backfocus for the Canon lenses when it is pushed fully home in the Letus body before tightening the thumbscrew. I get this from another description on this site. A much shorter precisely machined metal tubular spacer would work better but the Canon mount machining on back of the dual mount makes the precise fit difficult beyond my crude engineering capabilities, which is why so far have gone with plastic pipe and cardboard until I can get the dimensions just right then make something better out of metal. It is only a quick fix until I can get the design for a Nikon mount with adjustable backfocus sorted. The problem with this is the space available between the back of the Nikon lenses and the front of the Letus body. It is difficult to fit a backfocus lever, lock and button released pin lock to retain the the Nikon lens, all in the same confined area. I'll hunt down a .jpg of my cude mod to the Nikon end of the mount to secure the lenses. The lug the radial hole is drilled through and filed back is the longer one of the three. Feel free to post these .jpgs somewhere to help others. I have not been able to get them to take here at dvinfo because I cannot resize them. I cannot get a .jpg of the tubular spacer arrangement presently as the Letus is back with the owner.