just got my letus35a flip at DVinfo.net

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Old September 30th, 2006, 07:54 AM   #1
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just got my letus35a flip

There aren't any instructions, so i can get it to work but could just do with a few tips please.

When attaching the letus to my 72mm ring to get the image level and square to the camera i cant have it tightened up otherwise it is on its side. Is this normal?

I then zoom in to fill thr frame on my camcorder and focus on it, correct?
do i change any of the settings on the camcorder for irus, shutter etc. what should they be set as. Iris fully open etc?

I then use the iris and focus on the 35mm lens. At the moment there is some vignetting. it is an f1.4 50mm canon. is this normal? it's a nice effect but not one i want the whole time.

I would like to get a fast zoom aswell but if possible not too expensive, any ideas? when i shoot interviews i will need to reframe during them to avoid having to change lenses or move forward during.

thanks for helping me with my somewhat ignorant question!!!

Phil
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Old September 30th, 2006, 08:22 AM   #2
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Phil.

I wrote a bit of an unauthorised primer on the Letus Flip direct relay version a few weeks back. It won't be entirely relevent to your model of the device, but hopefully helpful in relation to managing the device from the flip enclosure forward.

Your version I have not had my greasy hands on so I don't know the issues relating to zoom-in with it. I presume but do not know whether there is a built-in close-up or macro lens on your version. If there is, it may likely be inside the tube which screws into the camera.

If there is none there, then you might have to consider getting a close-up (macro) lens of between 4+ and 7+ to help your camcorder zoom close-in on the groundglass for a smaller frame to get inside the vignette.

There is really only one close-up/macro lens type which works in this application. It is called an achromatic dioptre. 4+ varieties of this lens in 72mm filter thread mounts can be had, 7+ may not be findable and may not work with the Letus as the mirror path is a longer one than on my own experimentation.

Refer to posts by Dennis Woods and Wayne Kinney on this subject in the main alternative imaging methods forum. One or the other of them was getting custom HD capable macro lenses made.

Consult Quyen with an email on the subject of a close-up lens or macro and whether one is built-in to your Letus model.

I think I may have read that the DVX version screws into the camcorder's 72mm filter thread. Yours may be a similar arrangment.

I think there was some mention that on the Letus35 assembly, the rear tube this thread is on, being able to be rotated inside the Letus casework until the orientation is correct.

Unless I heard something from Quyen on your particular model, I would NOT be twisting or forcing anything to rotate as your appliance's design may be different. Try him with an email.

Given the weight of the Letus plus some of the lenses you may eventually put on it, I would recommend you use some added support for under the Letus body, like a bridge plate and rods arrangement. There is a strap accessory which will go underneath. I think Cavision supplies it.

I think you will find that the camera has to be zoomed in pretty much all the way to get inside the vignette. I find this on my own device with a +4 close-up lens on an FX1 or Z1P. (I now use a +7 but on my own device this brings both benefits and disadvantages, less zoom in so a bit of light saved but the strong magnification and closer couple of my device causes the edge of the prism path to intrude. This is not an issue with Quyen's generous mirror path and greater set-back distance from the groundglass than my own arrangement.)

Almost max zoom-in is the way with many of the adaptors which fit to video cameras with non-detachable lens systems.

You'll find the rest of my diatribes and dissertations here - please do not place reliance on my comments but do more research of your own :-

http://www.dvinfo.net/conf/showthread.php?t=75687

Your website is interesting and an education.

If you are into reading, have a look at "One Crowded Hour" by Tim Bowden - a bio of the late Neil Davis and "The Man Who Saw Too Much", author now unknown as I have loaned the book, a bio of David Brill.

Last edited by Bob Hart; September 30th, 2006 at 09:33 AM.
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Old September 30th, 2006, 10:07 AM   #3
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thanks Bob,

I am certainly getting there. You do have to zoom in more than i thought to get rid of those vignette corners, but the effect is love. I just need to play around with it until i can get a clean effect that is useful in all situations not just for the stylised ones. I am going to need to find myself a fast 28 or 35 to 70mm zoom for the letus for those interview and quick reframing situations, if you can recommened any...!

The letus flip though is one hell of a beast (have it fitted to my a1 at the monent. it works well but with the 50mm lens it it makes it twice as long as the camera!) but not have the inverted image makes life so much easier and will be much easier to sell to clients who just want my rushes rather than my complete services (all gratuities welcome)!

my website is an education? thanks, but how?!
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Old September 30th, 2006, 10:49 PM   #4
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got a nice quick nikon f2.8 80mm to 200mm and a nice quick sigma f2.8 28 to 700mm. they work very well but make the camera all very heavy.

i have some cavision 15mm rods but dont have the right bit to connect to my letus to support it. Anyone got any links or suggestions to what i need?

I'm still trying to work out how to get the image level when attaching the letus to my camera. when the mount is tight it is lopsided a fair bit so it needs to be loose. how can i get around this?

thanks

phil
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Old October 1st, 2006, 12:01 AM   #5
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Phil.

I think the Cavision to Letus support is a simple adjustable strap across the rods and the Letus mirror body sits on that. For more re-assurance, a thick stationery rubber band over the top back onto the rods or a couple chained is probably all that is needed if a bit inelegent.

The Sigma 2.8 28mm - 70mm is probably going to be the most useful. Tokina does a f2.8 17mm - 30mm and a f2.8 17mm - 50mm. Like all, wide-open is a bit soft but at about f3.5 - f4, really quite useful for final framing without moving people or tripods.

If you are using the 35mm movie frame off the groundglass, then to the camera, 28mm - 70mm is going to look a little more like roughly 50mm - 140mm in terms of field of view.

For the alignment of the frame, have a close look at the point where the rear tube attaches to the mirror enclosure. The end butts up against the rear face of the enclosure.

This tube fits up to a shoulder machined on the mirror enclosure on the relay versions. It is usually glued on to this shoulder which is quite narrow. On yours, the shoulder may be longer and if glue has not been used, then it may be possible to twist the tube around on the shoulder until the orientation of the groundglass screen is correct.

On some images I have seen on the web, this junction is sometimes secured by added screws.

At the junction of the end of the tube and the rear face of the mirror enclosure, look for a thin bead of glue. If there is none, then it may be that the fastening to the mirror enclosure is an interference (tight press fit ) fit onto a wider shoulder and movable.

For the support I made up for a relay version, I used a 15mm thickness piece of phenolic board, the stuff they use in household power boxes where the fuses and meters are. I drilled two holes for the rods and cut a large hole for the tube body which is for the front of the Letus to rest inside of.

I drilled and tapped a screwhole on top in the phenolic board to tighten gently against the Letus body to stop movement and two more lower on each side to tighten against the rods. To get the tube body to slip forward into the hole, the thumbscrew on front of the Letus has to be temporarily removed. When you do this, make sure no lens is on front otherwise the mount may drop out.

This method is a bit more bothersome to make than the strap arrangement but you can bump against things with some assurance you are less likely to do damage to the camcorder at the 72mm filter mount end. The whole lens subassembly on the FX1/Z1P is sealed and not repairable so it requires taking care of.
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Old October 1st, 2006, 09:06 PM   #6
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Bob,

is there any chance of email me a jpeg or two of your setup so i can see what you have done.

I also am having problems with the nikon lenses not staying put as there is no locking mechanism like there is for the canon side. any ideas?
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Old October 1st, 2006, 09:46 PM   #7
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Phil.

I shall have to get hold of the owner to see if he will photo it for me. It was for an XLH1 which has the camcorder lens offset to the left like a motion picture camera. It would prbably have been easier to make an offset baseplate.

The rods system was a modified teleprompter mount but the rods spacing and diameters were the same as for 12.7mm

For yours, the camcorder lens centre would be also a little offset but only about 6mm to 8mm to left. Sonys have the tripod mount screw a little to the left of centre as viewed from the front.

Quyen makes a mount for Nikon lenses only. It might be worth an email to him.

A quick and dirty fix is to drill and tap a 1/8" ( or nearest small size) screwhole in the mount on a radius. Find a small screw about 25m long ( enough for the fingers to be able to reach around and turn ) and use this to pin the lens against turning in the mount.

A wrap of gaffer tape or a piece of thin irrigation tubeing glued on the shank of the screw as a shoulder helps.

This only works on one position on the mount and about 1/8" has to be filed off one of the lugs on the mount where the screw comes through behind the matching lug on the lens itself once it has been turned fully home.

The screw is not and should not be forced tight as this will score the mouting area on the lens. It simply blocks the lug from turning back when you adjust the focus.

I will ask for an image of this also.
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Old October 1st, 2006, 11:29 PM   #8
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thanks Bob,

i will email him, the quick fix sounds terryfing as i quite a novice with DIY projects that arent to do with shelves and painting! I can't quite picture what you are suggesting!

Phil
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Old October 2nd, 2006, 03:46 AM   #9
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Phil.

It is probably left be as you suggest. The precision required taxes my skills to the limit and it still looks a bit ugly. - I am no engineer.

I have taken a .jpg of the working diagram I used for the Generic Teleprompter Mount to Letus Flip for Canon XL1.

This illustrates the principle only. Unless you have 12.7mm diam. rods at 60mm spacing, there will be no other similarity and for your camera, the optical centre of the Letus and the camcorder relative to mounts base plate etc., will remain different.

I'll try to send it to your email if I can find it here, otherwise if you send me an email, I'll send it as an attachment to a reply.

FOOTNOTE TO ABOVE:

Have sent attachment to your email quoted in caps at your web address.

Last edited by Bob Hart; October 2nd, 2006 at 05:06 AM.
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