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Old April 9th, 2008, 10:33 AM   #61
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Piotr- I feel your fustration. Perhaps you can offer some additional advice to Letus, and perhaps his device will not fullfill your needs. I am trying to make it work. I have ran into every obstacle with this device and have found a solution, hopefully these solutions and best practices will be implement into the LetusEX II.

Now some more best practices you need to know.

Never stop down the Sony EX1 camera lens to anything over F 5.6. Why?
Do this, go outside with the camera aim the camera for the sky. The Letus taking lens I will call it the Nikon lens in this case should be stopped down only 1 stop. The Sony EX1 close down to F 22, use or do not use the ND1 or ND2 on the Sony to get the Sony F stop so it is closed past F5.6 focus on the sky. Shoot starting @ F 22 start to open the sony lens one stop at a time until you get to F5.6. Take this fooage and look at it on a large monitor. Do you see spots?
I have spots on the Letus glass prisim, that I can not get off, and they are only visible when the Sony is @ above F5.6. This is true when shooting sky and or a light colored background. I do not use any F stop on the Sony that is over F5.6. If needed I use the ND on camera or before the Nikon lens to avoid the issue of seeing Letus spots, too much DOF. You have more flexablity when NOT shooting plain sky or backgrounds.

The other issue; do not bother to stop down the Nikon lens more than 2 stops from open, as it in the sky exsample above increses the DOF and the grain of the vibrating screen becomes more visible, and serves as a technical flaw. The SonyEX1 Lens stopped down too much increases DOF and shows dust spots inside the adapter.

So a few rules of the game to play by.

Let me know if any one can duplicate this by stopping down. Here are some sample pics showing the dust spots at F 11-16 on the left and no dust on the image on the right @ F 4-5.6 Dust is on the left side of the video grab & is very visible.
Attached Thumbnails
Letus Extreme and...-f11-16.jpg   Letus Extreme and...-f4-56.jpg  

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Old April 9th, 2008, 11:21 AM   #62
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I see the dust for sure. One question for you though Steve, how can stopping down the Sony create more DOF? Shouldnt that only be possible with the Nikon being stopped down as we're merely capturing an image from the GG into the Sony imager?

The tests I've been working on are actually trying to lengthen my DOF more. I'd like to operate at times with an f-stop of 4 to 5.6. Seems like I may be able to get away at times with 4. I'm working on an After Effects fix to see if I can make it work.

BTW, I'm working on this idea in AE where I am taking footage of the plain GG vibrating - taking it to B&W and inverting it and using it as a reset mask using add or screen to bring back up the dark areas. I then level and reset the contrast. I'll do some tests once my sched clears and have to post results.

How are you an Phil getting a deeper DOF in your shots? Such as Phil's stuff from New Mexico that showed some nice deep focus on the tramway piece.
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Old April 9th, 2008, 11:38 AM   #63
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Steve,

Thanks for your excellent hints, again. Yes - even though I only have a very basic experience - I can confirm most of your observations. When clear sky occupies considerable pat of the scene being shot, one must be very careful with the shutter speed and aperture combinations, as the GG can become visible. One thing I can say in favour of my own particular Letus unit is that there are no spots whatsover - all I'm getting (when shutters is too fast, or the prime stopped down) is some film-like, uniform grain; actually could be used for artistic purposes.

What do you think of my idea of using bushings/spacers/washers (whatever the right English term is best for it) under the lense mount's flange for backfocus adjustment without messing around with the adapter's innards?
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Old April 9th, 2008, 12:07 PM   #64
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Quote:
Originally Posted by Steve Cahill View Post
Let me know if any one can duplicate this by stopping down. Here are some sample pics showing the dust spots at F 11-16 on the left and no dust on the image on the right @ F 4-5.6 Dust is on the left side of the video grab & is very visible.
Yes, I had this problem big time. When I got my LEX it was still snowy in Finland and on a sunny day all you're shooting at is basically white. So i needed to stop down to f16 with ND2, thats bright I tell you! All the footage was totally useless as it was just full of this gg smudge.

Now that the snow is gone my problems are gone as well. But I do have an ND filter to stick in front of the glass (the Coking ND gives me weird red issues talked in other posts though).
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Old April 9th, 2008, 12:19 PM   #65
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Originally Posted by Jeremy Hughes View Post
,how can stopping down the Sony create more DOF?
It doesnt create more DOF in the image you are seeing but it creates more DOF to the ground glass of the letus. I bet someone more techinacal can explain why it is like it is. But I get best results with EX1 f stop around 4-6 just as Steve says.
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Old April 9th, 2008, 02:15 PM   #66
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Sami correct yes DOF to the Letus GG.
Remember we are talking about 2 lens here, The camera lens that focus on the rear of the letus GG and a taking lens that focus on the subject but puts its image on the GG for the Sony lens to focus on. Two DOF's that work independent of each other. Too much DOF and any dirt, spots on the Letus shows up, just trying to see where it is inside!

The new Nikon mount has some screws to adjust back focus but the old mount and the new mount are not the same thickness, the newer mount is thicker, which means the adjusting screws on the new mount push it out too much, the new mount needs to be thinner so the screws are at their min distant. If you make a adjustment the lens goes out too far, when we need it to go in, thus we have to pull out the GG to compensate. I had to adjust my GG when I got the new Nikon mount just because it was thicker. I think you could try to make a GG that is adjustable but with a rigid adjustable mount I think you would be introduceing new issues. But try it let us know how you make out and you will be in the adpater business. UGH... This is a big difference between spinner type adapters and vibrator type. Phil Bloom has a good FAQ called: "35mm Shootout" Read it @ http://www.philipbloom.co.uk/Philip_..._Shootout.html

The issue is with the weaker part of the adpater which is the CG. It needs not to move, fixed, and stay that way through-out the life of the adapter. Or better yet buy a camera that makes use of NO GG does not have a add-on adapter does not have 2 DOF's does not have 13 surfaces to keep clean allows the owner to concentrate on making pictures and not adjusting this and that all the time, it is a digital video camera and is called Red.

Not to say Red has it own set of issues, which are being sorted out.
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Old April 10th, 2008, 04:02 PM   #67
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I have one more question to more experienced Letus users, and those with Canon FD mount in particular. I have 3 Canon lenses, and all of them are extremely tricky to be mounted. Is it normal with the FD mount in general, or is the Letus FD mount ring a bit, well... unperfect?
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Old April 11th, 2008, 02:20 AM   #68
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My FD lenses also take a bit of jiggling to mount...
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Old April 11th, 2008, 02:29 AM   #69
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It felt a bit fiddly before I learned how to do it correctly. I've used both the old and new FD mounts. There could be a little red mark on the mount to show where to start mounting the lens from, once you find it you can put a little marking there. Mount the lens 3cm clockwise from the marking, turn counterclockwise so that it clicks into place and then turn clockwise until it locks to the mount.

There might be some differences with lenses but in general I can change a lens with one hand very quickly. Hmmm... Would be a great competition, who can change their lens the quickest ;)

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Old April 11th, 2008, 02:48 AM   #70
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Thanks guys.

Once you figure out how it works, I don't think any permanent marking on the ring is necessary (after I managed to properly mount my first Canon lens, I just turned the mount ring so that now, the red mark on the lens should be in the uppermost position before turning). I must say though that the whole "operation" is still fiddly, and sort of non-repeatable, for me... In the mounting speed contest, I don't think I'd be the winner!

As to my other woes with the LEX, it seems Letus have chosen to stop answering my messages to them on their support site. Oh, well - I guess I must adopt this "made by enthusiasts, for enthusiasts" attitude, and start messing around with adjustments myself. Please take a look how badly my GG is twisted in the viewfinder (sorry for the quality - didn't care for right exposure at that moment):

- on the left, when just mounted on the rails without any tension applied to the mounting brackets/screws
- on the right, the best position I can get with the current rails support system under a maximum tension I'd consider reasonable (ANY tension will probably increase the vibration noise, though)!

I'll probably need to modify the front supporting bracket...

Or - since I'll probably need to disassemble my LEX anyway in order to adjust the back focus - is there a way to adjust the whole innards' angle in relation to the housing?
Attached Thumbnails
Letus Extreme and...-gg-twisted.jpg   Letus Extreme and...-gg-unlevel.jpg  

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Old April 11th, 2008, 03:40 AM   #71
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yeah, that angle does look way off. Just nicely and persistently mail letus about it, they will answer Im sure. Sometimes it can take a few days. I guess since its propably only one guy, Aaron, doing the mails so he must be busy.

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Old April 11th, 2008, 08:07 AM   #72
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Quote:
Originally Posted by Sami Sanpakkila View Post
yeah, that angle does look way off. Just nicely and persistently mail letus about it, they will answer Im sure. Sometimes it can take a few days. I guess since its propably only one guy, Aaron, doing the mails so he must be busy.

Sami

Agree, Aaron was great with getting back to me. He was ready to issue a RMA and still will right away if i have any more issues. I got them sorted out myself so no need.
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Old April 11th, 2008, 08:34 AM   #73
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Couple of days ago, Aaron has offered issuing RMA to me as well - does anyone know how it works from Europe? When first importing my LEX bundle, it spent 2 weeks at the customes, and I had to pay the duty and VAT an the total price (Fedex rate included !!!)
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Old April 11th, 2008, 10:02 AM   #74
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If you're after a cinematic look, trust me, once you get it working it is worth all the trouble :)
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Old April 28th, 2008, 08:37 AM   #75
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Originally Posted by Steve Cahill View Post
Does your letus motor shaft have a dap of hot glue on it? My did and it came off and I believe I am getting less artifact and sky issues when shooting a plain background like the sky. See my blog with pics showing the hot glue.

Never got a proper response about why the hot glue is on the motor shaft for balancing, and how that is calibrated.

The extra noise may be because of the extra weight on the end of the motor shaft, also check to see if any thing is loose, make sure those allens screws are locked down! With the absence of the glue on the motor shaft the unit is more quiet but still it make a buz- vibration sound which is normal.

Instructions from Letus site for adjusting back focus:

1) Remove the front tube
2) You will see the plastic ground glass holder. Using a ruler or calipers, carefully measure from the back of this black plastic to the surface of the adapter behind it. It should be 7.5 mm all around.
3) If you find this distance is off, very gently push / pull the 3 metal stand offs holding the ground glass holder in or out to achieve a distance of 7.5mm all the way around.
4) If you are already at 7.5mm and your focus is still off, then adjust each of these to be slight less or slightly more all the way around.
5) If you cannot achieve focus at infinity at all, then you will want to pull the stand off posts out very, very slightly more than 7.5mm
6) If infinity focus is hitting before you reach the infinity mark on your lens, then you will want to push the stand off posts in very, very slightly to be less than 7.5mm.
OK, so I've found some time at last to try and adjust my Letus Extreme; here is the outcome:

- mine doesn't have the glue on the rotor shaft; instead, there are drops here and there on the GG holder itself

- as expected, the distance was well below 7.5mm (I suspected this, as I couldn't get infinity focus); I pulled the three stands out and it's now 7.5mm all around

- unfortunately, with the stands pulled out like this, to whole assembly now produces very high frequency rattle (or whine), which replaced the low frequency rumble/vibration it was making with original (factory) adjustment. Also, the GG has obviously changed the amplitude of its vibration - it's now shorter, hence the noise's higher pitch. It's this whining rather than vibration which is unacceptable now, after I made the adjustment to exactly 7.5mm!

- what's even worse, I still can't get true infinity focus!

All in all, this is extremely disappointing - how can an opto-electrical device worth $3,000 (yes - this is what it cost me after the duty and VAT), be so imprecise! As I suspected, there is no way to affix my unit to the camera so that the GG rectangle is level in relation to the camera, while the adapters "nose" is fixed to the rails bracket - it's simply machined not precisely enough. Also, after the adjustment I am now sure it cannot keep back focus even if I succeeded to get it right - the GG vibration would spoil the adjustment sooner or later.

Also, even though I was extremely carefully handling it, one of the glasses fell out of it - the glue holding it was so lousy weak!

This is so frustrating I'm considering to demand refund from Letus.
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Last edited by Piotr Wozniacki; April 28th, 2008 at 02:54 PM.
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