Need confirmation from other Letus Ex users

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Lander

Member
Hey All,

So I have been having a grain/distortion issue with my Letus 35 Ex. I sent it back and Hien replaced the GG. I got it back yesterday and went out shooting and behold the pattern is still there, only noticing after I spent the day shooting viewing playback on my 24"HD lcd monitor. I will try not to rant, but I an flipping beside myself.

Now, all of my footage was shot at or under F5.6 I made sure most was under but there were certain situations I wanted a deeper DOF.

The frame rate was 1/48, 24p. The shots were when the sun was low with nice amber tones, some including open sky in the frame. The HV20 for vid capture was adjusted to offset brightness since I do not have ND filters. Upon viewing the footage I can see similar static foot print in the footage, more noticeable in open shots like a sky or open fields.

Today I set the cam up in my studio and did this test to figure out what was going on. Here is the repro (I used a 24" HD monitor to view results during the test):



Step by step Repro:

-Set up your camera with Letus EX on a tripod.

-Remove any 35mm lens from the adapter.

-Turn your camera on and put in shutter priority mode, do not lock exposure.

-Set up light source to light up the GG at a brightness where your camera starts to stop down automatically. (Mine at 1/8th closed to f5.6 or so)

-Frame the gg, focus and turn on.

-Change shutter speeds letting the camera adjust the exposure.

-View your monitor for results.



My Results:

-I started to see the gg at 1/100th.
-There is a pattern seen at all shutter speeds. (If you find an anchor point to reference from, the same distortion/anomaly is there when the gg is on and off.)
-If you loosen the 3 hex screws that holds the ring on the back of the Letus (where your camera attaches to) and and turn the Letus while the gg is on and at any shutter speed, the pattern shifts.

In this folder you will find screen captures at various shutter speeds.
http://woodcreststudio.com/letus/tests/

Here are direct links:

image2.gif
1-100.jpg
image2.gif
1-15.jpg
image2.gif
1-30.jpg
image2.gif
1-8.jpg
image2.gif
adapter distortion.jpg
image2.gif
adapter_off.jpg


Now If you have read this far I am very thankful. If you are a Letus 35 Ex owner and could do this test I would be even more thankful and If you're local to Philadelphia area, I will take you out for a beer.

Thanks,

Tom
 
I'm not familiar with how the HV20 works, but I can say that pointing it at a white wall (or just about any adapter) is going to see grain.

Grab some footage from outside or the bathroom even (err, if it's a clean bathroom.)
 
Thanks Kholi,

I'll post some footage tomorrow. I pretty much burned myself out today with all of this. A couple of things I did after the post:

I pinned a sheet of white paper to the wall and lit it up. Pointed the GG at it, there was not as much distortion as when the gg was pointed directly at a light (I was pointing at a frosted one). I then put on a 50mm 1.4 and did the same thing with similar results, stopping down made it worse.

I'm going out on a tired limb here, but I a thinking about diffraction and it's effects, but this is a tired thought.

If you could try my test I would appreciate it, but if you are 100% certain every adapter would do this then I suppose you don't need to. I would just feel better knowing it is just not me.

Also, I would like to post footage, but everything I have rendered has been in the 100's of MB to see the issue very clearly. Is there a optimum compression to use with settings?

Thanks,

Tired Tom Out
 
Well, I know that pointing it at a white wall is going to show me grain Just as well the sky.

But you can check this thread for grain: http://www.dvxuser.com/V6/showthread.php?t=126192

A lot of that was shot between F4 and 5.6 on the HVX200 with the HVX iris rising and falling (2.8 - F8)

Just stills, but don't mistake HVX noise for GG appearances.
 
Here is a short clip compressed and encoded with cineform's avi codec that is uploading as I type this. Ftp's eta is 50 minutes:

http://woodcreststudio.com/letus/tests/grain.avi

You may not be able to see it in the footage except the sky, but the pattern can be seen printed over the trees as well when watching full resolution.

What do you think?

Thanks,


Tom
 
I also have another shot looking over a stream in a slow pan up to a house on the other side that I haven't captured yet. I'll do that tomorrow and post it.

ciao

Tom
 
I have uploaded footage that cleary shows what I am seeing printed on my footage (a static pattern isolated from the ground glass).

There are 2 video files encoded with the cineform codec because it shows very little compression artifacts. The videos are of the ground glass shot at 1/100th of a second so to visually see the gg moving a little. There is one file rendered to 30fps and 12fps. The 12fps file reveals it a little bit better since the gg movement is a little more "choppy". The 12fps file is encoded with the highest setting of the cineform codec in case you wonder why it's file size is greater then the 30fps encoded at.

Look at the box in the video file and look across the frame. You will notice the ground glass moving behind a static pattern. This static pattern is what is printing on my footage. It can be easily seen it viewing on my 24" high def monitor. Clients have confirmed it as well.

The files are uploading here this moment and should be completed in an hour or so (1:39am EST right now):

www.woodcreststudio.com/letus/grain_footage

I am sending this to Letus Direct as well. I am having a hard time convincing them that this exists. I wish they were local so to show them in person. The movement of the ground glass behind the pattern reveals what it is I've been seeing from day 1.

I would greatly appreciate feedback on what you see in the 2 video files I have uploaded.

thanks,

Tom
 
Last edited:
Lander said:
I have uploaded footage that cleary shows what I am seeing printed on my footage (a static pattern isolated from the ground glass).

There are 2 video files encoded with the cineform codec because it shows very little compression artifacts. The videos are of the ground glass shot at 1/100th of a second so to visually see the gg moving a little. There is one file rendered to 30fps and 12fps. The 12fps file reveals it a little bit better since the gg movement is a little more "choppy". The 12fps file is encoded with the highest setting of the cineform codec in case you wonder why it's file size is greater then the 30fps encoded at.

Look at the box in the video file and look across the frame. You will notice the ground glass moving behind a static pattern. This static pattern is what is printing on my footage. It can be easily seen it viewing on my 24" high def monitor. Clients have confirmed it as well.

The files are uploading here this moment and should be completed in an hour or so (1:39am EST right now):

www.woodcreststudio.com/letus/grain_footage

I am sending this to Letus Direct as well. I am having a hard time convincing them that this exists. I wish they were local so to show them in person. The movement of the ground glass behind the pattern reveals what it is I've been seeing from day 1.

I would greatly appreciate feedback on what you see in the 2 video files I have uploaded.

thanks,

Tom
Click to expand...

It would help if you posted these in a format that Mac users could view, AVI does not playback in QuickTime without going out and hunting down a bunch of extra components. Just spent 10 minutes downloading for 135mb of files, all I get are white screens. Can hear the audio but no picture.

In the future, I would suggest QT, WMV or good old MPEG1. Most Mac users now have Flip4Mac so we can see WMV files.

Dan
 
Cineform has the player on their site. I just installed it on my mac and am checking.

Sorry about it. I just couldn't find an export means that allowed for a manageable file size. I will try to export in mpeg and see what it looks like.
 
Ok,

Here is a link to the download page of cineform. I downloaded it installed it and did a save target as on the file at my page that has the footage. After cineform installation was complete, I double clicked on the file and it played.

I will still look into exporting in a more Mac friendly format. I know what it's like having a mac.

Cineform codec for mac:
http://www.cineform.com/products/Dow...layerStart.htm

Thanks for trying to view the file. I've been pulling my hair out over this and now that I isolated it I just want others to see what I have been talking about.

I'll be back in a few. I will try to export in another format that will view the same without adding compression artifacts.

thanks,

Tom
 
Hello everyone

Over the weekend, I set up the adapter on my cam with a Nikkon 180mm ED and shot at F2.8. Just to make sure I had not lost my mind doing all the tests a week ago. Here is a snip of the footage. There is no sky, but guess what there is ;) The grain in the out-of-focus areas shooting at F2.8, is this normal?


http://woodcreststudio.com/letus/grain_footage/treetrunk.mov

Hey, I think I'm getting better! Lol

Tom
 
Lander,

It almost looks like the LEX isn't vibrating. Or maybe isn't vibrating fast enough and the GG is showing due to your shutter speed. I haven't experimented much with higher shutter speeds and their effect but I have gotten a similar (although more prominent) effect when I forgot to turn my LEX on. (oops)
I'm going to assume it's on. Are the batteries fresh? What did Letus say when you sent it in the first time? Did they test the motor?
 
Hi Room39 (Curt?),

The shutter speed was 1/48 the batteries were fresh as well. The adapter was on, but I as well have forgotten a few times to turn it on. I keep a reminder card with me now to make sure I don't forget anything!:Drogar-BigGrin(DBG)

I had sent the adapter in and Hien replaces the gg. I have been exchanging emails with him but he doesn't believe there is a problem with the adapter. This was after the initial footage I posted here in the forum that I sent to him. I emailed him a link to the footage I posted today and an waiting to hear back from him and Aaron, so we'll see what happens next. This pattern is isolated to the adapter as well. When it's loose and when I spin the adapter the pattern moves along with it.:undecided

Do you shoot with a 180mm lens? It would be interesting if you did and had different results or even similar ones so I can at least finally figure this thing out

cheers,

Tom
 
Sorry Tom,

The longest lens I own is a 135mm so I can't compare results there.
But I can say, my footage does NOT have the grain pattern yours does.
That is definitely a static pattern in your footage.
Do you have a UV filter between the cam and the lex?
What other lenses have you tried?
What were the results of those tests?
I hope you get it squared away. It's a frustrating situation.

(yep)Curt
 
Hi Curt,

I have a 17-35mm f2.8, 50mm F1.4, 85mm F2 and the 180mm All nkkons. I see you use the Canon lenses. If there is a similar lens you have, I'll use that lens and compare results with you.

I took off the UV filter on the lens to make sure it wasn't in the front glass and I had done tests last month with all lenses that has similar results. I think I'll do it again today since I am in the studio and the lighting is similar outside as it was yesterday.

Yea, it is a bit frustrating. I hope the footage of the tree makes it easier for Hien to see what's happening here. It's been going on since January with no movement toward a solution except Hien offering a full refund since he thinks the adapter is fine and I am just not a satisfied customer. Aaron is going to test the same setup as I (HV20-Lex EX)when he receives the step up ring. So we'll see. We'll see...

I'm glad at least it isn't normal compared to your results you've had thus far. Hopefully I'll get a few more conformations from other users so I can point Hien to this thread and we'll get some movement forward.


cheers,

Tom
 
I see this from time to time as well. Spoke about it here: http://www.dvxuser.com/V6/showthread.php?t=125204

Mostly when its really bright outside and with lenses that have 2.8 max iris. I never got a really good idea why it happens. But most propable reasons are that too much light gets on to the ground glass (use ND filters in front of the prime lens).

Sami
 
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