For Letus35 extreme users

L

Lander

Member
Hi all,

Have any Letus35 extreme users experience this type of grain?:undecided


http://woodcreststudio.com/letus/grain.jpeg

^EDITED^

Is a frame of footage that shows the grain really bad. I was using a Nikon 17-35 ed af if lens in this shot with 24p 1/48 or 1/24. I'm not sure how far stopped down it was, but I can also see it without the lens attached with only the GG full framed.

The adapter is awesome but I'm sending it in and was just wondering if anyone has experienced this.
 
Last edited:
File doesn't work. Are you using FCP? If so, must re-export for non FCP users as well.

H.264
 
Agree with Phil. You can't stop down beyond 5.6 on a bright sunny day.

Must use your internal filters. Is the Ground Glass vibrating? The JPEG still looks like it's just too far stopped down on the taking lens.

Also, what camera are you using?
 
philip bloom said:
looks like your lens is stopped down too much. have you sent it back already before doing further tests?
Click to expand...

Hi Philip,


I did a ton of tests. Here is a copy of an email I sent Aaron.

I removed the 35mm lens from the barrel zoomed in on the GG and used my 9" cam monitor to focus, tack sharp. Kept lens off
Zoomed out as far as I can for the GG view.
I then locked all exposure settings and made sure there was no camera gain being applied to the video to eliminate that as a possible cause. Footage 24p and 1/48 shuttter speed, turned it on and you can see a pattern in the white of the GG.

Flexing the letus on the front of the cam with the allen keys loose caused the pattern to shift.....
Click to expand...

The only way to get rid of the pattern in the sky is to over expose it, otherwise it is always present. I didn't notice it at first on the cam, but when I played it back, it seems to be in all of my footage. Even when the lens is removed, the cam is set to auto and the light is bright enough not to apply gain, there is still a bit of pattern in the frame of the gg.

Stopping down using a lens does make it even worse, but what is the max stop-down you can use with the Letus 35?



thanks,

Tom
 
i have found f4 is smallest aperture before I start getting sky pattern, not great really! What is you aperture set to generally?
 
Ok Kholi,

I'm going to pop on a lens and see where the grain begins to be really noticable.

Be back in a second..


Oh, I'm using a HV20. This is the setup that showed the grain:

shooting_pose.jpg
 
I removed the 35mm lens from the barrel zoomed in on the GG and used my 9" cam monitor to focus, tack sharp. Kept lens off
Zoomed out as far as I can for the GG view.
I then locked all exposure settings and made sure there was no camera gain being applied to the video to eliminate that as a possible cause. Footage 24p and 1/48 shuttter speed, turned it on and you can see a pattern in the white of the GG.

Flexing the letus on the front of the cam with the allen keys loose caused the pattern to shift.....
Click to expand...
Do not use this method to set the focus on your GG. It's incorrect.

You need to find your frame FIRST, then focus on the GG using auto focus or whatever method you can to get hair focus on the screen.

Unless this is how it's supposed to be done on an HV20, I would suggest not doing that. Critical focus changes with your camera's zoom in regards to the ground glass.

At 55mm on the HVX, my focus is more like 5.00, at 27.3 it's like 5.35.
 
What you cant stop down more than F4 because the image goes too grainy? Thats really bad, what if you want to use a long or zoom lens that is slower than that?
 
Ok, I did a few tests,

Using a f2.8 180mm ed ais lens pointint to the sky through a thin tree line, completely out of focus, trees a soft pattern can be seen partially at 2.8 and fets worse and more defined the more I stop it down.

I focused on the GG full frame as you suggested and nothing changed.

I will try a 50 mm now..
 
hoarp001 said:
What you cant stop down more than F4 because the image goes too grainy? Thats really bad, what if you want to use a long or zoom lens that is slower than that?
Click to expand...

You can't. At this point you sacrifice light efficiency and go to an SGpro or M2. Or, you get more light.

Generally, if you're using a lens that slow anyway you're gonna be outside in broad daylight, so it's less of a problem.

This is the trade-off for light efficient vibrating GG's versus Spinning GG. Someone will bust the Spinning GG light efficiency thing wide open sooner or later, but til then the possibility of owning two adapters isn't far fetched.

Lander said:
Ok, I did a few tests,

Using a f2.8 180mm ed ais lens pointint to the sky through a thin tree line, completely out of focus, trees a soft pattern can be seen partially at 2.8 and fets worse and more defined the more I stop it down.

I focused on the GG full frame as you suggested and nothing changed.

I will try a 50 mm now..
Click to expand...

That sucks! You know I remember being able to hit 5.6 on my Letus when I got it in broad daylight, checking it out on all of my monitors (42" LCD, CRT, etc) and just barely picking up grain. I noticed as I used the unit more often that grain began to show up at 5.6 and if dark enough, at F4.

But never at 2.8 or F4 when outside. Somethin' might be wrong. New Batteries try? Not being focus on the GG completely can also be a culprit. If you try these things and the issue can't be eliminated or isolated then sending it back might be the thing to do.
 
With a 50mm 1.4 I can begin to see the grain at f2 and the further I stop, the more that is seen. This is when the lens is completely out of focus, shooting through the trees to have light and dary spots to compare to.

Is this normal to have some kind of pattern viewable all the time? Like I said, I the GG is not flat white without a lens in either viewing with the 9" monitor.

I just don't know if this is normal or not...
 
Kholi said:
You can't. At this point you sacrifice light efficiency and go to an SGpro or M2. Or, you get more light.

Generally, if you're using a lens that slow anyway you're gonna be outside in broad daylight, so it's less of a problem.

This is the trade-off for light efficient vibrating GG's versus Spinning GG. Someone will bust the Spinning GG light efficiency thing wide open sooner or later, but til then the possibility of owning two adapters isn't far fetched.



That sucks! You know I remember being able to hit 5.6 on my Letus when I got it in broad daylight, checking it out on all of my monitors (42" LCD, CRT, etc) and just barely picking up grain. I noticed as I used the unit more often that grain began to show up at 5.6 and if dark enough, at F4.

But never at 2.8 or F4 when outside. Somethin' might be wrong. New Batteries try? Not being focus on the GG completely can also be a culprit. If you try these things and the issue can't be eliminated or isolated then sending it back might be the thing to do.
Click to expand...


You were posting when I was! :) Cool, At least I have some other user opinions. I've been in contact with Aaron for a few weeks about this. At least I feel better knowing something is definately up.
 
I wonder if using a different type of ground glass would change things. hmmmm... And let you stop down more.....
 
Thanks Philip and Kholi for taking the time to respond with your experiences with the adapter. I'm now waiting for the RMA to send her in for a check up.

cheers,


Tom
 
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