Does anyone experience the Lestus35 extreme creating vignetting? I'm not sure if it has something to do with lighting (which I doubt) but I was trying it in a room at night with three 75watt bulb and I start seeing some kind of shadow all around the edges of the frame. I already zoom in all the way but I still see this vignetting problem.
Letus35 Extreme vignetting
- Thread starter myCharlie
- Start date
Michael Friedman
Active member
Camera and lens info will help.
I know that I escape vignetting well before Academy frame on my canon A1 with ef lenses. I have to imagine that it is something awry with your setup. The Letus is really strong in that area.
I know that I escape vignetting well before Academy frame on my canon A1 with ef lenses. I have to imagine that it is something awry with your setup. The Letus is really strong in that area.
Here's what it looks like when I'm looking at the GG without lens.
Charles Lowthian
Well-known member
i notice the same in low light with ceiling lights.
just have to zoom in enough to crop it from the sides. it's ashame, cos often you sacrifice one good side, because the other has some vignetting.
but in daylight it's a lot less.
just have to zoom in enough to crop it from the sides. it's ashame, cos often you sacrifice one good side, because the other has some vignetting.
but in daylight it's a lot less.
Essami
Well-known member
Yeah, this caught me by surprise as well.
You really have to zoom in quite a lot to get the advertised "absolutely no vignetting". But this is how its supposed to work.
Quote from Letus:"Our frame size is 20% larger than the standard 24x36 35mm frame size, therefore they need to zoom in about 20% into the GG. Wide lens need to zoom in a little further since light falling of the edges is more than the 50mm. It's not just FD lenses, any brand of lenses will give similar result."
And I can't really go under f5 or f8 on my lenses with the LEX. At least I start seeing quite a lot of grain from the gg and aperture vignetting from the lens.
Sami
You really have to zoom in quite a lot to get the advertised "absolutely no vignetting". But this is how its supposed to work.
Quote from Letus:"Our frame size is 20% larger than the standard 24x36 35mm frame size, therefore they need to zoom in about 20% into the GG. Wide lens need to zoom in a little further since light falling of the edges is more than the 50mm. It's not just FD lenses, any brand of lenses will give similar result."
And I can't really go under f5 or f8 on my lenses with the LEX. At least I start seeing quite a lot of grain from the gg and aperture vignetting from the lens.
Sami
Charles Lowthian
Well-known member
yeah, just also have to make sure the camera aperture is set to it's maximum - f1.8 ideal, but when zooming in so far the camera can't always do it.
emotepix
Well-known member
Gents
About the only quick and practical way to get this sorted is to cut a 24x36 mask out of paper and then cut the outside of the mask down so that it fits up against and centered to the GG inside the DOF box.
Now you know exactly how big your 24x36 gate is supposed to be.
If, after putting this true mask into your setup, there's still vignetting with a fast lens wide open (or with no lens at all) then there's something wrong with your setup and you maybe need another achromat, etc, to get rid of the vignetting. If not, it sort of gives you a guideline as to how much you should really be zoomed into the GG for an actual, 100% full 24x36 gate.
I used this method to set up a DOF box of my own design when I hit a similar snag. Helped me resolve the problem quickly after that (I found I was way off in my previous mental estimation of how far in I had to be zoomed).
In fact, I had the idea that if I were taking the DOF Box off a lot, I'd make a permanent mask out of matte black plastic card, around 25x37mm (a little bigger than the 24x36 gate) and build it into my box, so that when I put the box back on again I could quickly get the camcorder lens zoomed in and set up properly. The mask would also aid in cutting down internal reflections.
HTH
JM2C, YMMV
Chris
About the only quick and practical way to get this sorted is to cut a 24x36 mask out of paper and then cut the outside of the mask down so that it fits up against and centered to the GG inside the DOF box.
Now you know exactly how big your 24x36 gate is supposed to be.
If, after putting this true mask into your setup, there's still vignetting with a fast lens wide open (or with no lens at all) then there's something wrong with your setup and you maybe need another achromat, etc, to get rid of the vignetting. If not, it sort of gives you a guideline as to how much you should really be zoomed into the GG for an actual, 100% full 24x36 gate.
I used this method to set up a DOF box of my own design when I hit a similar snag. Helped me resolve the problem quickly after that (I found I was way off in my previous mental estimation of how far in I had to be zoomed).
In fact, I had the idea that if I were taking the DOF Box off a lot, I'd make a permanent mask out of matte black plastic card, around 25x37mm (a little bigger than the 24x36 gate) and build it into my box, so that when I put the box back on again I could quickly get the camcorder lens zoomed in and set up properly. The mask would also aid in cutting down internal reflections.
HTH
JM2C, YMMV
Chris
Last edited:
Essami
Well-known member
An instructional video on Letus site would be extremely helpful. Its kinda confusing reading about "absolutely no vignetting" and first setting it up and all you see is vignetting 
I mean who has time to read the A4 manual that comes with the LEX
But this is an amazing product and even with my miniDV Ive gotten really amazing looking footage. http://www.youtube.com/watch?v=dNFD4cXdx5Y
Sami
I mean who has time to read the A4 manual that comes with the LEX But this is an amazing product and even with my miniDV Ive gotten really amazing looking footage. http://www.youtube.com/watch?v=dNFD4cXdx5Y
Sami
I'm using the Sony EX1, zoomed it all the way, f-stop is to max and I still see this vignetting even without any lens on.
emotepix, I like to try your suggestion but I'm not sure I totally understand your explanations.
1. I cut a 24mm by 36mm paper and used that as a mask.
2. I trimmed that paper mask so it fits up agains the center of the GG on the Letus35 extreme adapter.
3. Put the paper mask between the DOF adapter and my camera lens just like when I'm setting up the DOF adapter
4. Then zoom in and verify if vignetting is apparent
Are these the correct steps?
emotepix, I like to try your suggestion but I'm not sure I totally understand your explanations.
1. I cut a 24mm by 36mm paper and used that as a mask.
2. I trimmed that paper mask so it fits up agains the center of the GG on the Letus35 extreme adapter.
3. Put the paper mask between the DOF adapter and my camera lens just like when I'm setting up the DOF adapter
4. Then zoom in and verify if vignetting is apparent
Are these the correct steps?
DeGrey
Well-known member
emotepix
Well-known member
You got it.
Just a visual check that you have the camcorder lined up and zoomed in correctly.
Also, if you cut the mask out well (and maybe color it black) you will have edges to focus on and also to check for square, barrel distortion, etc.
Bear in mind, that if you do this, to refocus on the GG after you've done checking focus on the mask. Of course the mask is closer to the camera than the GG so if you can achieve focus on the mask edges then you'll be good to go in the GG.
Also since everything is so close to the camera, don't be surprised if you can't focus on the edges of the mask.
Once I tried this, it became obvious to me that I didn't have enough macro in my lens (on a Sony V1u), so I installed an extra condenser (lens) between the GG and the achromat and now things are very good.
What that lens did was to provide a little extra magnification, like a supplementary close-up lens, and this put the V1's lens into the middle of its zoom range (rather than at the extreme macro end it was at before).
I believe the commercial folks all sell spacer rings to put the GG further away from the camcorder, which addresses the same problem in a different way.
If you look elsewhere at DIY 35mm adaptor threads, you'll see that fiddling around a bit with lenses, spacer rings and the like is pretty effective for finding the sweet spot on your camcorder lens and getting the most out of your adaptor.
HTH
JM2C, YMMV, etc
Cheers
Chris
Last edited:
It's not the light. That's an impractical solution to the problem. And your lens shouldn't be vignetting clean through the center.
I have never experienced this problem with the HVX200 + Letus EX combo, although I can attest to dark corners when I'm not zoomed in all the way, especially on wider lenses.
Can you zoom ALL the way in (end of the lens) and still see the vignetting? Have you tried another lens?
I have never experienced this problem with the HVX200 + Letus EX combo, although I can attest to dark corners when I'm not zoomed in all the way, especially on wider lenses.
Can you zoom ALL the way in (end of the lens) and still see the vignetting? Have you tried another lens?