Letus35 frame size and vignetting at DVinfo.net

Lucas Rodriguez · January 20th, 2006, 04:13 AM

Hello there,

I've had the Letus35 (attached to a GS400) for a while now, mostly shooting test footage with different settings and lighting conditions to get used to it and its strong/weak points... I want to shoot a short film but before I want to be really comfortable with it. Overall, I'm really happy with it and I'm already getting very nice results. :)

The only real issue I've found so far is that in order to get rid of the vignetting I have to zoom in all the way until the camera loses focus on the GG, and the zoom back just a bit in order to get focus again. The problem with this is that even if I use wide lenses (well, the wider I have is 28mm...), I get an undiserable zoomed-in effect, with a very narrow angle of view.

I don't have a video to show this right now, but I'll upload one as soon as I get home. Is there any way to overcome or fix this problem? I read something about a macro lens, but I'm afraid I'm not sure about how this works...

Thanks in advance,

Lucas

PD: Oh yeah... I'm using 50mm f/1.4 and 28-70mm f/2.8 lenses.

Leo Mandy · January 20th, 2006, 06:55 AM

I had the same problem - for me it seems a problem for the pana camera then the Letus35 itself.
I put a condenser right in front of the DV lens and it fixed the problem right up - even in low light it is pretty good now

Jeremy Hughes · January 20th, 2006, 03:36 PM

Hi Leo,

What kind and where did you get your condenser?

Leo Mandy · January 20th, 2006, 04:04 PM

I got it with a 8mm camera. I found one after looking and ripping apart many of them and just got lucky. Can't even remember what kind of 8mm it was. Just keep looking I guess - but it is definitely a glass condenser.

Tony Tibbetts · January 20th, 2006, 04:35 PM

I have a gs-400 and a letus35. I didn't have a problem getting it to focus.

Alain Bellon · January 20th, 2006, 04:40 PM

Leo,

I think by "what kind" he was asking if it is a PCX, a DCX, a fresnel, a doublet, etc. A condenser is really not a type of lens, any convex lens can be used as a condenser but also as a magnifier. So the term condenser doesn't tell us what kind of lens you are talking about.

Oh and I think if you put the lens next to the DV cam, then it is not acting as a condenser anymore but as a magnifier (as far as I understand).

Leo Mandy · January 20th, 2006, 05:00 PM

Could be the case. It is a convex piece of glass and it has gotten rid of the vignetting, so maybe it is magnifying, maybe condensing the light - all I know is that is work!

Alain Bellon · January 20th, 2006, 06:11 PM

Excellent! :)

Lucas Rodriguez · January 23rd, 2006, 05:25 AM

So, what kind of convex glass would be needed for this sort of "mod". Do you have any links or pictures to share? :)

Lucas

Dennis Wood · January 23rd, 2006, 06:42 AM

Most folks are using achromats for this purpose. It's a two element lens (glued together) which serves as a macro without colour aberrations.

January 20th, 2006, 04:13 AM	#1
Lucas Rodriguez New Boot Join Date: Nov 2005 Posts: 7	Letus35 frame size and vignetting Hello there, I've had the Letus35 (attached to a GS400) for a while now, mostly shooting test footage with different settings and lighting conditions to get used to it and its strong/weak points... I want to shoot a short film but before I want to be really comfortable with it. Overall, I'm really happy with it and I'm already getting very nice results. :) The only real issue I've found so far is that in order to get rid of the vignetting I have to zoom in all the way until the camera loses focus on the GG, and the zoom back just a bit in order to get focus again. The problem with this is that even if I use wide lenses (well, the wider I have is 28mm...), I get an undiserable zoomed-in effect, with a very narrow angle of view. I don't have a video to show this right now, but I'll upload one as soon as I get home. Is there any way to overcome or fix this problem? I read something about a macro lens, but I'm afraid I'm not sure about how this works... Thanks in advance, Lucas PD: Oh yeah... I'm using 50mm f/1.4 and 28-70mm f/2.8 lenses.

January 20th, 2006, 06:55 AM	#2
Leo Mandy Major Player Join Date: Dec 2004 Posts: 749	I had the same problem - for me it seems a problem for the pana camera then the Letus35 itself. I put a condenser right in front of the DV lens and it fixed the problem right up - even in low light it is pretty good now

January 20th, 2006, 03:36 PM	#3
Jeremy Hughes Major Player Join Date: Nov 2005 Location: Columbus, Ohio Posts: 276 Images: 2	Hi Leo, What kind and where did you get your condenser?

January 20th, 2006, 04:04 PM	#4
Leo Mandy Major Player Join Date: Dec 2004 Posts: 749	I got it with a 8mm camera. I found one after looking and ripping apart many of them and just got lucky. Can't even remember what kind of 8mm it was. Just keep looking I guess - but it is definitely a glass condenser.

January 20th, 2006, 04:35 PM	#5
Tony Tibbetts Major Player Join Date: Aug 2005 Posts: 385	I have a gs-400 and a letus35. I didn't have a problem getting it to focus.

January 20th, 2006, 04:40 PM	#6
Alain Bellon Regular Crew Join Date: Jan 2005 Location: LA Posts: 130	Leo, I think by "what kind" he was asking if it is a PCX, a DCX, a fresnel, a doublet, etc. A condenser is really not a type of lens, any convex lens can be used as a condenser but also as a magnifier. So the term condenser doesn't tell us what kind of lens you are talking about. Oh and I think if you put the lens next to the DV cam, then it is not acting as a condenser anymore but as a magnifier (as far as I understand).

January 20th, 2006, 05:00 PM	#7
Leo Mandy Major Player Join Date: Dec 2004 Posts: 749	Could be the case. It is a convex piece of glass and it has gotten rid of the vignetting, so maybe it is magnifying, maybe condensing the light - all I know is that is work!

January 20th, 2006, 06:11 PM	#8
Alain Bellon Regular Crew Join Date: Jan 2005 Location: LA Posts: 130	Excellent! :)

January 23rd, 2006, 05:25 AM	#9
Lucas Rodriguez New Boot Join Date: Nov 2005 Posts: 7	So, what kind of convex glass would be needed for this sort of "mod". Do you have any links or pictures to share? :) Lucas

January 23rd, 2006, 06:42 AM	#10
Dennis Wood Major Player Join Date: Mar 2005 Location: Ontario, Canada Posts: 916	Most folks are using achromats for this purpose. It's a two element lens (glued together) which serves as a macro without colour aberrations.