Backfocus plug for 35mm adapters

Does anyone know if a similar trick could work using the LANC input on an XHA1?

What a great widget!

Jim
 
This is an amazing device. How freaking clever.

Will it work on the DVX100B ? I can't imagine that it wouldn't.
 
JimmyC said:
Does anyone know if a similar trick could work using the LANC input on an XHA1?

What a great widget!

Jim
Click to expand...

Nope, unfortuneately not.

LANC is a serial protocol, not an analog input. And it has no provision for "absolute" focus position control, like the analog control inputs on the Panasonics.


- Mikko
 
Yeah thats fair enough mikko!

But I wonder if there is any way to 'lock' the manual controls by an input in the lanc control socket? That way you can do away with the taping and/or seting from preset every take.

Any ideas?

Jim
 
I'm not trying to be clueless but is this thing to help make sure your footage is accurately in focus when using 35mm adapters? I have a Go35Pro and I'm reluctant to use it a lot for fear of thinking the footage is clear in the viewfinder only to find its slightly out of focus. Someone told me it was a backfocus problem but I didn't really know what to do about it.
 
Here is the one I just built. I think it's working but I'm unsure. What exactly should I be looking for. I did notice it immediately focused.

Plug.jpg


Plug2.jpg


Plug3.jpg


Plug4.jpg
 
Something is off. Using the autofocus puts the focus at 30 and the back focus at 4.8 but when I plug the thing in all I get is a focus of 26 and a backfocus of 3.2 and it won't change even when I turn the screw and it is of course, out of focus then.

I did find this video which was very helpful:
http://www.youtube.com/watch?v=at9Fv24yXgQ
 
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I have successfully built two of these adapters now. My first has a limited range of between MF66 - MF71. It was made with a 1K pot and 3 resistors (2x 5.6K & 1x 1K) I no longer need it as my adapter has a new lens mount and the range no longer covers my adapter. I need MF61 now.

My second I made this evening. It has a 5K pot which makes the useable range much wider, but tuning the focus requires fewer turns of the pot. It is combined with 2x 1K resistors & 1x 5.6K resistor, making a total of 7.6K to 12.6K resistance, which results in a DVX100B MF range of MF38 to MF70. Much more useful. I have a long 35mm adapter and need MF61/MF62.

If you use a 1K pot, you have to loosely solder together resistors to get very close to your desired MF value. With a 2K pot you'll have a bigger range. With a 5K pot you get a huge range. It is the way to go, I think.

Also, I used a good right angled Neutrik 3.5mm jack with a 10cm wire to the resistors block, so that it would not be resistant to breaking off in the socket during use. The pot and resistors I Epoxy-resined to form a strong unit with no chance of a connection failure at the solder joints. Araldite is a good insulator.

If anybody needs MF66 - MF71 on a DVX100B, let me know. I have a nice little unit for that value.

All the best
Lucas
 
Lucas Adamson said:
Also, I used a good right angled Neutrik 3.5mm jack with a 10cm wire to the resistors block, so that it would not be resistant to breaking off in the socket during use. The pot and resistors I Epoxy-resined to form a strong unit with no chance of a connection failure at the solder joints. Araldite is a good insulator.
Click to expand...

Got any pics of the unit - sounds nice.
 
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