Measuring and Cutting IR Filter for Modification

[numzkull]

Its time for me to convert my D70s to a D70i!

I've been reading a couple of posts here but I still have some things I need to clarify. Hope these questions don't sound too duh coz I must admit I've been out-of-touch for a while.

1) How do you guys achieve the precise measurement of 29.59mm x 25.27mm for the filter? What tools did you use to measure?

2) Also is there a particular brand of carbide cutter that I should use that is available locally?


Thank in advance for all your tips!

[deadpixel]

Originally Posted by numzkull Its time for me to convert my D70s to a D70i! I've been reading a couple of posts here but I still have some things I need to clarify. Hope these questions don't sound too duh coz I must admit I've been out-of-touch for a while. 1) How do you guys achieve the precise measurement of 29.59mm x 25.27mm for the filter? What tools did you use to measure? 2) Also is there a particular brand of carbide cutter that I should use that is available locally? Thank in advance for all your tips!

Unless you have a glass cutting machine, try this:

1. Print and cut out a rectangle according to the measurements
2. Trace the rectangle on the IR filter using a CD/DVD marker
3. For each of the cut you are going to make, lubricate the line with machine oil and using a thin ruler as a guide, cut within 1mm or 2mm of the line
4. Immediately snap off the cut edge
5. Repeat for each remaining side
6. Sand/Grind the cut filter down to the exact size - either use carbide sandpaper of various grades or use a grinding tool with a diamond bit or take it to an optician and pay him a couple of dollars to get it ground down

An ordinary wheel carbide cutter will do, but you have to be sure to practice cutting on ordinary glass first, so that you can get the hang of it.

• You don't need a lot of force; what you need is even force applied throughout the cut.
• You must hear a sound like that of someone tearing a piece of cloth.
• NEVER, EVER go over a cut line a second time.

It isn't difficult, you just need to get over your initial fear.

Remember to use a brand new piece because old/second hand ones may have tiny scratches or pits in them that are invisible to the human eye but will appear on your photos.

Cheers,
Matt

[karnage]

Why not just use a Lee IR gel? #87 I think it's called. Can get the small one... 5cm x 5cm I think? $30. Easier to cut than glass? Or is there an optical quality issue?

[deadpixel]

Originally Posted by karnage Why not just use a Lee IR gel? #87 I think it's called. Can get the small one... 5cm x 5cm I think? $30. Easier to cut than glass? Or is there an optical quality issue?

The CCD generates heat and gel filters have too many tiny scratches and pits on them to allow them to be used in this manner.

[numzkull]

Originally Posted by deadpixel Unless you have a glass cutting machine, try this: Print and cut out a rectangle according to the measurements Trace the rectangle on the IR filter using a CD/DVD marker For each of the cut you are going to make, lubricate the line with machine oil and using a thin ruler as a guide, cut within 1mm or 2mm of the line Immediately snap off the cut edge Repeat for each remaining side Sand/Grind the cut filter down to the exact size - either use carbide sandpaper of various grades or use a grinding tool with a diamond bit or take it to an optician and pay him a couple of dollars to get it ground down An ordinary wheel carbide cutter will do, but you have to be sure to practice cutting on ordinary glass first, so that you can get the hang of it. You don't need a lot of force; what you need is even force applied throughout the cut. You must hear a sound like that of someone tearing a piece of cloth. NEVER, EVER go over a cut line a second time. It isn't difficult, you just need to get over your initial fear. Remember to use a brand new piece because old/second hand ones may have tiny scratches or pits in them that are invisible to the human eye but will appear on your photos. Cheers, Matt

thanks Matt for the detailed instructions.

Originally Posted by karnage Why not just use a Lee IR gel? #87 I think it's called. Can get the small one... 5cm x 5cm I think? $30. Easier to cut than glass? Or is there an optical quality issue?

i like what i've seen from others who have used the ELP filter so i've ordered the ELP filter for the mod. and like deadpixel mentioned, not too keen on gel filters. cheers.