Dual Use Modification for D7000

Clearly, H-alpha astronomical imaging would greatly benefit from a modified camera. A lot more nebulas are now within feasible exposure time. Yet this pose another hurdle to use the camera in daily photography as its color balance is compeletely thrown away. Preset WB is a way to go but scene are so variable from one another that it becomes a chore to keep a sheet of white paper with me. And besides, preset WB only correct for one light source. The correction ratio for different color temperature is no longer the same with modified spectrum in the sensor. Spatial varible lighting, street lights plus moonlight as an example, will be a real chanllenge to correct. This will all add an insurmountable task in post-processing.

A genius solution will be taking advantage of the original factory filter and making it switchable! So, here’s the plan, I designed a filter rack just like the one offered by Hutech LPS front filter, which now could hold the ICF stack in it. After measuring the rack and dimension of Nikon lens mount, I drafted the 3D model in CAD and exported the final version as STL file, which is an universal format in 3D printing.

ICF-FF-N4

ICF-FF-N4-2

The 3D rendering of the filter rack. I named it ICF-FF-N4

The printing process is accurate up to 0.1mm in XY, the precision in Z is not as high. But none the less, horizontal accuracy is needed for filter mounting. It turned out the filter could just be secured inside the frame without any screw. The dent in the upper beam is reserved for an extra bump in the middle of the reflex mirror while it flips up.

IMG_6649

The waveplate must be in between the 2 antialiasing layer. Since we move the ICF from behind the dust filter to in front of it, we need to make sure the AA layer is facing the lens.

IMG_6650

Now the only thing left is to spray the filter rack black. The ICF is multilayer coated. We could now take away the clear filter installed in front of the sensor as the original focus could be restored. But a offset in the focusing system is still needed, because the AF sensor has an additional piece of glass in front of it.

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18 Responses to Dual Use Modification for D7000

  1. OMG!! I can’t believe I finally found your page and your blog. I’ve been looking for the correct dimensions for the glass for months now!! Seriously!! Thank You So Much! Excellent How-to/Article! I have a D700 that I was trying to get a non AA-filter glass fabricated for, but don’t have the original OEM stack of filters that came with it. I found companies online that would do it for me, but would not sell a Non-AA-filter to me, instead they want to rip me off for $400-$500 when I could do this myself. Now I might actually do this instead. Thanks Agian! Looking forward to your reply! 🙂

    • Oh wait, Crap! I just realized the the size is for a cropped frame CMOS sensor on the D7000 and the d700 is full frame, but I can just do the math for the dimensions and I hope the thickness is the same. You think?

      • jackshencn says:

        Do you just wanted to get a clear glass to replace the AA glass or the ICF on D700? D700 is also a 2 stack design. A reflective IR rejector and a red absorber. To be honest I don’t know the size for FF cameras and the thickness really varies. I got mine custom designed from cheap Chinese manufacture. If you want I can get a quote for you.

      • Oh ok so now I see what your talking about. Thank you for that image. So if i wanted to go full-spectrum then I would need to get rid of both stacks and just get one piece of glass, is that correct?

      • jackshencn says:

        Yes, for efficient IR imaging, you need a clear glass to substitute both and you will lose dust rejection. If you only want minimal red sensitivity plus 10 fold IR, you could retain the dust filter.

  2. Sorry I think I was a little confused there. I should have been putting my questions on this page https://landingfield.wordpress.com/2012/04/25/nikon-d7000-h-alpha-conversion/
    That is where I saw your photo and explanation that you will be removing the stack but keeping the outer dust filter and that also has some UV/IR blocking. Let’s continue the conversation over there shall we? 😀

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  4. Jacob says:

    I’d love to get one of these to use with my D7100 as a light pollution filter. I’m pretty sure the 7100 and the 7000 are just about identical when it comes to the filter area as well. Do you know if this would work with a Nikon 12-24mm or the 80-200mm AF-D lens? Great blog!

    • jackshencn says:

      Hi,
      The incidence angle won’t be a problem with these clip in filter but I do not know if these lens will protrude deep into mirror box. Generally, less than 8mm of protrusion should be ok, otherwise you might want to disassemble the plastic aperture indexing post.

  5. thongchaipat says:

    Hi, Jack
    Could you please share filter rack design file for 3D printer? I cannot draft it by myself. Your sharing will be highly appreciated.

    TJTHAI

  6. Tom Wade says:

    Jack
    Thanks for your detailed descriptions! I have removed my ICF just yesterday so of course it is raining today. I was wondering if you were willing to provide your file for the self designed clip-in to use with an original ICF? If not, would you be willing to fabricate and sell one? 🙂

    Thanks again,
    Tom

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