LPS Filter for D7000

Just got my Hutech clip in filter for D7000, here’s a unboxing post of the LPS-P2-N4 filter. LPS stands for Light Pollution Suppression I guess. Overlaying the glass is a special interference coating that rejects the unwanted wavelength from most sodium lamps, while passing the majority of nebula emission light.

Package

ADs

A brochure of advertisement, including the spectrum of the filter

Filter in Box

The filter packed inside a SD card box, rolled in bubble wrap

Installed on D7000

Clip the filter into the lens mount

Now it’s time to mount the lens. It’s said on their website that lens with greater than 8.7mm protrusion are not compatible. The Samyang 14mm 2.8 AE works pretty well with less than 8mm of protrusion. And it clears my biggest doubt on using wide angle lens with interference filter. Here’s 2 images taken with filter on, absence of any color vignetting seen on front mounted LPS.

Cloudy day with LPS

Indoor shot with LPS 

The indoor shot showing distinctive spectrum from 2 fluorescent tube

And as expected, the AF 50 1.8D cannot be mounted because of an outstanding “Aperture Indexing Post” which transmit the maximum aperture mechanically. This is only required on old mechanical SLR like this one:

Aperture Indexing Post

The Aperture Indexing Post couples with the small black tab in the bottom of the mount on camera side

Since DSLR communicate with the lens electronically, it makes no sense to preserve this protruding post. One way is to simply shave it down, but the rear element could be damaged in the process and it will leave dust inside. During my last repair with the plastic mount on my 18-105 DX lens, I’ve found out that the plastic ring hosting the “Aperture Indexing Post” could be disassembled independently from the mount. And it turned out to be the same with 50 1.8D lens.

Plastic Ring

Disassembled plastic ring from the metal mount

If you unscrew 3 black ones seen on the metal mounting ring and 2 on the side holding the electronic contacts, the black plastic ring would comes out easily. Then just screw the contact post back onto the metal ring. The lens could be used with the clip in filter easily.

The 180 2.8D telephoto lens was my biggest concern. The screws on the filter holder scraped the 2 corners of the plastic baffled tube. It seems the baffled tube can be disassembled, yet it would present a problem when light from the last element deep inside shines onto the metal mount leading to stray light. This lens is unlike the 50 1.8D where the last optical element is outside the mount, while 180 has the last one and aperture blades deep recessed inside the mount.

180 Mount Scrape

2 corners next to the electronic contact post are scraped on 180 2.8D

 

Star Field Test

 

 

Spectrum

The spectrum measured fits reasonably well with the advertisement. The spectrophotometer used only has 2nm FWHM, meaning that the graph below is the transmission of 5nm moving average.

LPS-P2 Spectrum

Spectrum of LPS-P2 at 0 incident angle (Measuring interval 2nm)

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3 Responses to LPS Filter for D7000

  1. Redar Flingonstege says:

    Hi,
    I am doing astro photography with a modified D7000, and I really like that camera because of its low noise levels and also because I can shoot for a whole night with one single camera battery.
    The front filter thing you described was fantastic news to me, since I also want to use regular camera lenses for wide field astro imaging. In fact, I also own a 180 2.8D lens !

    So, what is your experiences with this setup ? Is the filter doing ok (no nasty reflections etc) ? Is it easy to swap between different filters ? Did you solve the issue with the screws scraping the 180 mm lens (it has only 8.2 mm protrusion, so how can it be an issue ?).
    In short, would you recommend this setup for astro photography ?

    I noticed you use the LPS-P2-N4, but it seems like it is discontinued. The Hutech pricelist has a LPS-D1-N4, I guess this is the current light pollution filter ? They also have a LPS-V4-FF-N4, would this filter be the right choice for Halpha nebula imaging ?

    Sorry for asking so many questions but this article really got me hooked up. Very useful information here, thanks !

    • jackshencn says:

      I only had used it once before lost that small piece of glass during a road trip. It turned out to be less useful in a national park as LP is already minimal. And it will still reduce SNR for reflection nebulae. It’s great in rural area. I had not check the reflection before that thus I could not comment on that. But I believe it should be great.

      As for scraping the lens mount, you could tighten the screws on the filter or remove the plastic ring on the lens, which I believe you could do as well on 180 2.8D.

      As for the name, maybe they just changed the catalog name. LPS-D1-N4 should work. Actually it’s not great for a RGB DSLR to work with H-alpha. For best SNR, a monochrome camera with Ha filter is the best.

      • Redar Flingonstege says:

        I agree about a Ha filter works best with a monochrome camera. If there was a replacement sensor without the Bayer layer for the D7000 on the market I would be the first customer. As I need a very portable setup I want to leave the laptop at home.
        In my dreams I can see a cooled ccd camera with an on-board sd card and a bluetooth connection talking to my smartphone. Maybe not for planetary filming due to memory constraints, but for dso work.
        Anyway, thanks for your quick reply !

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