NP101is Imaging the Skies over Maryland!
We’ve been watching Jim Johnson’s progress for many years on Flickr and feel he’s broken into the top-tier of imaging with his recent targets. In 2025 he told us: “Just this year I have reached a point in my photography journey that I am mostly (but never completely) happy with my work”, says Jim. As validation, Jim’s image of the Dolphin Nebula (Sharpless 2-308) was featured in the Gallery section (p. 79) of the September 2025 issue of Sky & Telescope. Congratulations Jim! This blog is a presentation of Jim’s current work.
Out there somewhere — Heart of the Heart Nebula (Hubble Palette)
Jim’s Heart of the Heart Nebula image is truly immersive at full screen. He’s “peeled apart” and added depth to the various objects in the center of the Heart Nebula (also IC 1805, and Sharpless 2-190). This central region glows in light from energy provided by giant stars in the open cluster, Melotte 15, visible at the center of the image. Stellar winds from these young stars are eroding “dust pillars” (star forming regions) visible in front of the cluster.
We asked Jim how he got started in astronomy and astrophotography, how he choose his equipment, and his favorite imaging/processing techniques. His responses are interspersed with the images here.
I got started in astronomy as a teenager with a 15 – 60x tabletop spotting scope. I stumbled upon Saturn and eventually found Jupiter and was hooked for life.
My start in astrophotography actually began a few years before I took my first astrophotos. Anticipating retirement in a few years, I visited Martin Cohen, at Company 7, in 2012, to talk about a real telescope, thinking that I would want a 10” SCT. He spent about 1½ hours helping me decide what scope I really wanted, and it turned out that a 4” refractor would be better suited to my interests. I chose the Tele Vue-NP101is for the quality, and the “is” (imaging system) model in particular because I thought that some day I would want to learn astrophotography. I was a visual observer and very active in outreach at Howard Astronomical League for six years with the TV-NP101is before finally beginning the transition to astrophotography. Light-polluted urban skies, growing bored with the same fuzzy smudges, and the technical challenges in imaging drove the transition.
Fish Head Nebula (Hubble Palette)
Fish Head Nebula (also NGC 896 or IC 1795) Is a bright knot in the western part of the Heart Nebula. They are both part of a complex of star forming regions along the edge of a large molecular cloud over 6,000 light-years away, The “fish head” shape arises from a combination of thick obscuring clouds and ionized, glowing gas — mostly hydrogen — energized by young stars forming within the cloud.
Jim writes: “Living beneath the Baltimore-Washington light pollution dome creates the need to travel to remote, dark sky sites for deep space imaging.” So we asked him where he did his Tele Vue-NP101is imaging from.
I do a lot of narrowband imaging from my Bortle 7 (suburban/urban) backyard. I have access to a Bortle 5 (suburban) sky at a farm about 1½ hours away, and I go there 3 or 4 times a year. I also enjoy Almost Heaven Star Party in West Virginia, and Winter Star Party in the Florida Keys.
The image results that I get from the TV-NP101is are what I like most about it. It is a fast scope (f/5.4 native, f/4.3 with reducer), which allows me to collect more signal faster. The apochromatic design removes all chromatic aberration. It has a 52mm image circle and field flattener allows me to use a full-frame sensor with pinpoint stars out to the image corners. With the reducer I am able to easily cover large scale targets like Andromeda Galaxy and all of Cygnus Loop in a single, un-mosaiced frame.
What is the “Hubble Palette”?
Several of the images here are marked as being in the “Hubble Palette” or taken through “SHO” filters and you may be wondering: “what does this mean?”
Similar to how Red, Green, and Blue (RGB) light can be combined to form color images on a television screen, astro imagers can use filter sets tuned to particular wavelengths (colors) of light to produce natural-looking or “false-color” images of a celestial object.
Professional astronomers are more interested in finding out what an object is made of and how it evolved into its present configuration. This takes a backseat to creating natural-looking RGB images. By imaging with filters tuned to the emission lines of specific light-emitting gasses, “false color” photographs are created that reveal the composition and evolution of nebulae. These filters are known as “narrowband” because they attenuate any light beyond the emission wavelengths they are designed to pass. This often conveys a sense of dimensionality not present in an RGB photo of the object. Widely distributed, eye-grabbing, false-color nebulae images from the Hubble Space Telescope (HST) inspired amateur astronomers to use a filter set that produced similar results.
The HST contains dozens of filters that can be used in many combinations, but the amateur astronomy community adopted the most eye-pleasing of the filter sets (SHO: Sulfur II, Hydrogen-alpha, and Oxygen III) for nebulae use as the “Hubble Palette.” This filter set is listed below by the color channel commonly assigned in the final image, the atomic emission line passed by the filter, and the position of the emission line on the spectrum. It may be surprising to learn that two of these emission lines look “red” to our eyes.
- Red = Sulfur II (deep-red spectrum)
- Green = Hydrogen-alpha + some Nitrogen (red spectrum)
- Blue = O III (blue-green spectrum)
The Heart (IC1805) and Soul (IC1848) Nebulae — 2-Panel (Hubble Palette)
This is a wide-field of the Heart and Soul region in the constellation Cassiopeia (the queen). It shows the features discussed in the prior images in location context. The Heart Nebula is on the left. In this orientation, the Fishhead nebula is the structure at bottom-left of the Heart. To the right is the Soul Nebula (Sharpless 2-199 or LBN 667), also an emission nebula that primarily glows from ionized hydrogen gas. A dark rift in the Soul Nebula almost splits it into two lobes. Several open clusters are visible in the lobes.
Jim explains his favorite processing technique for Hubble Palette images.
I like naturally colored stars in my images whether working on broadband or narrowband images.
If shooting broadband with an LRGB (Luminance, Red, Green, Blue) filter set, I am careful in capture to not over expose the stars, because that blows out the color in the centers of the brighter stars. In processing, I separate the stars from the target nebulae or galaxies and stretch the stars (gently) and target (aggressively). Separately, because the aggressive stretch required for the target will blow out the color in the star centers. I recombine stars and target images after both have been stretched.
In the case of narrowband (SHO filter set), I do not like the unnatural narrowband star colors. In capture I shoot about 30 minutes of short RGB exposures that will become a stars only image. In processing, I remove the stars from the narrowband target image and blend the RGB stars in after target has been stretched aggressively and after the stars have been stretched more gently.
Meet the Tele Vue-NP101is Photo / Visual APO Refractor
When we contacted Jim for this feature blog post, he told us: “I have had my NP101is for thirteen years now, and I could not imagine another scope that can do what this one does”. “People, me included, are amazed at the wide open field-of-view that the scope and reducer coupled with a full frame sensor cover. Right now I’m working on Cygnus Loop – covered it all in one go.”
Al Nagler took Petzval’s portrait lens concept and patented a fast telescope version for the purpose of testing eyepieces (the 5”, f/4 Multi-Purpose Telescope). By 2001, the NP101 (Nagler-Petzval) scope was the ultimate culmination of 20-years of refinement toward optical perfection for the “multi-purpose” concept. However, we did not rest on our laurels: with the CCD imaging revolution challenging telescope optics beyond anything ever placed at the focal plane, we were determined to make the NP series optically, mechanically, and functionally as perfect as possible for imaging on chips with up to 50-mm diagonal, without penalty to its near-ideal visual operation. The resulting Imaging System version of the NP101 is a 4-element, 2-group (Nagler-Petzval) design, with a 101-mm objective diameter, 540-mm focal length (f/5.4), APO refractor with a robust 2.4″ focuser with built-in tilt compensation. The NP101is produces a whopping 5.3° image circle at prime focus. Maximum visual field-of-view is likewise huge: 4.9° with 55-mm Plössl (10x) or 41-mm Panoptic (13x) so the scope can act as its own finder.
Every focuser is tested to carry 12-lbs / 5.4-kg of payload without flex, so it can handle most any OAG/filter-wheel / camera combinations or the heaviest Tele Vue eyepiece with ease. The OTA features a captive, sliding, metal dew shield, screw-on metal lens cover, and a rugged powder-coated aluminum tube. It comes in a custom-designed hard-shell carry case with room for all standard accessories.
All Tele Vue telescopes are built and tested at Tele Vue and come with a 5-year Limited Warranty.
The Dolphin Head Nebula — HOO Palette
This nebula in Canis Major has the appearance of a ghostly apparition suspended against the blackness of space. It goes by several names: many see the grinning face of a porpoise or dolphin while others see a gourd. It is cataloged as Sharpless 2-308. This bubble of gas formed when the Wolf–Rayet star at the center shed outer layers of hydrogen gas. Stellar winds from the star are forcing the gas to collide with slower-moving shells from earlier in the star’s evolution. This causes the shape of the nebula that we see today. The central star is named EZ Canis Majoris is in a pre-supernova phase. This future supernova will form a black hole and obliterate the nebula we see here.
We’re looking forward to more exemplarily images with Jim’s Tele Vue-NP101is. For now we wish him clear skies!
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More Info
- Jim’s Flickr Wall is where he shares his photos.
Great work Jim and the 101is is a fantastic telescope for astrophotography.
Wow great article . Jim is a masterful Astro photographer. Great equipment too. Awesome read👍🏻