Otis AstroImaging: April 2021

Friday, April 30, 2021

Upgrade the Celestron FirstScope with a Rotating "Multiple Eyepiece" Turret
This revolving eyepiece turret accessory increases convenience in switching eyepieces, cameras, and those with filters or other devices

Adding light weight accessories is important for maintaining telescope balance, especially for telescope tube OTAs that have no means of balancing. The Celestron FirstScope is one of those telescopes.

The Eyepiece Revolver fits my complete set of Svbony Gold series Aspheric eyepieces consistently. This includes 4mm, 10mm, and 23mm focus oculars. The Revolver has good lock rotation and can be adjusted with a centerline screw.

Tips & Techniques
It's ideal to put on camera and sight in first with eyepieces to center the image. The revolver adds about one inch of back focus so adjust the mirror position or substitute a different focuser accordingly to compensate for focus.

Procedure
The Revolver holds a complete set of Svbony eyepieces and rotates each into view on a Celestron FirstScope. Scope balance is not significantly changed with the lightweight revolver and lightweight eyepieces so manual tracking remains the same. The product is outstanding.

Adjustment
I adjusted wherever possible, including the tightness of the screw in barrel for rock solid performance. Overall, the unit matches the telescope and eyepieces perfectly and has free and smooth rotation. The eyepiece barrels are not too long and do not protrude.

Specifications
Item - 1.25" Eyepiece Revolver
Brand - KSON
Sold By - BestGoBuy
Cost - $28
Capacity - 3 Eyepieces
Adjustable - Yes

Focus - Adds 1-inch of Back Focus
Hold Other Equipment - Yes. Camera, eyepieces with filters

Spectacular Focal Reducer Discovery for FirstScope

Spectacular Focal Reducer

Discovery for Celestron FirstScope

by Mike Otis

Experiment Gone Fantastic!

Change your telescope's world with a simple Fresnel card. Turn your telescope into a very fast f/.5 system!

Over the years the flat plastic Fresnel lens about the size of a credit card has significantly improved and now forms much better grade optical images. The card is designed to be used as a low cost flat magnifier and conveniently carried in a wallet like a credit card,

I bought several flat Fresnel lenses for experimentation in the lab. I noticed a long focal length of several inches and the last night out with the Celestron FirstScope, I held one up to the rack and pinion and pointed the telescope at the Moon. I was surprised to see a very tiny Moon, as if the Fresnel lens was acting like a massive focal reducer.

I set up a rig to measure the focal length of the Fresnel and got 6 to 8-inches. The Celestron FirstScope has 2.99-inches aperture with a focal length of 11.8-inches at f3.95. Using the upper limit of the Fresnel focal length, I got f/3.95/8-inches = f/.5 and a magnification of 11.8/8=1.5x. Technically, the flat Fresnel performs like an 8-inch focal length eyepiece giving 1.5 power. After learning the very bright tiny dot in the telescope was the Full Moon and not a reflection, I realized the lens was acting like a spectacular focal reducer. Having a Celestron FirstScope converted to a very fast f/.5 system is like having an all new telescope, very fast lens, or a Schmidt Camera.

Aberrations

System aberrations include small effects of flexure - deviations from a plane surface, and achromatic aberration due to using the single plastic element. When taking images for processing, the blue end of the spectrum is easily subtracted or filtered out.

Fresnel Lenses - Tips & Techniques

I also discovered the opposite effect of the focal reducer is possible. Make a 2x or greater Barlow by stacking two or more credit card lenses and observe the overall magnification increases.

Extra Experiments

* Try making a telescope using the Fresnel lens as the primary objective

and stack two for the eyepiece

* Record the magnification increases when stacking cards for a Barlow effect

* Prop one up on the telescope tube for use as a finder card

* Place over the hand controller to enlarge the display

Thursday, April 29, 2021

Mystery Sky Light UFO

Mystery Bright Sky Light Identified

For the past several nights, a very bright UFO - static flashing sky beacon light appeared above the mountain range. Posing as a possible stationary geosynchronous orbital satellite, the beacon hovered above the mountain and was watched over the course of several nights. Sometimes it moved position from night to night. Other times it remained stationary as if hovering.

If you swing one of the very large telescopes over to the light, it can be resolved and identified. However, no telescopes were in operation most nights during the spell of inclimate overcast weather. Overcast skies only deepened the mystery.

But when the object was sighted just as the sun was setting, it became obviously clear it was simply a powered pulsating warning light located at the tip of a very large construction crane occupied in the development area of a new tall skyscraper. It was not a rotating satellite in space reflecting sunlight after all.

After identifying the hazard light, at least three more were found looming in the night sky. These contribute significant light pollution, thus destroying the darkness and beauty of the night sky, as the wide band multispectral beam emits strong light in all directions including skyward to warn low flying aircraft of its position.

Wednesday, April 28, 2021

Plastic Telescope Takes the Cake!

The World's First All Plastic Commercial Telescope Takes the Cake!

Designed for the Celestron FirstScope as a finderscope

Leave it to Celestron partnered with Chinese constructionists to make perhaps the world's first commercial all plastic telescope and at the lowest pricing imaginable. As far as we know, everything from the tube, mount, ring, dust caps, eyepiece, and even the lenses are plastic!

The 5x24 telescope is originally designed for the Celestron FirstScope telescope and attaches to two bolts on the tube. With an aperture of 24mm or about one inch, and magnifying 5x, the scope is intentionally made of plastic to keep it extremely lightweight, an absolute requirement when attaching as an accessory to a small lightweight telescope without the means for adjusting balance.

What is the performance of an all plastic telescope? Surprisingly good. Who would have guessed? The photo at left was taken with a camera phone by holding it in front of the eyepiece end of the scope and shows crosshairs and a crisp colorful view of city buildings located far away. It was shot through a curving fence. The image through plastic lenses has very minimal distortion and any slight achromatic fringing is negligible. The photo shows any spherical aberration is also negligible and hardly noticeable. Plus the price is right - at only $8.69 and free shipping when purchased from Svbony Optics.

Cleaning Note

When cleaning a plastic optic, do not contact the surface with anything, especially a lens cloth, tissue or any other means of wiping the lens. Soft plastic will easily and permanently scratch. Clean by using gentle puffs of clean dry air.

Specs at a Glance

Function - Finderscope for Celestron FirstScope, Spotting Telescope

Aperture - 24mm

Magnification - 5x

Weight - A Few Ounces

Size - About 15cm Long

Dust Caps - Included

Construction - Plastic

Crosshair Reticle - Yes

Finish - Glossy Black

Mounting Bracket Type - Celestron FirstScope

Focus - Adjustable

Image - Inverted

Cost - $8.69

Tuesday, April 27, 2021

Celestron FirstScope Index 2021

Celestron FirstScope Index 2021
This is the new updated index to various projects posts for the Celestron FirstScope, a cute little Dobsonian telescope sold in toy stores but upgraded to perform numerous experiments.

At 2.99-inches diameter and f/3.95, this reflector telescope is being used to the max. Follow the creative experience and see what happens when a tiny telescope meets creativity.

April 28, 2021 Plastic Telescope Takes the Cake - FirstScope Finderscope

https://otisastro.blogspot.com/2021/04/plastic-telescope-takes-cake.html

Celestron Firstscope Camera Mount

Celestron FirstScope - Mounting a Phone Camera

The Celestron FirstScope is a telescope sold at toy companies. It has serious astro abilities when upgraded. For astrophotography and astro imaging, a camera mount is needed to steady the camera and stop motion blur.

No ordinary camera mount will work, as the telescope does not have a tube that can be rebalanced. This means finding and using a very light weight camera mount is necessary. For example, the Celestron NexYZ camera mount may be too heavy for the small firstScope.

There are several good low cost mounts cast from polymer that weigh almost nothing. The mount in the illustrated example cost $6.98 including shipping and fits the iPhone Xs Max.

The camera is firmly held in place with spring loaded sides that tightly grip the phone sides. A screw adjusts to hold the ocular which carries the entire mount. The phone position is infinitely adjusted with a tightening knob after the phone is positioned directly above the eyepiece, or before attaching to the telescope (an example in the video). The photos are self explanatory. As the camera will add the majority of the weight, increase the tension on the Dobsonian mount. Make sure to mount the camera along the telescope tube and optical axis for best balance and to minimize any rotational imbalance. Experiment with other mounts, brands and sizes of phones.

https://www.youtube.com/watch?v=C8EIyocVRJI

https://www.youtube.com/watch?v=qoT44STXUhU

Saturday, April 24, 2021

Celestron Firstscope Experimenting Through Clouds

Celestron Firstscope: the Experiment, Can We Shoot Through Heavy Clouds?

Using a 2.99-inch Dobsonian to shoot the Moon through heavy clouds - is it possible?

by Mike Otis

THE VIEW at left shows the Moon totally obscured by heavy clouds on the night of Saturday, April 24th, 2021, captured with an iPhone Xs Max camera.

Photos are taken through the author's Celestron FirstScope with two Svbony Aspheric 62-degree eyepieces, using eyepiece projection, one at 10mm FL at 30x and a 23mm FL at 13x. The experiment is to see if images can be obtained by shooting the Moon through very heavy clouds without using filters.

At left, the first step is using the 23mm 13x ocular, holding the iPhone camera above the eyepiece and observe the effects at various exposures, noting the appearances across numerous images and seeing which images improve or degrade with various exposures. Low power seemed to accentuate the cloud haze across the front of the Moon and created less detail and surface features. It is also noted, focus will change based on the varying cloud density. It would be best to

place a lightweight plastic camera mount on the telescope rather than handhold the camera, thus allowing a greater ability to position the telescope, refocus as needed, and greatly minimize image motion without needing too many hands or bumping the telescope.

The final image shown above is through the 10mm eyepiece at 30x. The greater image scale is better at penetrating the clouds and showing lunar detail. The single prized image is software processed with PhotoScape X to remove cloud obstructions and water vapor haze. The image, towards the bottom right of the Moon shows some remaining water vapor, however it's not necessary to remove it as it does not appreciably cover the Moon. This experiment was far more successful than expected. Without the use of filters and only by adjusting image scale and exposure, a reasonable cloud penetration is possible with the Moon.

Celestron FirstScope Remote Land Tests

Celestron FirstScope Remote Land Tests
Enter the fascinating realm of the lowly Celestron FirstScope - a tiny beginner Dobsonian telescope that has taken Toys'R'Us by storm. But wait, is it a toy or is it real?

by Mike Otis

Left: Shooting through patio glass with a 1.6x zoom Apple iPhone Xs Max camera and enlarged here 3x, the crane hanging attachment is almost not visible.

The test is to use the Celestron FirstScope Dobsonian telescope from the convenience of indoors and test with (2.99 inches aperture at f/3.95) three eyepieces (23mm, 10mm, 4mm), with the same iPhone camera and compare the results. All eyepieces used are Aspheric in design with 62 degree views, available at reasonable pricing from Svbony Optics Company located in Asia.

Enter the world of the author's FirstScope Tabletop Observatory and take a look at what can be accomplished with a remote land test and three eyepieces, looking through patio glass at a slight angle, and discover interesting effects along the way.

First up is the view through the 23mm eyepiece at 13x. Due to hand holding the camera above the ocular and the exit pupil, the shadow of the secondary is visible in the upper left. In the photo, at the top right, is the crane attachment nearly invisible in the regular iPhone photo.

Next, dial in the image with the 10mm focus eyepiece and compare the 30x view. Note, the camera is handheld and the distance to the eyepiece may slightly vary.

The final handheld camera image, below, is taken with a 4mm focus eyepiece at 75x.

Note, there is a variance when photos were imported to this page as seen in the diameter of the circular view.

Wednesday, April 21, 2021

Testing Svbony Optics on the First Scope Telescope

Testing Svbony Optics on the First Scope Telescope
Tests included the 2x Barlow, .5x focal reducer, full focal length set of Svbony eyepieces (both Plössl and Aspheric) on the Celestron 3" f/4 Dobsonian First Scope Telescope. The results are surprising!

I UPGRADED my Celestron Signature Series FirstScope telescope using optical components from Svbony, including finderscope, focal reducer, barlow and new eyepieces. The results were exciting and surprising to say the least. Let's take a look at what was learned in the testing process.

First let's talk about the setup. I set the telescope on a small round table indoors and imaged through the closed clean patio window. The single pane of clear (white) parallel float glass is relatively optically pure and works well for quick tests and good focus inside the convenient environment of a bug free and perfect temperature telescope control room.

I selected a set of two types of eyepieces from Svbony, a reliable supplier of telescopes and accessories. The first set are Plössl and the second set are Aspheric. Note: different EPs are known to have different performances given short or long focal length mirrors.

Svbony Set One

40mm Plössl

32mm Plössl

Svbony Set Two

23mm Aspheric

10mm Aspheric

4mm Aspheric

Focal Reducer

.5x

Barlow

The results are surprising. The set of Aspheric oculars, with a more simple glass design, was vastly superior, giving sharp focus bright images across the FOV. The views were dazzling and exciting! Colors were exceptional, images formed clearly without distortions or aberrations, and the low cost of each eyepiece fit well with First Scope Telescope (a set of all three eyepieces currently costs $26.18, just a little over $8 each!). These EPs have outperformed other brands costing several hundred dollars each.

Another positive and greatly welcomed factor is the light weight of each ocular - weighing almost nothing - it does not upset the predetermined non-adjustable balance of the OTA. Aspherics won out over numerous other brands, for example, a 4mm Celestron ocular known for producing dim images has extremely tiny lenses that don't admit much light at all and it was very difficult for visual observing with an almost non-existent exit pupil. However, the Svbony Aspherical 4mm eyepiece was a pleasant surprise with its large diameter lenses, a comfortable exit pupil for visual observing, and exceptionally bright clear images especially for a short focus EP at high power.

However, given the fast focal length f/4, the Plössls, both 32mm and 40mm were a different story. Visual observing produced a black round spot in the middle of the fov, i.e. a shadow of the secondary, which can happen when the exit pupil is wider than 7mm. Clearly, the long focal lengths of these Plössls do not match the short focal length of the mirror. Therefore in conclusion, the Svbony Aspheric eyepiece set is the real winner and highly recommended for use with the F/3.95 Celestron First Scope Telescope.

Focal Reducer & Barlow Testing

Bonus Tip: Those thinking about trying a focal reducer ($9.45) with any of the tested eyepieces will soon realize the telescope does not have focus in range. However, the 2x Svbony Barlow ($7.90) is another big winner and works exceptionally well, even at the highest power when changing the 4mm into a 2mm. With the telescopes 76mm (2.99") aperture and 300mm (11.81") focal length at f/3.95, this gives 150x with tac sharp clear images. The Svbony 2x Barlow worked well with all three aspheric eyepieces (including the 23mm and 10mm) and is highly recommended for the Celestron First Scope.

Top left - Svbony .5x focal reducer attaches to the eyepiece. Left below - Svbony 2x Barlow also threads into a 1.25" eyepiece. The finderscope will be reviewed at a later date.

Celestron Firstscope Telescope Specs

Design - Newtonian Reflector

Style - FirstScope Signature Series

Manufacturer - Celestron

Mount - Dobsonian

Drive - None

Diameter - 2.99 inches (76mm)

Focal Ratio - f/3.95

Focal Length - 11.8" (300.2mm)

Prime Focus - 12x

Eyepieces - Original Celestron eyepieces melted

Resolution Rayleigh - 1.83 arc seconds

Resolution Dawes - 1.53 arc seconds

Limit Stellar Magnitude - 11.9

Light gather power compared to human eye - 118x

Adjustments - None

Highest Useful Magnification - 150x

Lowest Useful Magnification - 12x

Owner Added Accessories

* Svbony Aspheric Eyepiece One - 62 Deg., 23mm (.9") = 13x

with 2x Barlow = 26x

* Svbony Aspheric Eyepiece Two - 62 Deg., 10mm (.4") = 30x

with 2x Barlow = 60x

* Svbony Aspheric Eyepiece Three - 62 Deg., 4mm (.16) = 75x

with 2x Barlow = 150x

* Svbony/Celestron Finderscope - 5x24, Plastic, Crosshairs, Focus

* Celestron iPhone Software - Sky Portal

* Computers - Apple Mac

* Image Processing Software - Apple System Photos, Mooii Tech PhotoScape X,

GIMP, Soggy Waffles Paintbrush

* Apple Camera - iPhone

* Zwo ASI224MC Camera

* Svbony Focal Reducer - NA

* Svbony Barlow - 2x

* Svbony - Filters

Small Telescope Fun

Having Fun with Small Telescopes
Not every image taken with a small telescope will reveal detail like the Hubble Space Telescope but you can do the next best thing by processing your photos in new, unique, and artistically creative ways. Left: original image. Below: Enhanced

Take for example this original image of the Moon (at top), captured with a small plastic telescope at 4-inch aperture. At first glance, there's not much useful information visible and the photo is overall dark and gloomy, but what if we could have some fun and extract more data from our favorite crater Ptolemaeus?

The crater Lyot is barely shown but what if image processing could enhance it and show more, introducing shadow depressions and more detail inside the giant crater? And to boot, let's add some pizazz with creativing lighting and color flares to make it interesting and fun. The second image shows those results. A lot of detail appears inside Ptolemaeus and the entire terminator is more pronounced with new features visible. Lyot crater is clearly visible along with more terminator details. To process the image, I first used Apple Mac OS system software Photos to base enhance the image. A second program Photoscape X was used for refinement and special effects, light flares, color, enhancements and framing.

CAPTURE THE ENTIRE MOON

At left is the original gibbous Moon image taken with the same telescope. The image is small and lacks the clarity of lunar features. In the next image, the Moon is having a bout of processing with Photoscape X to increase image scale and bring out the clarity of features.

So next time out, get creative and have a ton of fun with your small telescope!

Friday, April 16, 2021

Filters

Astronomical Filters Directory & Library
This filters directory and library includes telescope filter information and the covetous spectral data sheets, when available, for developing applications

SVBONY CITY LIGHT SUPPRESSION CLS (ABOVE)

https://www.svbony.com/cls-filter

The bandwidth of Svbony CLS Filters is wider than that of Svbony UHC Filters, and the luminous flux is large, which is more suitable for use in places with less light pollution. The SVBONY City Light Suppression broadband filter is designed to improve the visibility of various Deepsky objects. By selectively reducing the transmission of wavelengths of light pollutants, specifically those produced by artificial lightings including mercury vapor lamps, both high & low pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow). Together with the highly transparent in main nebula emission lines at OIII(496nm and 500nm), H-beta (486nm), NII(654nm and 658nm), H-alpha(656nm) as well as SII(672nm), the Svbony CLS filter is suitable for enhancing the contrast and details for both visual and photographic purpose at sub-rural area. 1. Brand: SVBONY 2. Type: City Light Suppression Filter (CLS Filter) 3. Material: Optical glass lens, Aluminum Frame 4. Shape: Round 5. Barrel diameter: 1.25'' (Thread size: M28.5*0.6mm) or 2" (Thread size: M48*0.75mm)

SVBONY 1.25" MOON & SKYGLOW (ABOVE)

SVBONY 1.25" moon and skyglow filter is a multi band pass filter transmitting a high percentage of light in the visual spectrum; the filter enhances contrast when observing brighter objects including the moon and planets. Telescope eyepiece cutting light pollution; the filter has a mild effect of darkening the background of the night sky so that the fainter objects are more clearly seen contrasted against the blackness of space. The filter effectively filters out selective wavelengths of low pressure sodium and other man made sources typically used in street lighting; although it is not a nebula filter; it enhances the views of deep sky objects by increasing the contrast of these objects against the background sky

https://www.amazon.com/SVBONY-Astronomy-Telescope-Thread-Pure-Pollution/dp/B071CTYTQS 1.25" moon and skyglow filter is a multi band pass filter transmitting a high percentage of light in the visual spectrum;the filter enhances contrast when observing brighter objects including the moon and planets. Telescope eyepiece cutting light pollution;the filter has a mild effect of darkening the background of the night sky so that the fainter objects are more clearly seen contrasted against the blackness of space. The filter effectively filters out selective wavelengths of low pressure sodium and other man made sources typically used in street lighting;although it is not a nebula filter;it enhances the views of deep sky objects by increasing the contrast of these objects against the background sky. Premium quality metal rim and thread with blue glass lens;the filter will fit all standard sized 1.25" eyepieces and accessories;it is mounted in a nicely anodized housing and is threaded on both sides for stacking with other filters if necessary. Standard filter thread for any 1.25” telescope eyepiece and other accessory;comes with a plastic box to keep it safe and clean when not in use; It's mainly used for visual and photography of the planets, which can effectively suppress the interference of the sky's glow (589nm) and improve the contrast of planets. Graph not available.

SVBONY 1.25'' LINEAR POLARIZING FILTER

SVBONY 1.25'' Polarizing Filter Linear for Telescope Astronomy & Eyepiece Increasing Contrast Reduce Glare Increase Detail. The Svbony 2" Polarizing Filter is high quality anodized aluminum, optical glass polarizing filter designed to reduce the amount of light entering your eyepiece. You can progressively dim the view when observing a bright object, such as the Moon or certain planets, to a level according to your needs, while increasing contrast, reducing glare and increasing the amount of detail that can be studied. The 2" Polarizing Filter is the best all-purpose lunar and planetary filter.

SVBONY CPL CIRCULAR POLARIZER LINEAR (ABOVE)

The Svbony 1.25-inch variable Polarizing filter acts like a dimmer switch for your telescope. A CPL filter – which stands for circular polarizer/linear – is a glass attachment that can reduce the glare from reflected surfaces. It does this by taking what you could call “obstacles,” such as unwanted light, reflections or color, and reducing them to a certain extent. Adjusts the amount of light transmission from 1% to 40% by rotating the filter housing. Reduces brightness of the Moon or planets for great clear viewing. Finer control of the image brightness compared to a standard fixed-transmission telescope filter for optimal performance. Fit standard sized 1.25" eyepieces and accessories. Premium quality metal rim and optics glass lens. Sturdy plastic case included. Model: SV128. Type: Variable Polarizing Filter. Material: Optical glass lens + Aluminum Frame. Shape: Round. Barrel diameter: 1.25''. Thread Standard: M48*0.75. Weight: 1.258g / 0.99oz. The Svbony 2" Polarizing Filter is high quality anodized aluminum, optical glass polarizing filter designed to reduce the amount of light entering your eyepiece. You can progressively dim the view when observing a bright object, such as the Moon or certain planets, to a level according to your needs, whilst increasing contrast, reducing glare and increasing the amount of detail that can be studied. The Polarizing Filter is the best all-purpose lunar and planetary filter.

SVBONY UV/IR CUT (ABOVE)

The SVBONY UV/IR cut filter has a very high transmission rate, improved over most other brand filters. Example: use with the Zwo ASI224MC color camera to maintain color balance and sharp imagery. The filter passes visible light and blocks high frequency ultraviolet and low frequency infrared. Optical glass with low reflection coatings. Interface threads are M28.5x0.6.

ZWO ASI224MC CAMERA WINDOW (ABOVE)

Both cameras, ASI120MM and ASI224MC, have a clear, IR transmitting, protection filter in front of the chip to keep dust off the sensor. This is normal for a mono camera like the 120MM, where you might want to also use IR and UV filters, but not so for an OSC camera like the ASI224MC. OSC color cameras normally have an IR/UV filter rather than a clear glass because their sensitivity in the IR is poor. The ASI224MC, however, can actually image into the near IR with 30% transmission at 900nm and in fact behaving essentially as a monochrome IR camera in the range 825nm – 1000nm.

ASTRONOMIK PROPLANET IR 742 (ABOVE)

The ProPlanet IR 742 only allows infrared light with wavelengths of more than 742 nm to pass. In this wavelength range the effects of seeing are significantly lower than in the visible spectrum of the human eye. This allows much sharper images than are usually obtained from your device and location. Another advantage is that the sky background of advanced dawn is dark and so the filter even allows photography of the planets and the Moon at daylight. Main use: The Astronomik ProPlanet IR 742 cuts off the visible part of the spectrum and allows the light of wavelengths longer then 742nm to pass. Due to this behavior, the part of the spectrum that is most sensitive to bad seeing is rejected. This approach does a big improvement to the imaging of planets and the moon. The image is more steady than the image in the visible light with nearly identical exposure times. Darkens the background during twilight. Imaging of bright planets, stars and comets by day. Imaging of young stars in dust clouds and stellar nurseries. Alternatives. When the seeing is very bad and the instrument is 10" (250 mm) or larger, the Astronomik ProPlanet IR 807 may be the better choice. Webcam / Video (Planets): Very good, rejects problems with seeing. Webcam / Video (Deep Sky): Very good, rejects problems with seeing. more then 96% transmission for wavelengths of 742nm to 1100nm. blocking of wavelengths between 350nm and 730nm.

ZWO Ha H-Alpha 7nm 1.25" (ABOVE)

Narrowband filter does not eliminate the effects of light pollution or increase the object’s brightness. In many cases, they increase the contrast between nebula and night sky, not brightening the nebula.,It can reduce the transmission of certain wavelengths of light, specifically those produced by artificial light including mercury vapor, and both high and low pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow). The ZWO H-Alpha filter has a bandpass of 7nm and passes light at 656nm wavelength, light transmission rate comes up to 80%. Narrowband H-alpha astrophotography filter for high-contrast imaging and revealing rich details of the nebula even in areas with strong light pollution.

ZWO 1.25″ IR 850nm Pass (ABOVE)

Suitable for IR sensitive cameras. You don’t need to debayer and get the full resolution of this sensor when using it with a Color camera such like ASI224MC or ASI185MC, because the QE response of the sensor beyond 850nm is all the same. So you can use a color camera as mono camera with this filter, just don’t forget to keep the WB_R and WB_B to 50 (no White Balance applied).

ZWO LRGB SET (ABOVE)

Designed to approximately equalize the flux of ASI1600 mono sensor, Schott substrate material, glass thickness 1.1mm, polished accurate 1/4 wavefront, 90% transmission at passband, infrared wavelength 700-1100nm cut-off, precision off-band blocking, multi-layers anti-reflection coating

ZWO 1.25″ IR UV CUT (ABOVE)

Suitable for color camera with AR protect window, blocks infrared light from reaching the sensor of your CMOS camera or H-alpha filter. When imaging, the addition of this simple and inexpensive accessory will result in sharper images, and when doing solar work, the IR Cut Filter will your protect H-alpha filter from the damaging effects of infrared radiation. Infrared or IR light is invisible to the human eye, and so even though most telescopes are not designed to focus IR light, it does not matter when you are using your telescope visually. However, when you add a camera to the mix, it's a whole other story! Unlike the human eye, a silicon sensor is very sensitive to light in the infrared portion of the spectrum, and that is a problem because infrared images are blurry as all get out. That means your nice, sharp visual light image is degraded by the addition of the infrared layer. This problem can easily be solved by blocking the infrared, and the ZWO IR Cut-Off, will do just that.

Optolong L-Pro (ABOVE)

For light pollution. Best used for imaging most emission nebulae, reflection nebulae, and dark nebulae. Suitable for both visual and photographic observations. Effective in suppressing light pollution sources. This is a true broadband filter that aims to preserve the natural colors of stars in the night sky. It includes a mild filter against known sources of artificial light including LED street lights. Designed to improve the visibility of various deep sky objects. By selectively reducing the transmission of wavelengths of light pollutants, specifically those produced by artificial lights including mercury vapor lamps, both high and low pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow). Together with the highly transparent in main nebula emission lines at OIII (496 nm and 500 nm), H-beta (486 nm), NII (654 nm and 658 nm), H-alpha (656 nm), as well as SII (672 nm), the filter is suitable for enhancing the contrast and details for both visual and photographic purpose at sub-rural area with heavy light pollution. Unlike other light pollution filter UHC and CLS, L-Pro is multi-bandpass filter which offers better color balance by maximizing the transmission band. The balanced transmission allows astrophotos to be taken with minimal color cast to broadband emission objects such as galaxies, reflection nebulae and globular star clusters. L-Pro is the best choice for light pollution suppression.

Works well on most emission nebulae, reflection nebulae and dark nebulae. Suitable for visual observation and astrophotography, has a very low transmission reduction rate against continuous spectrum space objects, and thus is quite effective in suppressing light pollution sources when shooting galaxies, reflection nebulae and globular star clusters. The same holds true for visual star observations.

L-Pro filter alone suppresses infrared wavelengths, and thus can be used at ease for "L" image shootings with CCDs. Light pollution filters do not eliminate the effects of light pollution or increase the object’s brightness. In many cases, they increase the contrast between nebula and night sky, not brightening the nebula.

Optolong UHC Ultra High Contrast (ABOVE)

Light pollution filter for use in severely light polluted urban area. It selectively enhances emission from nebulas and suppresses the transmission of light pollution sources. UHC enhances the transmission of nebulas emissions and reduce background brightness mostly dominated by light pollution. It has narrower passband than CLS (City Light Suppression) and thus it is the better choice of imaging under severely light polluted areas due to its more rigorous light pollution suppression. Its wider passband towards the red end of the visible spectrum makes it exceptionally suitable for hydrogen emission dominated objects such as M42 Great Orion Nebula. UHC selectively cuts out light pollution emission. For example, mercury vapor lamps, high and low pressure sodium vapor lights and skyglow caused by emission from neutral oxygen in our atmosphere. Among the emission lines enhanced are OIII (496, 500nm), H-beta (486nm), NII (654, 658nm), H-alpha (656nm) and SII (672nm).

Highlights: 95% transmission at major nebula emission lines, 0.1% transmission at off-band at Na (589nm), Hg (435nm, 578nm), multi-layers anti-reflection coating, Precise and sharp roll-off at light pollutant lines, 2 mm filter thickness (1.25", 2" and 77mm) | 1mm (clip series), made on Schott substrate, finely polished to 1/4 wave accuracy, surface quality: 60/40 (MIL-O-13830 standard), equivalent to OD3. Recommended applications: Monochrome & one-shot-colour CCD/CMOS camera, Deep sky colour imaging, particularly emission nebula or DSO emitting in the H-alpha, H-beta, O-III and S-II lines. The Optolong UHC (Ultra High Contrast) broadband filter is designed to improve the visibility of various deep sky objects. It does this by: Selectively reducing the transmission of wavelengths of light pollutants, specifically those produced by artificial lighting (including mercury vapor lamps, both high & low pressure sodium vapor lights, and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow). Being highly transparent to the main nebula emission lines at OIII (496nm and 500nm), H-beta (486nm), NII (654nm and 658nm), H-alpha(656nm) as well as SII (672nm).

Main Feature: 1.25" astronomy filter with standard M28.5x0.6 male filter thread (no female thread, so it cannot be stacked with other filters). Ultra-thin filter cell to minimize vignetting; clear optical aperture of 26mm. Precision CNC-machined metal filter cell with sand blasted black anodized finish, anti-reflection treatment, and laser engraving. Suitable for enhancing the contrast and details for both visual and photographic purpose at urban and suburban areas with heavy light pollution. Suitable for color CCD cameras and unmodified DSLRs.

UHC has a narrower passband and thus provides higher contrast than a CLS (City Light Pollution / Light Pollution Reduction) filter. Thus it is more suitable for urban environments where you suffer from severe light pollution. UHC has a substantial red passband and offer superb views of objects like the Orion Nebula (M42). Spectral Curve Transmission Characteristics: 95% transmission of main nebula emission lines: H-beta 486.1nm, OIII 495.9nm and 500.7nm, H-alpha 656.3nm, and SII 672nm. 0.1% transmission of major transmission lines of artificial light pollution: Hg (Mercury) at 435.8nm, 546.1nm, 577nm, and 578.1nm. Na (Sodium) at 598nm, 589.6nm, 615.4nm, and 616.1nm. Technical Specifications: Both surfaces are fine optically polished, accurate to 1/4 wavelength or better, and parallel to within 30 seconds or arc. 2mm thick Schott B270 optical glass substrate material. Very high surface quality of 60/40 or better (US Military Spec MIL-O-13830). Optical Coating Specifications: multi-layer anti-reflection coated, non-cementing optical substrate coating. Electron-beam gun evaporation with Ion-assisted deposition coating technology for durability and resistance to scratching, as well as stability on CWL (central wavelength) so that there is no deviation due to temperature changes during us

SVBONY SV164 Dark Frame Imaging Filter 1.25-Inch (ABOVE)

Eliminate Camera Noise and Hot Pixels Black SV164. Pesky camera noise can leave distracting bright spots and unwanted fixed patterns on your captured exposures. Dark frame acquisition helps remedy such noise and "hot pixels" by canceling out these disruptive effects during image processing. This handy filter ensures your acquired dark frames will be completely free of unwanted stray light and reflections for great results. Capture dark frames quickly to optimize photo quality. Easily eliminate camera noise and hot pixels. Opaque filter blocks all light from imaging camera sensors. The 1.25" Dark Frame Imaging Filter is threaded for direct attachment to filter wheels.

Svbony 1.25" LRGB Set SV127 (ABOVE)

#15 Deep Yellow

#25 Red, better red filter goes into IR

#58 Green

#80A Medium Blue

Svbony SV183 IR Pass 685nm 1.25" (ABOVE)

Blocks wavelengths below 670nm to enhance contrast and surface detail and reduce the effects of seeing when used in IR-LRGB imaging of the moon and planets. Sufficient reduction of seeing effects; heightened contrast; the Filter can darkens the twilight sky background allowing images of moon and planets to be taken at dawn or dusk. In addition to astronomical uses, the IR-Pass filter can be used for nature photography in the Near-IR; revealing stunning differences in plants; sky and cloud. Atmospheric seeing and distortion diminish as you move further away from visible light into the infrared, and since CCD and CMOS sensors are sensitive to IR light, imaging in the infrared will improve your results.

95% transmission at bandpass. The SVBONY IR Pass 685nm Filter is made with Schott glass that has been multi-coated with an ion-assisted deposition technology to ensure scratch resistance and stability on the central wavelength, or CWL. The filter cell is made of lightweight, strong metal and is CNC machined, sand-blasted, black anodized, and then laser engraved. The result is a super thin filter cell that will produce a clear aperture of 45mm. Tip for use: Ideal for imaging, use for the luminosity channel. The normal spectral bandwidth is 400-700nm. This filter starts at 670nm in the deep red, just in the visual range so it can be focussed correctly. At this long-wavelength spectral range the atmospheric air turbulence (seeing) has much lower impact on the sharpness. Dark structures on Mars, Jupiter the Moon and the Sun are thereby rendered much sharper. The luminosity can then be combined with RGB creating a very sharp LRGB image.

Svbony Set 1.25" (ABOVE)

23A Light Red

56 Green

82A Light Blue

21 Orange

12 Yellow

LOOKING FOR #30 LIGHT MAGENTA

LOOKING FOR #32 MAGENTA

LOOKING FOR 44A light blue green

LOOKING FOR 46 DEEP BLUE

LOOKING FOR 57 MEDIUM GREEN

LOOKING FOR 58 GREEN

LOOKING FOR 64 BLUE-GREEN

Orion Premium Set of 20 Filters (ABOVE)

#8 Light Yellow

#11 Yellow-Green

#12 Yellow

#15 Deep Yellow

#21 Orange

#23A Light Red

#25 Red

#29 Deep Red

#30 Light Magenta

#32 Magenta

#38A Blue

#44A Light Blue-green

#46 Deep Blue

#47 Violet

#56 Light Green

#57 Medium Green

#58 Green

#64 Blue Green

#80A Medium Blue

#82A Pale Blue

1.25" Celestron MOON Neutral Density 18% #94119-A

Typical Percent Transmission

#8 Light Yellow (83%T)

#11 Yellow-Green (40%T)

#12 Deep Yellow (74%T)

#15 Dark Yellow (66%T)

#21 Orange (46%T)

#23A Light Red (25%T)

#25 Red (14%T)

#29 Dark Red (06%T)

#30 Magenta (27%T)

#38 Blue (43%T)

#38A Blue (17%T)

#47 Blue (03%T)

#56 Light Green (53%T)

#58 Green (24%T)

#80A Blue (28%T)

#82A Pale Blue (73%T)

Note: "%T" = %Transmission

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