Raw Astrophotography Data
Nebulae | Open Clusters | Globular Clusters | Galaxies

Astrophotography Equipment

Orion 8" F/3.9 Newtonian Astrograph

Celestron CGEM Mount

Nikon D300 DSLR

Baader Rowe Coma Corrector

Orion StarShoot AutoGuider + ShortTube 80 Refractor

Baader Light Pollution Filters

Orion 8 inch F/3.9 Newtonian Astrograph + Celestron CGEM Mount
Orion 8" F/3.9 Newtonian Astrograph

So far all of the images I have posted on this site were taken with my 8” Orion Newtonian Astrograph. It is a fast scope which is a big advantage when it comes to imaging deep sky objects. At a focal ratio of F/3.9 I can take shorter exposures, and take more of them. This telescope is specifically made for imaging and has a number of features which most standard Newtonians lack.

One major concern when using a Newtonian for imaging is back focus. Before I had this telescope, I owned a 10” Celestron Newtonian. It made a great scope for observing; however, when I tried to use it for astrophotography there was a serious problem. The camera could not reach focus. The Orion 8” Newtonian is designed to give extra back focus, and I can easily bring my camera to focus with room to spare. Despite this large improvement I am still limited by the back focus problem. For instance, I cannot bring my scope to focus when using the Baader Off-Axis Guider.

Along with mitigating the back focus issues inherent with all Newtonians, Orion provides some other features which enhance the scope’s use for astrophotography. To reduce the effects of stray light and increase contrast, the tube extends past the secondary mirror like a dew shield. The telescope also has internal baffles which further reduce the effects of stray light and increase contrast. Another aspect which is critical to imaging is focus. To help with that Orion includes a dual speed Crawford focuser which I think works well. There are some issues I have had with it losing focus when I tighten the locking screw, and with stray light getting in. To fix this I put one of my sister’s hairbands around the focuser tube and slid it up to cover where the light was getting in. Other than that the focuser does a great job, and allows for precise adjustment of focus.

Orion 8" F/3.9 Newtonian

Despite being a great scope out of the box there are a few enhancements I have made. The faster you make a newtonian the more precise collimation must be. This being such a fast scope, collimation is critical. Out of the box the secondary mirror can be adjusted using an Allen wrench, but I think this is a bit of a pain. I replaced the secondary adjustment screws with some Bob’s Knobs thumb screws. This makes the Job of collimation much easier. Another problem I had was that in a Newtonian both mirrors are exposed to the outside air and dew becomes a major concern. To solve this I ordered a primary mirror heater, a secondary mirror split heater, and a dew controller from Kendrick Astro Systems. Since I installed the heaters I have not had any problems with dew.

Orion 8" f/3.9 Newtonian Astrograph Reflector Telescope

Kendric Astro Instruments

Bob's Knobs

Baffling in the Orion 8" F/3.9 Newtonian
Celestron CGEM Mount

I have my telescope mounted on top of a Celestron CGEM mount. The mount if often considered to be the most important component of any astrophotography setup. This is because it is responsible for moving the telescope to track objects as the earth rotates, and responding to minute corrections from auto guiding. If the tracking is off by a little bit the stars in the image lose their roundness, and the picture is ruined. If too much weight is put on a mount then the tracking tends to suffer. It is recommended that you only load a mount with half its maximum weight capacity for astrophotography. Getting the mount to guide well is likely one of the hardest parts of astrophotography.

My first mount was a Celestron CG-5 which did a fine job for observing, but was a complete failure when for astrophotography. The RA axis on the CG-5 responded well to the autoguider but the DEC axis was a disaster. Every couple of minutes the guiding software would lose the star, and I would have to restart the guiding. In the end I sold the CG-5 and picked up a Celestron CGEM. The CGEM mount turned out to be a big improvement over the CG-5. It was capable of carrying my entire load of equipment and guiding accurately.

There are a few tricks I’ve found to increase the accuracy of the guiding. My CGEM never has any problems in the RA axis, but the DEC axis, if not balanced correctly (or I should say if balanced too correctly), can behave strangely. I’ve noticed that leaving the DEC axis back heavy often helps it track better. I think this is because the bias in the weight takes up the backlash, and keeps tension on the gears. This allows the axis to better respond to guiding pulses.

One particular feature I find very useful on Celestron mounts is the All Star Polar Alignment. This allows me to get away with only roughly aligning my mount to Polaris when I am first setting up. After I do a two star alignment, and add a calibration star, the mount tells me exactly how far off from the true celestial pole I am. Then I can align my mount to another star, and then have it slew to where the star should be if my polar alignment was correct. I have found that this method is far easier than using a polar finder scope or declination drift. It seems to be very accurate and is sufficient for my purposes.

CGEM Computerized Mount

All-Star Polar Alignment

Celestron CGEM
Nikon D300 Modified DSLR

The camera I have used for all of my astrophotography with is the Nikon D300. I use this camera because I had it for daytime photography before I started astrophotography. Many people recommend Cannon cameras for astrophotography due to better software support, and because Cannon makes a modified camera specifically for astrophotography. The problem with most DSLR cameras, which Cannon addresses in their modified cameras, is the UV / IR blocking filter. This filter blocks most of the important hydrogen-alpha (Ha) emission line. Being able to image Ha is very important for imaging emission nebulae. I had Spencer’s Camera modify the filter on my camera to be able to see Ha. Since then I have taken many spectacular images of nebulae. I also had them install their cooling system. It does not actively cool the camera sensor, but it helps it loose heat faster. It’s kind of like a heatsink. I’m not really sure how much of a difference having this cooling system has made.

Spencer's Camera

Nikon D300
Baader Rowe Coma Corrector

With any fast newtonian coma is a significant problem. I use the Baader Rowe Coma Corrector (RCC) which is specifically designed for imaging with fast Newtonians. As far as I can tell it does a great job. I can only notice slightly deformed stars towards the edges of my images. The RCC is also designed to be used with the Baader Off-Axis Guider ,which is why it requires a spacer between the coma corrector and the camera if you are not using the off axis guider. With my setup I need to fully insert both the coma corrector and spacer into the focuser tube in order to reach focus.

Baader Rowe Coma Corrector Comparison
Orion StarShoot AutoGuider + ShortTube 80 Refractor

Although the tracking provided by the mount alone is enough to keep the telescope point at an object, it is not perfect. Even with perfect polar alignment factors such as mechanical imperfections, wind, etc. will cause the telescope to drift slightly and produce noticeable errors in images. The solution to this is guiding. Guiding involves using a secondary telescope attached to the main imaging telescope to track a nearby star. The guiding then should make small adjustments to the tracking so that the star remains still. Although guiding can be done manually, and it was in the past, with modern technology it can be done automatically with a camera and computer. For my guiding I purchased the Orion Awesome AutoGuider Refractor Telescope Package. This includes an 80mm refractor telescope and small CCD camera. The scope is mounted on the back of my main scope, and the CCD is attached to the guide scope. On my laptop I run PHD Guiding which takes pictures from the camera, tracks how far a selected star has moved between quick exposures, and adjusts the mount. I have gotten good results with this setup.

Orion Awesome AutoGuider Refractor Telescope Package

Stark Labs - PHD Guiding

Light Pollution Filters
Baader Moon & Skyglow Filter

I live in a very light polluted area and one of my best tools for fighting light pollution are light pollution filters. There are two filters I use. The first is the Baader Moon and Sky Glow Filter. This is a broadband filter which means it blocks only specific wavelengths of light while letting the rest of the visible spectrum through. Some light pollution sources which emit across the entire spectrum, and some only emit at certain wavelengths. A broadband filter blocks those wavelengths which are particularly problematic. You will also loose the light from the object you are photographing in those parts as well, however, the benefits of outweigh the costs.

Baader UHC Nebula Filter

The next type of filter I have is the Baader UHC Nebula Filter. This is a narrowband filter meaning it only lets a few narrow bands of light through. This would not be beneficial for most objects since it would block most of the light. However, emission nebulae are known to only emit light in specific wavelengths, and it is these nebulae which narrow band filters are designed for. Narrowband filters only let in the light which comes from the nebulae and block everything else. This reduces the effect the light pollution far more than a broadband filter can. The only disadvantage is that a narrowband filter can only be used on emission nebulae.

Please email me your questions, comments, and photos.