Wednesday, November 29, 2017

The iOptron ZEQ25 Mount: The Good, The Bad, and the Ugly--An Owner's Review

The ZEQ25 doing its stuff on a cold night--imaging the Orion Nebula with an 8 inch f/4 astrograph. Note the lovely Christmas rug :)
As an astronomer, I made the unwise choice of buying a home surrounded by dense woodland. As a result, my main scope, a 14 inch Meade ACF, is located at my observatory, about 2 miles away. While that’s much more convenient than my old dark sky site, which was 8 miles away, there are times (especially in winter) when I just want to set up an imaging run and return to the warmth of my living room. I also wanted to have a portable imaging system I could take with me on trips to other dark sky locations.

I do have a reasonable slice of sky available through the treetops if I stand in my driveway, so I decided that a small, easily set up and aligned GEM was “just the ticket” as the basis for a grab n’ go/driveway setup.

My first iOptron mount was the Smart EQ Pro. This little, 11-pound mount was a great performer with my Orion ST-80, 125mm Mak and PST-DS. Gotos were “bang on” accurate, and the scope even managed to keep objects on the imaging chip after a meridian flip! The polar scope ensured good alignment, but it was not the most convenient thing to use, requiring a 90 degree axis declination rotation to access the scope, as well as the unlocking and rotation of the RA axis in order to properly align the polar reticle.

When I decided to upgrade my portable imaging capabilities, adding 2 Mallincam scopes—an 8 inch f/4 newt and a 6 inch Ritchey-Chretien—I also needed a new mount to handle the heavier OTAs. As I had had great success with the EQ Pro, I decided to got with another, inexpensive iOptron product—the ZEQ25, which I picked up from Amazon for around $800.

My first impressions were that this was a significantly more massive mount than the EQ Pro, and with the innovative “Z” design, it was unlike any mount I had ever owned.

Setup and assembly were easy. The polar scope was much easier to use than that on the EQPro as it did not require any axis rotation or reticle alignment. I also discovered a really useful iOS/Android app shows exactly how to position the pole star in the reticle for accurate polar alignment. Using this app, I was able to align the scope in 2 minutes with a accuracy that showed no field drift even after several hours of unguided imaging. The tracking and goto performance of the mount was truly excellent—periodic error appeared to be decent—well within the +/- 10 arcseconds claimed by iOptron, and probably closer to 3-5 arcseconds, though I did not precisely measure it. I was surprised and delighted by the mount’s performance.

The Bad: The ZEQ25 supports PEC training, BUT—it can’t be saved, so the mount has to be retrained every time you use it. For most users, this is unlikely to be an issue, especially as PEC is not too bad on this mount. If it is important for your application, I’d suggest an autoguider, which should pretty much solve the problem. In addition, the 32-channel GPS took several minutes (5-10) to lock onto satellites, but this is a minor inconvenience that can be mitigated by powering up the mount before adding the scope and aligning, By the time you’re finished with these tasks, the GPS usually has a lock.

However, any mount is a compromise, and there was one aspect of this mount I found downright ugly.

The mount uses a spring-loaded, meshing system on both axes to minimize backlash. This is a design used in much more expensive mounts. There’s a small, locking “bar” on each axis, and a chrome knob that adjusts the mesh tension. The manual is vague on the settings for mesh tension, but it varies from scope to scope and iOptron advises that worm wear is minimized if you use the lowest tension you can to support tracking.

Here’s where the ugly comes in: if you set the tension too low (especially in RA), the scope may slip back as the mount slews. The result is “camming”—and permanent damage to the worm and ring gear. This damage is not covered by warranty and fixing it can cost several hundred dollars. The user is caught in a “devil and the deep blue sea” scenario: too little tension and you can “cam” the worm; too much, and you risk excessive wear and neither condition is covered under warranty. In my opinion, the manual needs to be “beefed up” to tell users how to avoid this potential damage.
I would advise the following:
  1. Do not move the mount with the axes locked and the gears meshed. At the end of each observing session, with the mount in the zero position, remove the scope and back off the mesh tension by 7 or 8 turns (but do not fully unscrew the knob). Release the axis locking bar. Gently move the axis to ensure it moves smoothly before moving the mount.
  2. When setting up, add the counterweights to the unlocked mount. Add the scope and (this is very important) ensure that it is well-balanced. An unbalanced scope can put strain on the gears and can result in slippage and worm damage.
  3. Screw down the mesh tension knobs all the way. The degree of “backoff” depends on the weight of the scope, but in practice, I’ve found around 2 turns works.
  4. Lock the axis with the locking bar. Very, (and I emphasize, “very”)  gently “rock” the scope to make sure the mount is fully locked. If there is excessive “play” when the mount is locked, contact iOptron or take a look at the excellent ZEQ25 “tuning” videos on YouTube.
Finally, there’s one more “ugly.” The dovetail mounting saddle has a design flaw. On the “knob side,” the adjustment can allow a dovetail to appear to lock when it actually not locked. This problem may have been fixed on newer versions of the mount, but I am not sure on this point. It is important that you visually inspect the dovetail to make sure it is both properly aligned and fully locked. Failure to do so can result in your scope unceremoniously falling out of the dovetail as it slews (especially if the OTA is parallel to the ground).
 
Here's a picture of the front of the saddle:



Here’s my crude sketch of the problem:



The issue is that the two “lips” on the saddle permit unsafe seating of the dovetail. A dovetail secured like this will feel perfectly tight, but if the scope slews parallel to the ground, it will fall out of the saddle. The way to check is to look at the sides of the dovetail from the front to ensure if is seated properly. This step is essential, in my opinion, if you do not modify the mount as follows.

The solution is to use a file to file off the 90-degree angle for the full length of the lips to a 45-degree angle. If you make this easy mod, the dovetail will always slide to it seats and locks in place properly.

Please see this website for a good description of the problem and the fix: https://www.flickr.com/photos/astronewb2011/12245720203/

Conclusion:  Obviously, for $800, you're not going to get an observatory-class mount. What you do get is a mount that performs very well for scopes up to about 8 inches, with accurate gotos and superb tracking. But beware the "uglies" with this mount. A small miscalculation in tension settings could land you with a significant repair bill.

Tuesday, November 28, 2017

Lunar imaging with the Mallincam SkyRaider Solar System 3C

Mallincam's SkyRaider SLP is a passively-cooled, 3 megapixel CMOS color camera designed for imaging the sun and other solar system objects. It is a solid, well-built camera that uses the standard (and excellent) Mallincam Sky software. I had the opportunity to put it though its paces a couple of nights ago and found it to be a very useful addition to my collection of imagers. 

I ran the camera in monochrome mode for lunar imaging. I would estimate the frame rate to be 30-50 FPS--not as fast as I would like, but this was running at full resolution on a USB 2.0 connector.

Here's an image of the Alpine Valley area of the moon from a stack of about 300 frames, stacked and processed in Registax:


The image was taken with a 125mm MAK.

Of course, the capture is not as sharp as it would be with a dedicated monochrome imager, but the results, in terms of detail and tonality, are pretty decent (especially as seeing was definitely sub-par).



Tuesday, November 21, 2017

A Ghostly Companion



Mirach's Ghost is an 11th magnitude galaxy located 7 arc-minutes from the bright (2nd Magnitude) star Mirach. This lenticular galaxy was discovered by William Herschel in 1784. It's proximity in the sky to Mirach makes imaging challenging. In this image you can see it as a fuzzy blob at around the 2 o'clock position. The faint "donut" further to the right is due to internal reflections in the optical train. This image was taken with an ASI 120MM camera on a 6 inch RC scope with .5x focal reduction. It is a stack of 5 x 17-second integrations made in very windy conditions.

Friday, November 17, 2017

DSOs with an inexpensive IMX224-based imager the Mallincam SR AG1.2C



How low can you go? With the advent of easy to mass-produce, high-quality, CMOS-based, highly sensitive, low-noise imagers, prices are dropping daily on very capable imagers. I've been very impressed with what I've read recently about IMX224-based imagers--especially the low read noise of the camera and its ability to handle high gain settings--so I recently acquired a Mallincam SR AG1.2C, an imager that costs less than $300. This tiny imager could probably be carried around on your key ring! But, as a serious imaging too, does it cut the mustard?

As expected, the clouds rolled in the day the imager arrived, so I spent some time building a darks library at different gain and integration settings. These darks tell an interesting story. The AG1.2C is really low noise! Here are a couple of those images:


This is a moderate gain image (gain 20) and a 40-second integration. The image shows very little noise and amp glow--remarkable performance for an uncooled imager!

Performance on darks is one thing, performance in an imaging setting is something else. The night before last offered an opportunity to try the SR AG1.2C, using a 6 inch RC scope and a .5x focal reducer. This combination produced a nice image scale, as you can see from the image of M33 above (it was cropped very slightly at the edges to chop off some stacking artifacts). 

This image is a stack of 10 x 30s integrations at gain 20. Capture was in MallincamSky, with stacking in nebulosity. It is by no means perfect, but I'm quite pleased with the result from such a small and inexpensive imager (image is a jpeg processed to meet size limitations of attachments).
As a reference image-scale, here's a pic of the Bubble Nebula taken with the same setup. This is a stack of 50-second exposures at gain 20 (20 images stacked).

Sunday, October 29, 2017

A Ghost for Halloween


The Ghost of Cassiopeia (IC59 and IC63) is an emission and reflection nebula illuminated by the bright star in this image, Gamma Cassiopeia (also know as Navi). This is a stack of about 100 x 30-second integrations in H-alpha. Scope: ST-80 @ F/4; imager, Mallincam DSm. It was a cold night tonight and this little ghost seemed to be perfectly in the spirit of the upcoming holiday.

Friday, October 20, 2017

Thursday, October 19, 2017

A Celestial Pelican



The Pelican Nebula is part of the much larger North America Nebula. It is an interesting place--a bright, HII emission nebula peppered with evolving stars and gas clouds. Young stars are slowly heating the cold gas of the Pelican, causing a vast ionization front to move outwards in the cloud, with dense filaments of cold gas punctuating the cloud.

Below is an annotated version of the image:


Some of the dark pillars (especially the pillar at the 2 o'clock position), contain Herbig-Haro objects, which are clouds of nebulosity caused by narrow gas jets shooting from new-born stars  Herbig-Haro objects are short-term phenomena, lasting at most a few thousand years as the gas jets move away from the star into the surrounding nebula or interstellar space.

This image was captured in hydrogen alpha light. It is a stack or approximately 20 x 30 second integrations. Imager: Mallincam DSm; telescope Orion ST-80; mount iOptron ZEQ25.

Tuesday, October 17, 2017

Astroimaging is a bit like fishing...




Astroimaging is a bit like fishing--conditions can be great, but sometimes, the fish just don't bite. Last night was just like an unsuccessful fishing trip. The skies were clear and I fired up the big scope. Unfortunately, a lot of the things I wanted to image were in areas of the sky either obscured by trees or the edge of the observatory dome (that's a problem I need to fix). I did manage a couple of shots of the Triangulum Galaxy and the Helix Nebula, but the camera I was using had problems. The images were really noisy and there was lots of false color and amp glow (the purple tinge around the Helix image), to say nothing of the dust bunnies. The Helix is a difficult object to image at the best of times, however). I'm not sure why this happened (bad cable, software issues?) but the pix are pretty crummy. Oh, well--maybe I'll have better luck next time.

Saturday, October 7, 2017

My Observatories--a Brief History

Like most amateur astronomers, I dreamed for years about having my own observatory.  And it remained just that, a dream, until I acquired a Meade 14 inch ACF scope. I’d always wanted a large aperture scope, and I toyed with the idea of a big dob—18” to 20” aperture. But I also loved GOTO scopes and adding those capabilities to a dob added a lot to the price. The (at that time) newly-reengineered OTA and mount for the Meade 14 inch ACF offered large aperture and GOTO performance at a very reasonable price.

I remember the day the scope arrived in very large boxes from a freight delivery truck. I opened the OTA box and was, frankly, terrified by the size and massiveness of the scope. I stored the OTA in my home, with the tripod in the garage. Using it involved having my son help me haul the huge storage box into the driveway and then lifting the massive forks onto the tripod. Fortunately, the scope set up from that point on was fully automated, so once mounted, I was up and running quickly.
But then I decided to start imaging. Adding the ultrawedge to my setup complicated things a lot! I lost the scope’s auto setup capabilities and the extra few inches height the wedge added made it much harder to put the scope on the mount. It was obvious the I had to do something or the scope was likely to spend most clear nights in its storage box.

Enter JMI Wheelie Bars—a real life saver!  With the scope on the Wheelie Bars, I could just roll it out of the garage and within 5 minutes, be aligned and imaging. The only issue was that my home is surrounded by trees—much of the sky and many of the interesting objects are frequently below the tree line. If I was to get the most out the scope, I needed an observatory in a place where I could see more sky.

I toyed with the idea of buying some land out in the county. I was talking to a friend who ran a tree plantation out in the county and he made a very generous offer—could build an observatory on his land! I drove out the plantation and found an ideal site with a huge horizon. Add to this the fact that it was a dark sky site, and it seemed I had found the perfect place!

The only issue—I had a very limited budget to build an observatory.

Then I found an article online on how someone had converted an inexpensive 10’ x 12’ steel shed into a runoff observatory. This offered a perfect solution. I didn’t have much in the way of DIY skills, but I decided to give it a go! I had to build a roof frame for the rolloff, reinforce the walls and add some insulation, but the job wasn't too had, even for my limited skills.

The result was Walnut Ridge Observatory:
Roof frame under construction

Runoff frame installed on castors and anchored

Interior frame complete

Insulation in place

Hardboard walls installed

The Observatory is almost complete

Runoff frame built from treated lumber

The runoff works!

Holes cut in floor for tripod

Desk, scope, and Plaque Installed

The observatory was a great facility. I ran power from a nearby barn and I could be up and running is less than 5 minutes. Add to that a huge horizon and dark skies, and I was in heaven!

For a while…

There were a couple on nagging problems. One was that the observatory was on a plantation. That meant I had to unlock, open and close, and relock large farm gates to get to the site. In addition, it was a 9 mile drive to the plantation, a drive which seemed to get longer every time I made it. The drive back after a long session was not something I looked forward to. I began to dread clear evenings which I hated to waste, but the almost 20-mile round trip was getting to be a challenge. I had a great site, the ability to start observing quickly, but it was complicated by a long drive and farm gates.

It is a truism that the best scope for you is the one you use most and the 14 was at risk of being used only very occasionally.

With that in mind, I started looking for options nearer home.

The runoff shed had worked well—it had withstood near-tornadic and gale-force winds, but I was never able to completely waterproof it—there were small leaks in several places, so the scope had to be covered at all times. Add to this Indiana humidity and there were times the scope was dripping under its cover. I decided another steel shed would not work.

It was then that I discovered a product made by a Canadian company founded and run by a passionate observer who also happened to be a rock musician—Wayne Parker's Skyshed. Although they offered several different designs, including runoffs, I was more interested in the Skyshed POD. Small, expandable, waterproof, and (above all) with a dome (don’t all amateurs, deep in their hearts, really want a dome?), it offered perfection…if the scope would fit.

After a few very helpful conversations with Wayne Parker, the owner of Skyshed, I took delivery of a 5-bay, insulated pod with black bay interiors.
Lots of boxes!
Like the scope, the delivery was mildly terrifying—a collection of huge boxes that completely filled my garage!  The POD is made of thick, playground-style plastic—no need to paint and no problems with termites, rust, etc. Even in the boxes, it looked formidably robust!

And they are BIG boxes!

The first thing I did was to do a rough assembly of the walls in the driveway so see just how well the scope would fit—and it was perfect, even for such a big scope. Not too tight and with a good amount of room for equipment, chairs, etc.

Checking the fit

Then I got my break on a site. My wife worked as a teacher at a local Montessori School and they were highly interested in science and astronomy. I asked them if I could site the observatory there and, in exchange, offer observing nights and outreach programs. They agreed, and the Indiana POD observatory was built in their grounds.  While the horizon and sky conditions were not as good as those at the plantation, they were much better than at my home. I had a decent view of the eastern, southern, and northern sky, but I was blocked to the west by a building. It seemed a good compromise, as other potential locations on the grounds had interfering trees. I also could not get electrical power, but a combination of a Celestron Power Tank and a portable generator solved those problems.

The POD installed!

The build was easy as Skyshed had an excellent video to help assembly. Wayne was also available in real-time whenever I ran into a problem—superb customer support! The POD is watertight, but I added the extra insurance of the POD cover, just in case. The result—even in storm-force winds and driving rain, the observatory stays perfectly dry!

Checking the autoguider computer

An imaging run from the POD

Still looking good after 3 years!

There's lots of room for me, equipment, and the 14 inch, as this pic shows

More importantly, the POD has more usable space than the significantly larger runoff shed.  With the 14 inch in there on its tripod, as you can see, it's very spacious!

Monday, October 2, 2017

H-alpha Cocoon Nebula

I tried some Ha imaging with the 8 inch f/4 scope the other night, but the results were mixed. In Ha light, the Cocoon usually resolves into a number of delicate shells, but tonight's result does not show this structure. There was a slight haze, but I do not think the sky conditions created any problems. I stacked and processed about 24 frames, but the image is a nebulous blob. I will try again on the next clear night.

Thursday, September 28, 2017

The Sun 9.28.17

The sun continues quiet. ARs 2682 and 2683 dominate today's picture, with AR2681 barely visible toward the solar rim. Clouds and trees interrupted today's imaging session, but the final image is not too bad.


Tuesday, September 26, 2017

A Cosmic Wizard

The Wizard Nebula is fiendishly difficult to image, and I have never been able to get more than a fuzzy blob in any image I have attempted. But last night, my luck was in and I was able to take this image with my Mallincam DSm, VRC 6 scope, MFR5-II FR and H-alpha (7nm) filter. This image is a stack of 30 x 35s integrations with very aggressive histogram stretch.  It's not perfect (there are stacking artifacts from slight mount drift), but I'm very pleased with the result. I may try an OIII image of it later.


Monday, September 25, 2017

Dark Sky Bonanza with Mallincam!

I had the opportunity to capture some images from a wonderful dark sky site in southern Indiana--the shores of Lake Patoka.  The skies were amazing, with the Milky Way clearly visible. We were blessed with Mag 6 skies and good seeing. I took the VRC6, ZEQ25, DS16c, and a somewhat indifferent 2 inch focal reducer. As I had lots of people with me, I had to set up quickly and I didn't have time to fully adjust polar alignment or to ensure the best orthogonality of the imaging train--the idea was to just get some quick captures to keep everyone happy. I've posted some of the images to my album (briansxx), and they show just how well this setup works for fast imaging for public outreach. Integrations were between 20 and 30 seconds with x2 binning and gain close to max, with just 2 or 3 frames stacked in the MC software. I took one 30-second dark, which I used for all integrations (the only exception is the image of the Lagoon, which was a single capture with nio darks). I filtered out some of the noise, but the results are quite decent. With binning and a relatively fast scope (VRC6 at about f/4.5), the DS16c really delivers, with very little tweaking needed.