Things have changed a lot since the last time that I ran Focusmax. Among other things, I have built up a whole new astro-PC, and I never really understood FM well enough to just make it work out of the box, so I was essentially starting from scratch last night.

It was a gorgeous evening, dark sky because the moon is 3 days past full, and clear as a bell until midnight. I’ll get to that later.

I had characterized my focuser before sunset, so I knew that Pumpkin was near focus, and that the ends of the focus run were set properly.

As an aside, I also discovered “Configurations” in MaxIM. Very cool. It remembers which cameras, which exposure type, etc. were up so you can swap from “guider only = PEC” to “main cam only = Focusmax” to “main/guider = DSO”… nifty!

So I needed to set several parameters very carefully in Focusmax. I figured out several of them, but it took hours, and a lot of experimentation.

Here is how the night went.

I tried a “first light wizard”, which is supposed to “characterize” the focuser. The problem was, I couldn’t get it to stop scrolling out. It kept defocusing the star more and more until either the star was too big for the subframe, or the star was too dim for FM to detect.

I learned some things.

First, a 100×100 box is more than large enough for FM to work with a fairly out-of-focus star (anything that’s less than 1500 steps out of focus should fit, on Pumpkin). 50×50 is actually a pretty good size; it keeps “double stars” from creeping in, but you have to have the focuser in a pretty thin band of focus (within about +/- 500 steps), or you end up doing a lot of “it’s out of the box, increasing the size” stuff at the ends of the V-curves. Works, just twice or 3x slower.

You want to set a exposure length that is long enough to get a hit even when you’re at max defocus. I started with 3sec, went to 5sec and then 8sec. I think that 4 or 5 is probably the right answer now that I can restrict FM to the area near focus. Maybe lower, but again, you run into “can’t find a star, increasing exposure time” stuff, which just eats time.

I never got a first-light to complete. The “characterization” of the focuser never finished, because FM ran the star until it was bloated beyond belief and kept going until it lost the star. Here’s what I think was happening. According to something I read on the ‘net, there is a “max increment” or something like that, it’s in the focuser driver settings. I always thought this had to do with the “jog” function; ie “don’t jog more than ‘max increment’ in one go”. Something to do with overheating the motor or some such. I am now led to believe that this is “how many steps out of focus will FM go during the first light run”. So I need to change this from 10,000 (current setting; focuser never jogs more than 3500 anyway) down to about 1,500 or so. That might get the first light wizard going.

OK. So. I never got First Light working, so I just decided to force a V-curve. I did the “set the beginning, set the end, set the step size” type first, got a so-so curve, then swapped to the “set the middle, set the half-width, set the # of steps” type and ran off 3 good V-curves. With these 3 curves alone, the differential thingy (PI?) is at 26 (steps?) or so, about 50µm apart. Doing a quick calculation of focus tolerance:

Focus tolerance (depth of field) = 2 * f * d
where f is the f-ratio of the scope and d is the Airy Disk diameter, which is:
d = 2.44 * lambda * f
where 2.44 is a constant (why), lambda is the wavelength of light (bluer light has less tolerance than redder, so Ha at 656nm is easier than “white light”, which peaks near 555nm), and f is again the f-ratio.

Focus tolerance for Pumpkin in “white” (really “green”) light is 63µm. Veronica is about the same, 65µm.

So 26 steps (I already calculated the focuser to be doing ~2µm steps) is enough to hit the focus band, but getting it a little more dialed in would make me feel better. More V-curves next time out.

Now that I kind of understand what I’m doing, I need to start running lots and lots of V-curves. I’ll need curves for every setup; Each combination of scope, camera, and filter needs work. At some point, I will be able to figure out how much offset to use when the Ha filter is in; that will save time. But there is a lot of work ahead on Focusmax.

For Pumpkin, with the IDAS LPS and no Ha filter, I used exposure time of 8s, bounding box of 100, half width of 500, and step size of 25 (for 40 steps on the curves), and had pretty good success.

That’s a good starting point for V-curves for future scopes. I can crank it down to 3-5s exposures once I’m comfortable with the focuser.

I played around with different star fields. The area near M44 (but not the cluster itself; too many stars) is pretty rich with medium-brightness stars that FM seems to like.

I had to shut things down when the scope hit its safety limit and the clouds rolled in, both within a few minutes of each other, near midnight.

ASCOM driver: EasyFocus
Min steps: 0
Max steps: 30000
Speed: 250/Full

Pumpkin + 300d + FF/FR + no Ha + IDAS LPS = position 23456

Clear Sky Clock said it would be cloudy all night, so of course it stayed 90% clear until about midnight, when it socked in. But I’m getting ahead of myself…

I decided to get the autoguider up and running tonight. I wanted everything focused and aligned so that I can get started shooting again for real.

On top of this desire, my new clip-in Ha filter showed up today, and I really wanted to try it out!

So I hooked up the autoguider, got it all focused and balanced the rig. I booted up the scope, which wanted to cold-start again. No problem. Quick slew to Betelgeuse… and that’s where the problems started.

For some reason, the main scope and its finder (which were aligned as recently as 2 days ago, and have not been touched) are no longer in alignment. No problem; I see the star in the finder, I’ll just sweep the scope around until I find it.

No dice.

I don’t know what my problem was, but I tried everything I could think of, including sweeping the scope by hand, and I could not find *anything*. It took me 40 minutes to finally stumble over Rigel and then get the finder and scope aligned. While that was in the vicinity, I set up the guide scope to be roughly aligned, too.

As part of this fun, I figured out that the reticle is not centered in the guiding eyepiece. Again. That is a silly feature. But I figured out how to get it centered, so now the guide finder, guide scope, and reticle eyepiece all agree about the center of the field. Which is nice.

So after losing about 45 minutes of clear sky, I got the scope turned on and started an alignment run… the deep cycle battery died. argh. OK, set up the 15v power supply — deal with the battery later. Now I’m working the alignment (oh, I had mis-calculated GMT earlier in the evening, too — I was having a bit of a day), and the polar alignment is way off compared to a few days ago. Pulled out the polar alignment scope illuminator, and it’s got a busted power cable. Again. That is the worst design ever. I decided to just go forward with it; I’ll deal with polar alignment later. I need to be using my Gizmo anyway. Where is that thing? hmm…

OK, so I’m aligned. I boot up the computer, and shoot a test image of Betelgeuse through the Ha filter. It is of course not in focus. No problem. Fire up FocusMax (nothing can go wrong with the focuser — it’s on COM1), and …

all of the FocusMax windows show up offscreen. I have no idea why. I even tried to Regedit them into place; no dice. Meanwhile, tick, tick, tick, clear sky still, but I can see clouds moving in. Also, Orion is now well past meridian. grr!

Fine. I fire up the focuser in MaxIM (I tried to get the ST-4 and mount working in MaxIM, too, but needed to reinstall the USB-to-Serial drivers for reasons passing understanding, and never got that working right — you guessed it, deal with it later), did an autofocus run in MaxIM for the first time ever.

Let me say at this point that I really like the new MaxIM focus routine. It brings up a V-curve just like FocusMax, and while it seems to converge on a solution a little more slowly, it does seem to get there pretty well, as evidenced by the fact that in just a few minutes, I had autofocused the Ha filter on Betelgeuse! (FWHM of ~5.5, high winds and encroaching clouds and sketchy collimation, so give me a break, this is about what I usually get)

So I fired a 40sec exposure of Betelgeuse, so I could see some diffraction spikes, and got a bright fuzzy ball with lots of stars in the background. I looked up, and couldn’t even see the star through the cloud cover. OK, I get it. So I slewed over to M42 anyway, because I was going to make sure I was in focus.

A couple of 40sec and then 2min frames of M42 looked pretty good given they were clearly destroyed by clouds.

I tried to set up the ST-4, but it spent a lot of time losing the star and giving me “E E” followed by “-E -E” type corrections, so I turned it off. I only like guiding in MaxIM if I can help it.

At this point, it was about midnight, and we get to where I started this post… socked in solid with clouds, and no images to show for it.

And a longer todo list.

But a few more things are set up again, including of all things, the autofocus routine in MaxIM! Cool.

Fingers crossed for a clear night this weekend. Next one won’t be wasted.

I had moved the ST-4 to the main scope to do some periodic error testing on the mount at higher magnification. This helped me to see the errors more clearly, but also left me unable to do any DSO photography.

Also, I hadn’t rebalanced the mount since swapping in the 3/8-to-1/4 adapter, and I hadn’t rebuilt the pointing model since tweaking the polar alignment.

So I decided to do some maintenance tonight so that I can get some photography in before the moon is bright again.

While the D70 was off the mount, I popped the MPCC onto it. This required refocusing the scope, which meant some head-scratching with FocusMax before I got a good V-curve. That took over an hour. grr.

I hooked up the power cable and the shutter cable to the 300D (they run in the opposite direction from the rest of the cables, which makes things a little odd, but DSLRFocus wouldn’t find the camera. Took me a couple of minutes to figure out that I forgot to hook up the USB (image download) cable, too; I need a USB extension cable (and a free USB port — yikes). I used the parallel shutter release cable — I was worried that the 300D DSUSB would conflict with the D70 DSUSB, plus I’m out of free USB ports. At the moment, I’m using 4 USB ports + RS232 port + parallel port. That all works with the docking station so that I can just pull the laptop whenever I want. Adding the image download cable too will mean that I have to remember to unplug each time (or I need to use a USB hub).

I tabled the idea of using the 300D until I get it all hooked up. But it was good to try to start it up so that I can see what I’m working with.

Building the pointing model went fast; I’m pretty good at it. There are a very skimpy number of bright stars overhead right now. I pointed at every one I could, and only got 6 or 7. The polar alignment is improved in Az: 13′ -> 7′. El is about the same, 5′. Polar alignment is a very iterative process.

The new model put M57 (my target for the night) smack dab in the middle of the D70’s sensor (so close to the center, in fact, that the image-tweaking thumbnail in MaxIM bracketed the object — nice!).

Finding a guidestar and calibrating went easily tonight.

Because the focusing run took so long, I ended up grabbing an hour of data on M57 yet didn’t get to bed until 2am. ouch.

The rig is ready to roll now, though, with the exception of the 300D USB cable and the still-misaligned polar alignment.

I’ve decided to leave PE concerns for another day and concentrate on imaging. The autoguider is able to keep up with the errors at 2350mm, so I’m going to spend less time worrying about it.

Once I get the source of noise in the mount figured out (might be a faulty motor), I think the PE in the system is really low.

I finally knuckled under and bought a Moonlite CF focuser for Pumpkin. With the motor and the extra flanges (more on this in a sec), it’s a $425 focuser for a $300 telescope, but *man* I like the feel of Moonlite’s gear! It’s just solid, and it has all the bits and parts that I need (rotateable, finder mount, 1/4-20 mount).

I had to jump through a few hoops to get the focuser to work. When I bought it, it came without a flange, so I ordered that. Then, when the flange turned up, the focuser was too low-profile to work, so I needed to order a thicker flange. Now it’s got an extra piece in there that most won’t have, but it works great. Everything from 2” diagonals to the D70 come to focus. The scope weighs an extra half pound or more, but it’s totally worth it. Autofocus will really turn Pumpkin into a worthy imaging scope.

Here’s Pumpkin all set up for bird photography, with the Nikon and a photo tripod:

Normally, it would be mounted in the guidescope rings, but I had mounted up on a tripod so I could confirm that the D70, a 2” diagonal, and a 1.25” diagonal would all come to focus (they do).

What a handsome new addition to the rig.

I finally got around to taking a photo of the RoboFocus installation on the new C9.25. Because the back of the scope isn’t flat, the installation was a bit of a challenge; I had to install the focus knob gear upside-down, and the belt still isn’t flat. Works OK, but it could use a different bracket.

Here’s a detail of the upside-down piece:

And here’s the “working end” of the scope:

Looks pretty sharp. I just have to wait for the clouds to clear out before I can really give it a test drive.

All the new gear that I’ve picked up in the past few weeks has really given the astronomy gods a chance to send more rain to CA. We need the rain, but I could use a clear night or two, too.

This was one of Those Nights. Everything went wrong.

It started with killing power supplies. I am trying to get a reading of the amperage coming out of the mount, which will hopefully tell me if my worm gear is properly adjusted. But every time I hook up the Fluke to the power supply, the power supply shuts off. After much head scratching and testing, it turns out that I have something wrong with my Fluke. I’ll get it serviced (or a new one). So I can’t check the amperage on the mount.

On the other hand, the mount’s Voltage looks fine. It only drops 0.02 volt between idling at sidereal and full-on slew in both axes. Nifty. I don’t know if that’s a testament to the mount or to the power supply, though.

What was really going on is that I have a brand new scope that I’m trying to get in service. I’ve had the C9.25 for a few weeks now, but I’ve only just gotten all the extra parts that are needed to integrate it into my setup (in particular, I needed a top rail for the guidescope and I also needed a gear for the motor focuser).

So, once I gave up on checking the mount amperage, I had to focus the camera on the new scope. That took forever (RoboFocus is not fast without software, and I hadn’t hooked up the computer yet). I’m used to being able to just push the drawtube to get it close, but I can’t with the C9.25 — it’s an SCT, and the focuser doesn’t have a drawtube.

Then I had to get the finder lined up, also took longer than I was expecting.

Once the main scope was all ready to roll, I (prematurely, as it turned out) started getting set up to image.

I pointed over to M51. It’s a nice easy target, “let’s see what this 2350mm can do” I said.

So I start looking for a guide star and can’t tell if the guider is focused, so I have to go refocus that (which involves leaving M51 and pointing to a bright star and doing that whole mess, which I should have done before I slewed to M51 in the first place…), and get the guidescope and its finder all synched up, too.

OK, back to M51, again. The GOTOs are not dead-on at the moment (higher magnification, plus I’ve been messing with the mount and probably have a shaky pointing model — another thing for the todo list). So I spend a little time recentering; have to figure out which buttons move the object in which directions (it’s upside-down and backwards from the Newtonian).

Once I get M51 centered in the main scope, I point the guidescope to a guidestar and try to calibrate.

But the stupid mount won’t calibrate! I tried everything I could think of (throw it into Visual mode, aggro = 10, etc) and I finally give up and decide that the guidestar is too bright. So go find a dimmer guidestar (have I mentioned how bad my skies are? I can barely see mag 3 stars in the finder). Once I did that, everything is fine, the mount calibrated.

OK, deep breath. Last couple of things and I can start imaging.

So I go to turn off the Visual mode…

AND PRESS DEC- BY MISTAKE. GRRRRRRR!

So now I have to recenter the object (a few 10sec shots on the main cam) and reclibrate the guider. I get that all done, I start up the guiding, and for some reason it’s just hating guiding in Dec. I don’t know what is up. Dec errors are in the 15” range (normally I expect <2”) and steady.

So I try turning off Dec guiding; if the mount is properly polar-aligned, all Dec errors should be related to seeing, and since seeing is random, they should average themselves out.

WRONG. I got a huge Dec drift when I turned it off. Ouch. We’re back to polar alignment problems again (a problem that has been plaguing me for over a year now). Sigh. So, Dec back on, bump up the aggressiveness a bit to keep it in line, and we’re off and imaging.

I have the laptop in the observatory on a docking station so that I can use it with a screen if I have to, but during an imaging run, I keep it closed and use VNC to see what’s going on.

I have a new Mac (long story) and haven’t tried using Mac VNC to connect to the PC yet, so I try it…
Totally screws things up. Screwed it up so bad I had to shut down VNC Server and restart it on the PC. Even after that, I still can’t connect from the mac. I gave up and connected from an Ubuntu laptop.

At this point, it’s 10:30 and I’ve wasted basically the whole evening sorting out bugs.

And even after all that, for the first 15 minutes or so, the guider was still settling in , so the first 3 or so photos were unusable because of trailed stars (a result of guiding errors).

And then everything started guiding fine for the last 8 shots or so, which is nice. I would have shot for longer, but it was well past midnight at this point, so I shut down for the night.

Essentially, I was just doing autoguider/periodic error testing last night, so I wasn’t really expecting a great result.
However, the output photo is just tragic; M51 is escaping out of one edge of the frame, because between recentering and the initial guiding errors, the scope had drifted a *long* way.

What a night. Hopefully I’ve gotten most of the bugs out of the new setup and I’ll be able to just go out and image this weekend.

This is the second clear night I’ve had since Valentine’s Day. It was clear all night, but obviously it wasn’t really a night for deep sky photography.

I used the time to get Focusmax autofocusing working. I ran off 12 V-curves, and decided to take a shot of the moon while I was at it.

It’s so cute when I use my a highly-tuned astrograph with an eyepiece of all things.

Actually, I’m just lazy. Because I haven’t really figured out the whole motor focuser thing, I fear removing the camera, because then I’ll never get it focused right again, and I’ll be back to an evening of shooting photos of Sirius and checking out the diffraction spikes.

I have 5 eyepieces: 32mm Plossl, 10mm Plossl, 9mm reticle (Plossl), and 2 University Optics Orthos, a 7mm and a 5mm. The 5mm works really well as a “Barlowed” 10mm. If I’d spend the time to train my eyes to see astro-detail, I’m sure I’d enjoy using this set.

As it is, on a given night, I might use the 32mm to figure out where the heck that unfocused star is, then center the unfocused star with the reticle, then my use for eyepieces is done. I don’t think any of the glass has eyecups anymore, and all of it is in dire need of cleaning, since I don’t spend much time making sure they stay free of dust, either. sigh.

I feel a little embarrassed when I’m doing visual. Like I’m using my Ferrari to go pick up groceries.

I do need to get back into planetary photography, though. Saturn is about to become a pain in the ass to photograph. I refuse to shoot Jupiter while it’s down in the muck. It’ll be a couple more years before it becomes a good Fall target again.

Plus I don’t know where the webcam focuses, so I need to figure out whether I can just use a parfocalizing ring to bring it to focus. I am going to order a 3/4” drawtube from Moonlite. I shouldn’t need more focus travel than that, and it will hopefully cut down on vignetting.

1) rack focuser all the way in, set this to 30,000 (pos1)
2) drive focuser out until it stops, see what FM says the focuser pos is
(pos2)
3) set one end to 0 and the other end to pos1-pos2

4) set max increment to same as step size in FM (100)

see the LazyFocus manual