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Dan Lessmann

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Astrophotography MISTAKES!!!

 

The biggest problem with astrophotography is that there are way too many ways to make mistakes as we go along and those mistakes are rarely inexpensive.  Lately the manufacturers don't help much with their advertising.  If you look at just about any manufacturer's ad, you'll see that astrophotography is about as simple as shooting pics of Fluffy the cat using your favorite little point and shoot camera.  No brainer right?  One click Hubble quality masterpieces are just a UPS delivery away!  Nothing could be further from the truth but the manufacturers know that telling the real story would dissuade many from buying their products and they just ain't gonna do that now are they?

 

I too am hesitant to write much about just how difficult and expensive astrophotography can be.  I mean it's a hobby I very much enjoy and I'd like to see you give it a shot as well if you have an interest.  But you ought to know the pitfalls before you invest what will inevitably be thousands of dollars in most likely what will be the wrong equipment... Like I did and like so many others do.  I also am enough of a realist to know that most people can't learn from other people's mistakes.  Nevertheless, I'm going to tell you step by step just what I did wrong and how much it cost me in the optimistic hope that you can learn and avoid these traps.

 

I don't offer this up as a how to guide especially as it's very much oriented more toward how not to!  But if you're interested in a bit more conceptual approach to beginning astrophotography, at least as I've experienced it, I invite you to click here for some pointers.

 

Mistake 1 - Going on the Cheap

 

This mistake goes back before digital astrophotography was truly available to the amateur.  I naively bought an inexpensive Meade reflector on a GOTO German equatorial mount.  I then put together all of the pieces necessary to mount my film SLR to the focuser and was ready to shoot right? 

 

Wrong.  The scope I bought and more importantly, the mount I bought were both woefully inadequate to the task of film astrophotography.  The slightest breeze would put such a wobble on the telescope that the frame was inevitably ruined.  Now keep in mind that I live in Oklahoma, one of the windiest states in the union.  Essentially there is no such thing as a calm night here at least not to the degree that this cheesy mount would require.  But that doesn't matter.  The tracking on this mount is so bad that even on a perfectly still night I could never hope to get a quality exposure at the focal length of the reflector.  I did use this scope for some visual use but essentially this was the first waste of money.  I still own the scope but it never sees the dark of night.  Cost?  About $500.

 

Mistake 2 - Impulse Buy

 

In 2003 there was this little astronomical event that electrified interest in astronomy.  This was of course the 2003 opposition of Mars.  I knew enough to know that to be able to see and photograph this opposition I would need a long focal length scope and also knew that a long focal length scope would be necessary for most deep sky objects I was interested in photographing.  The time frame available for shooting Mars at a point close to opposition was only a couple of months so I got rushed and impulse bought rather than truly researching the options available at the time.  I came to the conclusion that I didn't have time to put together separate pieces to come up with an optimal astrophotography rig and buying an all-in-one package seemed the way to go.  So I purchased a new telescope, a 10" Meade LX200GPS in stock from Astronomics which happens to be down the street from me. 

 

Now don't get me wrong.  I'm not a Meade basher and I don't necessarily consider this purchase to be a mistake.  Nor do I feel Astronomics lead me astray in anyway.  In fact I'd have to say that this scope is a fine piece of equipment when used for its intended purpose.  The optics are quite good and the convenience of GOTO and the automated alignment routines with the GPS version are really nice when in an altitude-azimuth mode as intended.  So for visual use, this is a truly fine piece of equipment that is easy to use and set up.  But my interest was in astrophotography.  In that light, how does a fork mounted, 10" Schmidt-Cassegrain telescope (SCT) stack up?  Not well at all I'm afraid. 

 

Let's start first with the fact already mentioned, fork mounted SCTs are altitude-azimuth mounted.  That's just fine for visual use but it's not going to work for long exposure deep sky astrophotography.  In other words, I'm not done spending money to make what is already an expensive piece of equipment deep sky astrophotography capable.  I'll get to that later.

 

Next, let's accept the fact that these fork mounts, and Celestron's forks would be included as well by the way, are not in any way accurate tracking mounts.  I didn't know that at the time I bought but the information was available had I taken the time to look it up.  I didn't take that time because Mars was getting closer every day.  I was rushed and a scope and mount this expensive just had to be high quality right?  Wrong.  No, not wrong but wrong for astrophotography. 

 

Result?  Take a long focal length, in my case 2,500mm, and slow, f/10, scope and put it on a less than accurate mount and what I've got is a mansion built on a foundation of balsa wood.  Do this yourself and you might notice some disturbing creaks when you walk down the hall... and  you run down the hall at your own peril.

 

Next, my intent was to shoot the Mars opposition with a brand new camera Meade had just released, the Meade LPI.  Perfect right?  Designed specifically for lunar and planetary imaging and with software ready to rock and roll with my new scope and it's only one hundred bucks!  Well Meade had some production problems as is always the case with new products and apparently everyone else in the world had plans to do the same thing.  I wasn't able to get the LPI until three months after opposition and the software was still so buggy that it was basically unusable.

 

Cost?  About $3,500 for the LX200GPS.  Another $100 for the LPI camera.  I never did get those shots of Mars I was after.

 

Mistake 3 - Camera Compromises

 

Okay.  I missed Mars but I've shot some pretty good lunar and planetary stuff using the LPI and it worked quite well after Meade released a few upgrades to correct bugs in its first release of software.  But my goal has always been to shoot long focal length, long exposure, deep sky shots.  The LPI does a fine job on lunar and planetary subjects but anything deep sky is out of its reach. 

 

This got me into deciding what camera to get that would be sensitive enough to capture deep sky objects.  This was some years ago and the offerings available for true astronomical cameras were a bit more limited than they are today.  There were a few comparatively inexpensive offerings, then a big gap in price, and a number of very expensive options.  I wasn't ready to spend thousands on a SBIG camera or something so I settled for a SAC 8-II as a compromise.  The SAC 8-II is a small, 640x480 resolution monochrome camera that is kind of hacked together from webcam architecture.  That sounds like it's a cheaply built solution and that's not fair.  At the time, it was quite a good low end solution to the problem of deep sky work but it was low end and to a large extent you get what you pay for.  I wasn't ready to invest in a high end camera at the time but would probably do things differently if I had the chance to do it over.

 

The camera itself was okay albeit low resolution but the drivers and software to run it were in my opinion anyway a bit of a joke and extremely problematic.  I didn't know this going in and again, the info was available had I done the research.  Add to that a couple of other points that were also available to me at the time.  Meade was in development on the first production Deep Sky Imager, a small chip color camera and I always had the option of using what was then a new Canon 20D that I had purchased for daylight photography.  That would have doubled up the usefulness of what was already a comparatively expensive camera and this is actually where I ended up.

 

I knew it was possible to mount the 20D to my telescope but assumed that it wouldn't be sensitive enough to shoot deep sky.  I mean it has a CMOS chip albeit larger than the LPI's CMOS but I had learned by then that CCD chips were more sensitive and less noisy than CMOS.  I had also learned that chip cooling was important to keep down noise.  The SAC 8-II has built in thermoelectric cooling so it seemed this was the better way to go.  It may have been if it weren't for the cruddy drivers and operating software and as long as I was ready to settle for the very low resolution.  Now things are still more different.  The advent of so many entry level deep sky cameras in recent years makes my purchase of the SAC a mistake but that's hindsight.  Regardless, it now sits in my shed never used and not really worth much on the resale market.

 

Cost?  $1,500

 

Mistake 4 - Good Money After Bad

 

Problem.  The LX200GPS is an altitude-azimuth mount and you need an equatorial mount to shoot long exposure DSO's.  Solution?  An equatorial wedge.  This was going on at the same time I was considering camera options and here I actually did okay.  I did the research necessary to find that Meade's wedge offerings were not the way to go because they are not stable.  I settled on a Milburn wedge and it truly is a fine piece of equipment.  It took about six months for delivery and when it arrived I was ready to get way out there where those dim fuzzies live right? 

 

Wrong.  All I accomplished was to put some concrete footings under the balsa wood foundation of my mansion.  The balsa wood was still shaky I'm afraid.  The tracking on the LX200GPS fork mount is just not good and periodic error correction will get you only so far.

 

Cost?  About $500 for the Milburn wedge.

 

Mistake 5 - Bad Money After Good

 

Problem.  Periodic error correction can't smooth out the inaccurate tracking of the LX200 mount enough to be able to image at anything close to a 2,500mm focal length.  Answer?  Active guiding.  Given my current equipment this meant I had to have another camera.  That would make one a guide camera and the other an imaging camera.  I also would need a second optical tube to act as a guide scope.  Now consider, had I gone with even a low end SBIG astronomical camera, one with a guide chip built in, I could image and guide through the same scope.  But I hadn't gone to an SBIG camera so I needed another camera and another optical tube.

 

This wasn't so bad actually.  I mean I'd always intended to piggyback a refractor on the SCT for both guiding and for wide field imaging and I also wanted a smaller refractor and lighter mount for a nice grab and go portable option.  So...

 

First I bought an Orion 80ED with an SVP mount.  This was not a mistake.  The 80ED is without a doubt the best bang for the buck I've enjoyed and it's a fine little scope.  The SVP mount... well it's not GOTO and certainly it's not accurate enough for astrophotography but I knew that going in.  It was to be that grab and go visual only mount and it's perfectly adequate for that.  But... right after my purchase of the SVP mount with the Orion, Meade dumped a bunch of refurbished LXD55 mounts onto the market to clean up inventory as they introduced the LXD75.  The LXD55 is a lightweight, GOTO mount with guiding capability meaning it could, theoretically at least be used for astrophotography.  The price was low enough that this was somewhat a gimme and I picked one up.  This eliminated the need for the SVP mount and I sold it to a friend along with the cheesy tripod that came with the LXD55 keeping the steel tube Orion tripod.  That worked out okay or would have but...

 

The LXD55 wasn't about to be accurate enough for astrophotography.  It too is not a precision mount.  I worked it over and improved it and it's fine for a grab and go mount and can even handle truly wide field astrophotography using a camera and short lens but it will never be capable of carrying the 80ED for astrophotography.  Money wasted?  Certainly the cost of the SVP mount was a waste given that Meade happened to toss a bunch of LXD55's out at bargain prices but I had no way to predict that.  I'd say this purchase was okay... but only okay.  I was still compromising excessively on equipment with no truly accurate tracking capable mount.

 

Cost?  About $1,000 for the Orion 80ED (The OTA alone is around $500 so call $500 wasted).  About $750 for the refurbished LXD55.

 

Mistake 6 - More Bad Money After Good

 

Next step.  Remember what I was after was some active guiding capability for the big SCT.  This requires that the guide scope (the 80ED) be piggybacked on the SCT.  So I purchased a less than optimal but inexpensive piggyback rail kit.  It worked after a fashion but there was too much flexure in the rails to get good results or so I found out later.  That was a waste of money and there's a reason why quality rail and ring systems are so expensive.  They have to be to get the stiffness required.

 

Next step.  I needed a guide camera.  By this time I had determined that I could image with the Canon 20D for a lot of objects I was interested in so I needed to use either the LPI or the SAC for guiding.  The LPI should have been a capable guider using Meade's software but it's not very sensitive and it was often difficult to find guide stars bright enough for the camera to pick up among the noise. 

 

The SAC, while plenty sensitive as a guide camera didn't have a good guiding software solution.  I tried Guide Dog, which should have worked but didn't and the LPI guiding, even when there was a bright star in the field also didn't work well.  For both, the guiding kept pushing the mount all over the place until finally the guide star would drop out of the field of view of these small chip cameras usually with the scope still slewing at a dangerous rate.

 

About this same time, Meade released the DSI, the first one which was a color camera.   This seemed the answer to my prayers.  Here was a one shot color camera that was sensitive enough to use as a guide camera and it was color meaning I could image with it as well without having to mess with LRGB composites.  Perfect! 

 

Not so perfect.  Here I was back with a brand new product and brand new "improved" software.  The software was buggy (Didn't I run into that with the LPI?) and guiding was at best hit and miss.  I ran into the same sort of problems I had with the LPI and with the SAC using Guide Dog.  The guiding would, more often than not, push the scope all over the place.  I tried this using the LXD55 mount as well.  Same problem.  The guiding would just go nutz!

 

Now I want to make a few points here that you may not know and I didn't see.  All three cameras, the LPI, the SAC and the DSI, all guide by sending guide correction signals through a laptop serial port to the mount.  There is a dedicated autoguider port on the mount but it can't be used with these cameras.  Instead, the camera shoots an image then the software on the laptop picks up the image and compares it with a previous frame and sends the appropriate correction commands to the mount.  Further, for all three cameras, I knew of people that were guiding successfully using LX200 and LXD55 mounts exactly like mine and with the same software applications.  Hmm...  I'm still not active guiding successfully.

 

Cost?  About $300 for the DSI.  Another $250 for the substandard piggyback rails and rings.

 

Mistake 7 - More Good Money After Bad

 

I consider myself an expert problem solver as that's what I do for a living.  I know very well how to diagnose and remedy problems and know that it's a process of elimination to determine the true cause of the problem.  Now consider:

 

1.  People who have the same mounts I have are successfully guiding those mounts with...

2.  The same cameras I've got...

3.  And with the same software I've got.

 

Deductive logic tells us then that the problem is not the mounts, the cameras or the software.  What's left?  The laptop of course.  Well, my deductive logic circuits were apparently not functional.  It turns out that the problem with guiding with these cameras and software was due to serial communications latency between the laptop and the mount.  Solution?  One of two options, eliminate the laptop in the signal loop or buy a new laptop that may or may not have the same problem.

 

My choice was to eliminate the laptop from the signal loop.  The only way to do that was to acquire a guide camera that would communicate directly through the autoguider port of the mount.  There are a few options for this but I was in surrender mode and went with what I knew would work... SBIG, the recognized hands down leader in astronomical cameras.  I chose the ST-402ME and it was, I am pleased to say, an exceptional choice.  Suddenly auto guiding was working and there were no problems with software!  Everything just worked and that was a very pleasant result after all of my previous battles!

 

Did this mean I was now able to image long focal length to my heart's content?  Nope.  While this was a marked improvement, the guide camera could not keep up with the incredibly jaggy periodic error present in the LX200 mount.  I was however able to image successfully with the 80ED while using the SCT as the guide scope.  This did open up some deep sky objects to me but consider... Basically what I had at that point is a $3,500 guide scope and mount in the LX200 mount and SCT that allowed me to guide just well enough to successfully image through the $500 80ED refractor!

 

My primary problem was the same as it always had been; the balsa wood foundation of my mount!  Through all of these efforts the one recurring problem that keeps cropping up is the substandard tracking available from the LX200 and I had yet to truly address that problem.

 

Cost?  About $1,500 for the SBIG ST-402ME.

 

Solution!

 

Finally I addressed the true problem of the balsa wood foundation inherent in the LX200 mount's poor tracking.  I purchased a used Astro-Physics AP-1200 mount plus additional components necessary to mount the SCT and 80ED to that mount.  Tracking is now very accurate and guiding is even more accurate.  I am now able to track and guide accurately enough to image long focal length through the SCT.  The equipment necessary to do this:

 

10" SCT  - $1,500

Orion 80ED - $500

Canon 20D or 350D - $1,500

SBIG ST402 - $1,500

AP-1200 Mount and Accessories - $9,400

 

Total:  $14,400

 

This combination of equipment makes for a very capable deep sky imaging rig for both wide field and narrow field subjects.  It's not a small chunk of change certainly but given what I know now, and especially knowing the accuracies required for long focal length deep sky, it's not unreasonable.

 

Equipment I've purchased but do not need and in fact cannot use for deep sky astrophotography:

 

Meade Reflector - $500

LX200 Mount - $2,000 (Mount less SCT cost)

LXD55 Mount - $750 (Still useful for a grab and go mount)

Milburn Wedge - $500

Orion SVP Mount - $500

SAC 8-II - $1,500

Meade DSI - $300

Meade LPI - $100  (Still useful for lunar and planetary work)

Substandard Piggyback Rails - $250

 

Total:  $6,400

 

And I never did get that shot of Mars I was after!

 

A Few Points...

 

Please note, of the amount of money spent in the equipment actually necessary and that produces the results I was after from the beginning, how much of that money is in the mount.  That's as it should be.  In your own efforts, please, please, please start with the mount and make it a quality equatorial mount.  Anything less and you'll be disappointed and frustrated as building a house on a shaky foundation will never work no matter how nice the house.

 

Note how much money was spent attempting to remedy this one inherent flaw in my equipment selection.  This over the long term won't be a total loss as I'll be able to sell some of these items but it obviously would have been better to do this right in the first place.  If I were able to start over, I would purchase a smaller, lower capacity mount from AP or Losmandy and I would put an Orion 80ED on it to begin with.  To that I would add a used SBIG ST8 or perhaps an ST10 with an incorporated guide chip.  This would allow for wide field imaging of very high quality without all of the frustration of fighting an inadequate mount or initially dealing with the complications of second cameras and guide scopes.  I would then look at upgrading the mount to an AP-900 or perhaps an AP-1200 with a larger and longer scope for narrow field imaging as my budgets allowed and my interest grew.

 

Compromises are inevitable based on budgets as well as a wise and cautious attitude avoiding spending a big bundle before you know you're truly going to get hooked by the hobby.  But shooting yourself in the foot with an inadequate mount will most likely quash any enthusiasm you have for the hobby so don't do it.

 

I hope you can learn from the mistakes I made! Astrophotography is difficult enough even when everything works well.  You can compromise on the scope and get by.  If needs be you can compromise on your initial camera but don't compromise on the mount if you truly want to pursue astrophotography.  The mount is the foundation on which everything else is built.

 

Good luck!

 

--Dan Lessmann

 

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Last Updated: 11/12/2014  -  Copyright 2004-2013 by Dan Lessmann.  All rights reserved.  Please click here for my usage policy.