Equipment

Cameras

Quantum Scientific Instruments 532ws camera

QHY8 one shot colour camera

SXV Lodestar guide camera

DMK 21AU4 USB

Miscellaneous

Starlight Xpress adaptive optics unit

Astronomic narrow band, CLS and type II LRGB filters. Hutech 2" IDAS filter

Previous Equipment

Celestron Nexstar GPS 8"

Skywatcher ED80

Great Polaris DX

SXV H9F CCD camera

Takahashi FSQ 106

Little needs to be said about the FSQ. It is a modified Petzval design with four lens elements. It provides a true flat field, fully illuminates the largest CCDs and has superb colour correction. It is superbly engineered and feels like it has been hewn from a solid block of granite. I also have the Tak 0.73 reducer which brings the f/l down to around 370mm F3.63.

Takahashi EM200 equatorial mount

I bought this mount new from Nick Hudson at Trutek. The mount can be purchased without goto, with the Temma2 junior or the Temma2. I had planned to get the more expensive Temma2 but Nick happened to have a junior version at £500 less. It slews a little more slowly and might not be quite as accurate I decided I could use the extra cash to buy a Trutek motorised filter wheel. Still, at over £3000 it was, for me, breathtakingly expensive. I needed to sell a Laser sailing dinghy and my GPDX to fund it.

The EM200 works perfectly, tracking is smooth, accurate and very easily guided with typical RMS tracking errors well under 1 arc second. This is straight out of the box with no tweaking. It is mounted on a very substantial mahogony tripod and has a superb polar scope which gets you to within 2 arc minutes of the NCP within 2-3 minutes. It is rated at 16kg which is a true imaging rating. This is a conservative estimate (the Synta clone of the EM200, the EQ6 is rated up to 25kg which would be very optimistic for long focal length work. The electronics are fairly primitive. There is no computer hand set, control of the goto is from a laptop, neither does it have PEC or a park facility but there are some good free drivers available that allow a form of parking.

I have writtin more about my first experiences with the mount here

The scope picutred is a William Optics FLT110 which I had on loan from First Light Optics for review purposes.

10" Meade LX200R

Although I really liked the 8" Celestron Nextar GPS it would have been daft keeping a fork mounted scope having bought the EM200. Also I was looking for a flatter field for larger format cameras such as the QHY 8. The Meade is a bit of a beast, a couple of pounds heavier than a C11. The focuser is pretty hopeless with huge mirror shift so I added a moonlight motorised focuser with a James Lacey PC controller running with Focusmax. Once calibrated this enables effortless focusing.

I have been impressed by the optics of this scope. I collimate it during the daytime using an artificial star. CCDinspector analysis confirms that this achieves very accurate collimation which is held well. The field is flat across a QHY8 chip and fully illuminated. I'm tending to use it with a Celestron 0.63 reducer which works well with my SXV AO unit. Although it is a flattener it is a pretty feeble one and it's effect on the field isn't too detrimental using my QSI.. When not using the AO (lack of guide stars) I plan to use an AP 0.67 plain reducer, I am thinking about getting the off axis guide adaptation for the QSI with this in mind.

This shows the lengthy imaging train hanging off the LX200R (the flange between the focuser and the scope has now been changed to a lower profile version. Below the flange is the Moonlight motorised focuser followed by the SXV adaptive optics unit. The Lodestar guider sticks out at right angles on the far side. After this comes a Gerd Neumann filter draw and finally a QHY8 camera. My more usual arrangement swaps the QHY8 and filter draw for my QSI 532ws

GSO 8" F4 Newtonian

I bought this scope from Bern at Modern Astronomy It is a very fast newtonian which has been tweaked for imaging by using a larger secondary to fully illuminate large CCDs. It is also equiped with a Baader Steeltrack focuser. Coma is dealt with by the Baader MPCC. I have added Bob's Knobs to primary and secondary mirrors and upgraded the primary springs. The coma corrector turns it into a budget astrograph with a very useful mid range focal length. Unfortunately my imaging experiences to date have been thwarted by poor conditions or dew on the secondary. I hope to get some more use from the scope when my observatory is completed

William Optics ZS66 doublet

This is a lovely little scope with beautiful fit and finish. Nice features include a high quality dual speed rotatable focusser and a nicely graduated draw tube. The dew shield is retractable which makes it pack away into a tiny little hard case. Although people talk of it as being a great grab and go scope I've found it's small aperture limits it to pretty bright, large targets. It gives excellent colour free views of the moon. However it is really as an imaging scope that it comes into it's own. It is no weight for a small mount. with a focal length of around 400mm it frames larger targets well and the quality focusser makes it a joy to use. The combination of AP 0.67 reducer and the small pixelled SXV H9 is superb. Targets such as M31, M45 and the Rosette are fully framed. You can take in M42, 43 and the Running Man in one widefield frame and the image scale for the Horsehead and Flame provides a breathtaking panorama.
The scope is also a great little guider of course.

12" Skyliner Dobsonian

My favourite telescope! Once my imaging session is up and running this is the scope I turn to. Also, if there is a break in the clouds I can get this out of the shed and be enjoying great viewing in a matter of 5 minutes. The 12" tube sits on a simple dobsonian base, no polar aligning, no goto set up just swing the telescope to your target. Finding dim DSOs is great fun. Finding favourite DSOs becomes much easier with a bit of practice. My sky is only mag 5 at best but that still leaves plenty of enjoyable viewing. Some reports on this scope here

Skywatcher ED120

This scope was going cheap when I bought it on Astrobuynsell. The ED120 had a very shaky start with concerns raised about it's colour correction. The concerns appeared to come principally from people who hadn't used the scope and seemed to boil down to a disbelief that Synta could achieve the quality they have done with the ED120. Happily more people have now discovered that in truth the optical quality is very high. Although I bought it as an imaging scope and have been pleased with it's performance I now use it mounted on a Super Polaris for solar system observing. I may also do some lunar imaging with it at some point. I have found colour correction to be excellent. Optical quality is very good. Views along the terminator are stunning with super contrast. It also performs very well as a double star splitter.

For a brief report on the ED120 click here

Skywatcher (Synta) ED120 side by side with William Optics ZS66 doublet on a Vixen GPDX mount with Skysensor 2000PC control panel. The tripod is a Berlebach

Vixen Super Polaris and Great Polaris DX

The Super Polaris was a ground breaking mount in the early eighties being a portable german equatorial of high quality. It has been much copied since but without the same committment to the quality of the original. I purchased an elderly Super Polaris last year for a song. It seemed rather unloved with a rather battered wooden tripod, slightly rusty counterbalance bar and motors but no handset. I had a new "System 5" handset made by AWR Techonology (dealing with the most excellent Alan Buckman). The handset cost me quite a bit more than the mount. I stripped the mount down, polished the gears which looked in excellent condition and regreased. The backlash can be controlled very precisely with a bit (or a lot in my case) of practice. Working at a short focal length I was able to regularly achieve 90-120 seconds unguided. Alan had fitted a guideport to the handset. It took me a little while to get to grips with guiding and fine tune the mount. Once done however the Super Polaris started to turn in some outstanding performances. 10 min exposures produced perfectly round stars. I've never measured the periodic error but imagine it is very good for this class of mount and certainly smooth. The wooden tripod absorbs vibration very well. The excellent polar scope enables very accurate alignment with little drift alignment being.

For short focal length imaging my experience with this mount has been outstanding. It is rated up to 7KG and I am sure it could cope with this for imaging very well.

With the move up to a longer focal length I wondered if I should continue with the Super Polaris. I fancied goto though so when a very well priced GPDX with Skysensor 2000 became available I couldn't resist. The fact that it was sold without tripod was a bonus since it gave me the excuse to get myself a Berlebach ash tripod.

The GPDX is rated up to 10kg and is significantly beefier than the Super Polaris. The gears are supposed to be of a higher standard. The mount came with the Skysensor goto system but without a mount. This proved a plus since it made me purchase a Berlebach Uni 18 mount. The Skysensor motors are each held in place with a single bolt which doesn't seem very secure. The cog gears connecting the motor to the worm need to be well aligned. This is a bit of a fiddle but is ok with a bit of practice and a straight edge. The adjustment of the worm is that same as for the Super polaris - a single set screw and 2 outer screws to tighten the assembly. The worm itself has to be adjusted quite precisely to avoid slop and the nut which secures it tends to tighten it as well which is incredibly annoying. I have found that after leaving the nut a little loose the worm has worked loose during an imaging session leading slop and unmanageable backlash.

My impression is that with some TLC the GPDX will perform very well but it isn't a mount that will work "out of the box". The polar scope is quite superb giving very accurate polar alignment and is very nicely illuminated. The action feels very smooth and the clutches are very secure. The skysensor motors slew quietly enough but make a disarming clicking sound when tracking. Apparently this is quite normal and there is no vibration transmitted to the mount amazingly.

I finally discovered that the best way to get the DEC guiding to work smoothly was to substantially offset the balance in dec. This means that any backlash is taken up by gravity.

As for the Berlebach Uni 18 mount, well it's a work of art. Close grained ash with the grain running perfectly down the legs. Adjustments to the leg height is very smooth. It is rated to carry 50kg. I'm sure it could absorb vibrations from an earthquake. A major addition to any small to medium mount.

I eventually sold the GPDX when I got my EM200. However at the Autumn Kelling Heath star party I bought another old Super Polaris for solar system observing with the ED120, I love these mounts!

Quantum Scientific Instruments 532ws camera

more details here

QSI are a relatively new company who have put an awful lot of thought and expertise into their range of premium research grade CCDs. Given the very limited opportunities for imaging afforded by the weather and my troublesome light pollution I wanted sensitive camera which would work well with narrow band filters. The QSI 532 shares the same Kodak chip as the SBIG ST10 range i.e KAF-3200. They have designed the electronics superbly to produce a camera with very low read noise characteristics. Although the chip is non anti blooming gate the sensitivity and low read noise means short subs work very well which is a great boon when you have high sky glow.

The WS version comes with intergral filter wheel.

Build quaility is superb. The controlled cooling works very rapidly and the chip temperature is held very precisely. It will cool to around 38 degrees below ambient which is fine for me in the UK. I like to use the camera at around -25 C which is easily achieved even in summer.

Although the chip is relatively small by modern standards it is a good jump up from my old SXV H9 and has fairly small pixels meaning that good resolution wider fields can be achieved using short focal length refractors such as the FSQ

My main gripe relates to the chip's full frame architecture. Reading and downloading takes about 8 seconds and this speeds up very little by selecting a small area for focusing. This makes focusing by FWHM a particular chore to do manually. A manual focusing aid such as a Bahtinov mask, or a motorised focuser makes life much easier. However, the slow download means that a lot of time is lost when using short subs.

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QHY8

The QHY8 seems to be that rare thing amongst astro cooled CCD cameras - a bargain. At under around £1200 it is well under half the price of an SXV M25 which has the same 6megapixel Sony ICX413AQ super HAD chip. Of course the M25 has additional features such as a guideport but the cameras share the same engine. I know from the H9 how well these Sony chips perform - extremely sensitive for a non blooming chip - max QE of 60% with sensitivity remaining good in the critical HA part of the spectrum. Plus very low noise. On paper at least, their performance is a level higher than ABG Kodak chips.

So far I haven't used the camera a great deal but have discovered it's gremlins the main one being icing up the instant the filter in front of the camera is removed or if the camera is pointing downwards on a newtonian. I have done a couple of M42 images which have worked very well. I will be using it from time to time esp with the FSQ but it takes a lot to tear me away from the QSI.

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Lodestar guide camera

I bought this stand alone guider from StarlightXpress with the SXV AO unit in mind. It has a very sensitive chip which is significantly larger than the average guide chip. Although expensive it has proved itself to be a superb performer with the AO allowing faster than 10 guide cycles per second off a mag 7 star. The large size of the chip is very useful given the long focal lengths being used and the limited range of movement of the guider in off axis mode.

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DMK 21AU4

Although I don't do much solar system imaging it's nice to have a change from deep sky imaging every now and then. I have been pleased with the results for a humble Philips Toucam but the 60fps capability of the DMK along with the resolution of the mono chip were persuasive factors in making this buy. I have it connected to a non motorised filter wheel with a set of Baader LRGB filters. I haven't managed to get it running in a stable manner with Vista and it tends to vary in its capture rate but I think this is more to do with my laptop than the camera.

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Starlight Xpress adaptive optics unit

Conventional guiding is restricted by the mass of the mount and the inability to make quick corrections. As a result resolution is restricted by the seeing which becomes more troublesome at long focal length. Adaptive optics was actually designed for large professional telescopes which change the shape of the primary mirror to correct for seeing induced distortions. This is well beyond amateur equipment and a better term might be active optics. SBIG pioneered a system using a diagonal moving mirror. The SXV system uses a mobile piecel of glass. This can make a correcting movement within 5 milliseconds.. Light passes through the glass and a off axis prism deflects light into a guide camera, in my case an SXV Lodestar. Movements of the guidestar are detected and a signal sent to the AO producing a correcting movement in the mirror. The mount just trundles on without any corrections. Provided a suitably bright guide star has been chosen this allows very rapid guide corrections, sub 0.1 second cycles are comfortably achieved. Not only does this rapidly eliminate any guide errors but seeing effects can be reduced. There is a noticeable tightening of stars even using high end mounts.

In use the unit adds an extra layer of complexity to the imaging process. Using an off axis guider working at long focal lengths is a challenge in itself but when it is necessary to find a guidestar which will perform off sub 0.1 second exposures whilst still framing the target the difficulties can be severe. The Sky 6 is a great help in planning with its excellent FOV indicators. With a little practice however, the calibration routines become straightforward enough.

The good thing about the AO unit is that it picks of the light in front of any filters which is a big help particularly for narrow band work.

The glass is restricted in it's range of movement, if it drifts too far the unit sends a signal to the mount itself to make a correction, the AO glass rapidly adjusts in unison with the mount's movment to prevent any star trailing and to return to it's central position. This works surprisingly well provided the guidecycle is fast enough.

It is a well engineered piece of equipment and has alway worked flawlessly (except one occasion which was eventually tracked down to a faulty guide cable).

Celestron Nexstar GPS 8"

Celestron Nextar GPS 8" mounted on an APT wedge. Rails for guide rings and counterbalance weight (not attached).

This was my 1st "serious" scope which I purchased second hand from Roger Warner. Roger had worked wonders with the scope working in alt az using a simple Atik 2HS modded web cam and a fastar set up. The scope is fantastically simple to use in alt az, simply plonk it down, run a quick alignment routine and you are sorted. It is a lovely scope to use for visual work providing very comfortable viewing except right at the zenith when your head starts to bump into the forks. There is no problem around the meridian and no rotation of the scope.

It is a great scope for high powered planetary and lunar work and I have had a lot of fun using a Philips Toucam.

A couple of months after getting the scope I got hold of an Atik 2 HS and started taking deep sky images. The little atik 2HS has a very small chip and is pretty noisy, being cooled by a small fan, it is however very sensitive and very easy to use with K3CCDtools software. Initially I used it with a Meade 3.3 focal reducer or an Atik 0.5 reducer. After a few months I bought a fastar lens assembly which allowed me to work at F1.95. The Atik was ideal here with it's small pixels. The fact that the chip is small means that there is no problem with vignetting.

In alt az field rotation starts to creep in after around 45 seconds. The fastar allows you to grab a lot of light in this time but I eventually started to use a Celestron heavy duty wedge. This is a poor effort from Celestron. I found it stiff enough for the NS8 but the fine tuning controls (which have to be purchased extra for an outrageous amount) are very poor. I wouldn't recommend this wedge to anyone with a scope bigger than 8" and I think Celestron should be ashamed of themselves for producing such a sub standard product.

I finally gave up with the Celestron wedge when an APT wedge became available second hand. This is a beautiful piece of kit. Several times heavier than the Celestron with beautifully smooth alt az controls. The really nice thing about this wedge is that the azimuth can be adjusted without clamping and unclamping. This makes precise polar alignment a doddle. It could comfortably carry an 11 or 12" SCT for imaging work.

After buying an SXV H9 CCD camera in Autumn 2006 I stopped using the NS8 for a while. I tried it with fastar but it is difficult to achieve a flat field and vignetting is a bit of a problem. The combination is useable but problematic. However, in Spring 2007 I purchased the SXV adaptive optics unit. This is a very powerful piece of equipment providing extremely rapid guiding. It has been a pleasure to be using the NS8 again and as I have slowly got to grips with the AO results are promising.

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Skywatcher ED80

I guess very little needs to be said about this amazingly successful scope. Another second hand purchase. The quality of the optics are well known although I found it showed a little more colour than the ZS66 apo and, surprisingly, my ED120. You have to look hard though. It has a cheap finish which pleased me because I don't like paying for scope cosmetics. It has a Crayford focusser which isn't in the same league as the William Optics offering in terms of smoothness. However another problem is that the bar on the drawtube which engages with the focusser tends to be a little concave. This means that the focusser can slip under load especially when carrying heavy ccd cameras and filter wheels at the Zenith. The solution to this is to use a rubbing stone to smooth it out. This makes the focusser more secure and provides a smoother action since you don't need to tighten it as much.

The ED80 is also bigger than it should be with it's 100mm tube. This isn't good for imaging, not only is it heavier than it should be but it also catches the wind more. Despite these well known faults it was great value for money and the optics (which are what count at the end of the day) were well up to the job. I was never able to get a properly flat field when using a QHY8 and it has now been replaced by the FSQ.

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Starlight Xpress H9F and guidehead

For anyone entering this daft hobby of astroimaging it takes a while to come to terms with the cost of specialised cooled CCD cameras. I used a modified web cam with some quite pleasing results. Others were doing very well with the Canon DSLRs but there was no escaping the fact that the guys getting the results to die for were using CCD astroimaging devices. Artemis/Atik brough out the HR16 at a slightly more encouraging price point but still the eyes watered at paying over £1000 for a camera capable solely of taking pictures of stars.

After a number of conversations with Ian King my choice came down to the Atik 16HR, an SXVH9 or an SBIG ST2000. The deciding factors for the SXV were USB2, availablity of an adaptive optics guider for use with the NS8, compatability with fastar, a guide unit designed to work with the camera and external guiding for narrow band. I have since often wondered whether I would have been better off with a self guiding camera but on balance I have been very pleased with the H9.

The H9 has very small 6.4 micron pixels so is very suitable for short focal length imaging as well as being able to give very high resolution long focal length images when the seeing allows. The images produced are very clean with very low dark noise - darks just aren't necessary. Setting up the guiding is very easy with maxim. The guidehead is predictably pretty noisy and the chip is very small but so far I haven't had any real problems finding a suitable guidestar. Serious imaging presents so many difficulties and challenges that have to be mastered one by one. I am sure it is best to keep focal lengths low initially since everything is so much more forgiving. The SXV H9 is superb in this situation. Whether it performs as well at longer focal lengths I've yet to find out.

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