Imaging diary, reviews and general ruminations

21st October 2008 - My best ever observing session

Last night in Chesterfield there was a rare combination of great transparency, steady seeing and no dew. There was a good breeze blowing but, although this played havoc with my imaging it didn't trouble my Skyliner 300 dob. There was a bit more LP that usual which I guess is probably because of the amount of moisture in the air.

Started off with a star test on vega having read the article in this weeks S@N. This showed collimation to be spot on (having tweaked with a Baader laser), no astigmatism and diffraction rings appearing the same in and out of focus. The double double was just split at x150 using a Pentax 10mm XW.

Had my best ever view of M27 using the Pentax 10mm and UHC filter. The outer limbs were easily visible with direct vision. The brighter core stood out clearly and there was some variation of brightness within the core but not enough to give the appearance of mottling. M57 was very bright with clear dark at the centre. At first I thought the blue green was showing really well then remembered I was still using the UHC filter oops!

Onto M31, I wanted to see if I could discern the most prominent dust lane. This dust lane is actually much further out than I had previously thought and the nebulosity in this region is very faint. I didn't succeed with a 27mm Panoptic. Overall contrast was improved with a CLS filter but still no joy. Next time I will use a higher power and use M32 and 110 as a guide to where to place the scope.

M33 was in a fair bit of LP but showed up pretty well using the Pan 27mm and CLS combination. There was clear brightening towards the centre. From there it was onto M15 which is a beautiful glob. The stars were very well resolved at x150. Upping the mag to x210 with a Pentax 7mm increased the seperation of the stars but they appeared lest vibrant at this mag. Then a quick look at Almach. Again my preferred EP was the 10mm Pentax x150 which gave a comfortably wide split and lovely colour contrast. Followed this up with a look at Iota Cassiopeia. The double was easy to see and the 3rd star was just split at x150. A quick trawl throught the clusters in Cassiopeia. The highlight for me was the incredible Owl Cluster NGC 457. I didn't know that NGC was the owl cluster but it was immediately obvious. It was pretty spooky. There was an owl screeching away overhead and this bird with demonic gleaming eyes peering down my scope. The wings were quite dramatic. Took in the clusters in Capella with M37 taking pride of place. Lovely delicate colours with the Pan 27. A Nagler 17mm didn't really bring out anything that the pan didn't and overall I preferred the view at the lower power. Whilst looking at clusters I had the obligatory trip to the double cluster, again the Pan27mm came up trumps. This is an awesome EP which has been massively enhanced by the Baader MPCC. Pleaides was now well up. Looked ok through the pan but need something wider for this. A 40mm Paragon maybe??

Finally it was a question of peering into the LP low over the centre of chesterfield to see if I could make out M1. It turned up clear enough with a CLS filter. Only once I'd located it using the CLS was it possible to just discern it unfiltered. Upping the mag helped to improve contrast and some shape was discernible with the 10mm Pentax. And that was it with the scope. Had a sit back in a comfy chair and enjoyed taking in the constellations and the odd shooting shooting star. A wonderful Autumn Sky viewing.

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Nagler 17mm T4

A guy once asked me to listen to his new hi fi speakers. What do you think about the awesome spatial clarity of the sound stage he asked. I told him that I didn't think Lemmy, Motorhead and "The Ace of Spades" were the best showcase for his system.

Just as there are audioplhiles there seem to be opticophiles, people who spend hours peering through refractors (it's usually refractors) using a range of very expensive eyepieces observing nuances of astigmatism, edge of field distortion and the like. This makes it very difficult for your common or garden stargazer, who just wants to look at stars and stuff, to know what is worth having and what isn't.

I've gone and got myself quite an expensive curiosity in this departement so finally had to get one of those Nagler eyepieces that opticophiles rave about. Surfing through Astro buy and sell I spotted a 17mm type 4 - nearly new and pristine £70 off the new price of £320.... take some time out for a deep breath sunny sunny sunny, better now? Now this isn't just any Nagler, it is the one that many opticophiles say is their all time favourite because of it's combination of sharpness across the field, contrast and eye relief (see I'm learning the lingo).

Quick primer, the types are numbered in the order of introduction, so type 1 is the earliest, type 6 the latest (oddly there was never a type 3). They are all variations of design with slightly different characteristics. One type isn't better than the other. T4 17 and 12mm are still available new. Oh it's all so complicated!

Well I'm a bit of a sceptic about these views that will "blow you away" so I am going to serially review this eye piece with the mind of a hardened cynic. I'm going to learn it's ins and out and probably bore you to tears with the details of my observations. I have a few problems though - I am an inexperienced observer who doesn't have the vernacular to describe optical distortions and the like (but I'll try to blag it!). Also I don't have a lot of other eye pieces to use for comparison - a budget Moonfish UWA, a few Celestron plossls and a couple of Baader orthoscopics.

So, starting with the physical - it's big (the T5 and 6 ranges are significantly smaller). It's a similar size than my Moonfish and slightly heavier. It's in immaculate condition without any blemishes. It has the Nagler rotating, adjustable eyeshield. This is a sheathing around the upper half of the EP with a rubber eyecup at the top. It can be rotated and moved up in a series of clicks to give good adjustment of the eye shield for the individual observer. It does give the impression that the EP is about to fall apart Shocked .

First light then. I was planning on using an Skywatcher ED120 (x53) initially and then trying my Nexstar 8" (x118). At F7.5 and F10 respectively neither of these scopes provide a tough work out for eyepieces. A fast sub F5 reflector will show faults at the edge of the field of view much more. Maybe I've wasted my money!! In the end all the observations below were with the ED120. A lot of cloud and an early start at nightfall. My first view through the Nagler wasn't exactly a jaw dropping, road to Damascus experience. It was a peep at Jupiter through a Laurel hadge. All it told me was that I need to trim the hedge. Still in the half dark (I was excited) I looked at a few bright stars which were uninspiring (not surprisingly). One thing I did notice though is that eye shield placement is quite critical. The EP "kidney beans" if the eye is too close (ie areas of the view black out - very unpleasant). Move too far way and you are beyond the eye relief and loose the 82 degrees of apparent FOV. With the eye shield just right you can put your eye up to the EP to get the full view without the blacking out. Much less user friendly than the Moonfish in this respect though.

I had to wait for gaps in the cloud but the good news was that the transparency between the low cloud was good and the seeing was fairly steady with nice round out of focus diffraction rings. The bad news was that although the forecast was for a generally clear night there was also a high risk of showers. I wasn't going to hang around. I found enough of a gap to observe M57, not an ideal low power target. Still not fully dark the ring was slightly better defined through the Nagler than my 15mm plossl. Easy to see it as a ring rather than a disc. The stars were sharp to the edge of the FOV. I looked hard for any distortions but they weren't there, not to my untrained eye anyway. Surprisingly the Moonfish was also very good although the stars were getting stretched a small amount right out at the periphery. This surprised me because the Moonfish doesn't perform especially well with the F7.5 ED80.

I was following cloud gaps and moved up to the North American Nebula area. Still not dark enough to make out any nebulosity, just pleasing views of star fields. The Naglers are renowned for their so called immersive viewing - the space walk effect. This didn't have any wow effect for me since I am used to it with the Moonfish which also gives a similar FOV. It is a lovely way to observe though. Some people feel that this FOV is wasted because the eye can't take it all in at once however, for me, this is part of the attraction. I enjoy looking around at the view.

Next stop Alberio. Rather disappointing initially with poor colour but the sky was now starting to blacken up and within 10 minutes the clours of the double were very vivid. My 15mm plossl showed a little light dispersion around the star which diminished the contrast. The view was quite clearly less dramatic than with the Nagler.

Finally the sky was properly dark and the whole of the Summer Triangle area had opened up very nicely. I moved onto M27 and popped in the Nagler. Ooooh hello, never seen M27 look like this before - the core shape was sharp and clear with detail showing within it. Lots of contrast. Even more surprising was that I could make out surrounding nebulostiy in the OIII "ears" region. Was it the scope, the conditions or what. Quickly aligned the NS8 and popped in the Moonfish to compare thinking that at x67 this would be of the same order of magnification. And guess what clouds1 clouds1. 90% cover and black stuff heading my way so I was off.

That view of M27 has really stuck in my mind. I've recently been imaging it and I feel I know it's every nook and cranny. So was I like the music lover who listens to Beethoven's 9th and a tinny radio but still hears it in all it's glory inside their head? Was my brain filling in the gaps? I don't think so, I think the Nagler might actually be something a bit special.

I'll add another observation report as soon as I get the chance.

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29th January 2008 - Things seen and not seen through a Skliner Dob

Managed to get out last night between 10.30 and 11.30 with Skyliner dob. Moderate transparency with a dew slowly starting to form. Seeing quite good. Moderate light pollution, more to east than to west - Mag 4.5 sky at zenith Scope well collimated.

EPs used - Moonlight 30mm UWA, Panoptic 21mm, Nagler T4 17mm, Pentax XW10mm and XL 7mm. 9 and 5mm Baader orthoscopics.

Saturn - Cassini - just visible and then only intermittently at x150+ using Pentax 10mm and Baader 9mm ortho. Moving up from x166 with 7mm pentax and 5mm ortho didn't improve the resolution. The ring and it's shadow could be seen clearly in fron to the disc. Not visible - the bands. The disc was a very pale yellow with no surface detail. I guess the ring is obscurring the largest band.

Mars Again, maginfication of 150 to 180 was about the limit. Peach coloured disc with quite distinct darker dust areas, in fact as prominent as I've seen them. Still subtle though and become much easier to make out with more prolonged observing. Nothing to choose between the 10mm Pentax and the 9mm ortho in terms of what was visible.

Orion area - Unfiltered and using a UHC - S filter I couldn't make out the horse head or the flame using either the Moonfish or the Nagler. Need a darker sky. M42, 43 and running man - The UHC - S gave a dramatically improved view with no significant loss of nebular detail. The central nebula showed plenty of wispy detail with the central "square" of the trapezium then the ghostly bird like area of nebulosity. The outer areas were perceptible as a definite haziness but didn't contain any detail. M43 was also clearly seen with hints of the darker areas within it. The running man was clearly seen within the reflection nebula. Using the Pentax 10mm the E star was split from A and F was causing an irregularity in the appearance of C.

M81 and 82 More LP in this part of the sky and the background was quite milky. Both galaxies nicely framed at around x90 with the 17mm Nagler. No real detail. Stepping up to the 10mm Pentax and it was possible to see a division in the core of M82 (just).

Then clouds and bed time!
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14th December 2007 - Trutek motorised filterwheel

When I started imaging I thought any sort of filter wheel was a bit OTT but after faffing around screwing and unscrewing filters and getting condensation on everything I saw the light and bought a Scopeteknix manual filter wheel. This certainly made life a bit easier but the experience was often marred by getting in a muddle over which filter was where. This led to the ruin of more that one imaging session. When I started guiding I discovered an additional problem - it would often take about 30 seconds or so for the guiding to get back on track after turning the filter wheel. Still these problems didn't seem to justify forking out around £500 on a motorised wheel.

Trutek (ie Nick Hudson) is the UK dealer for Takahashi as well as making filter wheels. When I bought my EM200 mount I was able to secure a reasonable discount on the wheel. I thought I would give you a report on how this little piece of decadence has performed.

The wheel is quite a chunky bit of kit, a good bit heavier than the Scopeteknix with a thicker profile. I always use it with a 2" nose piece but also have an adaptor to allow me to screw it directly into an SCT thread. My H9 screws directly into the other side of the wheel It comes in a neat pelican case complete with all leads amd software driver cd It comes with a number of disc options - I went for a 9X 1.25"filter holder. This means the wheel houses my full LRGB, CLS and narrow band filter sets! The wheel is fully enclosed so I no longer have to move my filters around - wonderful! The wheel needs it's own power supply - the lead provided is a little on the short side but not a problem with careful cable routing. It also needs a serial computer connection - I use a USB to serial adaptor.

The wheel was immediately found by Maxim. It was a very easy and intuitive job telling maxim which filter was where. Maxim then remembers these positions from session to session. There is a home position which the disc is always moved to on connecting so provided the filters aren't actually removed no manual alignment is necessary. I now set up my imaging sequence in advance in Maxim. Anyone familiar with Maxim will know you can specify type of sub (light, flat dark, bias), suffix, exposure time, binning mode, number of exposures and filter. You can set the details for each filter you need to use during the session. The last time I was out I specified 10x20mins Ha, 20x55 secs R 20x50 secs G and 20x60secs B with the RGB all binned 2x2 Once you start the sequence Maxim will run through the filters in sequence. For the above sequence it will first take an HA then an R G and B. It will run another RG and B then return to Ha - it works out the sequence so that a balanced set of subs are obtained rather than do all the Ha then the red then the green then the blue. This means that if you session is interupted by cloud you still have a balanced LRGB image. Filter change typically takes around 1-2 seconds and has no effect on the tracking. I have a guider setting delay of 5 seconds to allow the guider to settle down after image download so the filter wheel actually doesn't slow things down at all.

It just works and it has transformed my imaging way beyond the bare description above would suggest. So what I thought was likely to be my most stupidly extravagant astro purchases has turned out to be one of my best ever.

Not much to look at but here it is hanging off an FLT110 with an SXVH9 and guidehead with ZS66 tucked behind.
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30th November 2007 - More fun with a 12" Skyliner

Got a Baader laser collimater from FLO and got the optics nicely on song. Plus a Wixey following Themos's recommendation ( a Wixey is a digital angle guage) it contains a magnet so sticks to the dob tube and tells you the altitude angle. Just check this against planetarium software - I've got The Sky 6 pocket edition on a PDA, once the angle is set just slew slowly in azimuth around the vicinity of the target and bingo. Great tip Themos, thanks for that.

Light breeze with reasonable seeing. Some high cloud progressively developing and the sky generally a bit milky and mucky.

First up was M27 - wanted to have a look before it disappears. The core shape was there with at 17mm T4 Nagler and a little clearer with a 10mm Pentax XW (x150) but the background sky brightness was just overwhelming things so no chance of seeing the dimmer OIII areas to the side. Moved onto M57 and the ring was clear enough but not that impressive. Rechecked the collimation and found it had shifted. Made some small tweaks with a definite improvement in appearance. Was able to go up to a 7mm Pentax XL with the overall oval shape being clear and some areas of differing brightness visible. No sense of colour.

Had an early look at Mars but just a orange disc - no detail to see.

M52 "the Scorpion" followed then by M103 in cassiopia. Some beautiful star colours in the latter with a bright, intensely orange star at the centre of the open cluster.

Found M33 but just a smudge.

Then M37,36,38 in Capella in that order. These really are delicate open clusters and I do enjoy looking at them. They are the sort of targets which are much more rewarding visually than through a camera. Even Rob Gendler and Russ Croman can't capture the ethereal beauty of these tiny pin point stars.

I was then off to M34 but the murk was getting worse so decided to go back to Mars. Glad I did cos it was now at a more respectable altitide and the seeing was quite good. With the 10mm Pentax I got my first ever view of the surface detail, so subtle and it took a while to get used to the brightness but with time I could make out more and more - the polar ice cap very clear and then a peachy disc with some darker areas. A 9mm Baader orthoscopic added a bit more but the best view came with the 7mm Pentax XL. A Baader 5mm orthoscopic was too much for the seeing at a still quite low altitude. I spent a good while looking at Mars.

By the time I was done, the moon was on it's way up and it was getting too cloudy to do any more. Great to be able to grab a brief interlude in the cloud. No wires, power packs or alignment. Just a little Wixey. Brill.

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19th November 2007 - Skyliner Dobsonian

Having a big change of kit - my NS8 set up has now gone Sad What a wonderful scope that has been. All my imaging is now going to be with my EM200 mount. The NS8 is being replaced by a Vixen VC200L. But I actually enjoy peering through telescopes and have chosen the Skyliner 12" dobsonian.

Ordered from First Light Optics last Wednesday and delivered Thursday. Got it home from work Friday night. 3 boxes - base, mirror cell and tube. The box for the tube looked like it contained a settee, it was huge. I was pretty worried I might have bitten off more than I could chew. Fortunately once all the packaging is stripped away it is a bit less intimidating. Assembly was very straightforward even for someone as cack handed as me. All the tools and bolts are provided for the base and everything fitted together perfectly. The base has a solid handle at the front which makes lugging it to the observing location very easy. Unwrapping the mirror cell is one of those unpleasant "this is all about to go horribly wrong" sort of moments but again no bother. A bit tricky getting the flexing tube around the mirror cell and best to recruit a bit of help. Not easy for me because Jackie was in a strong "that's ridiculous what do you need something that size for, you always have to go over the top" state of disapproval. Anyway she helped me to line up the tube screw holes with those on the mirror cell and that was the OTA sorted. Just a matter then of attaching the 9x50 finder which comes with the excellent synta bracket with the spring loaded screw. Also there is the Synta crayford which is a real plus.

I was relieved to find that I can carry the OTA very comfortably. Just cradle the upper section under one arm and grab the bottom of the ota with the other. Not too heavy at all, just clusy so watch out for steps and obstructions. Popping it onto the base is as easy as sitting down then just screw in the side handles. One of the side handles also acts a tensioner which makes it very simple to achieve the perfect tension in alt. The collimation of the secondary was spot on leaving just a small tweak for the primary. Movement of the ota on it's base is delightfully smooth. There is a bit of back movement which isn't a big deal.

The scope comes with a couple of Synta super plossls 25 and 10mm with a 52deg FOV. I have had a quick look through these and they seem like a perfectly competent pair of EPs which complement the scope well.

Well with the scope all set up, quite unbelievably it was a starry starry night. I didn't have much time because of other commitments but was able to have a little scan around. Without go to and motors and tracking I feel as if someone has cut my umbilical cord. Where's the handset?

Being used to an SCT and refractors the first thing that struck me was diffraction spikes and coma (using uwa eps). It will take my brain a while to switch off from these. The seeing wasn't really good enough to enjoy good views of Mars. The double cluster looked sensational but it always does regardless of scope. Comet Holmes filled most of a Nagler 17mm EP and looked very impressive - I nearly called Jackie into the garden to have a look but thought better of it. M81 and 82 were a disappointment quite frankly - they are quite low in the sky in a bad area of LP for me. The 12" aperture scooped up all the LP very nicely so the views were really no better than I have had before with smaller scopes. M31 was well placed but couldn't say I saw any dust lanes.

The following evening confirmed what a good move buying this scope was. It wasn't yet dark but the moon was bright, frontal clouds were moving in and the forecast was grim. In 5 minutes I was set up on the lawn looking at the terminator through a Pentax 10mmxw. Now this was impressive. I can't tell you what I was looking at but it was good! Given that it wasn't properly dark I wasn't possible to judge contrast but the resolution was impressive despite only moderate seeing. This settled over the next 30mins allowing me to use a Pentax XL which pulled out more detail still. Sorry this is very vague but one of my plans is to learn what the hell I'm looking at when observing the moon. Then came the expected cloud but what an enjoyable half hour.

Grab and go with diddy refractors has no appeal to me but this dob is another matter. So tha plan is - lots of observing whilst the imaging set up does it's stuff. Learn the night sky and be able to hunt down messiers in a trice. Also get out for grab and go sessions when conditions aren't suitable or too transient for imaging. Hopefully lots of oberving reports coming up.
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30th October - ED120 put to the test

I've posted a review on SGL before about this scope and have been very impressed with it. The problem I've had is not having much experience of high quality apos to use as a benchmark. Now I have an WO FLT 110 on loan from Steve at First Light Optics that problem is solved. The FLT is a TMB designed triplet of very high quality and a perfect instrument to use for assessing the performance of the ED120 (I will be writing a full and detailed review of the FLT in the very near future).

The ED120 is 900mm f/l F7.5 compared with the FLT 770 F7 2 nights ago there was some scudding cloud but in between transparency was good. Seeing was variable - moderate to good. I had both scopes mounted side by site on an EM200 (now that was a good sight). I was concentrating on the moon which was 2 days past full with the terminator nicely picking out the western edge of Mare Crisium and Cleomedes.

EPs used were Moonfish 32mm UWA, 17mm Nagler T4, 7.5mm Pentax XL, 9 and 5mm Baader orthoscopics, 6 and 4mm Celestron plossls.

Looking through both the moonfish and the nagler there was a thin rim of colour along the edge of the moon when this was viewed out to the edge. To my eye this completely disappeared when the rim was moved into the centre of the FOV. Slightly out of focus the colour was slightly more pronounced with the ED120 but this difference was not apparent in focus. For such a full moon the contrast was excellent especially around the terminator but I needed to up the magnification to see what the scopes were capable of. As the magnification was increased the views just became more and more impressive. Shadows were black with the shadows of the mountains on the edge of Mare Crisium being picked out with marvellous crispness. The tiny craters at the edge of the Mare were small but seen with a clarity that made you feel there was nothing between them and the eye - glass, atmosphere and 250 000 miles just dissolved away.

Both scopes gave their best view with the Baader orthoscopic although the wider FOV of the Pentax might be preferred by some. I did try pushing the magnification up with a cheapo 4mm plossl and also by barlowing the Pentax but both scopes were running out of steam at this point. As could be expected, the ED120 was able to resolve a little more detail than the FLT thanks to it's extra aperture.

The point of an apo when viewing the moon is not really about not seeing any colour in the rim, it is that good colour correction reduces light dispersion and enhances contrast. The high power views in both scopes was immensely impressive - a tiny hint of colour along the rim in both scopes (more in the ED120 off focus but not in). I am sure the ED120 will show more colour than the FLT in poor seeing conditions. The 120 matched the FLT in terms of contrast and sharpness of detail.

There's no doubt the WO FLT is the superior scope - it is actually quite a bit heavier than the ED120 and looks chunkier, it has a nicer focusser which rotates as does the nose piece holder making it much easier to achieve comfortable viewing. The finish is altogether superior. It is the faster scope and can be fitted with a TMB flattener for very flat wide field imaging. So there is no doubt it is a much more of a package than the Skywatcher. What this has cleared up in my mind though is that optically, the ED120 is a mighty good performer and a true apochromat.

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23rd October 2007 - EM200 1st review

Just like the economy decides elections when it comes to imaging, "it's about the mount stupid". Well having tweaked and tweaked my Vixen GPDX and finally got to understand it's moods I decided to upgrade. The GPDX needs nursing along when auto guiding. I was wasting too much time under precious clear skies fiddling. Also the load capacity of 10kg is ok for my current kit but there isn't much in reserve. I wanted a mount that just worked, straight out of the box, that I didn't have to fret over, that was portable and very quick to set up.

The EM200 along with the Astro-Physics Mach1GTO are the most expensive of the medium sized mounts and it really is difficult to justify spending this sort of money. In the end I didn't have to - I just sold my Laser dinghy which I hated sailing! I went for the EM200 over the AP because of availability, UK dealer but most of all the wonderful polar alignment scope which I reckon will gain me at least 15 mins on every session.

The mount is beautifully engineered. The tripod is solid mahogony, adjustment is sacrificed for rigidity - perfect for imaging. It doesn't need to be flat which is a further time saving. You can set it up on a hillside if you want! The clamps are very solid and all movements are silky smooth. The mount fits to the tripod using a through bolt. When this is nice and secure the the azimuth adjustment knobs still turns the mount very easily allowing very accurate adjustment.

The very chunky and rigid tripod

The polar scope is remarkable. The RA axis has a spirit level, you turn the RA until this is level. This ensures the polar scope is properly positioned (hence no need for the mount itself to be level). There is a longitude off set which is a one off adjustment unless you travel. The polar scope covers are screw on so nice and secure. Illumination of the scope can be adjusted by a small screw on the control box. There are 2 circular scales, one for the date and the other for the time. Simply rotate the reticle until the time lines up with the date. You then simply line up polaris between two lines matching it with the year (this scale goes up to 2030!). If done properly this gives an alignment within 2 arc minutes of the celestial pole. Plenty for normal imaging without the need for drift or software alignment. You would only need to adjust more finely at very long focal lengths. Adjustment of alt and azimuth is a doddle with the mount moving easily in alt and az with no jerkiness and no need to loosen and tighten the bolt fixing the mount to the tripod. The only thing I'm not keen on is that the altitude adjuster has just one screw which increases the altitude. The mount is prevented from moving the other way by a clamp and a friction pad. This appeared to work very well until it started moving during an imaging session. I have now learnt to make sure this clamp is fixed very tight after adjustment. Fortunately there is no movment of the mount when this is done.

One surprising absence is a latitude scale, perhaps because it wouldn't be accurate if the scope wasn't level. Even so, it would be very helpful when attempting to use the mount for the first time.

Spirit level for setting orientation of polar alignment scope (protected in this picture by the screw on metal cap

The mount comes with two versions of the Temma goto - Temma and Temma junior. The junior version slews at a snail like x250 (more than 3 times slower than an EQ6). Having said that, it is £500 cheaper than standard Temma and was available for immediate delivery so I had that one and have spent the "saving " on a trutek motorised filter wheel. The mount has a dinky hand set, again beautifully made in a solid metal casing. This handset merely moves the scope at slow or fast speed and is used for positioning the mount. Although it will run off 12v slewing speed is slower still. It comes supplied with a 24V mains adapter so that saves having to get a couple of leisure batteries until I need to go to a remote location.

Neat little handset hanging from it's peg on the tripod.

There isn't a hand set for the goto! You have to use planetarium software. Sky 6 has it's own dedicated Temma driver but it works perfectly well with Starry night pro using the ascom driver. I can also operate it from my PDA using The Sky Pocket Edition using either a blue tooth or a cable connection. Getting to target is very easy. Work out the nearest easily identifiable star and manually swing the scope onto this star. Centre it in the scope and in the software then sync. Centre the target in the software and then slew to centre of screen. A doddle and very accurate. Slewing from Vega to NGC 7023 put the Iris bang in the centre of the chip. The scope makes a gentle, unobtrusive whining noise when slewing but is a little sedate. Temma control box (click to enlarge)

The first guiding calibration in Maxim was a bit nervy since any significant backlash would be revealed. The first attempt was a disaster. I hadn't realized that the speed of movement continues to be determined by the speed setting on the little handset. Maxim was set to calibrate using 20 second movements and, with the handset left on the fast speed the scope was well on it's way back to Vega before I realized what was happening. I am going to make this mistake lots, I just know it. It does the same when guiding - a 0.1 pixel error is give an 10 pixel correction! When I finally did the calibration Maxim ran a 20 second move in RA then back again, then a 20 second move in dec and back again. A perfect right angle was traced and the guide star came back to the identical pixel co-ordinates it started from. I think that is pretty phenomenal, in fact I didn't think it was possible for a mount to have no apparent backlash.

My first guiding run I was working off a guidestar exposure of 2 seconds. Maxim was reporting an RMS tracking error of just 0.07 pixels in both axes . The error would occasionally creep up to 0.2 pixels. When I put on the tracking error graph in Maxim I was quite disappointed by the jaggedness of the line. It took me a while to realize that the scale was only 0.5 pixel max and that the movements weren't sufficient for Maxim to trigger a mount correction. The jaggedness of the graph was down to the seeing! The mount was putting in a correction around every 15 seconds. It would be quite possible to work with a guide star off a 10 second exposure.

With everything running smoothly I went inside for a coffee and some "quality family time" but on coming out again there had been a large movement of the target on the chip. Looking through the subs there had been a massive movement of the mount. I now realize that the altitude must have slipped. I hadn't tightened the clamp sufficiently. There continued to be more small movements which the guiding managed to pull back but polar alignment deteriorated. The images that came out (other than the ones when the altitude slipped) showed perfectly round stars off 15 minute exposures. This was at a focal length of 770mm.

I ran a 5 minute unguided exposure which produced this: -

A close up of stars from the same image:-

So, I'm thrilled with the mount (which is a relief after what I've spent). Fantastic build quality and it just works - no drama, no fiddling, nothing going wrong, no inexplicable behaviour. It just tracks and tracks and tracks. Feels a bit like cheating really!
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