astronomer2002

After using Gemini 1 system on my Mi250 mount for many years it has developed a very odd fault. I am using it just with the hand controller and sidereal mode to slew to Mars for imaging. I just use it in sidereal mode so I can nudge the planet back to the middle of the sub-chip ROI I have chosen. I have used this method on planets for over 15 years. All goes well for 15-30 mins and then the hand box lights up and starts scrolling through menu items some of which I have never seen. I cannot get it to accept input from any button on the hand controller. When it is doing this teh scope sometimes starts slewing. A week ago all looked fine after a 1 hour ession and then clouds rolled it. I left the scope running and when the sky cleared 20-30 mins later I went out to teh observatory again to continue imaging. I found the scope had slewed 180 degrees in dec and about 3 hours in RA. The control box was scrolling through menu items. I can therefore say this error occurs regardless of whether I have the control box in my hand or not. To try and sort the issue I have opened up both the hand box and the main control box to clean them out, but found no debris and boards look new. I have changed the battery, twice, replaced the handbox cable and even replaced the 1.05 version eprom with the earlier 1.04 eprom I swapped out 7-8 years ago. The symptoms are the same. I can only conclude there is a problem with the on-board electronics of either the handbox board or the main board. Has anyone come across anything like this? I am obviously on the lookout for old handbox and/or main control box that someone may still have after upgrading to Gemini II Any help, advice or the offer of either/both electronics boards will be gratefully received as I am at my wits end Ian B

Thankyou for all who posted suggestions, they have all been very helpful. As I said initially I have no knowledge of this scope and was working on the assumption there was an issue as my friend, who has had it for many years, indicated it no longer worked. I have finally got it to work properly in alt-az mode. The key was to start with the scope pointing North and to have the single arm on the west side of the mount. My process was: Switch on Pont scope at Polaris (suggested here) Move tube to horizontal with aid of spirit level Set time and date and check location Select 2 star alignment and choose Deneb Drive to Deneb and centre in ep. Press Align Select Capella and drive to it through southern path (ie not going through North) Centre Capella in ep and press align Get the usual 'congratulations' message Tell scope to drive to M37 - Eurika - it does! Tell scope to drive to M57 - once again it does. Tell scope to goto M15 - it's in the ep! Basically nothing wrong with the scope when set up like this. I have not tried the other methods but don't believe there is anything wrong, except the large gear backlash which seems endemic. Thankyou all again Ian B

Thankyou all for the heads up on date and time needed to be entered every time - seems it is a design feature rather than an issue just with this scope. Still not sure if there is a battery somewhere that needs replacing to keep the entered data, or is it that one of the eproms is written to each time you enter anything? I'm used to hidden batteries in handsets or mother boards that die after a few years. I'm running the scope off 12v 5a power supply that I use on several modern mounts, a lot simpler and cheaper than 8 AA batteries. I tried it with rechargeables but it didn't like the ~10v that provided. The manual does not tell me to do anything more than put the tube horizontal for the 2 star align so I guess not orienting it North is going to be the issue. I really hope so as that is a simple 'fix'. Dates/times/lat/long and time zone are all correct though I note the time zone seems to be lost when you turn the scope off as well. I will try the set up procedure again - if we ever get clearish skies! Ian B

Thankyou for the suggestions. I'm sure the date is correct way round as there is no month 18! From the Instruction Manual there appears to be no reference to date and time if yo are doing a 2 star alignment. I would really like to know whether 2 star alignment needs all the date and time elements to be correct and the tube pointed North before it will work. It seems unlikely as it is relatively hard to get to the date, time etc through the menu. I would also have thought the date and time would be accurate after the scope had been turned off for a couple of days rather than simply remembering the last date/time it was on. Not sure if something is broken here. Manual is unclear and there seems to be no battery to keep the clock running, which is another oddity. It states you need the tube pointed North and horizontal plus the correct date and time for the Automatic alignment, which is understandable as it is then going to select alignment stars and slew to them. Has anyone still got one of these original mounts or can remember if the 2 star alignment worked if the date was a couple of days out? I have had, and still have, quite a few mounts each with their own idiosyncrasies, but this one seems either broken or the instructions are wrong I am using this copy of the manual: http://www.company7.com/library/celestron/nexstar_8_manual.pdf Ian B nexstar_8_manual.pdf

This topic has just reminded me of my endless fights with dew on refractors, reflectors and SCT's. Nothing really worked better for me than a long, cheap, black art drawing paper dew shield held on with elastic bands. Tried it out of desperation once when at a school outreach session and it stopped the sct from dewing up. The soft black drawing paper came from their art dept! Worked better than any purchased dew shield! Worst scope for dewing up I have at the moment is a truss RC. the main mirror goes almost as soon as the secondary. If I heat the secondary the main mirror still curtails observing. Open tubes in this country are a liability. Don't imagine a refractor will be immune, I have had issues with these as well, though to be fair they take longer to dew up if they have decent dew shields. Once again the long art paper dewshield worked with them too even if they had long metal dewshields. Ian B

I sympathise with your problem Matt. I have struggled with this for years. I tried Dew shields, multiple bands desiccant in the tube etc. Trouble is the air is so moist in this country at this time of year. The only way I found to hold it off for a while is to thoroughly heat the tube and corrector with a hair dryer about 15 mins before observing. It cools down just in time for visual use and a few mins longer for imaging. Then I have 1/2 an hour to an hour before the corrector dews up again. I have heard some flocking material does a decent job of holding off dewing. I cork lined an SCT I had many years ago, it was a messy and tricky job and to be honest made no noticeable difference to dewing. Ian B

I am trying to help a friend set up his old Nexstar 8 and it's got me beat at the moment. The telescope is an original version from the 1990's and has a hand unit version of 2.12.12.6 I have checked the stored location is in the UK though I believe the 2 star alignment process for alt-az use doesn't use this. The date and time are also correct, though I notice it does not keep date and time up to date. When switched on it displays the date and time of the day it was last used. Maybe this is a clue? I don't know if this is how the scope is supposed to behave. Anyway......... I switch on and go through the 2 star alignment ie set tube horizontal and then centre on 2 stars widely separated. I chose Vega and Capella. It comes back and tells me it's aligned! Easy - so far. Then I tell it to slew to M45, nothing too hard to start with and not far from Capella, and it tells me it's below the horizon and starts to turn the scope upside down! Turn off and start again. This time I choose Capells and Deneb. Congratulates me and tells me it's ready. As my second star was Deneb I suggested it might like to try going to M27. It tells me that is below the horizon and when I overide it the tube starts to go upside down. This age of Nexstar appears to have the OTA permanently fixed in place so cannot be upside down. Also I figure if it was something like that then the alignment would fail. I am now stumped. Can't see how it can calculate that it is aligned after I do the alignment and then not know where it is. Any help would be greatly appreciated. Ian B

Thought I would post an update to this saga. Having tried the 41 Panoptic and ES 40 for some time I conclude I like the Panoptic 5% more than the ES. This sounds pretty arbitrary but I have tried to put a figure on it and there is no area where I can say the ES is better through my eyes and my telescopes. To be honest the ES has a slightly larger field despite having a shorter focal length and the same declared angular field. If it were a question of finance alone I would opt for the ES, but this is astronomy and once you have gleaned a 1% improvement that clinches any decision. I am therefor probably going to sell the ES. Having said all this I find I use the 31mm and 26mm Naglers more often than the big Panoptic. Indeed the old 20mm Nagler still sees many more outings. For those who said for wide ,flat, fields you are using the wrong telescope I can agree that a decent short frac has the right credentials and to that end have added a FLT132 to my burgeoning scope collection (and overloaded mount!) Now I have my widefield eyepieces sorted I am looking at the other end. I have found myself using my old Ortho's on planets even though I have Naglers down to 7mm, since the crispness of Ortho eyepieces surpasses that of any other eyepiece I have ever owned (had a monocentric a long time ago but it went walkabouts before I had a decent enough telescope to appreciate it). After comparing recent acquisitions to my ancient Meade RG ortho's (7mm and 16.8mm) I once again I find myself looking for the best. I don't need higher powers for my long SCT's but for the FLT I need to fill the gap in fl's less than 7mm. I have 1970's volcano top orthos in 6mm and 5mm fl, but they just aren't as crisp as the 7mm RG Meade. I acquired a 10mm BCO, which to be honest does not give the crispness of the Meade RG's followed by a 12.5mm Fujiyama HD-O to fill in the 16.8mm to 7mm gap, but am looking for 4mm, 5mm and 6mm to use with the FLT to get the best out of that scope on planets and doubles. I have been put off the BCO's as they appear no better than my 40+ year old volcano tops. I believe I have sourced a 6mm BGO but also need a 5mm semi-premium ortho at least. I am also trying an old 4mm from the volcano top days to see if that is usable and if so will need the best 4mm Ortho I can source. I find it very odd that there are no mid price range Ortho's out there today with the plethora of short apo's on the market. To get the best out of your 4-6 inch apo on planets there seems to be nothing better than a decent ortho and today they are as rare as hens teeth new and about the same on the s/h market. The BCO's and Kson examples are available, and are cheap, but no better than the ancient volcano tops despite the improvement in coatings there has been in 40 years. I also note the BCO range now stops at 6mm, which seems an odd marketing move. I really hope the weather picks up soon so I can get out there observing as getting my astro fix through buying kit is getting expensive! Ian B

3 months after I acquired the ES68 Argon filled 40mm I was offered a 41 Panoptic and so now have both. Given the lousy seeing conditions we have experienced this year it is unfair to make too strong a claim for these two eyepieces that obviously require the darkest possible sky to perform to their max however I do have some initial observations. The 41 Pan turns out to be less of a problem to use than many on astro sites suggest. I find it quite easy to position my eye in the right place and the shorter eye relief actually makes using the ep more convenient than the ES 40 since the eyecup on that ep is too short to form a good barrier against external light interference. The adjustable eyecup on the 41 Pan scores here. The stars are definitely sharper across the field in the Panoptic and the sky a little darker. I do not find the field stop particularly fuzzy with the Panoptic, which was an issue I worried about. To be honest the slightly out of focus stars at the edge of the field in the ES are more noticeable than any lack of sharpness in the field stop of the Pan. Measuring the true FOV I would have to conclude there is little to choose between them. I got the impression the ES had a very slightly larger TFOV, though this is very hard to quantify. Both eyepieces seem to suffer some vignetting when used with a 2 inch star diagonal. The outer part of the field is definitely darker in both eps. Without the star diagonal the situation improves, but is still just about noticeable. I suspect that if the sky was darker it would be hard to detect. All in all the Pan wins out for me, but not by much. I will wait for darker, clearer skies before making a final decision because both eyepieces show too bright a sky background in the current nighttime conditions. As a result the 31 Nagler continues to be my favorite low power ep. If anyone want's an ES68 40mm in pristine condition in a couple of months I expect I will be passing that one on. Ian B

Since I cannot find a 41 Pan for sale s/h I purchased an ES40 as suggested by several people here. It was s/h so would be a 'bargain' if it filled the role. The skies have not been brilliant since it arrived but I have seen enough to make comparisons. Compared to the 31 Nagler I see more sky, but the outer edges are not as sharp as the Nagler. There appears to be field curvature, which isn't apparent in the Nagler 31 and is certainly more noticeable than in the Panoptic 35. The sky background also appears brighter than in the 31 Nagler or 35 Panoptic. This may be due to the sky conditions but I have read that some ES eyepieces yield a 'dark gray' background sky so it may be a real effect. Oddly my ancient 40mm Meade SWA yielded a slightly smaller field but with a darker background. I'm trying hard to like this eyepiece but it may need a Paracorr to be a perfect eyepiece, which will defeat the advantages it offers namely cost and wider true fov. I wish I knew someone with a 41 Pan so I would know whether it's the holy grail of widefield eyepieces or not. ? Ian B

Sounds like the ES works for you. I am glad it does as with my f4.3 Newt I find low powers with widefield eyepieces have too large an exit pupil. There's no doubt the big Newts score when it comes to seeing faint galaxies and nebulae though. Ian B

Geoff, That's an interesting story. A friend purchased an ES 82/18 and was very happy with it in a F10 12 inch SCT. I tried it in my scope and the Naglers were just so much better. I was both happy and disappointed as there was no potential saving. As a result I chose to wait for the 26 Nagler to be available s/h and continue my Nagler odyssey. I have tried other ES eyepieces but felt they weren't any better than Meades. Price performance may put ES at the top, but for pure performance there are alternatives. Ian B

Paul, The 22 Nagler has an eyecup that can be extended and that makes observing with it quite comfortable. It's a shame the 26 and 31 don't have the same. I can use them as I am used to manouvering my eye to the sweet spot but when showing people objects through the scope I often find they cannot manage and I have to switch to lesser eyepieces. Scopes are all about compromises and I guess I should be happy with 0.78 degrees. This is enough for nearly every object, apart from the largest nebulae, and I am afraid those are simply not visible to the human eye in the polluted skies we have to endure. It amazes me Herschel found so many of these from Slough! I'd just like to get the maximum field that I can. Ian B

Thankyou for this info. I had heard the MaxVision 40 was supposed to be a Meade SWA in a different housing. Hopefully it is just that as I already have a Meade SWA 40 which I never found as sharp round the edge as the Nagler or Panoptic. It's OK, especially at longer focal lengths, but the actual fov seems to be on a par with the Nagler 31 (despite the sums saying it ought to be about 5% more). It appears there are no really good 40mm+ eyepieces around. I should own up that I also have a Meade 56mm eyepiece which yields about the same fov as the 41 Pan would, but it is like looking through a narrow tube at an overly bright sky and still the outer regions are not sharp. At least it reminds me that going to too long a focal length is pointless in 2" format. I initially discounted the 41mm Pan due to the perceived fuzzy field stop, which to me would make it a poor eyepiece, but I just cannot find a better one. I was hoping to pick up a decent priced s/h one that someone didn't like. New price (with a bit of bargaining and not using a credit card) is around £450 so, to me, at least, a s/h one ought to be not much over £300, after all a Nagler 31 can be picked up for £350 if you are patient. At that sort of price the Pan could be moved on if it did not provide the view I am after. The cost of going to 3" would be horrendous and not financially viable for just one eyepiece. It seems most people are singing the praises of ES eyepieces, which offer cheaper alternatives to the Televue offerings, but are not quite in the same league. Ian B

I thought my eyepiece collection was complete until I bought my "last ever" telescope. This operates at a native F8 and is just over 3250mm fl. I have the longer Naglers, 31, 26, 22, 17 etc and 35mm, 27mm Panoptics. I was always a little disappointed with the kidney-beaning in the Naglers in other telescopes, though they were overall better than any other eyepiece I have used, but in this one they seem to be affected less and even the 26mm is now a keeper. Before I got the Naglers (over many years all s/h) I had 35, 27 and 19 Panoptics. These were my favorite eyepieces until the Naglers came along. I kept the 35mm as stars seemed a little sharper in the inner 50 degrees than the Naglers, but trailed off in the outer regions and the 27mm as it really is an exceptional eyepiece. In any case I often wanted to darken the sky with higher magnification so the longest ones were primarily used for sweeping and finding. Given sky brightness is becoming more of an issue I thought I would never need a longer focal length. Now the Naglers seem sharper over the entire view and with the higher magnification of a longer scope the sky is darker and I hanker after the widest possible field. The issue is that the 82 degree 31mm Nagler gives me a true fov of 0.78 degrees and the 35 mm Panoptic 0.73 degrees. There is noticeably more sky in the 31mm Nagler. A 41mm Panoptic will yield 0.85 degrees, an improvement of nearly 10% over the Nagler 31. As I can readily see the difference in the amount of sky covered by the 31mm Nagler and the 35mm Panoptic I believe the time to look at a 41mm Panoptic is here. Before going into a debate on whether ES eyepieces could fill the slot all I can say is that having been able to compare my old Naglers with new 82 degree ES ones in my scopes I and convinced that, for me, there is a small improvement with the Naglers at the outer regions of the field and so I am minded to discount them. They are fantastic value and I won't deny they are very good eyepieces. The 41mm Panoptic would seem fit the bill for this long fl scope though I suspect it would be a disaster in a fast Newtonian, which I also have. My quest is to find someone willing to part with theirs and/or suggestions of an alternative that someone has used in practice. Thankyou for reading Ian B

I'm afraid mounts are usually the Achilles heel of any telescope. I had a C9.25 for a couple of years and found it was only really stable enough on a Losmandy G11. That combination worked well, far better that the SW HEQ5 I first tried it out on. However that setup isn't easily portable for one person. If I had one now I would look at an Ioptron eq45 mount. They are pretty easy to set up and stable. However they are weighty and cost nearly twice as much as the skywatcher offerings. In my opinion they are better built than SW, quieter and easier to use. If you need to buy on price the the SW EQ6 is your best bet for weight carrying, but I always found ease-of-use determines whether you use a scope or not. A second hand Losmandy G11 or Ioptron EQ45 will hold it's purchase price pretty well though like cars there is a big hit for the original purchaser. If you don't use the equipment you have then it is the wrong setup for you. I would start by trying to find a mount you are happy with. This can be very expensive and time consuming as I have found out, so best to try and find someone local to you who already has the mount you would like to try. I recently lent someone who had previously owned SW mounts my Ioptron EQ30 for several weeks and it persuaded him to buy his own. He said it was so easy to use and quiet compared to the SW ones.. Ian B

I have built quite a few observatories but never been lucky enough to have a large choice of where to put them. The best place for an observatory is where it will cost you less grief from the family or intruders. Observatories that are a long trek from your house will get less use than those you can get to easily. Power is pretty much essential to run equipment and heaters to keep the observatory dry and unfrozen in winter. I have lost many a clear night when the domes have been frozen up. Having heating over winter also means your eyepieces won't mist up when you touch them. Of course, heating is intended to be on when you are not using the observatory! I have built both run-off sheds and domes and it is my opinion domes offer the best protection for observing in this country. They shield the telescope and user from both wind and external lights which plague most of us in suburbia. As mentioned here - size matters! Build the biggest you can as equipment grows in size at an alarming rate. I once built a tiny flip-top shed (4.5ft square) to cover what I intended to use as a remotely controlled telescope. The trouble was that to try and check alignment of the optical train and to sort out why the goto wasn't going to required uncomfortable contortions and often working from outside the structure. The result was I rarely used it and eventually replaced it with a small 2.2m dome. If there is any light pollution in your area it is better to make sure your observatory has good access to the darkest part of the sky. Clear southern sky is the best option, of course, but access to the darkest part of the sky if that is in the east or west will mean you can get the most out of your scopes even if you have to wait for objects to rotate into that part of the sky. Also bear in mind any trees that are not under your control. Trees have a habit of growing very, very large! I have multiple observatories to try and get round obstacles I cannot remove (that's my excuse anyway). Ian B