Tiny Clanger

Just checked my own DIY foam dew shield for my 127, and I made it 26cm deep, of which maybe 6cm is on the tube and therefore 20cm protrudes. It has worked perfectly for me, no vignetting (which is what a photographer would call the light fall off in the corners from using too deep a lens hood on a camera lens) . What limited my decision on size was the stiffness of the material : I used 3mm closed cell foam https://www.efoam.co.uk/closed-cell-polyethylene-foam.php and it seemed likely that a much longer dew shield might either sag or get blown around and out of shape if it was breezy . Heather

I was out with my heritage 150 dob from 2am until about 3:30 am (after putting my new refractor through its paces earlier while the Moon was up ) I had to take the dob out , it was my first proper scope and yesterday was its first birthday 🙂 I got a quick look at Saturn (which, with the poor seeing appeared to fizz like an effervescent tablet with any serious magnification) before it vanished behind the trees, Then switched to faint fuzzy searching, and having finally managed to see the Dumbell Nebula which is somewhat of a challenge in my light polluted back garden, , I spent the last 30 minutes or so until the sky brightened nudging the dob to keep Jupiter in view. My 8mm BST was too much mag.for the conditions (94x), the seeing was not good enough, but the 12mm gave a decent view ... that's just 63x in the dob. Still, the orange banding was visible, and sitting watching for a sustained time gave brief glimpses of structure and finer detail. As you saw, Jupiter is bright, you can be dazzled by it when your eyes are dark adapted, but give it some time and you see more as eye and brain adjust. If you have a Moon or variable density polarising filter , you could always try that , or even the slightly mad stopgap of sunglasses ... I didn't use any filters last night , but I have tried various coloured filters before. Some people like them , some see no point. To find out which I was, I bought a very cheap set of half a dozen no-name Far East ones for about £15 from Amazon, and found when Mars was well placed in the winter the filters really helped increase the contrast of the surface features, so I bought some better quality but still fairly basic ones second hand . I've not had the chance to try any on Saturn & Jupiter yet. Here are a few links with information about filters, there seems to be a fair bit of variation in what different people say are useful for particular situations, I think it may well be heavily dependant on both your telescope and your eyesight. A relatively small aperture 'scope like mine and yours isn't going to work well with strong filters which cut a lot of light out ... the dark red filter which was included in my cheap set was useless in the 'scope, just too dark an image, but is doing sterling work taped onto the front of a small torch to make it a red light ! https://www.firstlightoptics.com/flo-guides-colour-filters-to-improve-lunar-and-planetary-visual-observing.html https://astunit.com/astunit_tutorial.php?topic=filters https://sas-sky.org/wp-content/uploads/2011/09/SAS-The-Use-of-Astronomical-Filters1.pdf (I think they put some images in the wrong paragraphs there) https://agenaastro.com/articles/guides/visual-and-imaging-filters/choosing-a-color-planetary-filter.html Heather

If you are asking for local government funding, then I suspect the awe and wonder arguments , whilst exactly what I'd give to try to enthusea member of the public , would not have any effect . The people holding the purse are probably only interested in money (which is why they got the job ...) so you want a solid, financial basis for your request . I don't think 'pure' astronomy will give you anything they would appreciate, any more than the study of Renaissance painting, or Shakespeare's sonnets or pure mathematics would . However, what might support your cause with clear statistics and economic benefits would be the applications of the theoretical knowledge gained by astronomers, and the employment opportunities open to graduates in the subject . For instance , India has recently become a country with the ability to launch large satellites into space , and can provide that service (at a cost) for other countries, astronomers will have been involved in that financially huge, successful project's set up and its continuing development , which has enormous economic implications for communications and GPS systems. wikipedia has this quote, and if these numbers don't make the money men impressed, they probably don't know how many zeros there are after a figure in billions : "In 2019, the space industry of India accounted for $7 billion or 2% of the global space industry and employed more than 45,000 people. Antrix Corporation expects the industry to grow up to $50 billion by 2024 if provided with appropriate policy support" Weather forecasting is an area of employment I know astrophysics graduates have taken , as is climatology and the implications of global warming to future weather patterns, flooding, agriculture etc. , a financially important and urgent areas of study. Disaster management is an unfortunate but important topic where satellites provide planners and rescuers with invaluable information too. Heather

Just a reminder that the radio programme 'The Blind Astronomer' is repeated tonight in half an hour's time at 9pm: https://www.bbc.co.uk/sounds/play/live:bbc_radio_fourfm It lasts 30 minutes. Heather

That is fascinating, Barry, but I am a bit worried about what the impressionable folk might make of it ! ("Airliner and airport terminal buildings seen on Moon !" 😉 , "Ryan Air announces Mars airport opens ... " 🙂 ) I am in no way a structural engineer, igneous petrologist or someone who knows anything about growing plagioclase feldspar crystals, but with a little bit of distant and vaguely remembered geological education, my initial thought was that looks too ...organised for igneous petrology to explain away. Columnar basalt is a pretty common phenomenon all over the Earth (Giant's Causeway etc ), but those are entire areas of vertical columnar jointed basalt, not isolated fallen specimens. Then I thought of lava tubes , which are found on the Moon as well as the Earth and (on Earth) can have structures within them somewhat similar in appearance to the stalactites of limestone caves . Presumably the absence of atmosphere and lower gravity would change the likelihood and probable form of such a structure. But how such a thing might end up lying in the open ... I'm intrigued. Heather

I believe the Bresser finder shoe on some 'scopes is not the usual fairly standard one, but replacement shoes can be bought which have slots rather than holes for fixing, so can fit a range of existing spaced holes. The Bresser dob might have a standard shoe and a Bresser/Explore Scientific type one as well, I'm not sure . I'm trying not to yearn for one too much .... the lead times are so very long .... The 102 mak has a focal length of 1300mm in a small body (not sure exactly how small , but my bigger 127 has a focal length of 1500 mm in a tube 320mm long) a refractor of that focal length would actually be close to that physical length itself , and therefore be that bit harder to mount properly ... a quick look suggests the Bresser 102L at 1000mm focal length for a fairly similar price to the mak for comparison https://www.firstlightoptics.com/bresser-telescopes/bresser-messier-ar-102l-1000-refractor-ota.html Every 'scope type has strengths and limitations, which is why I need three 🤪 , and actually have a 4th en route .... Heather

I have only used my AZ5 on my old Manfrotto 55 series photo tripod , and with a skymax 127 on top , which weighs ( I think, from memory) 3.5kg ish, I've a RACI, Rigel quickfinder and decent diagonal on it, so perhaps 4 to 4.5 kg including eyepiece (BST starguiders, not giant hand grenades !) It's the only decent AZ mount I've ever used, so the fact that the clutch knobs are tiny hadn't even crossed my mind until you said that 😁 , they are all I've ever known ... Yes they are small , but I've used the mount through the winter (I bought it last November) and twiddling the tiny clutches has not been a problem for me, even when I took the mak out when snow was on the ground (I used fingerless mitts so retained my dexterity) I only use the az slo mo cable, I find it easier to reach the alt slo mo with just the knob attached , keeps the set up more compact too. One thing I had not anticipated was that the 127 skymax OTA has the dovetail underneath ( altho' if you buy it bundled with the AZ5, the dovetail is to the side) . As you side mount on the AZ5, I had a conundrum : either have the finder shoe underneath 😞 and the AZ5 clamp and arm to the right of the 'scope tube as the AZ is designed to be, or effectively mount the 'scope backwards , i.e arm/clamp left of the tube (as seen from the eyepiece) which means that despite changing the angle of the arm to the more vertical setting, the back of the mak tube touches the az slo mo cable when I go higher than 60 degrees. Which is a pain, and means taking the cable off. Just using the knob not the cable would be no better. Obviously this may not be a problem for you, especially if you have tube rings , or a more appropriately placed dovetail. As to the tube diameter, I did just out of interest try out my 150mm heritage dob on the AZ5 just once when I first bought the mount (the dob has the dovetail on the 'proper' right hand side so would have no alt problems) and as I recall it was fine. I've got to say thank you for drawing my attention to the AZT6, I'd been wondering about something lightweight simple, reasonably strong and not too expensive to replace the photo pan tilt head I have my little 'frac on, and that looks ideal ! Heather

It does. The lower 5kg rating is based on using the AZ5 on the aluminium tripod, where the tripod is the limiting factor. 9 kg with a decent tripod. Heather

You may recall that I started with a heritage 150 dob, which I still use much of the time , if no Moon or planets are showing themselves, it is the 'scope I take out. Short cool down, decent light gathering, and the simplicity and stability of the base just works, no faff. Bad points : low alt objects can be unavailable to it because it has a low viewpoint, and my fence gets in the way. High magnification can mean a lot of precision nudging to keep targets in view too. As with any newt, you get stars which have diffraction spikes, which some folk dislike.. Would I buy a full sized dob ? Yep, in a heartbeat. The Bresser 8" (200mm) would be my choice: it is a little more expensive than the skywatcher equivalent, but it seems better made, with nicer accessories and a superior alt bearing . It also seems it may be a bit lighter than the SW one, altho' reports of the skywatcher weight vary (while Bresser publish their measurements ) Bressser base 9.5 kg, tube 11.5kg , SW tube officially 11kg, and the base I've seen given as anything from 12kg to 17kg. The lighter weight would contribute to ease of getting the dob outside, so another point for the Bresser. However ... for the Moon, and planets, the longer focal length of a mak is great, as is having the 'scope on a mount with slo mo controls . The SW 102 mak is sold by FLO bundled with a pronto mount , so I'd be confident the mount you already have would be fine for the 102, while the 127 mak at a bit over 3kg really needs a more substantial mount like the AZ5, pushing the price up. Cool down takes a half hour or so, and dew on the corrector plate can be a pain, but with the mak design doing clever origami on the light path, you have a compact 'scope with a long focal length. If I was starting again , knowing what I do now of what works for me practically, , I think I'd go for a bigger dob (200mm not 150mm) and a smaller mak (102mm not 127mm ) because using the mak only on bright objects I don't think I'd miss the extra aperture, but it would make a difference to DSOs in the dob. However ... I've used my cheap second hand ST80 more often since I bought it than I have either of the other two 'scopes : If I'm waiting for the mak to cool, or when there are brief gaps in clouds, and quick daytime forays out to look at today's sunspots , the ST80 is out, tripod extended and in use in a matter of moments. I've enjoyed using it to the point where I am keen to try a step up to a 102mm frac So, whatever you buy next, keep hold of your 'frac too ! Heather

The site says it is repeated 9pm next Monday, it might be available online for a while after that . Heather

Just started on air (online at https://www.bbc.co.uk/programmes/m000wyzg ) 'The Blind Astronomer' about a Puerto Rican astrophysicist

Just to get an idea of what 800 kg plus might need by way of wheels (and the not so far mentioned strength of supporting patio slabs and base material below them ... ) I just searched 'Ford KA in kg' and plenty of results came up ranging from 870kg to 120 kg.

You start at the closest star you can see, and work from there. If the angular distances are greater than , say 3 or 4 hops of the greatest red finder circles diameter, then, for me, the RACI will be a better choice ... I don't want to be doing the equivalent of measuring a room with a 15cm ruler . That's why I have both RACI and Rigel, in some situations one is better than the other. In situations where I'm finding it really hard to locate an object with both finders, and there are few stars nearby to hop from, I use a small, cheap electronic level which gives me a precise alt reading for the 'scope tube, (taking the alt/az from stellarium , other programs & apps are available) which means I only need to pan the az dimension. The levels are often referred to as Wixies on forums, which I believe is/was a trade name. Probably the most useful £10 astro purchase I'll ever make. Worth checking out information on DIY setting circles too for the az dimension. When I bought the mak, I thought I could get by with the stock RDF only , turned out it was frustrating not to have a RACI, so the single shoe on the mak was used to hold a RACI instead. Now I missed having an RDF available (and I'm too much of a wuss to take the mak apart and drill it to fit a new one, doing that to my dob was nerve wracking enough !) So I bought the Rigel primarily because of its stick-on base. Subsequent use has shown me that it was an accidental excellent buy , I never anticipated how useful those circles would turn out to be for me.

The point is that you have circles of known size (two on the Rigel at 0.5 of a degree and 2 degrees , three on the Telrad, which has an additional outer circle, 4 degrees if I recall correctly ? ) Using a star map, or app , you can make a note (in advance on paper if you wish, which is often what I do, sometimes on a free printed out starmap ) of the angular distance between a bright star and an object you want to find, but which may be too faint for an optical finder. So, for instance , the Crescent Nebula , 3 deg. from Sadr, the centre star of the Cygnus cross. I got Sadr centred in the Rigel inner circle, shifted the 'scope the correct direction to move towards the nebula until Sadr was on the 2 deg. circle, then estimated a further 1 degree shift, using the 2 deg. circle to gauge it. The optical finders I have (a 9x50 RACI on the dob, a smaller 6x30 on the mak where the bigger finder just seems too large by comparison) have, as far as I have been able to ascertain, a FOV of approximately 6 degrees, but I've not been able to track down precise info on them. The fact I couldn't flippin' see that particular nebula (which is why I still have the note about where to look for it) , despite knowing I was looking straight at it, is down to the bright summer night plus local light pollution ! But I tried, and I'll try again, and one night ... The system has worked perfectly well for me to find plenty of other faint stuff , and I really miss the Rigel's circles when using my heritage dob ... I haven't worked out a way to mount the Rigel on it in a place I can actually use it yet, so am stuck with the stock RDF on its tiny flimsy non-standard fitting. If some smart individual can design and 3d print a suitable platform to fit the little block for the RDF, and stick a Rigel base to, I'd be very happy to buy one ... Heather

I've a suspicion that in the case of that specific job, you have to pay FLO .... 🙂

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Despite my interest in photography, I've never taken a pic before through a telescope ... because I have high standards which I couldn't afford to live up to ... but as I was occupying myself in the long waits between thin cloud patches by taking pic.s of birds & bees in the garden, I had a camera to hand, so ... first ever attempt at eyepiece projection ( F15rules, that 40mm plossl came in very handy for this, thanks !) and a couple of cloudy souvenir snaps : nearly finished ... very nearly finished ! Heather

Cloud, cloud, cloud ... lighter cloud, slight brightening, try to line 'scope up, boo, thick cloud again 😞 But 8 mins around noon of thin cloud, and as I'd fetched the electronic level off my dob, and used it to set the alt for the ST80 from stellarium, I was already in the right area, quickly on it for a second view, not perfect, but better than nothing 🙂

99% cloud here in Leic.s, but I'm sat outside with the ST80 set up and waiting ... and was rewarded by a tiny window in the cloud at 10:21, which gave me 7 minutes to see the start of the bite out of the disc. Some strong winds high up, apparently, as the clouds are moving fast , looks like there could be more gaps heading my way ...

I have a RACI and a stock RDF on my heritage dob ( i.e. a newt on a dob base) too 🙂 , as i said, I need all the help I can get ! Because only half of the heritage is solid tube and the stock RDF is on a non standard mount out at the front on the extending part, I've left the RDF as it is, and the fairly heavy 9x50 RACI I got for it has to be on the solid tube, some way from the eyepiece. Which is a bit awkward.

You are welcome. Stay safe, hope you get to enjoy the partial eclipse even if you can't take the photo you envisaged.

6x30 RACI and Rigel Quickfinder on my 127mm mak, , (that's 5" in old money) only very slightly bigger than your 'scope. In the background is my little ST80 refractor, which is thriftily using the stock RDF which came with the mak , the little 'frac has such a low magnification that it is its own optical finder ( people actually do use ST80s as finders on really big 'scopes ) A 32mm plossl produces 12.5x magnification in the ST80, not much more than I get with my binoculars ... I used to have a celestron 114 (I inherited it) ,the RDF on that was held on by a couple of bolts, and I had to pack some paper or card between RDF base & 'scope tube to get it aligned. I think the bolts might have been spaced so you could use the same holes for one of the finder shoes with slots like this (it is upside-down in the photos !) for adding a RACI, or an RDF with a standard base. The Rigel Quickfinder comes with a base you stick on with supplied sticky foam pads.

There is no way you can record both the Sun and the landscape safely at the same time with your telephoto lens. Let enough light in to your camera to expose the landscape correctly, and the Sun will be too bright to register, and almost certainly overheat and damage your camera too , lots of plastic components to melt in all that energy you are focussing inside it. Filter the Sun with proper solar film to safely include the Sun, and the landscape will simply not register at all. You can do one or the other. Please don't try any telephoto lens photos with a well above the horizon Sun in frame and no solar filter, or risk looking at the Sun directly to line your camera up. It's remarkably difficult to 'find' the Sun .

Both . They help you find stuff in slightly different ways, and I need all the help I can get : RACI plus Rigel Quickfinder plus little £10 (probably £15 now ) electronic level to use with an alt. measurement taken from Stellarium . Heather

A note of caution here ; OP does not say where in the world they are : in the UK the partial eclipse is when the Sun is high in the sky around mid-day, not when it is low at sunrise . Not using a filter in such a situation could be disastrous.