SIDO

Has me already curious what has landed on waxing cresent portion of the Moon 😉 

Nice challenge indeed...

Edit ;

"Curiosity" got the best of me and I thought to share a little with my fellow runners up...

Clickable Missions Map Here :

https://en.m.wikipedia.org/wiki/Moon_landing

Best of Luck and Clear Skies Everyone!

                            Freddie.

Welcome to SGL Mark, Best of Luck and Clear Skies of course...

                         Freddie.

When my asi390 arrived it had dust on the sensor, sharp dust bunnies appeared when trying eeva with it.

Removed the protect window and used a qtip to remove the dust and all was good, same senario with my asi385 I don't blame zwo as it's dust and its everywhere...

A couple more hours and I'll give Jupiter and Saturn a go, got intermittent cloud Sunday and did ok on them but just ok and really think I can do better even with them so low. Did hit the Andromeda triple M57 M51 M63 and a few Ngc's before and after the planetary stint on Sunday but seeing was mediocre and transparency less than adequat and cloud almost ever present, the Milkyway did brighten just as the bird's began singing though gotta love when that happens...

The rainy season just keeps dragging into summer here and the last two years have been wet all summer, summer usually means dead grass and hot dry air here so things are outside of normal and I'm hoping the trend ends soon.

                      Freddie.

Haha, Spoke too soon...2 separate systems now approaching looks like I'm all wet again and maybe all night.

I"'ll be up all night anyway so if there's any chance my scopes are on wheels 😉 

5 hours ago, John said:

I use a plastic magnetic strip (intended for kitchen knives) and a couple of iron weights which I can switch around to counterbalance my 12 inch dob. The tube of my scope is aluminum so I can't use magnetic weights directly onto the tube. With 2 inch eyepieces, and a couple of finders, my dob would be top heavy if I did not use this:

Several years ago before becoming disabled I ordered two high end chrome roof rack slides for automobiles for use on my 12 and 16" dobs as counterweight slides, my circumstances left them stored in the garage rafters until now and your photo reminded me of them. Thanks for the reminder...They can be cut to length and the endcaps re attached so I've got quite a system just have to get that sorted. Can't believe I forgot a $200 purchase, must be the injury trama or maybe just old age I guess...

4 hours ago, wimvb said:

 

Actually, the psf of a defocused star can have a dark centre even for a refractor at the right amount of defocus. Theoretically, that is.

https://en.m.wikipedia.org/wiki/Airy_disk#/media/File%3ASpherical-aberration-slice.jpg

 

I have seen this with my st80 and reducer...

48 minutes ago, Ags said:

Do you have a link to this product? I've never seen anything like that before?

These are just the set rings that hold common 1.25 filters or reducers in place, just the threaded ring with 2 digits on one side. Just make sure to face those digits outward and away from the reducer.  Your reducer has one of these threaded rings holding it in it's case, I borrowed my second one from a cheap #12 filter that I had laying about.

Using less focal reduction provides better images when using my st80 with asi385, I removed the reducer from it's case and inserted it in the camera's nosepiece...It's held there by two set rings that allow for adjustment within the length of it's internal threading.

Easy way to adjust or finetune reduction or achieve focus.

                         Freddie...

Very nice Geordie, Do load the image and take a closer look at this one folks...

Welcome to SGL, Best of Luck and Clear Skies!

                        Freddie...

The coolest thing I found to balance a small dobsonian is magnetic tape, they sell it in rolls two inches an one inch wide. You don't tape it to the scope but to itself then place it on the scope.

Just wrap a strip around the tube adhesive side up then cut a matching strip and apply it bonding both adhesive sides together. Must be done on the tube so it takes it's shape, I did this for countering my laser, 8x50 finder and extended dew/light shield on my 8" dob  and it works great simply sliding it up or down or removing it to balance...Very inexpensive, functional, uniform weighting and good looking solution applicable for many telescopes and counterweights not just dobsonian tubes not to mention this streamlined approach will not get in the way of rockerbox components or cooling fan wiring when used on a dobsonian. Did I mention it will never scratch the finish either 😉 

Here is a pic...

Best of Luck and Clear Skies of course Everyone!

                       Freddie...

Patients and consistent observation wins the night again, this hobby has always reminded me of fishing in that regard.

Cool you had a "bit" of success Stu, I rolled the dob out last night but unrelenting haze to the south with strorms passing through northern Illinois prevented using it, will try again tonight...

Some like to believe the Universe is a projection or a hologram or it was constructed in some way, my belief is it's certainly constructed but by the mechanics of physics, mass, elemental composision, action and reaction of those criteria in complete chaos with our perspective being orginized chaos as we look from afar in ultra short exposures of time. If one could view the universe from overhead as a giant in real time and watch it from its tiny beginning to its massive end all taking place as an object 3 feet spherical in a few seconds it would become quite clear the unorganized reaction before us.

                      Freddie.

Awesome stuff Bill, "no astronomical darkness" bites the dust in that shot, nice capture indeed...

Thanks for the links too.

                         Freddie.

Hello Nikki...Welcome to SGL, Best of Luck with that Future Telescope and Clear Skies of course...

                        Freddie.

Very nice, seeing objects appear onscreen can be quite entertaining doing visual mostly I never quite caught that until starting in eeva and now like you I have been bitten and the only cure is clear skies and more kit, alot of fumbling about and there is the learning curve too but very well worth what is revealed.

Best of Luck with it all...

                        Freddie.

7 hours ago, MSammon said:

It’s the mounts that are putting me off a refractor especially as I don’t really do astrophotgraphy. I do like the dob mount. I’m going to order another filter just to try. Perhaps a variable polarising one. I will get a 7mm eyepiece as well. Also a Cheshire collimator and maybe a new focuser as the rack and pinion thing is awful. Got lots to try to get the best our of this scope first. Thanks everyone for the replies. I will let you know if I get to look through a refractor or if improve my view with the dob. 

I hear you on the mount issue, I run an alt az mount with slow motion controls for my 90mm f11 refractor and to be honest upgrading to a 102mm f11 likely would be a bit shaky on my 20# capacity gso mount due to the overall length/weight of the scope and it's corresponding moment arm effect though at some point an Ed doublet of some shorter focal length but similar aperture will be upgraded eventually as I'm not getting any younger lol... My 90mm weighs in now at 8 pounds due to a new original style synta focuser and light weight dovetail & diagonal replacing the heavier items I had in place for some years due to the disability thing coming about, the scope only pushes about 120x in average seeing so I have the crosshairs in the 50mm right angle finder removed so that larger targets can be viewed without obstruction at widefield and due to the limited mag of the telescope crosshairs are of little need to an experienced observer. The scope has for years provided a quick and easy alternative to my larger scopes and has complimented them well.

For a filter idea I would suggest a neodymium coated moon & skyglow filter as it's just a great filter for Jupiter and Mars providing enhanced views of the grs and other details of those two worlds, if I could only keep one filter for those two planets it would be the Moon & Skyglow.

When observing the planets the meridian will mark their highest altitude and this marker can be enabled in Stellarium or similar planetarium software, when observing planets I stick to one hour before and after the target passes it but not all observer's have the unobstructed southern views I have and I get that.

When using my 200mm dobsonian for Jupiter, Saturn and Mars I do incorporate a Dispersion Corrector and do fully see an improved view using the device and have not peered through a larger scope without one installed while visually observing bright planets in some time and inturn have lost the ability or need for reliable comparison. Some swear by them others see no advantage I just use them and do not promote them as alot of variables are in play observing the bright planets and these devices can be very confusing and overly complicated for those just starting out.

Do try the Moon & Skyglow though if you haven't already, I think you will like it...

                          Freddie.

12 hours ago, James said:

Everytime I suggest to my wife that a bigger telescope or an observatory is a good idea she asks "Oh yes? And how often will you be able to use it?"

So, no bigger scope or observatory yet...  American and Australian astronomers must face the same pressure?? Surely?

James

I read your post over several times James but can't quite figure out wich pressure you are referring,  I will assume here you are referring to weather in the UK and your wife is just providing great advice 😉  

The US population is 50/50 with 50% residing in the major cities and the rest living in rural areas and the major city land mass combined would not fill the state of Texas so massive open countryside with way less LP and an acre or more the average land parcel in the countryside mine being .86.

People who have larger gardens and more room for outbuildings and less LP would indeed be more inclined to larger apertures...Their could be other input criteria but my guess is that these are the core tenants.

                           Freddie.

5 hours ago, Sunshine said:

I think the OP has more than he expected in response to his question lol, its ok MSammon, sometimes  posts turn into cerebral wrestling matches.

Even worse my wife won't let me buy the Ts let alone the Tak and this thread has me wanting them both...

Another nice one Ibbo!

I agree with Andrew here but all of the right conditions have been met to evolve a species intellectual enough to bring such a question as you ask, that in itself might que the question beyond just the slight unique character of the system and would be my reason to ask the question but of course I am not.

To construct such a solar system would require a 4.5 billion year ongoing project still underway as we speak so as this would not be a set it and forget it task, so at random it is entirely possible but planned it would be quite  impossible.

                          Freddie...

1 hour ago, Stu said:

This is where some will say 'none at all', and others (myself included) will say the 'quality' of the view.

Until you have looked through a decent quality 4" apo refractor then you will not understand the differences. Nice tight star shapes, no diffraction spikes, contrast etc 

I would not expect a £150 achro to outperform a 10" dob, but with the planets down low, a high quality apo will quite possibly do it, that's why I (keep!) suggesting a 100ED! With a cheap achro you may just miss the point and not prove anything.

@John has recently posted that he is preferring the views through his 4" Tak to his 12" dob on the planets this year because they are so low. I have found similar with an 8" Mewlon vs my 4" Tak; the larger scopes normally win but struggle down at 16 degrees or less where Jupiter and Saturn are currently.

One reason being is that a 4" frac will not be as bothered by atmospheric dispersion as atmospheric dispersion correctors for visual are only suggested for telescopes 200mm and up, it's for this reason I think even 90mm f10 achro's will show some benefits but also have false colour of their own meaning Ed and Apo scopes will do better than achromats in this area.

For achromats f11 is where false colour tends to show less distinction but not all f11 achromats are equal and a better optical figure will often show less false colour, too bad the f11 and up achromats are harder to come by these days mine is 30 years old now and I still can't part with it...Was the one scope I had that saved the 2018 Mars opposition when the others failed me.

                           Freddie.

2 hours ago, MSammon said:

Thanks for very thorough replies. A lot to take in but I do like the science and maths side. It’s still tough to work out to me if a 4 inch frac of any quality will outperform my 10 inch dob. Perhaps if they were closer in size? My collimation might not be the best. I just do it with a collimation cap followed by a star test. I plan on trying a Cheshire eyepiece but I can’t see anything wrong with the star test so haven’t bothered buying new collimating equipment. 

I’m definitively going to try magnification of around X 170-200 but it was the same with much lower (X 120). I’m going to try moon filters as well. 

I feel like buying a cheap refractor for £150 just to try and that would rule out problems with my mirror or collimation if it’s the same. 

Best of luck of course and do work on collimation by laser or cheshire, you should be getting some pretty pleasing views of Jupiter with a 250mm dob and there must be a significant issue preventing that.

                       Freddie.

1 hour ago, Sunshine said:

Those details seem to be apart from the question by the OP, I think he’s talking from a performance at the eyepiece POV, resolving power, yes, one can certainly load a 4 inch frac into a car a lot quicker but, if i had to choose between a final lifetime scope, a 4 inch frac or 10in dob, not much thinking to do.

I answered your question in response to the way you framed it, the generalization of your question allowed this to happen. And yes vehicle load times are another area where small fracs trump larger dobsonians, thanks for throwing that one in there.

The op already has the 250mm f4.7 dobsonian, of course a 250mm dobsonian will outclass a 90mm f10 achromat visually for planets and that has been fully represented in responses thus far and I was not disputing this. But the refractor is the fastest scope on the planet outside of f ratio and on nights were time is limited due to responsibilities or impending cloud the achro can get the job done and be stored away before the dob is acclimated and ready for collimation...

        I was going to leave it right there and even said so...

                        Freddie.