ollypenrice

What always strikes me as odd about dual rig flexure is that the slave scope can show trailing even when the primary scope is carrying a guidescope rather than an OAG. If the primary were guided by an OAG then, sure, we might predict trailing on the slave. But since, in most cases, folks seem to use a separate guidescope mounted on the primary (which is what makes it the primary) you'd expect focuser flexure to cause problems on that scope as well. If the problem always strikes the secondary scope (which seems to be the pattern and is something I occasionally get) then surely the flexure must be arising between the two imaging scopes. In that case the culprit must be in the mounting hardware, so the dual bar, alignment device or tube rings? I know Sara found that the clamshell alternative to rings in her original dual Tak was causing flexure. Unless... there is some geometric effect we're missing concerning the location of the guidescope relative to the imaging scopes. I know I once tried centering the guide scope on the same FOV as the imaging scopes, something I wouldn't normally bother to do. Unfortunately I can't remember if it made any difference! Doh. Olly

Make a vee block to hold the laser. Don't panic, this is ludicrously easy! 😁 You need a flat bit of wood and four six inch nails. Bang in two nails crossing each other to make an X. Bang in a second pair to make a second X separated by the length of the smooth body of the laser. Lay the laser in the cradle formed by the two pairs of nails and point it at a wall as far away as conveniently possible. Say ten feet or more. Fire the laser at the wall and rotate it in your high tech vee blocks. The beam from a mis-collimated laser will describe a circle on the wall when rotated. A perfectly collimated laser will produce a dot on the wall when rotated. Olly

You need a better magazine!!! Olly

I'm outta here!!!!! Olly

So would I if all things were equal and reflectors 'just worked' like refractors... But, and this is a big 'but.....' 😄lly

I wouldn't try to make a dual rig for simultaneous shooting with a reflector. It's likely that mirror movement will produce trailing on one side. But is it your plan to have alternative fields of view? If so you'll be wanting something with half or less the metre FL of the Quattro? My favourite scope in this class is the original Tak FSQ106N. They go for reasonable prices and can cover full frame chips. Personally I prefer them to the new ED106 scopes but I do have some odd opinions! 😃 Olly Edit: I wouldn't guide the refractor with an OAG on the reflector, either, since mirror movement may get you that way as well. You may not have been planning this but I mention it just in case.

The Meade might prove to be far easier to set up. Some people get the GSOs into good working trim but some struggle for ever and a day. It's worth noting that, a few years ago, several suppliers were working on re-engineered scopes using GSO optics but these have, it seems, gone rather quiet of late. Maybe it wasn't as simple as it seems to get these instruments working well. There's also the Celestron Edge series to consider. Personally I've concluded that I can work close to the limits of the seeing with a FL of a metre from a 140mm refractor. The 14 inch I used to use could out-resolve it very slightly on a good night, maybe, but refractor simplicity is such a bonus. Since pixels are getting ever smaller I wonder if I'll ever really want more focal length than I now have. Some examples of 0.9"PP from a 140 F7: Olly

Well I was a great admirer of SteveL, and greatly miss him, so I stand chastized on the matter of those horrendous monuments to the processed food industry! 😁lly

I can see fried eggs taking over from those horrendous tangerine biscuits (what are they called?)* on SGL. Jolly good thing, too. Olly I remember: Jaffa cakes. Give me alien slime any day!!!!

Which are rare in the north west... 😁lly

“Aliens exist, there’s no two ways about it,” Dr Sharman told the Observer Magazine. “There are so many billions of stars out there in the universe that there must be all sorts of forms of life. “Will they be like you and me, made up of carbon and nitrogen? Maybe not. It’s possible they’re right here right now and we simply can’t see them.” Here are two statements presented as verbatim. The first, that 'there is no doubt about it,' is factually incorrect since there is, among professional scientists and the general public, considerable doubt about it. Paul Murdin, in his book on the subject, says he began the study by thinking the universe would be full of life and ended it having changed his mind. However, a non-pedantic person would read this as Helen Sharman's opinion on the matter and a perfectly reasonable one, shared by plenty of people including many professionals. However, it is no more than a working hypothesis. The second, that they might be present among us and undetectable, does not of itself condemn Helen Sharman to the ranks of the Bacup Nut Jobs. No less a luminary than Fred Hoyle argued that infectious organisms come from space. The opinion that most of the universe is in an almost undetectable form is actually a mainstream view in cosmology. Being open to the notion that undetectable stuff might be used by nature to make undetectable aliens is surely a sensible position to take even if you thought the odds were very long? The problem arises when the statements are taken out of context in a world in which the Bacup Nut Jobs (a sub-sect of the Portsmouth, New Hampshire Nut Jobs) assert that aliens made of the same stuff as us are just behind that cloud and itching to take us for a spin in their saucers. This is what the journos want her to be saying, but is it what she's saying? Olly

As this is in the 'getting started' section I think it would be appropriate to say, here, that the term 'crop factor' should be dispensed with in astrophotography. It offers a means of comparison between the field of view of 'chip x' and a traditional 35mm film-sized sensor. This is not a useful comparison in astrophotography and leads to confusion with regards to being 'zoomed in.' (This is another phrase which we should abandon.) 'Crop factor' implies 'zooming in' which in turn implies an increase in captured detail. In reality more detail requires an increase in focal length or a decrease in pixel size or both. Detail and sensor size are entirely unrelated. We should stick to focal length, chip size and pixel size in this kind of discussion and describe resolution of detail in terms of arcseconds of sky per pixel. That way we can avoid confusion. Olly

Welcome from another Lancastrian - though I've long lived away from my birthplace. Olly

If you want to optimize it you can save two versions with different expand-feather values for smaller stars and larger ones. Olly

In this image I think you've black clipped it so much that none of the rotating noise of the first one would be visible anyway. Some field rotation remains visible in the stars, though. The only defence against field rotation with an alt-az mount is to shoot short subs. (Actually no, you do have the option of relocating to either the north or south pole... 😁) If you're feeling diligent and have Photoshop there is a simple software dodge for making stars round. Saved as an action it can work quickly but only on one star at once. Your action, saved to a function key, should record the following once the magic wand has been used to select a star: -Select, modify, expand (try 5), -Select, modify, feather (try 3). The chosen values depend on camera-scope specifics. -Filter, blur, radial blur set to best quality and spin. Run the filter twice. -Deselect. (Don't forget to record this.) Once done you magic wand a star and hit the function key. Voila, round star. Olly

Both of mine have been 100% reliable and so have the three I host. The SiTech does seem to be tricky to set up (mine are ArgoNavis) but in terms of reliability Mesu have the high ground here. No question whatever. Olly

I used to like you, Andrew! 😁lly PS And Vlad can shut up as well!!! 🤣

Now, Alacant, your insistence upon remaining forever in the beginner section should, in my view, preclude you from making 'in jokes' regarding focal ratio which, for real beginners, are a source of serious confusion and sometimes the wasting of money. While those of us who know you know that you do not fall for the F ratio myth, we must be sensitive to the needs of genuine beginners in search of real information. Play fair. Olly

Believe me, I'm not an expert on computers, hardware side or software. Ahem, 'not an expert' is likely to remain the understatement of the year, world wide, despite the year being only four days old... 😁lly

You may be right but, unfortunately, I love using it and hate learning new software! (Old gimmer, stuck in his ways!!) Olly

This is a good point with a wide application in astronomy, I think. It's in the nature of commercial lens manufacturing (and probably in the nature of high end lens manufacture as well) that final quality will be variable. When a supplier makes a batch of products they will find some that don't meet their customer's specs so either they won't send them or they'll have them sent back. Are they then going to take a hammer to them? I very much doubt it! They'll go to the dozens of re-branders out there. I haven't bought an SCT reducer for years since I don't image with our SCTs and the reducers offer no advantage in visual FOV over a 2 inch back and a widefield EP but I've never noticed any difference between Meade and Celestron reducers. That may have changed. Quality control is really one of those things you pay for when you buy expensive optics. Olly

You could crop the top out if this if you so wished and it would still be an attractive framing. It hasn't happened to you this time but, quite often, when you move a bright star out of the frame it throws up a big flare like a light house beam. When we imaged this in a 14 inch reflector we had such beams from the bright blue stars west of the Horse. Olly

Your Crab's nice and a classic in the LRGB/OSC genre on this object. The problem, if there is one, is not that the core is saturated (it isn't) but that the filters you're using are not holding down the broadband spectrum around the filaments so these don't show strongly against the light around them. The bolder Ha filaments show strongly but an OIII filter would find an intricate network of fine lace-like lines. I doubt that any image can have it both ways, ie the natural look of LRGB/OSC and the contrasty filamentary detail of narrowband. (I hope to find out next month by taking some LRGB to go with this month's NB.) Your version, colour apart, gives a good idea of the eyepiece view in large apertures. I like it. Olly

Filter Wheel Runner, I think, is just an Atik download. From memory it was part of the Core Software. I only discovered it by accident so you may have it already, perhaps. Olly

Ah, all mine are Atik EFW twos... (Not what you wanted to hear!) My most consistent problem is that they fail to connect properly to Artemis. When this happens a lot of plugging and unplugging sometimes works but occasionally it doesn't. When I try again in the morning they connect. However, the arrival of Atik's Filter Wheel Runner offers an alternative control software which gets me back in business, though without the ability to run sequences in Artemis. Olly