ollypenrice

'Twas ever thus. Take the bulk fix and do the rest by hand. Olly

I think Dave has it. These are propbably StarX artifacts. I was aware of them and tried to reduce them cosmetically but could probably do so a little better. I do use 'Large tile overlap' and, oddly, don't find it takes too much longer. I wonder if partially stretching the red channel through an inverted mask of itself might work. Star size has become a difficult call. I think a small presentation of the image looks better with larger stars while, zoomed in, smaller stars look better. One thing I did do for the first time is an extra stretch of the stars-only through a mask made of the starless image with boosted contrast. That meant that stars against bright nebulosity got an extra stretch beyond those seen against darkness. This is photometrically incorrect, of course, but is visually more natural since tiny stars seen against brightness simply disappear, visually. Olly

Not in imaging. I wouldn't want to image with an 8 inch Newt on an HEQ5. Too big. Olly

Interesting. In our robotic shed we have found that any kind of little 'roof' placed over a piece of equipment keeps dew off it. We now make little doll's house covers to put above above everything electronic. Some of the effectiveness of this will arise from the heat of the items in use but even when they have been switched off for days, in long spells of wet and humid weather, the items beneath them stay dry when the 'roofs' are wet. Olly

I imaged for a little over two years (about 400 nights) with an OAG and a 2.5 metre focal length. I never once failed to find a guide star on the guide chip after framing the target to my liking. I've nothing against the new technology but I have to wonder if the 'missing guide star' is more imaginary than real. My experience was with a CCD Lodestar guider as well, far less sensitive than modern guide cameras. Olly

I host a number of remote imaging rigs and, without hesitation, I would say, If you can, just go for a desktop PC on site with as many USB connections as you need. I have replaced an inordinate number of scope-top mini-computers and hubs but big desktops with direct USBs just get on with it. Olly

Magicians, yes, but the magicians are the optical engineers at Samyang, the electronics gurus making the chips and the software guys like Mabula of APP, the Pixinsight team, the Photoshop folks and the mighty Russ Croman. Paul, Peter and I are just what used to be called 'The poor bloody infantry.' 😁lly

Paul Kummer planned the capture (tricky because so low from our Lat 44:19N), drove the scope and stitched the linear panels in APP. Peter Woods provided mount and camera and I post-processed the mosaic and hosted the rig. Great job by Paul on all counts. Capture details: 8x3 minutes per panel (this is not a typo!) binned in Super Pixel, so half of full size. 24x24 mins makes 9.6 hours all in. It is all in one shot colour. The Eagle, Swan, Sagittarius Triplet and M22 had help from telescopic data in stock. The difference made to the nebulaie was trivial but M22 was transformed from a blobular into a globular. So how did the 24 panels look in super pixel at half size? Clean as a whistle. We run the lens wide open at F2. Larger one here: https://ollypenrice.smugmug.com/Other/DUSTY-DARK-AND-MILKY-WAY-TARGETS/i-khRN6vQ/A Olly

Love the interactions, tails and wisps. Olly

That's excellent. Some very faint stuff showing. Olly

Mount adapter ordered only a few days ago arrived in remotest southern France just now. You can't beat FLO. Thanks, Steve and the team. Olly

I wouldn't recommend the Bubble-Lobster in broadband. The whole region is a red fest with little colour contrast and only comes alive in narrowband. I started it once but got so bored by it that I never finished the thing! You should get a decent Veil but my own preference would be lower Milky Way, still around in September, I think. We're about to post a Samyang 24 panel galactic centre that would give you an idea of what's in there. Olly

If you are going to crop the potentially distorted corners anyway, just shoot away without the reducer. You'll get a little more resolution and lose no time. This is 'F ratio myth' territory so, briefly, the reducer will bring in no more object photons for objects which fit on the chip without it. Olly

Compared with the central obstruction - which doesn't inconvenience any of us - it's trivial, and it's also the right shape for dispersing its own diffraction artifacts. If we are surprised by this, maybe we should blame those misleading O level ray diagrams! Olly

This kind of hardware, bought new, is very expensive and out of all proportion to the quality of the final image. I'd be inclined to devise a failsafe additional strap of some kind. I've concocted all kinds of variants on this theme. Olly

Anybody had this? The mount is an Avalon Linear but, for this issue, it should be the same as the EQ6. (They have the same motherboards, handsets, software and motors.) The mount turns on OK and the handset setup routine works normally. When you ask it to slew to the first alignment star it says 'slewing' but it isn't. The mount remains still and silent. (No grinding noises!) We have done these tests: Tried another handset. Tried control from PC and tried two EQ Direct cables when doing so. Tried a new motherboard. Any thoughts or experiences welcome. Thanks, Olly

Interesting! If we use a larger aperture telescope requiring 4 panels next to a smaller aperture telescope requiring only one - and a) we bin the 4 panel image down to the size of the single panel b) shoot the same total exposure, which will be better? It's surprising that this topic isn't discussed more widely. Olly

This does depend on how big you want the final image to be. I've done mosaics where the project was to make a zoomable mosaic in which small objects could be viewed at full resolution. However, if you don't want it to be zoomable, but just great to view at a moderate size, you need only a fraction of the data. You can hardware or software bin, depending on you camera technology. Olly

I live at a dark site with very consistent skies so the many large mosaics I've done have generally been done 'one panel in one go.' One could make a case for mixing them up at a less favourable site so as to get an 'averaged' result per panel. However, this panel would have multiple gradients to be removed and maybe the gradient software will be more effective at dealing with one consistent gradient? How's that for not answering your question??? lly

You seem to be familiar with the HDR layer masking technique widely used to combine different exposure lengths in M42. Instead of using different exposure lengths you can simply use different stretches, so a very soft stretch for the nebula and a harder stretch for the background sky. Olly

When replacing stars in widefield images, we now have the luxury of total control over their size. If we want a powdery coating of tiny stars, we can have it. The problem, though, is that such pinprick stars when seen over brighter nebulosity are invisible, giving the impression that they are not there in reality. This doesn't look right and is inherently misleading. What I'm exploring, now, is a possible Photoshop solution: 1) Take your fully stretched starless image, convert it to greyscale and greatly increase its contrast. (Eg use the equalize filter and then fade it to taste.) Here's one I made from a Milky Way widefield. Clone out the residual stars ff you like but this was just a test. 2) Open your 'Stars only' image, partially stretched in my case, make a copy layer, add a layer mask and paste the mask above onto that. Stretch a little more through it. That's it. What happens is that stars will be further stretched in accordance with the brightness of the background underneath them. Where the mask is black, they will receive no further stretch while, where it is white, they will receive the full extra stretch. While this does not respect the captured brightness of each star, it does reduce the false impression that the brighter regions are starless. Olly

This is how I'm tempted to think of it as well. What gives me pause, though, is the thought that the idea requires space itself to be able to define a location and I thought that relativity prohibited this, insisting that position can only defined via a relationship between different objects. Olly

When we think of the expanding universe we think of Hubble's observation of the linear relationship between recession velocity and distance to galaxies. We then think of the fact that observers in any of these galaxies will see exactly the same thing under the 'expansion of the universe' hypothesis. It seems to me, therefore, that every observer in every galaxy feels that they are at rest and will be tempted to attribute any 'motion' to all the others. None of these observers considers themslelf to be accelerated. It also seems to me that they are right in this view since, if each observer were being accelerated, in what direction would they be accelerated? If they were being accelerated they would have to be accelerated in one direction but not all the others, so violating their equivalent of Hubble's observation. The notion of the expansion of space allows them to remain at rest and yet move away from each other. This allows them to move away from each other at superluminal velocities. Now, I'm not daft enough to imagine that I have this right but I'd like to know, from those with a proper understanding, what is wrong with my thinking. Olly

That I use... two. I'm using a long FL scope at the moment. I'd bring out a third for more magnification if using a shorter FL scope. So, not many - but they are good ones. I find too many EPs to be a distraction from what matters, which is really looking. Olly

Late to the party but I think you were bringing a visual observing perspective to an astrophotography purchase. In considering the two scopes, what matters isn't aperture but field of view and image scale in arcseconds per pixel. The difference in FL is not enough to make a very significant difference to resolution of fine detail but it is enough to restrict your field of view. I think you made the right choice because you'll notice the extra FOV far more than you'll notice any miniscule loss of resolution. Choosing a scope is like picking out a lens from your camera bag: nine times out of ten your first though will be, 'What focal length do I need for this shot?' Olly