ollypenrice

Yes, perhaps so. However, one of the ironies of widefield systems is that the user often wants to go much, much wider with them and do mosaics. (Personally I have lost interest in my 530mm/full frame rig for single panel targets. I only want to use it for mosaics.) In this case the ability to cover large formats also comes into play so a system which needs multi panels to cover full frame ceases to be as fast as it looks. Olly

In any event, no free lunch in AP... Olly

Goran, there's nothing wrong with that calculation but, like Datalord, I think F ratio is a complicated way of referring to aperture. It's only sensible to compare the same focal lengths, in which case the only physical variable is aperture. As we've concluded on previous occasions the ratio we really want is area of aperture per area of pixel. Olly

I've used the 3 and 5 Astrodons and the 7 Baader in Ha. For me the 3 Astrodon is the clear winner. It gives the most striking contrasts and the smallest stars. Would I pay the Astrodon price for the 5? I'm really not sure... The Baader 3 isn't slow, it's actually faster than my Baader 7. As said earlier, it's 'wanted light' we're after and good throughput. Halos afflict two Baader OIII's I have and an Astronomik (which is supposed to be a no-halo replacement for an earlier one. Sorry, it's hopeless.) The Baaders are 'less bad.' I agree that for this reason alone it's worth going up-market for OIII. Olly

😁 The clouds in Florida, I suspect! Ralf took this at the Florida star party. Believe it or not it can resolve two Jovian cloud belts and I could read car number plates in it at over 200 metres. Bar stool? How dare you! That's an over-engineered pier, I'll have you know, with unique anti-vibration top plate. Olly

Well, let's say you use this scope at F2... It's probably the smallest Newtonian in the world at 1.5cm aperture, made by my friend Ralf Ottow and being used here by Al Nagler. Are you suggesting that with this instrument and a reducer taking it to F2 you would catch your present image in 6 hours when it would take me 70 hours in my TEC140? I really don't think you are asking that question!! Super image. Red, less red? Still a super image. If in doubt, trust Maurice Toet. 😁lly

Comparing a first and last image is very informative. If your software will do it, ask it to align on stars and combine images without cropping the borders. You'll then be able to see just what has happened to the pointing during the run. To align your polarscope set up the mount so you can see a distant feature like a steeple or chimney through it. It should be distant, a mile or two. Put the crosshair on the feature. Now rotate the mount in RA to rotate the polarscope. Does the crosshair stay on the distant feature? It should, but it may describe a circle, in which case you need to adjust the three radial screws which locate it. Olly

The others have done a nice job of this so I'll offer a different take on it. When trying to flatten the Lum in DBE I found it very difficult. The problem is that we want to retain the faint and considerably extended outer glow around the galaxy but lose the gradients at around the same brightness. What DBE was not taking care of (and what it isn't designed to take care of) was a slight imperfection in the mosaic's levels to start with. To get the best out of this data I would, therefore, go back a step and spend longer on the joining of the panels. You've joined them at the linear stage. There's something to be said for that but when it throws up a problem an alternative approach might prove better. What I would do is edge crop the two panels and DBE them. I'd then give them a 'half way' stretch and combine them in Registar. This output image will become a template for the final one, it won't be the final image itself. I'd also save the two 'registered-calibrated' halves of the mosaic from Registar and open them in Photoshop. Paste them over the template and measure the background values of both halves where they overlap. This will allow you to check how well Registar has equalized the levels in both halves. In all probability it will have done a good job, as your software had done, but not a perfect job. Now you can aim for hand-measured perfection by locally adjusting one or both halves to match the other. You can use Levels or, for more local control, the Dodge and Burn tools. You can use a feathered eraser to reduce the contribution of a stubborn bit to the final blend. And once you've flattened the blend you can run the Equalize filter on it to test, brutally, the real smoothness of the blend you've created. Discard the Equalized image: it's only there to expose imperfect blending. In a nutshell I'd spend longer on the joining of the two halves before trying to proceed. DBE won't eradicate mosaic artifacts. Olly

Agreed. I noticed mine didn't like being left out in the damp. If the next one lasts sixteen years I won't be worried! (Since ours is in visual use I prefer the handset to the PC.) Olly

A really attractive image with everything just right. Olly

Yes, I saw that price difference. TS said it wouldn't work for mine but I think it will. I'll give it a go. Thanks. Olly

No, alas the screen is kaput. However, it seems the current Autostar II will work after all. Thanks Dave, Olly

Thanks, Stuart. I've just had this confirmed by Opticstar who initially told me it wouldn't. I think they thought mine was a pre-autostar scope. Much relief! Olly

The handset of my 14 inch LX200 GPS has packed up after threatening to do so for a while. I just need to buy a replacement but - it seems not to be as simple as that. My scope is not an ACF but nor is it the original kind of LX200 with the substantial square-ish handset. It has always had the 'Autostar II' handset from new. I think it may be about 16 years old. Telescope Service tell me that an identical looking Autostar II handset which they can supply will only be compatible with an LX200 ACF. Does anyone know whether there really are compatible and non-compatible Autostar II handsets? This strikes me as pretty bizarre. Wouldn't a normal manufacturer, making a radical change, call it Autostar III? Thanks in advance for any insights or experience. Olly

Hooray! 😁 Here's another spanner for the works: you do have control over image size simply by downsizing an object image from a longer FL/larger aperture to the size of the same object from the smaller scope. That way you get the extra light concentrated onto the same number of pixels - ish. It may not be as good as real binning. Vlaiv knows more about how to calculate this correctly than I do but I know from experience that reducing the display size of an image has a massive effect on its signal to noise ratio when it comes to stretching. For a couple of years I was working with a big scope at an unrealistic 0.6"PP. Not to worry, we never tried to present an image at 100%. 66% still gave a big image and the smoothness was the benefit from the big aperture/generous supply of light. This is a very close crop from an Eagle Nebula image shot by the oversampling rig but reduced. Note that it's essentially a broadband LRGB image enhaced by Ha and OIII, not a NB-only image as produced by those cheats at Hubble. 🤣 Yes, this is a joke! Olly

I think it's the 128C. Olly

Like the others I'd avoid sinking timber into the ground. I'd use raised blocks or, ideally, poured concrete to keep the timber out of the damp. Roofing material: I've used all sorts and gravitated unconditionally towards corrugated steel. It may not be the prettiest solution but it is foolproof and effectively everlasting. It can be bolted down with no-nonsense bolts, it doesn't tear or sag or degrade in the sun and it is gradually replacing all the other systems I've tried on our sheds. It works. The rest work for a while... Anti-lift: this is very important indeed because roofs love taking flight. I would make the roof wider than the walls and give it sides which come down below the tops of the walls. You can put batons along the roof sides below similar batons on the walls. This means you don't have to remember to use fixing devices. The roof won't be able to lift. While tongue and groove or shiplap are popular my own preference is for marine ply. 1) It makes construction ludicrously easy. You take a ply 'wall,' possibly cut to size by your supplier. Long walls might need two panels but the principle remains. You screw your structural timbers around the border (usually 5x7cm here in France) and you cut triangles of ply to reinforce the inside corners. Once you've made four of these walls you have, in effect, four box sections which simply screw together to make the shed. The ply itself doesn't need to be thick or load bearing. Its role is to keep the structural timbers aligned. 2) It is easy to maintain. If, eventually, the ply sides start to look grotty, you can unscrew them and replace them or - even easier, simply cover them with a new panel of the thinnest marine ply you can find. Here's an example: The foreground shed is a small robotic one, the one behind a 3x4 metre multi-panel equivalent. The imaging shed below has a 2.2 metre square footprint, not including the warm room. It really is too small for visual use. I'd want 2.5 metres as a bare minimum. Have fun! Olly

Absolutely true. No question. With the right tool the job does itself. Olly

I must buy one of those. Thanks for the information. At present I tend to use two nails clamped in a vice with a trial-and-error separation. That might just be an improvement! 🤣lly

I never stray far from experience, Steve, and when CMOS and OSC technology evolve - so do I! Yves' is the first such camera which has produced data I've thoroughly enjoyed working on. One caveat: I've only processed dark site data from this camera so I've no idea how it would perform under LP. Olly

I'm out of my depth here but I, personally, would probably have chosen term 'radial' chromatic aberration over 'lateral.' Hey-ho. I'll gladly be put back in my box! For me the thing about a Registar co-registration of three channels over a regular alignment 'x-y and rotation' is that Registar resizes each channel to the reference one. If one channel has a longer FL the object will obviously be larger in that channel, meaning that, if everything is perfectly collimated, the 'long' channel will give round RGB stars in the middle with an 'x-y-rotation' alignment but the long channel stars will be centered radially outwards from the short channel stars in the corners. Registar's 'x-y, rotation and resizing' seems to me to correct this. Any tilt will throw in the complication of the 'radial' effect becoming eccentric. And then I really am out for the count... Olly

Quite outstanding and yes, Maurice, modern OSC cameras are not like the old CCD ones I used and discarded. Your capture of the brown dusty nebulosity 'outside' the Veil loop is the best and deepest I've ever seen and I've always been particularly intrigued by this region. Brilliant. On the other hand I've seen more Ha structure in the secondary 'broom handle' from mono HaLRGB and more Ha in the over-aching loop. But, hey... Globally I love the 'look' of this image and the excellent star colour. And, as we both know, it was damned hot at night for this capture with an uncooled camera. I'd say that was a great Veil and, in some ways, one of the best to be found at any price! Olly

My experience with Yves' data was so positive that I can say with certainty that I'd like to use a full frame QHY OSC in our Tak (530mm FL.) https://stargazerslounge.com/topic/360110-cepheus-cygnus-megamosaic/ Near the end there's a highly relevant comment from Yves. I hope Santa is reading this but I don't suppose he is... What is certain: the camera has picked up the faint Ha signal very well indeed. There is no added Ha here. The stars are remarkably small. Sure, I further reduced them but they began smaller than my CCD stars, and this is an almighty bonus in widefield imaging. The data is incredibly clean. I was half expecting to be told off for excessive NR in the darkest regions like the NAN dust lanes when, in fact, no NR whatever has been applied anywhere despite the very short integration per panel. I also like the 'look' the camera has delivered. There's something about the gradual way the Ha emerges from the dust which is very natural and pleasing to my eye. And, finally, 27 meg is not way OTT. I have a fast machine but the file sizes are not preposterous. Olly

This is certainly better than a tottering column of threaded bars and there is no need to level precisely the base of a GEM, especially N-S where you are going to tilt the mount to the equatorial angle anyway. More and more manufacturers are cottoning on to how annoying they are in requiring access from beneath! 😁lly

Yes, the 'texture' is also rather odd in our data as well. Olly