ollypenrice

Ah yes, I'd overlooked that fact. Olly

Oh how I love the Servocat-Argonavis version. In the last ten years I don't think I have ever read a post asking why this or that didn't work. I have no intention of upgrading my difficulties! 😁lly

Oh how I love the Servocat-Argonavis version. In the last ten years I don't think I have ever read a post asking why this or that didn't work! I have no intention of upgrading my difficultioes! 😁lly

Yup, that's what I have to do to TIFFs created in AstroArt if I want to take them into Registar. Olly

A cheap alternative to step-down rings... You also have an infinite choice of apertures. Olly

So much is right in this image. The star colour is great, the background is flat and neutral except for that small bit bottom right, which would be an easy fix. Neither of these things is at all easy to get right. Where it could be better is in the focus, which I strongly suspect to be a little off. How did you focus? A Bahtinov mask is an inexpensive and reliable solution. Focus also needs checking regularly. Olly

Hi folks, I know nothing about EEVA and have never so much as seen an EEVA setup in action. I do either deep sky imaging or eyepiece visual. However, this thread... ...has moved into the EEVA arena and I wonder if expertise on the subject might be available from regulars on this part of the forum? Olly

It's important to note that the kind of astrophotos posted on the deep sky section... ... are not captured in real time but over many hours, around 30 in this case. After that the data captured go through many hours of processing. However, there's an observing system called Electronically Assisted Visual Astronomy in which almost real-time images are presented on a screen. What you see is more like what you see at the eyepiece but in some cases I think you see considerably more. I've no experience of this process but it has its own section on here: https://stargazerslounge.com/forum/286-eeva-discussion/ In principle I imagine that, using Anydesk or Teamviewer, you might be able to share in someone else's EEVA views in real time. I'll pop a post into that section to ask the experts how and if it might work. Olly

Sorry, I didn't see this question back when you asked it. What I meant was that many emission nebulae are surrounded by faint extensions which are often overlooked if you don't have enough data. A classic case, for us, was the pair of emission nebulae near Gamma Cass, IC 59 and IC 53. When Tom O'Donoghue and I decided to do a very long, deep run on them in Ha we suspected that they were acutally just the bright parts of a larger structure so we did a 3 panel mosaic. It turns out that the two nebulae are really one and go all the way down to the Pacman nebula. Olly

I always think it best to start with the object you want to image. 1) It has to fit on your chip unless you're up for a mosaic. Field of view is controlled by focal length and chip size so balance the two to fit your needs. (Big expensive scope and big expensive chip or vice versa!) 2) The object needs to be properly sampled to be viewable at full size. I think this is pretty flexible. You get a nice 'look' up to 3.5 arcsecs per pixel and, below about 1.5"PP you are probably oversampling and losing speed. (If you're doubtful about 3.5"PP check the APOD records because the Kodak 11 meg plus Tak FSQ106 has more APODS than you can shake a stick at.) 3) Remember that speed isn't determined by F ratio, it's determined by the relationship between area of aperture and area of pixel. What matters is 'aperture per pixel.' So, first of all, what exactly do you want to image? One rig cannot do all. Olly

You'll want a software package which lets you process after stacking and calibrating. Astrophotos, even when stacked, are not 'ready to view.' The main reason for this is that most of the interesting signal is compressed into a very narrow range of brightnesses just above the level of the background sky. The process known as 'stretching' opens these up. What can be confusing for beginners is that some screen previews automatically stretch the data in a temporary 'screen stretch,' meaning that what you see is stretched but the file on the hard drive is still linear (ie unstretched.) An unstretched astrophoto generally just has a jet black background, maybe a few hints of the brightest nebulosity and then stars. There will be a lot more than that in the data, though. Extracting it is the fun part! Olly

I like 30 minute subs for CCD narrowband. Occasionally I like them for luminance as well. You have a problem finding time for 5 minute darks??? 😁 Fortunately, I found that darks did not deliver what they were supposed to deliver, even with an old-school and very noisy, set-point-cooled, Kodak CCD. Of course I know the theory. I've read it a thousand times. I just found it didn't do, for me, what it said on the tin. To put it simply, there is no way in the world that you will notice a difference in your final image between calibrating with 20 darks and calibrating with 50. Of all the things standing between you (or any of us) and a good image, it ain't that. Put your energy into more productive lines of thought. Olly

What attracts you to the SXP2? It has made no friends of whom I'm aware in the imaging world and it is the imagers who are the most demanding in terms of tracking accuracy. When the Sphinx first appeared those imagers who bought it burned their fingers. It was poor. Is it now much better? Perhaps it is, I have no idea, but it has a payload comparable with an AZ EQ6, which can be configured in Alt-Az mode which is surely better for visual observers? With an 8 inch telescope in visual use we are asking very little of the mount. I cannot see why I would pay more than the price of an AZ EQ6 because I can't imagine what I'd be paying for. If I were to pay more, it would be for an Avalon Linear Fast Reverse for its outstanding build quality (I've had two in commercial use) but, for visual, I would simply use an AZ-EQ6. I once made the mistake of paying a fortune for a Takahashi EM200 mount. While it had some strong points it proved to be more trouble than my EQ sixes and I was glad to see the back of it. As for the choice of telescope, I would be disinclined to to go for a reduction in aperture that could not, at the same time, give me a big increase in field of view. A purely planetary observer might, of course, look at this differently. Olly

An everyday term for what Vlaiv's describing is 'empty resolution.' The image becomes bigger but has no new information. Olly

I agree with Vlaiv but would want to add some thoughts on cropping. I often feel that, when folks talk about cropping, they think they are 'doing something.' But that isn't really true. To crop is to do very little. Your uncropped image has a certain resolution of detail. If you are neither over nor under sampled the best way to see this resolution is to view the image at 100%, which means 1 camera pixel is given 1 screen pixel. The trouble is, your screen is unlikely to be big enough to look at the whole image this way, so you have to drag it around to see different parts of it at any one time. When you crop, you are just choosing which bit of your image you are going to look at yourself or present to the public. All you are saying is, 'my screen isn't big enough so let's just look at this bit.' But you have done nothing whatever to the bit in question by cropping around it. It is exactly as it always was and is entirely genuine and unadulterated. Forgive me if you already know this, but I know from experience that many people don't. They feel that cropping is somehow a form of cheating, of inventing resolution. This simply isn't so. Olly

Tom's always at sea! 🤣lly

Atik had a facility in Portugal almost from the start, I think, but it's run by Rui Tripa who's as good as guy as you could ever hope to meet. He's been more than helpful to me on occasion. Olly

We dd briefly use Yves' SX H36 in the Tak dual rig and, less briefly, Gonmus' Moravian in the TEC. For me a big Atik plus is not having to use third party software, some of which seems infernally over-thought to me. The simple matter of filing image x in location y is far too simple for many of these packages. And, as you say, Atik are local with a stable team and a speedy and personal response to any queries. I think they were a bit late to the CMOS party but, now that they're here, it's good news. Atik have always been my go-to manufacturer as well. Olly

I look forward to meeting this astonishing bit of technology! Olly

If your aim is precision focusing then there's a lot to be said for an add-on, draw-tube, fine focuser but, equally, there's a lot to be said against a tacky one. They are not cheap. If you use a driven version of the original moving mirror system it is important only ever to make the final adjustment a push of the mirror up the tube. Olly

I use an ST80 to guide my TEC140 imaging rig which has a sampling rate of 0.9 arcsecs per pixel. I get a guide RMS of 0.3 arcsecs. That's better than I need but, as said above, you can't over-guide. The ST80 is a great guide scope but be sure to do three things: make sure the cast metal back is tightly held to the main tube with its 3 radial screws. I wouldn't hesitate to put a bit of Araldite between the two parts to be double sure. Make sure the draw tube locking bolt is nice and tight to stop draw tube flexure. Use some kind of extension tube to get focus. One of my guide cameras has a very short backfocus so I needed two Barlow bodies (without lenses) to add the distance. I Araldited these together and also Araldited the complete extension into the draw tube. (This ST80 is going to be a guidescope for life but it's totally reliable.🤣 ) Olly

It's worth remembering what noise reduction is. It works on the basis of pixel to pixel communication, to the best of my knowledge, which means it is a form of blurring. How much blurring do you want in your image? And where do you want it? It's not a very appealing word to my ear, blurring. The best noise reduction is to be had by shooting more data and background sky noise is better dealt with by compressing the pixels values without getting them to talk to each other. NR should surely be a last resort? Olly

I wasn't thinking of naming and shaming on SGL, just of what is required by GDPR legislation. We don't know whether the vendor is on here or not. If he is, I rather hope he will choose to remove himself. Olly

I can't see why naming a person who put their own identity into the public domain in order to sell an item can be controversial if you stick strictly to the facts. Nor do I see why the manufacturer would refuse to repair a faulty product. If you're not the original owner then, sure, they'd charge you for it but, if they refused, the negative publicity would be disastrous. 'No repair out of warranty' is not something any manufacturer wants to have attached to their name. Olly

I stack in AstroArt and find it intuitive, organized, effective and incredibly fast. The speed has become much more important since we started shooting larger numbers of shorter subs with CMOS cameras. Olly