cfpendock

Very nicely done, Martin. I think you've got the blue absolutely right, and I like the star colour. Personally, I think I would dial the red back a bit, but really this is an excellent image. Chris

Nicely done for a difficult target. I like the processing, and you've managed to reduce the stars very well. What scope was this? Chris

Keep going and eventually you will get there! I frequently image at 2800mm focal length and although it is true that SCTs do produce rather larger "wooly" stars, this can be overcome with careful setting up and processing. I have found the following helps: Use of an off axis guider - almost essential for long FL work, and you should be able to guide at around 0.25 secs. But in order to achieve this, attention to balance is critical - I usually balance slightly off so the mount is always pushing slightly - I find this helps with overcoming backlash. With my C11, any significant wind ruins everything. As has been pointed out, round stars are no indication of good guiding. When focussing the SCT, I always make sure that I am focussing so that the for the final adjustment the mirror is being pushed upwards ( I do use an auto-focus system), but I find focussing at F10 anyway is not too difficult compared to short focal lengths. To keep the stars from bloating, I always re-layer a less stretched version into the final image as Olly suggests above. It seems to me that your subs are quite short. Do you have a lot of light pollution? I normally have average rural light pollution, but I do use subs of around 5 minutes. For your information, my sampling rate is just over 1"/px using my Atik 4000 and binning 2x2. I stack in DSS and process in Photoshop. My version taken at 2800mm FL is in my album: https://stargazerslounge.com/gallery/image/33396-ngc-891png/. Hope this helps. Chris. (No, seriously!)

Thank you very much, Martin. Your comments always very encouraging! Chris

Thank you very much Hallingskies. Yes, the tracking from my EM200 is pretty good - around 0.3 arcsec, but I take care under-balance slightly so that the mount is always pushing. Yes, I think you are right - the noise reduction is excessive, but because of the light pollution, the image was otherwise horribly blotchy.... But I did cheat on the core by using some selective sharpening which absolutely did not work on the outer areas....I shall try again when I have a moment. It is exactly these kind of comments which I find extremely useful - I get blinded by looking too much at the same thing! So once again, thanks. Chris

M74 is a rather faint galaxy around 30 million ly distant. It measures around 10' across, so a perfect size for my C11 at 2800mm focal length and Atik 4000 camera which gives around 20' field of view. I managed to get 16 x 5 minute subs each of RGB to add to my previous 24 x 5minute subs of luminance. I decided that this was enough for now due to banks of LED lights on nearby roadworks (which will continue until April), but I have managed nevertheless to squeeze out a bit of colour. Any comments / criticisms welcomed. Chris

Thank you very much Martin. Yes, I was a bit surprised to get much detail with the light pollution. Unfortunately the bank of lights will stay until April, so although I will try colour, I suspect it may be rather "washed out". The EM200 does indeed work well - I would say almost faultlessly, especially with around 16kg of kit on it. And guiding to well less than 0.4 arcsec.... Chris

Thank you very much Dave. I think for using as a luminance I suspect that I may need a tad more contrast as I have experimented with as below, although I have to say that as a stand alone image I prefer the first. Chris

This was my first go at imaging since February so everything was a bit rusty. However, all the kit still worked, together with my trusted Windows XP, and I managed to get two hours worth on this galaxy. Surprisingly difficult to find (it is rather faint), especially as I have serious problems with light pollution from nearby 24/24 roadworks which use amazingly bright banks of LED lights to illuminate the surrounding countryside. However, it was the first clear night for ages so I just had to give it a go. I managed two hours of luminance before the fog/mist rolled in, so hopefully I might be able to augment it with some RGB soon. So, definitely “work in progress”, but despite the light pollution problems, I am quite pleased with the result so far. It is rather blotchy, but perhaps some more time will help to sort that out, or even better, if someone on this forum can point me in the right direction? Processing was Photoshop CS5. Imaged with my C11 at 2800mm focal length and Atik 4000, all on an EM200 mount. 24 subs at 5 minutes each. All comments and criticisms very much appreciated. Chris

So would I. What is the existing roof - not asbestos I hope as this is a pain to get rid of. Chris

Very nice and detailed, especially considering it's apparent size of only around 5 minutes. And excellent star size and colour (as can be expected from this source). And that TEC certainly works! I must give this one a go with my C11- if our skies ever clear...... Chris

I am not an expert - I use a 23mm Luminos. But they can be expensive....around £150. Chris

A lot. I have one. Stars, clusters and planets are very good. Of course, it depends on the eyepiece - you should have a good one to see the best. I don't have very good skies, and galaxies and nebulae are not outstanding, although that is normal for any visual observation. I also use this scope for astrophotography where I find the long focal length very good for small galaxies. If you look on my DSO albums on my profile, the wizard, NGC660, NGC891, Stephans Quintet, and NGC 3718 among others shows what this scope is capable of. Chris

I like the 3D effect your processing has given this. Very nice. Chris

Oh yes. My kind of image.... Chris

And I especially like the big screen. But it does look a bit tidy... Chris

Ok. Sorry Rodd, but I'm not familiar with your camera and filter wheel set up, it seems the difference is the filter wheel / OAG assembly. So I don't think that I can help anymore. But I wish you luck with it and keep my fingers crossed for you.... Chris

With the prism in the position shown in the photo, it is picking up a good view of the sky. The attached screen shots show the stars, one for the Tak and one for the C11 (labels on the blue line at the top of each image). Just to keep you going and show that it can work with no fiddling between scopes. Chris

Ok, so I could't get enough light to photograph the set-up through the scope, so I took the OAG package off the scope so you can see the extension of the prism into the nose piece - which either fits directly into the Tak or into the C11 - you can see the prism is clear of the sensor - especially because I lined it up so the edge of the prism was in line with the sensor. Sorry about the quality of the photo - it's rather cold, but it's good enough to see. This complete assembly is simply attached either to the Tak or to the C11 - no changes to it at all. Chris

Good start - it seems to me that the camera works, except I'm not sure why the image shows white where no light is on it. When I look down my scope (from the objective end), I position the Loadstar prism so that it is just up to the side of the sensor (which is quite big on the Atik 4000). Of course, you can only do this with the Lum filter (or no filter) - otherwise you won't see the sensor. That way, I know that the prism will not interfere with the light falling on the sensor, but is easily far enough in to pick up plenty of light. This is not so difficult with the Tak 106 because it has an enormous image circle. I will try and photograph it if you give me an hour or so - it's rather cold and snowy here. Chris

Thanks for your confidence, Ray, but I'm not at all sure of that! It's just that my system seems to work, for whatever reason, and like you, I also look forward to seeing some more of Rodd's images, which I am afraid leave my own looking distinctly amateurish.... Exactly. I was lucky as the C11 has an enormous range of focus, so once the Tak was ok, then it was easy to make the C11 work also. Chris

And that is exactly what I was picking up on. My original point was that I use my OAG "package" with both the Tak and the C11 - vastly different focal lengths. When I originally got the Lodestar, I set everything up for the Tak - it's lighter and easier to manage than the C11! When I subsequently transferred the package to the C11, sure, I had to fiddle with the focus on the C11 in order to achieve focus, but I made no change to the package (Atik 4000, filter wheel, OAG and Lodestar) itself. No spacers, nothing. That is why I think maybe I was just lucky. On the other hand, there is no change to the length of the light path within the package, whichever scope I am using. This all explains why I cannot really understand Rodd's problem, unless he has a faulty Lodestar, or that the imaging camera he is using has a light path which is absolutely incompatible with his filter wheel / OAG assembly. I don't understand......it should work! Chris

Thanks for clarifying that Ray. I think that I read your post too quickly. But I also agree that I have probably been just lucky... my OAG package works the same, with or without the focal reducer - but I can only say this for the Tak 106. Sadly I don't have a reducer for the C11.... Chris

I think my test would be more definitive......and can be done from the comfort of indoors. But from what you say, your camera is certainly sensitive to something..... As Allinthehead indicated - it is often easier to do some tests in daylight - I also set up my focus in the daylight, keeping the computer in a nearby shed so I could see the screen in daylight. Chris

You won't see any words without a lens. But whenever I get a new camera - including the Lodestar, I connect to the computer (indoors...), and using the SX software or any other suitable software, switch on the camera (without any lens). It should register the difference between dark and light, so you can test this just by covering and uncovering the camera. Then if you run your finger (or something similar) from one side of the camera to the other, you should see the image go dark on one side, then dark when your finger is completely over the camera, and then dark on the other side as your finger passes across and away from the camera. This will at least demonstrate that the camera works. Chris