johneta

Give Siril a go also. Its free and says it works on Mac (I use PC). Its free and Ive tried a few - DSS, Nebulosity, Pixinsight, APP. Siril is better in my opinion than DSS, and similar to Nebulosity and PI, and APP. Except processing after stacking is not as extensive as PI or APP

Thanks very much seelive and bottletopburly. I will look into both these ideas. I'm interested in the concept of stacking medium size bunches of images. Ive never done that before. Always thought, the more the merrier. In the meantime I went ahead and did this.... I stacked the 3 sessions separately and ended up with 3 result images which I didnt use. I went back and put all the pp_light.... images from each stack into a new folder. I renamed the files by getting rid of the 'pp_' bit. Leaving them as just 'light...' etc. Then I stacked all those images with the script "no darks, no flats, no bias" thinking that they had already had those applied to them individually. Seemed to work well and I was happy with the result. It was a pretty clunky way to do it, so I will look into your ideas. Thanks again

Do you mean - if I have 3 nights, I will have 3 stacked images. Then I should stack those final 3 together? If so, doesnt that miss out on some of the benefits of stacking heaps of images (Sigma rejection etc). So I might have 30 lights from each night. So each 30 images is stacked into 1 image, then stack those 3 together. Wouldnt stacking all 90 together somehow be better?

Great, thanks. I appreciate it

Hi Can anyone help me with a brief rundown of stacking multiple nights with Siril. I have just started to use it, and use the premade scripts, and stack with 'preprocessing No Darks' It works well and I like it, but I'm having trouble figuring how to use different flats on different nights Thanks

I somehow missed this positive sentiment when I was thinking about getting the Ha filter. Also the day after posting this I saw a whole lot of Ha, and Ha OIII DSLR images on Astrobin 🙄

Thanks Olly I did briefly try just using Ha for the red channel(or mixed in with the red channel), and didn't like the different red hue it created. But I didn't give that much time. I concentrated on the Luminance end of processing. I will give the Ha/Red a good try soon. I had seen your similar posts on your technique there, and description of the salmon pink colour that results from full-on Ha Luminance. I had hoped that the detail and contrast gained with the Ha image would magically enhance the whole image , but alas that cant happen without some drawbacks. I need to use it with more subtlety as you suggest.

Hey thanks guys, I hope it does help people decide either way. -Yes I enjoy Trevor's channel- always a snippet or two of inspiration in there. Good luck Snoani if you get the new piece of kit

I wanted to post my experience with an Ha filter and a DSLR Camera. I had thought about getting an Ha Filter for my Modded 550d for a while, and the only real positive comments I'd seen for it were from Trevor at Astrobackyard. Most other Discussions around forums, talked about the issues with loosing so much signal via the green and blue filters over the sensor and only getting 1/3 (1/4?) the amount of light a Mono cam would get. Thus rendering it really a waste of time. But if you're like me, and not ready to fork out the big bucks on a Mono cam, and you already shoot with a DSLR, then I can confirm that, despite the science, - it does work well. Judge for yourself: First image is 1 light of the Carina area - 550d, Pentax 200mm lens at F6.1, ISO 800, 300secs Second image is 1 light with a ZWO 7nm Ha filter. F4, ISO1600 300secs (Note: the filter is the old type that is known for halos around bright stars-but I didn't find it too bad in this image) (Also Note.. ignore the blown out core--Photshop RAW does something weird with these red only images, but they open fine in the image stacker of your choice) As you can see above, I increased the light gathering on the second image, but it seems brighter than the first image, so I think I could have easily gone down to ISO800 I half expected that I would open the shutter for 5minutes and get virtually nothing at the end, but I was amazed to see so much signal from my little old DSLR. So if you were wondering if its worth it-- well I think it is! Two Caveats though..... 1. My plan was to use Ha as a luminance layer and boost the faint areas of Nebulosity. - But it's surprisingly difficult to do, and keep natural colours. I ended up doing the best Processing I could with just the regular colour image. Then I added the Ha as a Luminace layer on the colour image and revealed the faint stuff and detail. This HaRGB image had great detail but was a pastel soft pink colour, which was very hard to change. SO in PS I had 2 layers -HaRGB image on the bottom and RGB image on the top layer. I then painted in just the faint stuff from the HaRGB image onto the RGB image. This kept the majority of the image natural looking and the faint stuff blended into this quite nicely. 2. This is my first outing with the filter and I chose the Carina Nebula. This is an EASY target! It's super bright, and as most Southern Hemisherer's will know, a reasonable length image gives you a dazzlingly bright picture. Like daytime photography 🙂 -- So further tests on dimmer targets will be interesting.

I understand what your saying there. My issue is with areas of nebula that are buried in the milky way or close by, which are an absolute mass of stars. It is extremely difficult to remove the stars in that kind of image by hand, and to therefore feed it to the Starnet Algorithm. I don't have an issue with images such as the excellent Horsehead one above, where there are a medium amount of stars which are easy enough to deal with by normal methods. Also some of the Starnet 'starless' images I have used are of quite good quality, but I still have difficulty getting a natural looking image in the end trying to blend stars back in. I guess I'm just frustrated with Starnets wow factor, and my inability to get anything usable out of it. Again, good luck. It seems like a worthy objective your shooting for.

Hey that's a great idea good luck.... Can I just question it a bit? If you can do good star removal by the method in the link you mention, then why use Starnet. I only mention this as I always struggle with star reduction and getting artifacts. Ive tried Starnet (I also have a 200mm newt) and have had limited success. If you train it with starless images with artifacts, aren't you just training it to produce starless images with artifacts, which are then hard to deal with? I know its a bit of a circular argument I'm expressing but I guess I don't quite get it. Ignore this if its too off topic or hijacking the thread.

Looks like field curvature to me. Others here could describe it technically better than me. But I have had similar issues with wide shots of the milky way. I usually do deep sky, but the few wide field's I do are difficult. If I use an 18mm lens (on APS-c sensor) the field curvature at the edges means that DSS cant stack the edges at all. It is actually not possible for it to do so, as far as I know, if you get too much movement between frames. The outer stars are at physically different places on the frame if there is movement between images. I initially wanted to dither between images to reduce noise, but doing so moved the images between shots of course. -Then DSS couldnt stack it. So I ended up not dithering and taking Darks (which I prefer not to do) to reduce noise. This meant I only took about 12 Light frames for the shot as my theory was, that I would get minimal movement over those 12 frames. It worked well for me! Its not a problem over about 35mm in my experience, as longer focal length lens have less curvature.

Pixinsight has given me the best results, and Photoshop for finishing and daytime photography

I really like minimal stars in my images, but I prefer the left. Stars on the right are not full brightness at the center and look soft. Ive tried for a while now to work starnet into my workflow but have had mixed results. It is amazing how it works, but I always get too many artifacts with my final images.

Try stellarium too. Its quite easy to setup a FOV for telescopes or lenses. Ive got my scope saved and about 8 different lens focal lengths. You input you sensor dimensions and it calculates the crop factor for you.

Oh yeah, thanks I forgot about that one. I thought similar to you regarding fit image to the preview box, but I cant see any mention of it.

Has anyone had this. Im using framing mask to line up a new image with a previous night. Its close and I need to rotate the camera. I rotate it and take a test shot. It rotates a little, and then when I go past a certain point, the image that comes up after I take the shot is flipped. So I have to tick Meridian flip on the Framing mask box so the framing mask is oriented correctly. now if I rotate the camera backwards, the image flips the other way, so I have to untick the meridian flip on framing mask to get orientation right again. It gets confusing!! Does anyone know why this happens. Im using a Canon 1200d and the menu on the camera is set to not auto rotate image

Also, are you talking about the noise on the sky background part of the image? What camera/lens and camera settings are you using as usually you can use a low iso setting on the camera and a short shutter speed which will give you noiseless black effectively. I looked at an old pic I had- settings are 300mm lens, ISO 200, F8, 1/200th second exposure. No noise on blacks.

Try using Registax program. Designed for this stuff. I don't do much moon imaging but this software makes it easy to get a clean sharp image. This tutorial will start you off. https://www.youtube.com/watch?v=JkTiVdx30CQ Basically take a hundred or so images so that you are" lucky imaging" and then feed them into Registax. I'm a super basic user of it, and I'm sure others will have better suggestions

Hi I agree with many others here. Get a slightly better mount if you can. But if money is too tight the EQ5 is OK. Ive got an Orion 8" F3.9 on mine (very overloaded) and I can still get good images. But only if the motor drives are stepper motor type ones. I modified mine (Astro EQ Mod) (I'm not sure what the EQ5 GOTO model has on it) I found the dual motor drive kit for the EQ5 was poor and a constant headache

Can someone recommend a low vibration fan for a peltier cooler for DSLR. Ive made an external peltier cooler for a Canon 550d. Wasn't keen on a cold finger. This one basically keeps reported EXIF temp at ambient, which I'm reasonably happy with. Trouble is, I have had a difficult time with vibrations. When you hold the fan when its going, you can feel a low vibration.- It is audibly quite quiet though. This vibration shows up on stars. They turn into rectangles, instead of circles. I have tried all sorts of mounting, including attached with foam rubber, or thin springs. This lowers vibration a bit, but I'm amazed how much vibration can still make it through a thin spring wire or piece of foam. I've seen a few posts here, and for the most part people don't have much problem with vibration. This surprises me as mine is so sensitive to it. Also it seems to me that the cold finger type modifications would be ultra sensitive to vibration, as the fan/heatsink is closely coupled mechanically -straight to the back of the sensor chip! I used this fan/heatsink https://www.aliexpress.com/item/33044944143.html?spm=a2g0s.9042311.0.0.27424c4dRCwcIA All the places online say that their fans are super quiet of course,- But I'd like to hear a real world example of a particular fan that someone else has had success with. Thanks for any help

Thanks for the replies. Vlaiv -Your second reply makes sense to me. I did use flats in the stack I did of this image and it didn't fix it. I was thinking about reflections as you suggested. I thought it might be a common issue with the Horsehead, as it has Alnitak in the frame. Any work arounds people do? Flocking the inside of tube help or other ideas? Thanks John

Hi Has any one had this before? I imaged the Horsehead Nebula properly for the first time. I only got 13 x 360 sec ISO1600 images on a DSLR. (Its Summer here which makes for very late nights when it gets dark late) In the final stack- when I stretch it, I got a darker dim circle just to the right of the Horse head. I ended up doing a HUGE amount of stretching on one image to see if it was on each frame. It was, and you can clearly see a doughnut shape. The circle seems too big to be a dust spot on the sensor( plus I am using flats which should sort that in the stack). My guess was, the intense light from the brightest star in the image is bouncing around the tube of the Newt and reflecting an image of the sticker onto the image. Is that a thing? Thanks for any help John

Just wanted to post a note that I started using my ebike battery for remote imaging. I'm guessing a few imagers have an ebike (another cool tech toy) Ive got a 48v 16A/Hr battery on my bike and I bought a chinese 48v-12v DC converter (around $15-20). So I can run my power supply hub with it. Ive done a 4 hr session running - Laptop, dual drive EQ5 mount, 2 Newtonian dew heaters, 1 guide scope dew heater, canon DSLR, QHY guide cam. It used around 1/4 to 1/3 of the Battery capacity. Would need a pretty big Sealed Lead Acid Battery to do similar. Its a handy dual use for the battery. 🙂

Oh thanks. Nice explanation. That makes sense re wide and long FL. I will let those hot pixels through in preference to the other artifacts. Regards