DaveHKent

It depends on what you are imaging. I have only ever done a mosaic for lunar imaging and I do that manually, though I'm aware there are tools that can help. Once I have stacked the videos and got my final stills, I use GIMP Create a new image and make it large enough to fit all the stills. I often default it to a bright green background, rather than black so I can really see where I have put things Open all the other images as layers, either as a bulk operation or pull one in at a time as needed. If you open all of them, make sure the Layers tool box is open and use the eye icon to make them all invisible You may wish to name your layers at this stage if that will be helpful Make the first layer visible and position it to roughly where you think it should go in your final image Lock the layer in place Hit save! Hit save again and keep saving after every operation. Now make the next layer visible. This should be one that overlaps a little with the first. Drag the opacity slider down to about 50% Use the move tool to position the second layer over the first. With the lower opacity you should be able to align far easier, placing craters directly over the same crater from the previous layer Once you are happy, drag the opacity back to 100% and you should have a neatly aligned image Optional: Sometimes you can get a visible but not too obvious line where they join, due to slight colour variations. On the second layer select the erase tool with a fairly wide and medium hardness airbrush. Go down the joining edge and remove some of the image to give a softer edge Repeat for the other layers. Crop the final image to remove the green around the borders, or if you do need to fill in border gaps, use the colour dropper tool to select the background sky from the image and flood fill that colour. If you pick black (#00000) from the colour pallet you will find the sky you captured was less black than you thought. (Fans of Father Ted, think priest socks) Once complete, you can leave it as it is or merge all the layers down. When you export into another image format it will merge the layers down anyway, so I usually leave all the layers in my GIMP .xcf file in case I want to go back to it later. Depending on your equipment, you might also have to rotate some images. I have an altz mount, so if I'm imaging an almost full moon, for me that is 9 images and the final shots can be rotated in relation to the first by a couple of degrees, depending on how long the imaging session took.

Thanks for all the advice. I've tried Siril and it does looks pretty good. Following a couple of videos, the background removal was nowhere near what they got, but I could see on the histogram view that I had a lot of noise there. I'm annoyed at myself for not capturing darks, flats and bias, which would have made a lot of difference and got rid of all those red and green flecks. I've have nothing to learn if the first one was perfect. I think this is the best I'm going to get it. Most of the work done in Siril, as per the advice here, but I did use gimp at the end just to bring down the brightness of the background a bit. I'm reasonably pleased with the final result.

Thanks. That looks like the opposite of what I did, which was stretching first. More googling and learning required. Having only done planetary and lunar imaging before, it is amazing just how much of this is in the post processing.

Cheers, I do seem to have lost the running man in my processing. What did you do to bring that out?

My first attempt at the Orion nebula. I'd appreciate any comments about my image processing technique. Taken on a night with a lot of humidity in the air and a half moon giving a nice haze over everything. Skywatcher StarAdventurer, Canon EOS 700D 75-300mm lens at 300mm f5.6. 75x30 second shots. Stacked in DeepSkyStacker and processed in Gimp. I didn't take any flats or darks, but clearly should have done. Processed mainly by dragging levels. This brought out a green halo around the nebula, so I used curves to remove the green. I think I've perhaps stretched it too much because at higher magnifications the gradients between the colours are very visible. I think when I selected just the background to darken that, I've given too harder edge to the nebula and should have taken some shorter stills as the core is over exposed. I'm not sure what all the small red and green flecks across it are. Perhaps something that could have been removed with darks. Should I have gathered more data? Would it have been better to select around the nebula for a lot of the stretching, so the stars don't seem blown out? It's my first attempt at any DSO so I am pleased with what I've got, but want the next one to be better! Attached, the processed image and the original TIFF. 2021-01-09-m42_stacked.TIF

Is this thread still the best place for issues with oaCapture? I'm running oaCapture 1.9.0 on astroberry (Rpi 4, Raspbian 10) and it fails when trying to save an AVI file. It does preview the camera and save as a SER. $ oacapture --debug-level debug --debug-type all --debug-log - libEGL warning: DRI2: failed to authenticate qt5ct: using qt5ct plugin qt5ct: D-Bus global menu: no [I] oaV4L2GetCameras ( 0x14ba68, 2048, 0 ): entered [I] oaV4L2GetCameras: exiting. Found 0 cameras |QHYCCD|/home/pi/QHYCCD_SDK_CrossPlatform/src/qhyccd.cpp|EnableQHYCCDLogFile start |QHYCCD|/home/pi/QHYCCD_SDK_CrossPlatform/src/qhyccd.cpp|SetQHYCCDLogLevel start [D] oaZWASI2GetCameras: allocated @ 0x6861d0 for camera device [D] _oaCheckCameraArraySize: cameraList was (nil), realloced to 0x6de2a0 [I] oaEUVCGetCameras ( 0x14ba68, 2048, 0 ): entered [I] oaEUVCGetCameras: exiting. Found 0 cameras [I] oaToupcamGetCameras ( 0x14ba68, 2048, 0 ): entered [I] oaToupcamGetCameras: No cameras found [I] oaMallincamGetCameras ( 0x14ba68, 2048, 0 ): entered [I] oaMallincamGetCameras: No cameras found [I] oaAltaircamGetCameras ( 0x14ba68, 2048, 0 ): entered [I] oaAltaircamGetCameras: No cameras found [I] oaAltairLegacyGetCameras ( 0x14ba68, 2048, 0 ): entered [I] _AltairLegacyInitLibraryFunctionPointers: can't load libaltaircamlegacy.so.1: error 'libaltaircamlegacy.so.1: cannot open shared object file: No such file or directory' [E] oaAltairLegacyGetCameras: _...InitLibraryFunctionPointers() failed, exiting [I] oaStarshootgGetCameras ( 0x14ba68, 2048, 0 ): entered [I] oaStarshootgGetCameras: No cameras found [I] oaNncamGetCameras ( 0x14ba68, 2048, 0 ): entered [I] oaNncamGetCameras: No cameras found [I] oaOmegonprocamGetCameras ( 0x14ba68, 2048, 0 ): entered [I] _OmegonprocamInitLibraryFunctionPointers: can't load libomegonprocam.so.1: error 'libomegonprocam.so.1: cannot open shared object file: No such file or directory' [E] oaOmegonprocamGetCameras: _...InitLibraryFunctionPointers() failed, exiting [I] oaZWASI2InitCamera ( 0x6861d0 ): entered [I] oaZWASI2InitCamera: exiting [I] oacamSetControl ( 0x8bf870, 112, 0xbeb27af8, 0 ): entered [I] oacamSetControl: exiting [I] oaZWASI2CameraTestControl ( 0x8bf870, 52, 0xbeb27b08 ): entered [I] oacamSetControl ( 0x8bf870, 52, 0xbeb27b08, 0 ): entered [I] oacamSetControl: exiting [I] oacamSetControl ( 0x8bf870, 10, 0xbeb277d8, 0 ): entered [I] oacamSetControl: exiting [I] oacamSetControl ( 0x8bf870, 10, 0xbeb278e0, 0 ): entered [I] oacamSetControl: exiting [I] oacamSetControl ( 0x8bf870, 27, 0xbeb275a0, 0 ): entered [I] oacamSetControl: exiting [I] oaZWASI2CameraTestControl ( 0x8bf870, 52, 0xbeb27b68 ): entered [I] oacamSetControl ( 0x8bf870, 11, 0xbeb27b48, 0 ): entered [I] oacamSetControl: exiting [I] oacamSetControl ( 0x8bf870, 12, 0xbeb27b48, 0 ): entered [I] oacamSetControl: exiting [I] oacamStartStreaming ( 0x8bf870, 0x55840, 0x14a140 ): entered [I] oacamStartStreaming: exiting couldn't open codec 152 , error: Invalid argument add video stream failed The couldn't open codec 152 message appears after I click record. It looks like the error is coming from the section at line 513 on outputFFMPEG.cc, but I'm struggling to trace back to find what it is actually trying to open. If I run oacapture as root it does work, which suggests a permission issue somewhere, but when I export the AVI file, it thinks it is only 2 seconds long and only plays a couple of frames. I think it was about 15 seconds long. Is this a known issue, or is it better to just use ser files?

Thanks for the suggestions, a few to look at there, and I appreciate it will never be accurate. I think rather than knowing when will be good, I’m more interested in if there is a slight chance. If there is heavy cloud and rain I know it is probably worth not bothering.

Does anyone have any recommendations for a free astro weather API? I've been building a display screen at home for a few various sensors and have a bit of space at the bottom. Giving a rough indication of how clear the sky will be for either that night or the next 4 nights would be great. I found once reference to DarkSky, but it looks like earlier this year they were bought out by Apple and dropped all useful features. I have found a few, but not many of them give things like seeing that you get with some of the apps like AstroPanel.

You posted the same one twice there. The one I used is: https://www.thingiverse.com/thing:241592 I picked up a Celestron Red Dot finder for about £15 and printed one of those, then I'm not always taking it on and off my scope. It has been really useful and cheap to produce. There are some 3d printing services online if you don't have a printer. I'm sure they would knock one of them up for a very small amount.

I had a go at imaging Mars on Sunday night. No cloud but high humidity (I could see a triangle of light coming down from a nearby street light, which is my usual judge of conditions). Any advice on the following image? I decided to do a mosaic of a raw frame->stacked->sharpened then reduced to normal size again. Did I sharpen it too much? The image increases in size, as I used "Drizzle 3.0x". Kit & process: Celestron Nexstar 90 SLT (90mm scope), ZWO ASI120MC, SharpCap. Processed in AutoStakkert, taking the best 40%. Sharpened in RegiStax. I did struggle with the focus. Being so small on screen and wobbling due to atmosphere, I could not get anything I thought was crisp. In the end, I opted for the spot in the middle of two points I could clearly tell were out of focus.

Cheers. I have been subscribed to sky at night for a few years and never noticed that service. I have probably ignored it as a spam generator. I’ll give that a go.

Rather than the long dovetail bar, I have started using the small green dovetail, which my camera ballhead can connect directly to. I polar align, slot in the ball head and adapter and swing my camera around. It was taking me a while to get my targets framed up, so I bought a celestron style red dot finder for about £12 and got an adapter so it could fit on the camera hotshoe. I have to make sure I don’t knock the tripod and make sure everything is nice and lose before I turn it.

Cheers for the further advice. There are a good couple of lens options there from MPB. I get another pay day in a week, I probably need to set a bit more aside but it looks like I can get something reasonable for only a bit more than I planned.

My budget at the moment is probably £100 max. I can wait for a better lens but £900 is a long way off my spending for a lens at the moment.

Cheers. Macro is not that important. I was mainly wondering why many of the lenses I was looking at were described as macro and does that make them unsuitable for astro.