Snoani

Thank you both for your replies. It is still looking like I shall have some clear sky time tomorrow night, so I'll start the night by taking a few images at 90 degrees before returning to my normal rotation and undertaking an image run. I hope that it will be that simple to identify, albeit maybe not to resolve the problem. I've not attended a star party myself, although I believe that it is still running, albeit not in the last 10 months for obvious reasons.

Thank you for your reply. I don't think it would be tilt because I think this would have shown up on the experiment that I ran earlier. However, I hadn't considered rotating the camera or testing the exposure length. I am forecast some clear skied on Thursday and hopefully these will materialise. I'll give your suggestions a try then.

Evening all Since putting together my rig earlier this year, I feel that my images have improved massively and continue to improve as I gain experience and learn from my mistakes. However, one thing that I have been plagued with from the start is elongated stars in the corners of my images. I had honestly believed that these were due to a back focus spacing issue but I have taken the opportunity tonight to run an experiment and it appears that my field flattener and flattener/reducer are both spaced and working perfectly, so I am now left with the conclusion that it is another issue. I am therefore looking for a little advice. My setup consists of a Meade 6000 Triplet APO at 480mm, a ZWO mini guide scope at 120mm focal length and a ZWO ASI 120MM mini guide camera which are guiding an HEQ5 (Rowan belt modified). I am current imaging with an ASI 1600MM and filter wheel or DSRL when I want to shoot in colour. I have both a field flattener and an 0.8x flattener/reducer depending on what focal length I want to use. To give an idea of the problem the image below the corners of a stack of 6 images for the other night which show that I have elongated stars in all corners, but that these are predominately worse on one side, although sometimes all corners are affected more equally. As I say say I believed this to be a spacing issue but tonight I have run an experiment where I created a field of illuminated dots and focused the telescope on these to see if the dots became elongated in the corners, but the result of this was that they generally were not affected. The dots are slightly wonky because I had to capture each corner separately but they stayed round, showing that the flatteners are doing their job. I am therefore left to consider that the issue could be down to three things, or a combination of factors. Mount/guiding accuracy: When I first started with this mount I was getting a total RMS error on PHD2 of about 1.5-2 seconds. However, over time I have taken more time to level the mount, improved polar alignment (currently using Sharpcap) and I have installed a Rowan belt modification to reduce backlash, all of which means that I now see a RMS guiding error of between 0.5-1 seconds. The ground that the tripod is setup on is solid and there shouldn't be any vibrations that I can think of, so I am not confident that this is the issue but I am happy to be told differently. Differential flexure - I therefore wonder if the issue is related to differential flexure. As you will see above I have a guide scope attached via the finder shoe, which I assume leaves the rig open to flexure of the guide scope in relation to the imaging scope. If people think that this is likely to be the issue, would an off axis guider be the best solution for this, although I am conscious I wouldn't be able to use this with the DSLR due to the back focus. Balance - I am happy that the setup is balanced well at the beginning of each session. I used to try to make the balance slightly east heavy, but I have stopped doing this since installing the Rowan belt mod to the mount. Should I still be balancing east heavy even with a belt driven mount? If anybody has any other suggestions for this problem they would be more than welcome if it helps me eradicate the issue. Thank you for taking the time to read this. Jem

I've just tried and can access but just a few days ago I received an error when trying to access the manuals. I did manage to circumnavigate the problem to find the manual I needed by going to the product in question and clicking on the manual link from that page. Jem

They can and should be taken for each and every filter used. Jem

I can't claim to be an expert in any way but it looks good to me. A really nice image. When zooming in it looks like you have a hint of DSLR walking noise. If you didn't do so, I would recommend that you consider dithering as it a god send, particularly when using a DSRL. That said, it doesn't remove anything from this image and you should be pleased.

I've taken advantage of a few clear evenings over the last week to make my first serious attempt to capture the Horsehead Nebula. It is made up of just 20 x 180s of each RGB and 20 x 360s H-Alpha using an ASI 1600MM Pro, Meade 6000 80mm and HEQ5 guided. It does have a little bit of light from nearby Alnilam intruding from the top of the frame, but this is significantly better than what I had to crop out. All in all with the limited data that I have taken I am very happy with the result. Constructive criticism is always welcomed.

Thank you both for your replies. That makes sense and now that I have looked at the FOV on Stellarium, it makes complete sense. I am frankly just glad it is not an equipment issue. I left my rig in tact last night and have just setup as I have a lovely clear sky currently, and I will continue to capture as it is and crop the final image. I very much appreciate your help with this.

Thank you for your suggestion James. I ran a search and looked through numerous posts but couldn't find anything similar. All frames are showing the same issue so I decided to end the run on that filter and try others. It is appearing on all filters apart from H-Alpha, which I assume is because the light frequency is being blocked. I think that there must be something in my image train. I am therefore undertaking a significant H-Alpha run tonight, because my mount is guiding as good as it ever does, and tomorrow I'll break down the image train to check for artefacts before the forecast clear sky tomorrow night.

Evening all I have just setup for a night of imaging and have trained my scope on the Horsehead and started the image run as usual. However, I have just looked at the first light frame to find a 'streak' in the corner that I have never experienced before. I wonder if anybody could provide some advice about what it may be? I am using an ASI 1600MM Pro on a Meade 6000 APO. It is only the third time I have used the camera, but I did not experience this the first two time. I don't know if I have problem in the image train or whether it can be removed with calibration. Your help would be appreciated. Jem

I have been intermittently capturing data towards this throughout December on the few occasions that the skies have been clear. I managed to capture and intergrade H-Alpha data during the full moon on New Years Eve, before the freezing fog moved in and interrupted what was meant to be a full night of stars. It is not perfect by a long shot but it was a good test for my new camera and I am ready to apply what I have learned on a new target in 2021, hopefully sooner rather than later. IC 405: Flaming Star Nebula taken with a ZWO ASI 1600MM Pro, Meade 6000 80mm APO and HEQ5 mount, guided. Luminance 80 x 3 min, Red 16 x 3 min, Green 16 x 3 min, Blue 16 x 3 min and H-Alpha 6 x 10 min.

Merry Christmas Peter. I have just shown your photo to my wife and she has asked me to capture it for next Christmas so that we can make Christmas cards using it. I only have a small refractor (480mm) and note that the scope you used would be 4x more zoomed into. So that I can gauge what may be possible, can I confirm whether you cropped your image to frame the 'tree'? Thanks Jem

Hi Simon I have an HEQ5 and originally powered it using one of these. It worked perfectly until I upgraded to a neater option this year, i.e. with less cables. Jem

Thank you very much for your advice. I will definitely take a look at the link have a play with the data available.

After several years to taking astrophotos with limiting equipment, earlier this year I finally purchased my first guided rig, which I am rapidly adding too. I think that I have fallen down the rabbit hole. My latest acquisitions are a ZWO ASI 1600MM, filter wheel with 5 spaces and LRGB filters. However, with the weather and the Moon as it is, I would like an option for this camera when LRGB is not really an option. I have considered narrowband but while I have an aesthetic appreciation for narrowband images, and the necessity if you live in an area where this is the only practical option, I am more of a fan of broadband imaging and the colours that this will produce. I live in a Bortle 3-4 area and so have this luxury, particularly to the south which has basically no light pollution, and so I was about to order a H-Alpha filter with the belief that I could use this as luminance for emission nebulas. However, before I ordered I decided to a little more research and I am now doubting whether this filter is a good option or not. Essentially, from the research that I have done I now think that I understand that adding H-Alpha as luminance will give a washed out pink nebula but that it is still possible to blend H-Alpha images into an LRBG image (to each separate colour channel in different proportions but particularly red) to produce a more striking image. My editing software is an old version of Photoshop (CR2) and Affinity Photo and I use both to edit images for the advantages that each give. What I would like to know is whether the community here would recommend an H-Alpha filter or not? I have an increasing wish list and I wouldn't want to buy a filter if it wouldn't be of significant benefit when there are other things that would. If it is not an option that would be particularly beneficial, I think I would rather put the money towards a cooled OSC camera for the summer months, which at some point I will buy anyway, but I obviously don't what to waste if I can help it. Your advice would very much be welcome. Jem

With 3-4 hours of clear skies forecast on Saturday night I decided to setup for a run with my newly purchased ASI1600MM Pro and LRGB filters. With the options available inside the field of view that I have at 6pm, I turned my scope towards the Flaming Star Nebula, initially with a plan to try and take 3 hours of luminance data. However, the weather forecast developed during the night and clouds held off for 6 hours in the end, so I decided to switch things up and take a little colour data as well. The image below is therefore made up of 38 x 180s luminance, 15 x 180s of each RGB, taken at temperature of -20C, gain 50, offset 21. I settled of these settings after a little research for my Bortle 3-4 sky, but being my first attempt I am not confident that these were optimum. Taken using a Meade 6000 80mm F/6 and HEQ5 Pro. I spent a number of hours on Sunday trying to learn how to process L-RGB data with the hope of bringing out more of the nebula, but I think that I am just lacking data. I therefore hope to take a few more hours of luminance on the next clear night. Feedback and guidance is always welcomed. Thanks for reading.

Hi The L-Enhance is a narrowband filter but it is designed for colour cameras and can/is often used with DSLRs. I have the similar L-Extreme filter that I use with a Canon 1300D and it produces very nice images. The issue that you will have though is that your DSRL is not modified and so the filters in the camera will block most of the light that the L-Enhance filter is allowing through. While a dedicated cooled camera is going to produce images with less noise, with processes such as dithering, DSLRs can produce nice images and can be modified, or purchased modified for far less that a dedicated cooled camera. I therefore wouldn't automatically go straight for a dedicated camera if you are at the early stages to AP and what to save a little money at the beginning. I'm not an expert on newts and so will skip this question. Jem

I'm not 100% as I have only attempted colour to date, but I think the answer would be to take flats for each filter. The reason being is amongst other things, flats correct for dust in the setup. Therefore, if you have any particles on one of your colour filters that will appear on the light frames, you would need to correct this by taking flats using the same filter.

While the outcome may not have been what you were trying to achieve, it remains a beautiful image. Well taken and processed in my opinion. Keep them coming.

As the Heart Nebula was taken using the L-Extreme I've also been experimenting creating a pseudo HOO image by following this tutorial. I'm not sure if the colour should look like this because I was expecting it to be more of a mixture of red and blue, but it still gives quite a pleasing image.

That is very true. To be honest I am red/green colour blind which puts me at a slight disadvantage when it comes to processing, however, it is a challenge am happy with if I can produce worthy images of the cosmos. Thank you very much, your comments are most appreciated. While I have identified room for improvement (I am my own worst critic) I feel that these two images are a huge step forwards in my astrophotography journey. I look forward to the next period of clear skies.

Thank you for your input. I forgot to mention that the Heart Nebula was taken using the Optolong L-Extreme filter, so the longer exposure time was to compensate for that, but I think that it has also produced a better image because of it. While I dithered and used darks on Orion, the Heart Nebula was dithered only, this was because there was a 8 degree different between my lights and darks I took and so I felt it better to just not use them. I haven't made the full step of dithering only yet as I have read that there is an advantage of dithering and darks. I have only just started dithering properly. I had dithering set previously but didn't set a distance so I think I was originally dithering by about 1/2 a pixel. Now it is dithering properly, I have noticed a huge difference in the quality of the stacked image and no longer experience the walking noise that I was battling before. It has made a massive difference.

I've been out of action for about 6 weeks after the motherboard on my HEQ5 blew. However, with a new board now fitted (with much appreciation to FLO) and a Rowan upgrade also installed, I have taken advantage of a few hours of clear skies this week to test both on some classic targets. This is the first opportunity that I have had to take a proper image of the Orion Nebula since upgrading my equipment earlier this year. I am happy with the detail but the colour is off in comparison with others that I have see. That being said, it provides me with a good benchmark to try again before the end of the winter. 15 x 3 min light frames with 18 x 1 min lights. Having seen numerous posts about the Heart Nebula I thought that I would give it a go myself, and all in all I am very happy. It is a bit grainy, which I am struggling to control during processing, but then I am currently using a DSLR and hope that this will improved when I upgrade to a cooled camera in the spring. 50 x 5 min light frames While I still have a lot of room for improvement, I am happy with the progress I am making but welcome constructive feedback.

A great image, well done. I hope to train my scope on that area sometime next year. I purchased an L-Extreme a couple of months ago, and I would recommend it. It is great for when the moon is out and have now managed to create my first HOO image by manipulating the colour channels. It just provides me with options until such time that I decide to head down the mono route.

I can't answer your original question entirely as I have not used the new William Optics version, although I recall a comment in an Astrobackyard video review of a WO scope that he liked it the Bahtinov mask because it let through more light of the focus star. That said, I have one of the Starsharp masks and generally don't have any issues with it. I focused last night on Polaris without any problems.