Adreneline

Thank you. I am using the 200mm at f2.8. It is very new to me (hardly used since I bought it three weeks ago) and to be honest I have no idea how to step it down - there is no aperture control on the lens - I assumed it was fixed at f2.8 but I would be happy to be told otherwise. Adrian

Hi Alan. Just to clarify this was taken with a Canon lens but not a Canon camera - I used my ZWO ASI1600MM-Pro - a CMOS but not a dslr. Adrian

Thanks for all the advice Rob and Mike. I've followed your advice and am getting pretty much the same result on the resulting image. However, I have recently acquired (purchased!) a Canon 200mm f2.8 and I used that the other night to image IC1396 - so 200mm mounted on exactly the same setup as the 135mm with just a minor adjustment to the tube ring I use to support the lens. The result was surprisingly good with good and consistent star shapes across the whole image and in all four corners. (I won't post on here because this is 135mm only). It makes me think maybe my 135mm is not quite 100%, which is a bit disappointing. If I crop the 135mm image down to the same as the 200mm I lose all the offending stars but it kind of defeats the objective of using the 135mm! Umm? Not sure what to do now. At the next opportunity I will try the 135mm on the Canon 70D and see what I get on a widefield image; I'll post the result. Thanks again for your help. Adrian

Hi Everyone, This is my first image using my ASI1600MM-Pro with my Canon 200mm f2.8. Conditions were not ideal and I only captured 12 x 120s of Ha, OIII and SII. I was really interested in comparing the result with my Samyang 135mm in terms of star shapes, especially at the extremities of the image. This is 5h5s+3h7o+o : RGB all processed in PI with no noise reduction - just ABE and HT. I've also included the Ha. All C&C welcomed. Thanks for looking. Adrian

Very nice result. Can you provide an insight into the equipment used? Adrian

Having finished a futile 65 subs of Ha session on Sh2-240 I was about to strip down the 135mm + ASI1600MM when I caught sight of Orion coming up above the houses to the SSE of me. This is just 12 x 30s of Ha, OIII and SII followed by 12 x 60s of Ha caught just before the dawn started to come up. Combined in APP and processed in PixInsight with a final colour tweak using Selective Colour in PS. Adrian

Four imaging sessions mosaic taken over three nights covering the region from NGC7000 to NGC6888 - North American Nebula to the Crescent Nebula. The image comprises 12 x 120s exposures of Ha and OIII for each session using an ASI1600MM-Pro Cooled and Samyang 135mm lens unguided on an iOptron CEM25-EC. The mosaic was assembled in AstroPixelProcessor. PixInsight was used for BackgroundExtraction and HistogramStretch prior to combining in PixelMath. The resulting image was then transferred into Photoshop for iterative application of Levels, Curves and Selective Colour and finally Dfine2 to reduce noise across the image. Adrian

So far I am really impressed by my new iOptron CEM25-EC. I've pushed it as far as 300s and still can see no evidence of trailing. I am sure if I start to increase the focal length problems may start to reveal themselves but so far, with 135mm and 200mm, everything seems very hopeful. Thanks again. Adrian

Thanks @AbsolutelyN, @rockinrome, @Dark Horizon, @PaulB, @stephencamptonjones, @JamesF, @x6gas and @alan potts for all the very kind comments - I'm overwhelmed! I only did it for a bit of fun but it turned out far better than I expected with whole thing spanning about 12 degrees, I think (please correct me if I'm wrong with that). I've got the SII subs as well but not sure adding them will be of any benefit. I'll resist the temptation to head off in the opposite direction until I get to the Elephant's Trunk! Adrian

Thanks Adam for the kind comments. I'm sure APP is really good for calibrating and integrating. I never use any outlier rejection because I am sure that although it might remove things you don't want it can also aggressively remove perfectly good data if you're not careful. So I stack everything and sort out the cosmetics later. I try to keep noise reduction to an absolute minimum and resist stretching the data too much. The Samyang is a great photon hoover and it's amazing what it does when combined with the ASI1600. Adrian

Came down at 4.15 a.m. to put the scope away after imaging the Cygnus region and spotted Orion lingering over the house tops next to the moon. I couldn't resist giving it a quick go so this is 12 x 30s of Ha, OIII and SII and 12 x 60s of Ha, calibrated and stacked in APP, processed in PI and combined in PixelMath and colour tweaked in PS. Taken with a Samyang 135mm with ASI1600MM-Pro, unguided on a iOptron CEM25-EC. Thanks for looking. Adrian

Thanks Alan, I used AstroPixel Processor to assemble the mosaic - it is brilliant at doing it and (for me) so much easier than using PixInsight; you literally just throw all the lights in as separate sessions and it chonks it way through and produces a virtually seamless result. Glad you like it. Adrian

Having imaged NGC7000 and Sadr on far from perfect evenings when there was a large moon I decided there was little point in doing anything different last night so decided to image the region between the two targets. I can't/won't afford a camera rotator so this is a compromise mosaic planned as best I could using CdC over three nights/sessions. This is 12x120s of Ha and OIII on each target frame (I also have 12x120s of SII but I don't think it will add anything). The whole lot was thrown into APP (which took as long to register it all as it took to take the images) and the resulting pair of masters was stretched in PI and tweaked for colour in PS with minimal noise reduction. I found background noise extraction really difficult on the uncropped image so this is the best I could achieve. All taken with my Samyang 135mm + ASI1600MM-Pro Cooled atop the iOptron CEM25-EC - all without guiding. Thanks for looking. Adrian

I'm loving me new iOptron CEM25-EC. The fact that I can get what I consider to be a decent image with 120s subs and no guiding is just perfect for me. Fewer wires, fewer things to wrong, Ioptron Commander is so much easier than EQMOD, quicker setup and really easy to clear away at the end of a session; I can literally pick the whole thing up and bring it back inside as soon as the camera has warmed up. Love it! I am definitely going to try your processing approach - not come across that one bofore. Thanks for sharing. Adrian

I like the colour scheme! I need to ask you the same question - how did you map the Ha and OIII to RGB? Another couple of dozen sessions and you should have a mosaic to cover the lot Onward and upward. Adrian

Haha! As my mother would have said "there's now't natural about that!" but then she was probably referring to the colour of someone's hair! I am inclined to agree but sometimes I think Hubble can occasionally reveal detail and structure that was not so immediately apparent in the conventional 'red' approach. I also produced a red version but didn't use STF; I used the usual multiple/incremental HistogramStretch approach on the Ha, OIII and SII masters followed by PixelMath in PixInsight and a final tweak in PS. It's all part of the fun - and frustration! Adrian

If you 'right-click' on the EQMOD Toolbox icon and select 'Run as Administrator' you should just get the "Success!" window.

This is SHO : RGB - each one was processed in PixInsight using ABE (subtraction and then division) followed by a stretch using ScreenTransferFunction on the Ha, OIII and SII masters. I then combined them in Photoshop using Annie's Astro Actions and then used Levels (to align the histograms), Curves (to balance the colours) and Selective Colour (to suppress the Cyan and increase the Blue) to try to arrive at a pleasing result. Finally I used Dfine2 to reduce the noise and saved as a jpg. I have LR but never use it for Astro imaging. Thanks again for the kind comments. I'm glad you like the image. Adrian

Thanks Brian. I think where you can end up is largely a function of what you start with and the OIII and SII were not the best because of the 90% moon. Even under ideal conditions I think the quality of filters also affects what you can achieve.

I think I may well have lost my way with this - I find the Hubble palette so hard and I never know when I've arrived at the correct end result. This is 12 x 120s of Ha, OIII and SII in a 90% moon using a Samyang 135mm + ASI1600MM-Pro all unguided. Pre-processed in APP and processed in Photoshop. Any advice on how to improve the colour balance would be gratefully received. Thanks for looking. Adrian

Hi Rob, Thanks very much for the comments. I use FWHM in SharpCap to focus. One really odd thing I find is that I can achieve the best FWHM with the Ha filter - OIII and SII never seem to be quite as good - 2.0 for Ha compared with 2.5 for OIII and SII, however, when I pre-process in APP it gives an estimate of the FWHM range for each sub and the OIII and SII are always lower than the Ha - it's a complete role reversal! SharpCap requires that you select a ROI and in particular one star. It never occured to me to focus on a star in one corner of the image and then see if the result holds true for the other three corners. I am pretty sure it is not alignment of the imaging train but I am not convinced as yet it is not the lens. I need to take the same star field using my 70D with the 135mm and see what FWHM value I can achieve with BYEoS. Thank you very much again for you help and advice. Adrian

Still looking to see what my CEM25-EC + 135mm + ASI1600MM-Pro can achieve unguided. This is the Sadr region : 12 x 120s of Ha, OIII and SII - pre-processed in APP and post-processed in PI with a final colour tweak in PS - I've tried not to overprocess the image. Cropped the very edges of the image to ensure DBE wouldn't get confused. Star shapes toward the extremes are still not perfect but I am pretty sure it is the lens and not droop or lack of guiding. Again I would welcome the views of others. A 90% moon didn't exactly help but clear nights are not to be squandered! I've uploaded this as a png high resolution image. Thanks for looking. Adrian

Hi. I'm no expert but why the need to get to 1/3? I use a Canon 70D with an ED80, WS-ZS71 and/or a Samyang 135mm and I use BackYardEoS to take all the calibration frames including flats. I set the camera to Av mode with the same ISO and the resulting flats along withe the darks and bias are just fine for calibrating the lights. I use a stretch white tee-shirt on the lens with an iPad as a light source. Not sure exactly where the flats histogram sits but they work a treat. Adrian

Thank you! I have to say I do like to see images of galaxies with a fair amount of 'space' around them - I feel it represents the reality far more - they are one heck of a long way off! It is interesting to compare different nebula with the same FoV - IC1396 and the Heart & Soul fill the frame - I'm just imaging Sadr and that also fills the frame - diminutive Pacman often appears to be of equal size but is so much smaller. The ED80 never gets a look in these days - I love my 135/1600 combination. Thanks again. Adrian

Thanks for the feedback and advice. Re. the flats I recalibrated the filter wheel which has improved the flat situation but it is still not totally symmetrical. I do wonder if the lens is slightly suspect so when the opportunity presents itself I will use it on my 70D and see what results I get. I mount the lens on the filter wheel using the ZWO EoS adapter. Placing a digital level on the camera and the lens gives the same result so there appears to be no differential droop between the lens and the camera. I have to hope the camera sensor is orthogonal to the lens plane. This is a fairly ridiculus shot of the Pacman taken after I calibrated the filter wheel - not an ideal choice of lens for this target but useful for testing the tracking and imaging train I guess. There is only minimal edge cropping to the image. This is 12 x 120s of Ha, OIII and SII - all without guiding. Thanks again for your help and the critical assessment of my images - much appreciated. Adrian