Catanonia

Fantastic colours there. Love to see this target done well and this is up there.

Wow, that 300 is really a beast. Great detail there buddy and have some of these waiting for processing. Unfortunately they were from the Rasa8 and would probably only take up 2 pixels on your image

I have changed the thread name to more reflect this discussion as I think it contains some VERY useful information from @vlaiv and @ONIKKINEN Others may like this thread and the title change will help to search it out.

I uses blink for Elon trails and obvious issues like out of focus I will then start to use SubFrameSelector before integration of channels to check and get the best ones. Played with it a few times so know how it works.

Thanks, those are the magic numbers I needed. The rest I can work out from a couple of images dropped into PI analysis

I did a quick check on unbinned (software or hardware) files. I put in 0.79 as the arsecs/pixels = is this correct ?? If so, then I am hovering in that range and so may be worth it BTW this is pretty poor data that was rejected as only 16 subs listed here worked out of 100

The process for those wanting to follow - Basically a summary For my scope and camera combination I should be aiming at 1.5"/px If I bin my data by 2x (software or hardware) on 2000mm @F8 then this will be almost twice as fast as using a 0.67 reducer @1400mm and F5.3 and no loss in resolution. Therefore I will only use the reducer "if and when" I need a larger FOV for a target. I will do software binning in PI The workflow is as follows for me on OSC ZWO 2600 MC Pro Calibrate all images with darks, flats and bias Blink images and remove bad ones Perform a SplitCFA process on the calibrations to split them into CFA0 (R), CFA1(G), CFA2(G), CFA3(B) channel directories Combine the 2 greens directories into 1 Align all the images to a reference one with ImageRegistration ImageIntegration to produce Red, Green and Blue channels Perform an IntegerResampling 2x bin on each of the RGB channel integrations Use LRGBCombination to bring them back to a RGB image Process as normal

Tried out the process on some old data and worked out how to do it. Will remember this now for the next imaging session and go with 2000mm F8 @bin 1 and use software binning. I will only use the reducer when I "need" the wider field Shame I have a couple more images with the reducer to process and binning them would not be wise at 2.2"/px so will not re-bin them Thanks @vlaivfor taking an extraordinary amount of time to explain this.

So bypass Debayer and do it yourself with the SplitCFA and of course allows you to IntegerResample at will Just did a SplitCFA on a non Debayered sub and it did split to down to 4 components which is nice So if I do this to all the calibrated images, move the greens, I can then process like a RGB image as I used to in mono camera's A bit more complicated, but not too much hassle. Thanks for your time @vlaivfor this discussion. Much learnt

Update. The 2 tools in PI are SplitCFA and MergeCFA. SplitCFA will take a load of images and split them into the 4 channels in a nice directory tree structure, BUT and here is the kicker, the MergeCFA can only take 1 set of files, ie cannot process a whole directory like the Split does. This means realistically it is limited to being done on a stacked linear image otherwise I would have to manually merge 100's of files at a time, very long and laborious clicking on 100's of 4x images and getting them in the right order. So routine in PI is Calibrate Debayer Align Combine - linear stack SplitCFA IntegerRe-sample to 2x or 3x on each channel MergeCFA to give back the final 2x or 3x binned stack It seems to work

Thanks, trying to work this out in PI and keep coming up with Drizzle. Not sure if I am going down a dead end here. Edit - In PixInsight it is called SplitCFA and MergeCFA - Reading up on it now

Ah this is key and not what I was doing. I was Integer binning (in PI) after all the processing doh !!! and that is probably why I did not see any differences or reasons to go down the software binning route. My process will now be as follows Take the images at 1x bin Calibrate them Debayer them Integer bin them Stack them Process as normal

Thanks buddy. The Old Hall was done up about 6 years ago into a new fancy pub / restaurant. Quite nice now. Sandbach is a nice quiet / quaint little market town. One of the many reasons I bought a house here.

I meant with reducer I would get wider field of view compare to without reducer where I would need to crop the image to get the same framing on non reducer compared to a reduced one (of course there is still cropping for star shapes in potentially both scenarios. Your long explanation above makes sense now you have described it that way. My take home from all this is that I really should be imaging at 2000mm F8 and then binning that data to give me 1.5"/px UNLESS I cannot get the framing I want, ie wider field of view and hence adopt the reducer with the known loss in SNR The question is, should I bin in hardware or software. Hardware would save disk space, load times etc etc, but then I would loose raw data and the ability to change my mind. I have been in the past processing the 1xbin data and at the very end Integer reducing it down to size. I think this might be the wrong way What would be your recommendation for this setup in terms of hardware / software binning and if software binning, when should it be applied ?

@vlaiv I think I have my head around this and it seems to be a question between a. No reducer - 1x hardware bin and 2x bin in software and cropping the image versus b. With reducer - 1x hardware bin on the camera and not cropping the image (assuming you can frame your target) Edit After looking and playing with CCD Suitability calculator it seems I have the choice between A and B above. A would be more optimal if I can frame, B would be more optimal if I need more widefield view. But the differences are close, 1.5 "/px compared to 1.1 "/px and fall within the green band. I still (am sure others as well) need to get head around that 1x bin does not always give you more detail than 2x bin

Thanks buddy. This is going to take some time to read and digest, but yes this was the topic we touched on before this thread.

I use the Ocal for collimation and then star test / tweek The Ocal this time got it very close (about 1/4 turn on one of the secondary screws)

Serious question mate On one of my previous posts about the RC and reducer, you indicated that it might not be worth while due to crop / sensor / etc / etc Is this still valid considering the results I have posted here ?

Yes, I was quite surprised at the result and was expecting to have to crop quite a bit. I ordered and received the one in the original post and URL I listed. I can only assume this is what TS Optics sent me.

Here is one debayered and colour neutralised. @vlaiv Stars are not "too" bad on the edges Light_M81_180_0s_Bin1_0003_RGB_VNG.fit

@vlaiv - Uncalibrated, but shouldn't matter. Will need debayering. Looking closely, yes I can now see that there are elongations as you move out from the image and hence for a "perfect round star image" you would need to crop. Light_M81_180.0s_Bin1_0001.fit

@vlaiv - Attached is a calibrated sub Light_M81_180.0s_Bin1_0001_c_d_r.xisf

I don't have to crop any of the final images after calibration of flats / darks / bias (both native and 0.67 reducer) Well if I was being nit picking, perhaps 10% off the edges for perfectly round stars I just decided to crop for framing and presentation of final image.

Thanks buddy. I am at 2000mm FL here and not sure what FL you tried at. I was quite surprised at the detail I got considering my Bortle 6 skies You are missing out, Bodes and Cigar are great "big(ish)" galaxies for us northerners

I am still working out all of the fun parts of the 10inch Open Truss RC from TS Optics. So far I have gotten the collimation down to a tee and now was the time to try out the TS Optics 2inch CCD Reducer 0.67x that is recommended by TS Optics to use with this scope. https://www.teleskop-express.de/shop/product_info.php/info/p8932 This should have brought down the 10inch RC from 2000mm @F8 to 1340mm and @F5.3. Interestingly, after plate solving, the ZWO ASI Air Pro reports the FL as 1426mm, so I don't know what is going on here. Here are my thoughts of the scope and reducer combination Getting the recommended 85mm back focus is not an issue and fairly easy to do with T2 adapters and there is plenty of room for filter wheels / drawers if you wish to use them. My back focus was bang on 85mm with good results. Getting focus was a completely different matter. Even with the smallest focuser adapter in place on the RC, I had to arrange the image train with the reducer right at the end of the train and push it all the way into the 2inch focuser. This I found strange that the only way to get focus was to push the reducer so far into the focuser, but at least it worked with about 15mm focus wiggle room. Getting good flats is essential - The flats are a reverse doughnut shape (See attached image) but do work. The ASI Air Pro completely messes up auto stretching of the flats and is worrying at first until you realise and manually stretch the sub. I found the best way was to take flats was to use the white teashirt over the scope and point to morning sky. Light seep from the open truss was not an issue, but I did use an additional after market cloth scope shroud. Collimation was still bang on as expected and even out to the edges of the frame. So the reducer didn't mess with the good flat field the native 2000mm FL RC has. With the WO66 and ZWO 120mm guide camera on EQ8-R I can get 3min guided subs with no issues. Not too bad considering not a OAG setup. I did try 5 mins and got some slight eggy stars, so 3mins is my max. Images look great and well worth the relatively cheap price for the reducer. 1340mm is still a good FL to get good close in images with the advantage of the increased F ratio, Image Details M81 in OSC 4.5 hours Scope - 10 inch Open Truss RC from TS Optics with TS Optics 0.67 Reducer Main Camera - ZWO 2600MC Pro and no filters ZWO EAF for focusing. Mount - EQ8-R Mount with WO66 / 120mm guiding (0.4 RMS PHD2 ) Computer - ZWO ASI Air Pro 4.5 hours OSC data in 3min subs from Bortle 6 Skies Image Attachments M81 - 4.5hrs Flat frame Single 3 min sub Setup