gorann

I do think you are right Valiv! When I now compare several of those star pairs in my image with that posted by Olly @ollypenrice I do see more split between them (ene if I have less than 2 hours of data). I am also impressed by the relatively small star size of the 14" Meade. I often see quite big and bloated stars in other big SCT images. Let's see what tonight's Lum will contribute, if I get the sky and technology on my side.....

OK, I will just do 1x1 then. I am getting a power nap now for two hours so I am ready and alert - did not get much sleep last night, that is the life of a keen astrophotographer😀.

But I am moving from f/10 to f/6.2 so maybe 15 min is a bit over the top. I could also take a few shorter exposures to at least save the galaxy core if needed. As I understand it CMOS could equally well be binned later but maybe to save disk space and processing time I should at least bin 2x2 on the camera?

Thanks again for the thoughtful hints! So what exposure time and gain/offset do you suggest. At least last night 15 min was OK (I could probably do 30 min) but that seems a bit long for the ASI unless I use a really low gain. However, tonight I thought of using the 0.62 reducer since chromatic aberration will not be a problem for Lum and the chip in the ASI1600 is a bit small compared to the APSC in the Canon and it would be nice to cover about the same FOW. I will of course examine the first image and adjust accordingly (exposure or gain?) to make sure I am not blewing out the brightest parts.

Thanks a lot Vlaiv, much appreciated! I never imagined that I could use this scope for imaging at its native FL, but had a little hope to do it with the 0.62x reducer, so I am a happy bunny now! Regarding the resolution, I just brought it down for the jpg version in PS, changing image size from 4444 x 3042 pixels (after crop) to 2000 x 1369, so nothing fancy. Not sure how I could bin a DSLR image, can it be done and is that a better way to do it? I may bin the Lum I get from the ASI1600mono tonight. I probably run 2 or 3 min exposures with the ASI1600 (gain 139, offset 50) so it will be quite a number of subs, but it is only really dark here for 2-3 hours right now so it will be managible.

Friends, here is the result from last night. First a single raw sub, then a raw stack of the 7 x 15 min I managed to grab (only done Canon banding reduction and SCNRgreen in PI), and finally a processed more presentable version. Maybe @vlaiv want to have a go at dissecting the images to extract some useful ideas for future improvement? The image was done at native FL of 3556 mm (f/10), so without reducer and with the CANON60Da as imaging camera. Guided with Lodestar X2 on ZWO OAG. Reomoving the reducer may be the mail reason why there is now much less chromatic aberration, but I also collimated it (was slightly out of collimation). I still have some problems with varying star shapes. My guess that there is some tilt but since I am not going to use it with DSLR in the future, I will try to deal with that if I also get these star shapes when using one of my cooled cameras. The plan tonight is to collect Lum with the ASI1600MMpro that I can add to this RGB image. So Olly @ollypenrice, does it still look like a rather hopeless endeavour? At least I am surprised about how well the EQ8 appear to handle 45 kg scope with over 3.5 meter FL. Bear in mind that this is still only 105 minutes of DSLR data collected at 15 °C. Cooled CCD & CMOS will so be attached to the scope.

Now 02.00 and I have to get up early tomorrow🙄 but the guide curve looks great (RMS around 0.4"/pix) and I am very impressed how well the old EQ8 is handling 45 kg. I am shooting away on a small galaxy far far away at FL 3.5 meters: NGC 7331. Should close the roof and go to bed.....

I had a go at collimating it. It came with Bob's nobs so at least I did not have to fiddle around with metal tools in the dark next to the corrector plate. I did it by looking at the DSLR screen at 10X live view. The defocused star looked very centered to me at the end but it was not too bad to start with. Right now it is collecting data without reducer so at a FL of 3.5 meters - never tried any FL more than 2 meters before so a bit overwhelming. PHD2 shows 0.4"/pixel RMS which is better than I ever had before but then I invested in a Lodestar X2 and an OAG. Still, I am quite impressed with the old EQ8 managing to do this while carrying about 45 kg. I am aiming at a galaxy - NGC 7331. I will report on this thread tomorrow.

He he, then I have a challenge Olly - should I take it? Yours is not an ACF (is it?) so maybe I may succeed.... In any case it will be something to play around with in the second obsy while my Esprits will be collecting data in the other one, so no stress😎

Just try the settings I suggested and the ASICAP program can be downloaded for free from the ZWO site. The camera is not necessary much more sensitive than you DSLR but much less noisy so you can stretch the image more for dim objects. I am also useless at computers (especially Windows since I are normally 100% Mac) but the ASICAP was quite easy to get goingt and use. You find it here: https://astronomy-imaging-camera.com/software-drivers

Thanks guys a lot for all your suggestions! I will for sure check collimation thoroughly using an eyepiece rather than just the live-view of the camera. The scope do have a mirror lock so I do the fine adjustments of the focus with the Meade electric Craywford focuser (sits first in the image train). I will also try without the reducer. Still I am generally rather pleased that things did not look worse after the first try.

Thanks for the input! I will try without the reducer and have a closer look at defocused stars tonight.

This spring just after astro-darkness left me up here I bought a second hand 14" Meade LX200R (later renamed ACF). SInce I had invested in a Mesu200, my old EQ8 was just taking up space in my garage and I though it could be a good match for the 14" SCT, at least for visual use. It also meant that I had to spend the summer building a second obsy for the large SCT which would not fit under the roof of my old obsy and it is too heavy to be taken down every night (weighing 40 kg). Now yesterday it was dark enough to allow me to test if I could use this set-up for imaging. The imaging train consised of a Meade Electronic focuser, a Lepus 0.62 (reducing the FL from 3.5 to 2.2 meters and giving f/6.2), a ZWO OAG with a Loadstar X2 (run on PHD2), and for the night I used my Canon 60Da as camera (if it all works out I probably end up using my ATIK 460 or ASI1600). There was no filter in the train. The image is 5 x 3 min at ISO1600. Stacked in PI and no stretch done. It was meant as a test to see if I could satisfactory guide this beast on my EQ8. With regard to guiding it went suprisingly well (RMS around 0.6"). I was mainly interested in star shapes so I had the scope pointed where it ended up after 2-star alignment, in this case Deneb. That created some apparent reflections (possibly in the reducer) and I do not worry so much about those since I will not normally point it at the brightest stars in the sky. QUESTIONS: My main worry now is that there is some chromatic abberations in the stars, particularly red appears to be a bit shifted. My experience with SCT is very limited and I would be very happy if anyone can tell me what the cause of the chromatic abberation could be. Could it be collimation? Or is it the reducer? I did do some primitive star test and it looked fine to me (rather symmetric rings around a defocused star) but I could play a bit with Bob's knobs. What is the best way of collimating a SCT? Any comments on how I could improve the performance of this set up are most welcome.

Do not give up yet Alan! I do not think unity gain is the best setting. I run my ASI071 on gain 200, offset 30 and -15°C (lower temperatures does not help much according to the dark-current curve for this camera). I think I got the gain and offset from some thread (SGL or CN) but cannot remeber where (but I am sure I did not just guess). I use ASICAP (ASI's own capture program) to run the camera. Depending on target I expose between 2 and 10 min. I have made a library of master darks to match the gain, offset, temperature and exposure times (another reason to stick to the same settings except for a few different exposure times). I am quite pleased with the results so far - considerably better than my Canon 60Da. Here is an example (Esprit 150 on Mesu200, 42 x 5 min so 210 min):

Not sure that the 290mm would be a better choice and more light sensitive since it has smaller pixels (2.9um) compared to the 120mm (3.75 um). Maybe someone knows. And the 290mm is only marginally cheaper (340 Euro) than the 8.3 um pixel Lodestar X2 - 378 GBP at FLO until midnight - so you have 35 minutes 😱

Well, if you want to be full proof for the future I think you should go for the Loadstar but the 120mm will do its job as long as you do not go for OAG with a SCT. I spent my first 5 years of imaging with relatively cheap CMOS guide cameras and rarely had a problem with them.

I think there is almost a general agreement that the Loadstar X2 is the best (most light sensitive) guide camera you can get and will always find stars even with OAG on a long focal length scope. The main reason being its CCD chip with large light sensitive pixels. However, in many cases the cheaper CMOS cameras like ASI120MMmini or QHY5L-II-M will do fine, especially on guide scopes. I just bought a Lodestar X2 (arrived yesterday), since as Wim @wimvb pointed out I had great trouble finding guide stars with an OAG on my Meade 14". I bought the Lodestar X2 from FLO that has it on sale right now but I see that the sale ends TODAY! So maybe you should make a fast decision!

Thanks a lot for the answer I wanted to hear!

Friends, I am not new to imaging but I am new to the Lodestar X2 guiding camera that arrived today so I post it here in hope of getting a fast answer. I installed the drivers according to the instructions (on a Windows 7 machine - I have to admit that I am a Mac person so I know litte about the Windows world). However, when I shall choose the camera from the menu in PHD2 I only get one Starlight Xpress option and it is named Starlight Xpress SXV. It allows me to connect to the camera but is that really the option I shoud use for optimal use of the camera and settings? Is it anything I can do to get a Lodestar X2 option in the menu?

Great idea but I doubt our small amateur AP-camera manufacturers would ever talk Sony or Panasonic into making such a chip. The LRG (or LRB or LGB) suggestion by Stub Mandrel with calculated third colour is also very interesting. Only problem is that it would not save much time (at most 1/4th) but it could be a way out for someone lacking one colour after the clouds moved in one night (as they often do). Strategy should then be to shoot Lum and then one colour at a time and be happy to get at least two. This thread is really interesting and creative!

If you go for an EdgeHD, I think the 8" would be a better match for your mount, almost half the weight of the 9.25", and the scope is also about half the price. The light gathering of the 9.25 is only 30% more. If you want to see what can be achieved with that 8" scope, have a look at the astobin page of Jason Guenzel: https://www.astrobin.com/users/Thirteen/

On possible start for you is to go for a mono camera like the ASI1600MM and then initially use it to shoot Lum and/or Ha to improve the RGB images that you already have from your DSLR days. Then you have many possibilities for the future, and could either get RGB and NB filters for your mono camera and trust Olly that it will be faster than OSC, or still use your DSLR to collect RGB. Currently I have a dual rig where I often collect RGB with an ASI071 in one scope and lum or Ha with an ASI1600MM on the other, and then combine the data.

If I got you right it seems like you have settled for the Esprit. I think that is the right decision since the price difference will be much less after you found that you had to replace the focuser on the SW80ED, and with the SW80ED you would always wonder if those not so perfect stars would have been perfect if you had gone for the Esprit.

This one could be worth a try and the cost is not astronomical, or at least do some googling to see if someone has experience with it. I think maybe Olly @ollypenrice has tried it (or at least talked about getting one). https://www.firstlightoptics.com/narrowband/baader-ultra-narrowband-45nm-oiii-filter.html

Very nice! I agree with Wim, you probably need better filters or live with the halos. It could be that Baader filters could be good enough, especially their new narrower ones. Good thing with the ASI1600 is that you could probably use 1.25" filters.