Adam1234

I have my first Ha exposure going now, so will check on that in a mo, and see how it looks. 

At least I'm in focus - the autofocus doesn't like me, after running the routine I checked with BM and was way off focus, so just used the electronic focuser to focus manually using the controls and BM. Now my focus looks great, I think I'll continue using the BM instead of autofocus

Scope is out and cooling down. I'll let you know how the images come out once I get going!

Thanks Vlaiv and Paul M.  As my scope isn't exactly heavy ( in comparison to a larger scope) and also probably doesn't act like a sail, I think I'll give it a go. 

The worst that can happen I guess is that I find out 20mph is too much and I get some unusable subs - at least I would know for next time  I image or someone asks the same question with a similar setup.

The best that can happen is I'm unaffected by the wind and can get some usable subs. 

At this stage in my astro journey, and considering the frequency of clear skies I get here, I think I'd rather go out and get something if there's a possibility of getting some good images than staying indoors wondering what if.

Obviously too much wind + astrophotography could be asking for ruined subs, but how much wind is too much? 

CO is saying about 20mph, dropping down to about 16-17 by 21:00.

I image using EQ6-R Pro, ED80 with 0.85x reducer and asi1600mm pro, and guide using evoguide 50 and asi1200 mini, if that helps - I imagine longer focal lengths will be much more affected. 

Just trying to determine of it's worth going outside, was planning on getting some Ha of the Crescent nebula. 

Cheers

Adam

Thanks again for the great data - here's my attempt processed in the SHO palette using Photoshop. Levels, curves, selective colour, sharpening

Adam

I had a similar autofocus issue with Ha (using APT autofocus, I don't use SGP). Seemed to work more or less fine with the RGB filters and checking with Bahtinov mask, focus seemed ok and lovely small stars. 

When I tried with Ha the FWHM values went straight past the lowest value and settled on somewhere 5 - 6, checking with BM showed focus was way off and I had donut shaped stars. 

I don't know what settings are available in SGP but APT recommend setting the correct threshold, coarse and fine focus settings to get the best results, so going to have a play around with these on the next clear night 

10 hours ago, tomato said:

I find automatic  focusing to be a big step forward in accuracy and time saving, it’s certainly not just another nice to have gadget.

I shared your dilemma last night, a big cloud bank rolled in just before a planned meridian flip and I powered down only to find clear skies about 10 mins later. Fortunately having a permanent set up up meant I could get going again in about 10 mins, when I had a temporary set up once I had made the decision to dismantle I resolved not to look up for fear of being tempted to change my mind.

Very handy to have a permanent set up then! 

I managed to have another clear sky here last night to, up to about 23:30. I think I need to experiment with the best setting etc to use for auto focusing, as the G and B frames I took last I think looked ok, will have a look this evening and confirm, but I took some Ha as well and after running the autofocus routine in APT, checked with a bahtinvov mask and the focus was considerably off! I was watching the FWHM numbers during the autofocus routine and noticed that it didnt exactly settle on the lowest number, in fact, it got to a low ish number, continued adjusting focus and then settled on one much higher FWHM of 5-6! 

Thanks Olly

Bit late for me to make a home made dew heater now, will be a waste of money if I don't use the ones I've bought 😂 30 -50% sounds good though, I'll try that out to start and increase if necessary.

Cheers

1 hour ago, Adreneline said:

Hi Adam.

I have owned and used an EAF now for over a year in combination with a belt drive to either a Samyang 135mm of Canon 200mm. The unit itself is amazing and I am delighted with the way it performs with an ASIair. In terms of repeatability it works perfectly with my 135mm because I have glued a toothed belt to the outside of the lens so there is no 'creep' or 'procession'; I've not taken that step with my Canon lens so repeatability is not great.

After the best part of three years doing battle with autofocus in various programs I have given up and am a total convert to the BM and manually focussing between filter changes and rarely checking during imaging with a given filter (like tonight when I am hoping to get 40 SII images over three hours and will probably pause image collection and check the focus half way through). I should qualify my conversion to the BM approach by saying that using the ASIair interface on an iPad lets you use the 'zoom' feature on the iPad screen which makes it very easy to interpret the BM interference pattern.

I pre-process in APP which gives an FWHM value for each frame - I typically achieve 1.3 - 1.8 whereas I used to be lucky to get below 2.5 prior to using a BM and adopting a manual approach to focussing.

HTH

Adrian

Thanks Adrian. After just looking through the Ha subs I've just taken, I think I might go the route of manually focusing using the EAF and a bahtinvov mask too rather than use the auto focus aid - whilst my R, G and B looked ok, my Ha is definitely out of focus! 

Hi, so as luck would have it, despite the weather forecasts saying otherwise, I have a clear night tonight so I'm extending my test of my new ZWO EAF and getting some G and B data to go with the R that I got last night on the Crescent Nebula.

A couple thoughts occured to me just now about the EAF and also the use of dew heaters.

ZWO EAF

 So last night and tonight I have focused automatically with the EAF using the automatic focusing routine in APT based on FWHM, and it took probably less than a minute or thereabouts. Could be a silly question, but I just wondered though how accurate the EAF is on it's own and whether you should just run the routine once, or twice to make sure and also check with a bahtinov mask? I mean the stars look great in my opinion for sure, probably much better than I've got focusing by hand and using bahtinov aid, but I did check the focus with the bahtinov and it was slightly off (according to bahtinov), but it did make me wonder. As I said though, at the moment the stars look great, and I will post the image up once done (in fact I posted just the R data last night in the Deep Sky Imaging section)

Dew Heaters 

I recently bought some dew heaters as well, for main and guide scope, and the HiTec Astro 4 port dew controller, I just wondered

- When the best time to power them on is

- And what setting to use on the controller, - low/midway/high etc)

I.e. power on when setting up before focusing even if temperature hasn't yet reached dew point? Or wait until the temperature is beginning to approach the dew point, or when it has reached the dew point? Which also begs the question, how do I know what the dew point is? I was also going to ask how I know when the temperature is getting near the dew point but then realised that may be a silly question as I have the temperature probe with the EAF so can measure the temperature.

Thanks

Adam

54 minutes ago, Paul M said:

Good to see you getting the EAF working nicely. It's on my wish list but the mount belt mod kit just pulled rank due to constant guiding failing to calibrate , so I think it's a while off.

I'm not yet sure whether I'm struggling with focusing or not but it's become my least pleasurable "chore" in my new life as an imaging wannabe  

 

Hope you get your mount sorted out. 

Yeah focusing is not my favourite part either, sometimes when focusing by hand it seems to either go really well and I'm focused with a 5 mins, other times I'm still focusing after half hour! 

Took less than a minute or so with the EAF!

2 hours ago, Spitfire said:

Hi Adam,

Did you use manual focus for the ZWO or are you using NINA/APT with the auto focus function?

Geoff

Nice image by the way.

Thanks Geoff. 

 I used the autofocus function in APT using the FWHM

Lovely image

9 hours ago, andrew s said:

Nice start. You have to grab what you can in the UK. Regards Andrew 

Thanks, and yes indeed! Clear skies here almost as rare as a blue moon

Looks like it's probably dust on the sensor (or somewhere else in the imaging train), flats should sort them out

After having bought the ZWO Electronic Automatic Focuser a few weeks ago I've been dying to test it out, but crappy UK weather has meant I haven't been able to get out recently (my last image, of the Elephant's Trunk, I got back in September), and I've been getting withdrawal symptoms from lack of astronomy. 

Fortunately there was a bit of a break in the clouds this evening so I took the scope out to test the EAF - I was a bit optimistic and hoped to try getting 45 mins each of R, G and B on the Crescent Nebula while I was out, despite the current moon phase and knowing that it could cloud over at any moment.

Managed to get 45 mins of R before the clouds started coming in, oh well! At least I tested out the EAF, and it was so much easier than manually twiddling around with the focus knob! As sods law would have it though, I started packing up and the clouds started to clear, but I know if I had set everything back up the clouds would probably have returned, so I called it quits.

Anyway, here's the 45 mins of R (45 x 60s subs). Hopefully soon we get some clear nights so I can at least get some G and B to go with the R (that's probably also a bit optimistic, but one can hope)

Adam

6 minutes ago, Jezphil said:

 Might these not be in different places on subsequent nights? 

You could be thinking of flat frames which reduces vignetting and shadows caused by dust bunnies (which could well be in different places each night if you remove your camera after each session).

Hot pixels are an artefact of the camera sensor, and as far as I'm aware don't change on a day to day basis, hence why most people using cooled cameras reuse darks, and maybe redo them a couple times a year perhaps. 

@vlaiv could probably provide you with a better understanding of hot pixels and dark frames.

22 minutes ago, Jezphil said:

Cooled CDD Astro cam. 

In which case if you had the camera set to the same temperature for both nights, you can use your same set of darks for both nights (provided the same exposure, gain etc were used)

No problem. Yes if you put the respective dark frames (and any other calibration frames you have, if any, that are specific to each night) in with each group. 

The purpose of the unticked frame in the Main Group is so that you get the subsequent groups - you can't get Group 1 without putting something in the main group, hence putting in an image that you're not stacking and unticking it.

Of course, if you have a set of calibration frames which are not specific to each night and want to apply to both sets of data, say bias frames, you can put these in the Main Group instead and DSS will apply these to all groups.

Hi, it shouldn't make a difference if you stack all the subs in one go, I've taken images over several nights and stacked all together. 

If you have specific calibration frames for each night, make sure you apply these to the appropriate subs before then stacking the calibrated subs together. You can do this easily in Deep Sky Stacker using the Groups tab I.e. put night 1 subs + calibration frames in one group, then night 2 subs + calibration frames in another group.

FYI any calibration frames in the Main Group tab get applied to all groups, so I put a random sub that is not being used in the Main Group and uncheck it so that it is not used, then put night 1 in group 1, night 2 in group 2.

Looks like the SkyWatcher 250px 10-inch dobsonian to me, I have the same one. I actually call mine R2D2 😂

Aligning the Ha to the RGB in DSS is quite easy -

1) load all the images into DSS and register,

2) Right click on the image with the highest score and select it as a reference frame, this will mean that all frames will be aligned to this

3) Stack only the RGB frames - untick the Ha leaving only the RGB ones ticked and press stack. 

4) Then stack only the Ha - there should be a button near the top to go back to the original view with your files - untick the RGB files and tick the Ha files, then click stack 

You should then end up with 2 autosave files, one for the RGB and one for the Ha and these will then be registered and aligned. 

Hope that helps

I suppose I could just blame it on me living in the UK