Astrophotography + wind

[Adam1234]

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

 

Edited November 2, 2020 by Adam1234

[vlaiv]

That is a good question.

I have no idea about that setup - and I presume it will be much more resilient to wind than larger scopes.

I do know that 8" RC on HEQ5 does not like anything above about 3-4m/s. 1-2m/s is fine, or even a good thing - some wind will keep dew of the scopes and optics close to ambient as it is natural circulation of the air.

That means anything up to about 7-8mph is acceptable for even heavier compact scopes on lighter mount.

I think that small / lightweight scope on heavy mount working at lower resolution should be fine at up to 20mph but that is just an assumption / attempt at extrapolation.

[Paul M]

My big 10" newt struggles with anything more than a breeze on the NEQ6. The 127 Mak on the same mount isn't bothered by any wind in which I could happily work!

It's forecast to clear up here later for a while but the wind is going to carry on. So if it is doable it would definitely be the Mak tonight!

[Adam1234]

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.

[Paul M]

I tried a few weeks ago with my big gun on a windy night. Set up in the most sheltered spot I could find and I struggled to get any usable subs. Even at 30 sec there was sure to be a gust that ruined it.

By some standards the 127 Mak is "over mounted" on the NEQ6 but it's nice to have the combination available. As you say, clear skies are so rare it's a shame to miss out because of another aspect of our relentless weather.

[Adam1234]

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

[Astrosharkey]

I run a very similar setup and regularly image in wind, just get it as sheltered as possible and have done 5 min subs in 15 kts of wind

[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

[Starflyer]

21 minutes ago, Adam1234 said:

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

Best to try and fix it in the longterm, autofocus isn't just about getting you best focus at the start of a session, it's about keeping you in focus as the temperature drops.

With my frac I need to refocus every 1.5°C temp drop or the focus shifts noticeably. Even at this time of year it can drop a good few degrees in the first couple of hours.

What software are you using, maybe you can post up pics of a V curve or two?

[Starflyer]

Back to the original question, I've imaged successfully in a near gale with an 80 frac and an EQ6 Pro.  With my 10" newt I lose frames in anything above a slight breeze.

[Adam1234]

3 minutes ago, Starflyer said:

Best to try and fix it in the longterm, autofocus isn't just about getting you best focus at the start of a session, it's about keeping you in focus as the temperature drops.

With my frac I need to refocus every 1.5°C temp drop or the focus shifts noticeably. Even at this time of year it can drop a good few degrees in the first couple of hours.

What software are you using, maybe you can post up pics of a V curve or two?

Hopefully I can get it working eventually. I hopefully just need to get the correct threshold, fine and course focus settings sorted perhaps.

I'm using APT, I haven't seen anything in there about V curve so not sure if it gives us the curve 

[Starflyer]

I'm not sure how autofocusing works in APT.  SGP, NINA etc generate a focus curve Like this, the shape of the curve can help diagnose what isn't working properly.

[Marvin Jenkins]

Having been a recent convert to AP (in the last year) I live in an odd world between AP and Observing.

I have an NEQ5 with SW150PDS Pro Goto, without guiding and using a base model DSLR. This outfit from what is stated is below the minimum for AP so I consider it my learning rig.

Now I only post this because with careful polar alignment I can get 60 second subs with a six inch newt.

The first windy night, at best gusts of around 15 kmh the stars in my subs looked like spermatozoa! White tadpoles!

If there was ever a definitive about mount to scope size, wind on a newt will give you trouble, especially if you are under mounted.

By the way I only feel I am under mounted with my setup when it is blowing. I note other astronomers have 200p on my mount, but not for ap.

Marv

[old_eyes]

I never had much success with Autofocus on APT, although its manual focus aid is great and the bahtinov tool works well. NINA (free) has an excellent autofocus routine that has worked extremely well for me. As I try out different software I have also used Voyager. I find NINA is slower, but able to cope with a starting position that is way out of focus. Voyager is quicker but gets lost much more easily and wanders off focus completely if you don't start from a good position.

Going through the focuser set up procedure properly is vital for all the software I have used.

[Hallingskies]

+1 for a dome!  Before that, I used to set up a screen around my observing pad, mostly to block out stray light but it also stopped the breeze as well.

[Adam1234]

44 minutes ago, Starflyer said:

I'm not sure how autofocusing works in APT.  SGP, NINA etc generate a focus curve Like this, the shape of the curve can help diagnose what isn't working properly.

I may investigate SGP and NINA at some point, are these paid for software?

[Andy R]

1 hour ago, Adam1234 said:

I may investigate SGP and NINA at some point, are these paid for software?

Nina is free you can use Nina and apt to focus alongside each other as shown in astroquest1 video

Sgp has a free version, I gunk, with limited functionality.  Good luck with the wind 

[Starflyer]

SGP is paid for, I've used it for a few years now, it can be temperamental at times.  I tried NINA recently, it's open source, so free unless you want to donate, and is every bit as capable as SGP.

I'd say try NINA first.

[Adam1234]

9 minutes ago, Andy R said:

Nina is free you can use Nina and apt to focus alongside each other as shown in astroquest1 video

Sgp has a free version, I gunk, with limited functionality.  Good luck with the wind 

Thanks I'll give that a watch and investigate NINA at some point soon.

RE the wind,  I'm doing 600s exposures and they look to be coming out ok to me! I think the houses across the street and the garden hedge act as a slight wind breaker.

Feels like the wind has dropped a bit since I first took the scope out too. 

Either way, I'm glad I took the scope out. I'll give it another half hour or so then call it a night. By about 23:30 the streetlight on the corner will be getting in the way, but I will have about 3.5 hr worth of subs by then.

Edited November 2, 2020 by Adam1234