Starwiz

16 hours ago, Dannomiss said:

does mean i will need to invest in another £30 for a manufacturers fault

Absolutely not.  You are fully covered under the Consumer Rights Act, so the retailer must fix the problem or give you a full refund at no extra cost to yourself.

I'm sure FLO will sort it for you one way or another.

John

23 hours ago, Kenboy said:

But mainly I'm hoping to capture nebulas/galaxies without just with my dslr and star tracker mount

Have a go at some of the brighter ones first.  M27 is a good planetary nebula to have a go at.  It's fairly bright and large enough that you will be able to see some detail.

John

52 minutes ago, John said:

Here is another guess - they used a similar pattern to the 130 but did not make an adjustment to allow for the parallax effect that the larger diameter optics and tube would create ?

Would parallax matter at infinity?

John

On 22/06/2020 at 01:11, Adam1234 said:

I don't know what to do, I don't want to damage the camera buy shutting APT without cooling, help please??

I've had this a few times with APT & the ASI1600mm-Pro.  With APT hung, it's not cooling anyway, so there's no choice other than to shut it down and get it up and running again as quickly as possible.  I'm fairly certain that it's due to the USB connection reliability.

Electronics undergoes much more extreme thermal shock during the manufacturing processes.  Also, there are no warnings about the dangers of thermal shock in the cooling section of the ASI1600 handbook, so I think you have nothing to worry about.

However, with the camera warming up quickly in this way it's possible condensation may occur on the sensor in the same way as happens with your telescope optics when you take it from outside into a warm room, so you still want to do a controlled warming if possible.

John

Here's what Astronomy.net came back with on the stretched image.

You can stretch the image using  Photoshop or, if you don't have that Gimp is a free bit of software that will also do the job.  In Gimp, use the Colors - Levels and Colors - Curves features.

Here's a quick stretch I did on your image.

The North America nebula is a tough target for an un-modded camera as much of it is Ha and it has a low surface brightness.

You seem to have some light leakage getting in somewhere in the bottom right corner.

John

23 hours ago, Waldemar said:

In your picture, it looks like there is a crack in your mirror, running from the top to the left side... is it?

As Ricochet said, it's the spider vane reflection.  Had me scared for a minute though. 🤣

Thanks for the document.

John

23 hours ago, Ricochet said:

Reflection of the secondary spider, I think.

14 hours ago, jonathan said:

If it is just dust or sand then you could first try a can of compressed air (DO NOT SHAKE IT) or a camera 'bulb' blower (without touching the mirror surface at all), see how much of the dust it removes.  You will need to remove the mirror from the OTA in order to do this properly.

Cleaning the mirror shouldn't be difficult or scary, it's just requires a very gentle touch and some distilled or de-ionised water to rinse off the soap, then leave to air dry in a warm place (preferably not outside when there is a south westerly breeze!)

Thanks Jonathan, sounds like a good plan.

John

Welcome to the SGL.

John

A problem in Malta is that any breeze from the south or south west tends to deposit tiny particles of dust from the Sahara.  I'm very nervous about cleaning the mirror, but is it time to do so?

John

Welcome to SGL Dan.

You'll find this place a fantastic resource and as you've already seen, everyone is very helpful.

Ref. your question on eyepieces and why you might want extra ones.  There are different types of eyepiece and some give wider views than others.  The focal length of the eyepiece and the focal length of the telescope determine the magnification.  A good 2x Barlow lens is also very useful for doubling the magnification.

https://en.wikipedia.org/wiki/Eyepiece

John

Welcome to SGL.

John (also in Malta).

Thanks for the replies all.  When I get another clear night, I'll run some experiments and report back the findings.

John

I recently went over to OAG using an ASI120mc for the guide camera.  Not the best camera for this sort of work, I know, but it's what I have available at the moment.

The scope is a SW200P on NEQ6 with an ASI1600mm-Pro as the main camera.

So, my question is, would using 2x2 binning with this scope/ guide camera combination have any significant adverse effect on guiding?

I'm thinking of doing this to increase the apparent sensitivity.

Thanks

John

On 02/06/2020 at 20:38, Freddie said:

I can’t imagine why everyone would suggest a guide scope would be better than an OAG on a Newt.

I agree.  I went from guide scope to OAG on my Newt in April.  Before that I used to throw away loads of frames and now it's hardly any.

I'm not using the ideal guide camera either (ASI120mc), but it works.  The stars are elogated due to the coma, but PHD2 handles it fine and my tracking is much better than it ever was with a guide scope.

John

I have the ASI1600mm-Pro and have recently done a couple of nights imaging NGC6960, the witches broom which obviously has bright 4.2 mag star and I'm not seeing any of those reflections.

I can't say what the OP's problem is but I am using OAG, ZWO filter wheel and SW200P.  Hence, I wouldn't think the problem is to do with the camera or filter wheel.  I'm also not using a coma corrector yet.

John

What are you using for power?

Insufficient power such as a dodgy battery can cause these sort of problems.

John

16 hours ago, daemon said:

Brilliant analogy from John there!

Thanks for saying so, Steve.

John

4 hours ago, Adam1234 said:

Thanks John, it will be interesting to see what you get with the HDR settings compared with say unity gain

First indications are that it looks a lot smoother when I zoom in, but I have a significant gradient having not applied dark frames, so hope to get these done in the next day or so.

John

I've got the ASI1600mm-Pro myself and have only recently been getting my head around all of this.

A few things I've learned:

Gain doesn't change the sensitivity of the camera.

Each pixel can be thought of as a bucket (or a well - hence the term 'well-depth') that collects photons in a similar way that rain drops would collect in a real bucket.

At the end of the exposure, the fuller the bucket, the higher the ADU value for the pixel (higher ADU = lighter, lower ADU = darker).

Gain determines how quickly the bucket gets filled.  A higher gain means the bucket will fill more quickly, but there will be less levels possible within the bucket, so a higher gain means less dynamic range and lower gain means more dynamic range, although it's not a linear curve.

Offset determines how full the bucket already is before the exposure is started.  An empty bucket to start off with is undesirable in case there are no photons collected.

I'm currently experimenting with the HDR (Highest Dynamic Range) settings for the camera (Gain = 0, Offset = 10), but haven't yet processed anything.

John

17 minutes ago, uhb1966 said:

Hmmm last time when i checked it it was OK ...erm that was 2016

Maybe i should recheck it

Definitely.  You may want to check it a lot more often as it can easily go out as with any Newt.

Is your collimation OK?

Thanks.

I'm not expecting much difference, but will do some trials just to satisfy myself and my own understanding. 

My sky is about 20 mags per arcsec sq, so I'm going with shortish subs that I've calculated to be long enough to swamp the read noise.

John

5 minutes ago, Gina said:

Yes, just a subjective approach.  There's probably a way of measuring it but I haven't bothered.  That is just looking at individual subs - I use darks and flats to calibrate the light images.

Thanks Gina. 

John

8 minutes ago, Gina said:

I run at -20°C or -25°C.  I've found lower temperatures definitely give better results.  I used to run at -30°C or -35°C but haven't managed that over this mild winter.  Now it will have to be -20°C or warmer as the ambient temperatures increase.

Thanks Gina.

In that case, I think I'll run for at -20C for a few more nights to so I can do a comparison with -10C frames I've collected over the last year.

How do you compare noise levels - is it just a case of zooming in on an individual frame with the same exposure, gain, etc. and doing a visual comparison?

John