How to prevent Jupiter getting blown out!

[lune lupine]

23 hours ago, CraigT82 said:

Yup your collimation is definitely out.  Good collimation is essential for SCTs so I would habea crack at collimating it, plenty of guides online and YouTube bids to help. 

ok. is this any better? taken with 9mm lens which is smallest I have.  sadly all clouded over now till 26th at least by all accounts here in ireland. If this is good (fingers and toes crossed)  I shall write a blog or something for other beginners out there!!

[happy-kat]

That looks better :-) I'll add info later re a great like little app that checks concentric circle alignment.

[happy-kat]

There is a neat little application that you overlay on an image to see the concentric circle shapes against your own star test. I think it is really designed for using a webcam to colimate with but I think it gives an idea. I guess the image it works with is only as good as the flat plane it was taken in too when used in this manner.

The application is called AlsCollinationAid.

I had to boot to my other disc to show you an example so please do not read anything into the squased shape I need to update my graphic card driver.

Hoping that you first real life test shows that you need not do anything further.

Edit: I did a nother one and it lined up better when I spent a bit more time lining the tool up over the image (not shown).

[cjdawson]

Looking at your latest image, the collimation could use a little tweeking.  It's not hard.

The main thing that I'm seeing is that when you look at the image, the top of the circles are squished together and the black blob in the middle is pushed up.   All you need to do to correct the collimation is move the black blob down until it's dead centre of the circle.

The black blob is actually the secondary mirror housing.

To alter the collimation, just use an alan key to turn one of the collimation bolts 1/2 a turn.  See what happens to the blob in the middle.  If it's better, do it again, if it's worse, undo it.  Go too far, undo it, then turn again but 1/4 of a turn.  Keep going, until you can't move things without jumping over the sweet spot.   Use your camera to make it as perfect as you can.   IF you can include a barlow in the optical train do it, and get that perfectly collimated.  What will happen is that when you remove the barlow, the collimation will be much closer than needed, which will give you that extra bit of sharpness.

 

That said...

I don't think it's so far out that you'd have not been able to achieve focus on Mars.

One of things  that you need to remember about mars is that it can vary in size through huge amounts over the course of a year.  Currently, it's about 90° (ish) away, and getting further, so it will be getting smaller and harder to image each day.  Our next "fly by" of mars will be in July 2018.  So I'd expect that mars will be a challenge until then.

 

Whilst mars is getting smaller.  We are soon going to be approaching Jupiter, so that it ripe for the picking.  Also, just after we'll be passing saturn, so again that'll make a great target.   These will be great fun for the next 6-12 months or so.

[cjdawson]

2 hours ago, lune lupine said:

ok. is this any better? taken with 9mm lens which is smallest I have.  sadly all clouded over now till 26th at least by all accounts here in ireland. If this is good (fingers and toes crossed)  I shall write a blog or something for other beginners out there!!

That looks like your collimation is spot on.

[lune lupine]

Thanks Happy-kat! You have made me happy!! So I am good to go?! Do you have an app for clear skies btw

Thanks to everyone else too. Great community

[happy-kat]

You say that at cjdawson but when I took time to line AlsCollimationAid up with the image I took from this post it was pretty good. My image I shared I didn't align it a well as I could so please don't comment on my image but check the original.

 

Edit: I would have a go with that, but why not install the little app and check yourself.

[lune lupine]

3 minutes ago, cjdawson said:

That looks like your collimation is spot on.

Cheers! I got a early Christmas present of some bobs knobs which have to say gave me the confidence to attempt the collimation. 

[happy-kat]

well done, I would be well pleased to have had a go and sorted it like that

[lune lupine]

Other than Jupiter, when will I likely see saturn in the Irish skies and is this a good year for seeing it?

[CraigT82]

Nice work with the collimation!  Easier than it sounds.

Next few years won't be the best for saturn, but you'll still get some nice views on decent nights so it's worth trying for (if only so you can appreciate it more when it's high in the sky again!)

[cjdawson]

10 hours ago, lune lupine said:

Other than Jupiter, when will I likely see saturn in the Irish skies and is this a good year for seeing it?

I was looking at this site when I was putting together my last set of comments.

http://www.theplanetstoday.com/

 

Using it, you can see when earth is closest in it's current orbit to the planet in question.

Using that, we're closest to Jupiter in April.  So that's when it'll be biggest in your camera.

Saturn will be biggest in June.

Neptune in August.

Uranus in october.

 

Then in 2018

Jupiter in May

July for Saturn again

Then finally Mars again in July!

 

Of course, there's nothing stoping you from taking photos in the meantime, but this is when they're biggest, and easiest to focus on.

[Pete Presland]

Well done with your collimation issues. Venus is also worth a look, its very interesting to see the phase and size change over the months. 

[cjdawson]

Yep. Venus is look good at this time of year.  Also, as it's an issue planet, we get that quite frequently.  Mercury is a bit more of a challange as you only get about 30 mins after sunset before it sets as well.