kirkster501

For LRGB I struggle to tell the difference between Astrodon and Baader. Narrowband is another matter entirely and Astrodon excels.

Hi, is there a 101 or beginners guide document or using gain and offset on CMOS cameras please for soemone coming over from the dark side of CCD? I'm a bit confused on the subject. For instance, what is "unity gain" ??? Many thanks, Steve

You're welcome. The airy disk can be hard to see and you need a dark sky and a medium brightness star, magnitude 2 or so is perfect. Too bright a star and I find the centroid of the star drowns out the airy disk and you can't see it properly. Metaguide has a good collimation tool. Completely free and excellent. Lots of videos on how to use it.

Had it been something of huge and popular significance it would have been in the mainstream media - like the M87 black hole for example. So it can't be that much. Sorry to dampen the mood!

That is not the way to check for accurate collimation. What you have done is a very "rough" collimation, to get you in the ballpark. You need to be *at* focus and to observe the airy disk and then check the rings of the airy disk are concentric around the star. https://www.cloudynights.com/topic/623603-collimation-of-an-sct-from-scratch-a-photo-guide/

Probably to say it's been cloudy of late in the UK.

Arcturus is a red giant "only" 36 light years way. Sirius B is currently eight light years away. Suppose it was still eight light years away 120 million years ago (it wasn't as has been explained, but just suppose). So Arcturus is a tad more than four times further away. So since light intensity decreases as a square of the distance, since it is four times further away and assuming they were both of the same absolute magnitude (maybe Sirius B was much brighter than Arcturus) means Sirius B would have been 4 squared or 16 times brighter than Arcturus is today, again assuming the same absolute magnitude. In other words it would have been a very, very bright, red star at about magnitude -4 or -5 if my reasoning is correct, a red version of how Venus appears to us, roughly. Maybe a bit brighter. So it would be very, very bright, certainly, but nothing unbelievably spectacular - 8 light years is still a vast distance. Now, if it had blown as a supernova we'd have been in trouble!

I would research "Bob's Knobs" and you will see there are thumb screws that you can get off of ebay for £1 or so.

No need to worry. These scopes are not precious snowflakes - they are mass produced, commodity items and are quite robust. Get those stripped collimation screws out first and foremost and get some Bob's Knobs (or equivalent) installed so you can collimate easily. Then, even if it did twist the secondary assembly ever so slightly, it won't matter that much. In terms of the rotating secondary, you will see if you remove the corrector again that this can be tightened from the back of the corrector (i.e. inside) of the scope.

Welcome to SGL. The Hague is a lovely city as is Scheveningen at the beach! Been many times!

Interesting. At 3 billion light years away probably not ET.

I think OSC and mono are both here to stay. There used to be compromises with OSC cameras. However, OSC cameras are now so good that the disparity between the two is much less. Mono will always win technically because the entire sensor can be dedicated to each filter, making all its pixels available to that channel. However, we are not trying to compete with HST images or those that can be acquired by those who live in clearer sky climates (and can run the scope multiple nights per week) and on that basis the OSC route is a very credible option nowadays.

Fabulous! It is a superb object that I have observed several times and it is utterly breathtaking. It is such a pity that this is so far south we do not get to see it from Europe.

Some great places on the tip of Cornwall near Sennen.

I’m sure it would be cloudy for several months none-stop if it did go.

I have been waiting for these to come on line Steve but I do not want to drop £600+ and have to wait that amount of time with the money gone. Hopefully in the pursuit of fulfilling demand they are maintaining the quality?

They are not disappearing. There will be ASI 2600 and QHY268 mono versions later this year. I am not turning my back on mono either. But the latest generation of colour, cooled, 16 bit, zero amp glow CMOS cameras like the QHY268C are spectacular. I spoke to Ron Brecher last week about this - top bloke - and he is starting to collect his RGB with OSC now and adds the luminance from a mono camera.

The 3nm Astrodon Ha is the best filter I have. I have it in both 1.25" and 31mm. It is a spectacular filter on Ha objects. You could just image with this one filter alone. You have to swallow hard when pressing the buy button so it is a "are you in or are you out" moment.... I got both mine when Ian King was closing down and I got 20% off.

Which full frame QHY OSC did you use Yves/Olly for the picture in the other thread? Sorry if I missed it but you just mention QHY OSC... ?

Did I read that right? Olly praising OSC and CMOS ?😂. A road to Damascus moment Olly?

I am waiting for that 268M camera too. But back to the thread title and OSC. I must say, looking at some recent examples of images taken with the QHY268C, (https://www.amateurastrophotography.com/qhy268c-test-report) it is pretty amazing of what OSC is capable of now with the current sensors. Of course, assuming the same resolution, nothing will ultimately beat a mono sensor and filters. It is a question of is OSC good enough?

Yes, it is possible, if you're prepared to wait thousands of years. However, maybe the question should be "Is it feasible?" The answer to that is no, it isn't.

I heard things are not looking so good for the Yerkes 40" scope and it may be mothballed. EDIT: Things are looking up: https://www.chicagotribune.com/news/breaking/ct-yerkes-observatory-university-of-chicago-new-life-20200501-xmdjrdwau5hqvdb63ls6q2jauq-story.html

That 2600MC Colour gets an amazing write up. I nearly went for one two or three months ago but I wimped out to wait for the Covid situation with my employment to bottom out. FLO did not have any in stock then and have not had any since. Likewise the QHY268C, similarly great write up. https://www.amateurastrophotography.com/qhy268c-test-report EDIT: Bern has the QHY268C in stock!

Hey guys, I am also eyeing the 2600 mono. I am also hoping it will work with 31mm filters so I can port over my Astrodon Ha and LRGB filters over to it.