Clarkey

Crescent Nebula from last night during a full moon. Not the best time for imaging, but when clear nights are such rarities better than nothing. I am actually not too disappointed with the result given the horrendous gradients that we present in the stacks. Also, I was having some problems with guiding which was getting worse during the session. Thanks for looking and all feedback welcome.

3hr 20min Ha, 3hr 5min OIII bi-colour image with a recently re-collimated RC8 and 1600mm f8. Definitely needs another night of integration to get some more detail.

16 hours ago, licho52 said:

I would leave it as is and upgrade from 1600 to 2600.  The field will be wider and QE is 50% higher so that will get you the speed of acquisition.  And 2600MM will last you a decade.  Given that you already have RC8 /ED80 combo I don't think there are any low-hanging fruit out there.  I am pretty sure 150mm newtonian isn't it.

Last but not least, it's the last chance it seems to sell the 1600 for a good price.  Next year they will tumble due to being completely outclassed by the 2600, the word is out.

Interesting idea but I am not sure my current finances could justify the cost of a 2600. I would also need new NB filters and wheel for the larger sensor. I accept the 1600 is now getting a bit left behind but I still think I can get quite a bit going from F4 (or 3.5 with reducer) from F6.3.

Being into AP has now made me a poor person🙁🤣

3 hours ago, happy-kat said:

Samyang 135mm f2 lens gives lovely wide views, there's a thread on it

This or something very similar is definitely on my shopping list at some point as it certainly gives some great results - but for now I am looking for something of a similar FL as the ED80.

Congratulations! Well done.

I am looking for some opinion from the SGL collective regarding imaging scope options. Currently my wide(ish) field imaging is done with a SW ED80 which is good but quite slow at F6.3 with reducer imaging at 510mm. I am considering the TS Photon 150mm F4 Newtonian as an upgrade. I just wondered what people opinions are of this option and whether there are better choices at a similar price point? Obviously I will need to collimate and there will be pointy stars - but I can live with these. Any thoughts?

23 minutes ago, Grant93 said:

What minor tweaks are those you do in APP may I ask? Hopefully I can do something similar in GIMP.

Unfortunately the are not reproducible in Gimp. I do background gradient removal on the stacks before transferring to ST. I find it helps give a better result on some targets. To be honest I do not have a fixed work flow. I always stack in APP as I think it gives excellent results. Sometimes I combine RGB in APP sometimes I use Startools. I try lots of different versions until I get one I am happy with.

I think with a near full moon and bortle 5 with such a wide angle lens it will be challenging - but as you have proved not impossible. You could try and more restrictive filter which would help and as you say, more integration time. Personally for relatively dim targets I would aim for a good few hours if possible.

With regards to the background, much as I like Startools, I have found that it can make the background a bit 'messy'. This can be improved in the settings - I quite often use the manual develop rather than the autodev to avoid over-stretching the background. I also use APP to do a few minor tweaks before processing in Startools (not as per the recommended methods but it works for me and I keep the data virtually linear). However, at the end of the day, the better the data the better the end result.

That framing really works well. Great image👍

Really nice images of one of my favourite targets. Total of 36 hours is about half the years imaging here. Can I borrow your sky please😁

300 Euro's is not a large budget to get a significant upgrade, but for visual use some form of dobsonian would probably be the general advice. However, what you can see with very much on where you are located and how dark your skies are.

I think this thread would be a good starting point:

On 06/09/2021 at 17:27, Quetzalcoatl72 said:

but on NINA I have ASTAP set up as my plate solver which doesn't seem to work, I have the file locations correct, because it does run it but then fails and Astrometry boots up as the backup

I use ASTAP on NINA and it has been fine. Very occasionally it fails to solve, but it is rare and usually because I am trying to set up when it is not quite fully dark. Have you tried loading an image directly into ASTAP to see if it will solve?

4 hours ago, vlaiv said:

You are now using 200mm diameter 1600mm FL scope - and you are happy to bin x2 (while in reality you should be binning x3 most of the time and sometimes even x4).

I probably should have been more specific with my question to state that it would be aperture limited. With my current set up I could push the aperture a bit more, but I would not want to go above 250mm as I don't want to go sailing🤣

3 hours ago, ollypenrice said:

I don't think we can assume that binning will 'just work.'  I've had two CCD cameras on which it produced too many artifacts to be of any use at all and others on which it worked perfectly. This includes two cameras of the same make and model. I'm also finding with a CMOS camera (ASI 2600) that software binning in AstroArt is giving me poor stars on which the colours are not properly mixed. I get different coloured stellar edges from one side to the other. Perhaps other software will work better but I mention it as a 'problem in progress' which we're still exploring.

Interesting thought. If software (or hardware) binning does not actually represent the limitations linked to seeing and pixel ratio then it adds another variable to considered.

4 hours ago, newbie alert said:

As an option you could buy a ccd47  as a x.67 focal reducer and you're be imaging at 1072mm or f5.36 for the f ratio freaks...

I have got a ccd47 reducer which I use to about 0.73 which works OK with the ASI1600. However, I decided that although the results were pretty good - I managed to get round stars across the frame - it was one more piece of glass to add optical aberrations / reflections etc, so I only use it if I need the extra FOV. But then I could use the ED80 instead......

Currently I have an RC8 which I use for imaging which gives a pixel scale  just under 0.5"/pixel when used with my ASI1600. I usually bin 2x2 to give a pixel scale just under 1"/pixel and the scope is at F8.

I am considering an F4 -F5 newtonian for imaging which would be at a FL of around 800 - 1000mm. At this FL is gives the right pixel scale for 99% of seeing conditions in the UK but the additional benefit of a faster scope. (I am talking about DSO imaging - obviously planetary / lucky imaging is different)

My question is simple really. Is there any benefit in using a FL of more than 1000mm with modern small pixel CMOS cameras if rescaling on a computer will ultimately give the same result?

Any thoughts would be appreciated.

15 minutes ago, markse68 said:

Hi Clarkey, could you elaborate on that a little?

I think NINA is easier to use and to set up for different scopes. If you are still doing relatively basic stuff APT is fine - I used it for quite a while. The main benefit to me of NINA is the framing assistant. It allows you to get the exact framing you want and then it sends it directly to the sequencing page. Very useful especially if you want to do mosaics. The imaging screen set up is also very good as you can customize what is shown and how it is arranged. It's been a while since I used APT, but I know I was much happier when I changed to NINA.

The only thing I preferred in APT was the flats wizard. NINA's flat assistant is OK but can be a little temperamental. Also, if you are using two different gain settings you have to run it twice.

To be honest, if you are happy with APT and it does everything you need there is not need to change. If you start using multiple set ups I think you would find NINA a better option. At the end of the day use the software you find easiest. Given all the other hurdles in AP, we just need some of it to be easy😀

Yes. The RC8 gets a lot of use in galaxy season. Great scope for DSO's.

As requested. Needs a little bit of a processing tweek, but I quite like the result. Luminance plus SHO.

I had an issue with the auto focus so it is not as pin-sharp as I would like. Live and learn.....

Just to add to what has already been said. 3hr 45m is not that long for a nebula. I took 4 1/2 hours with an astro camera (ASI1600mm pro) and my image was still noisy. I added another 6 hours data earlier in the week which made all the difference. I was doing narrowband which will help, but I think more integration time would really improve the SNR.

Great first attempt. Much better than mine (although the day I did it I was waiting for the cloud to clear and the seeing was poor). I would have been very pleased with that result. Using an RC8 which is not ideal for planetary but probably better than a 4" achromat.

FWIW I would give my vote to NINA. I have used APT and NINA is far superior. For planetary I actually use Fire Capture as I think it is better than Sharpcap - but to be honest I do very little planetary imaging....

Technically you can do it with a star test. However, I did this with the TS RC collimator and an artificial star as described above. I was not paying £500 for the collimator! I did buy an M90 focuser tilt adaptor but it is not being used. Collimation is a bit of a pain - but it does not seem to move once 'dialled in'.

TS 2" Led RC Collimator | First Light Optics

Eventually yes. I sort of developed my own method. Technically it might not be perfect but it worked for me. Basically I collimated the secondary first using the TS RC collimator. Then I used a star test (or in my case car headlights on a road a few miles away) to get the primary right as per the DSI method. I then went back to the secondary with the collimator and repeated these steps until it was right. I might still get the Ronchi grating to confirm the FL is correct for the mirrors (currently it plate solves at 1626mm), but I am not unhappy with the result so far.

This is a single sub - the stars look OK to my eye.

To get perfect results you need to be very accurate, particularly on larger sensors. Even on my ED80 and ASI1600 the spacing is critical within a fraction of a mm. Just go out and take a series of images whilst altering the spacing. If it varies from in different corners that is more likely to be sensor tilt.

It is certainly worth the upgrade. I have been very happy with my ASI1600 and filters - you won't regret it.

Everything the Lazy Astronomer is correct, but I will add my bit as a RC owner.

I have an RC8 which is a FL of 1624mm which I use binned at 2x2 to give a pixel scale around 1"/pixel. For the RC6 you could use a focal reducer to get the FL down to around the 1000mm mark which would give you a reasonable pixel scale. Personally I really like the RC as an imaging scope. Although the collimation is tricky, once set it does not seem to need much adjustment. It took me a while to get a good method for getting the collimation right - but once sorted it was not too bad. The other benefit is that although it is not the best option, it can be used as a planetary imaging scope with a barlow.

Just to check, do you have a HEQ5 or 6 as it mentions both above? The HEQ6 will easily handle it but I suspect it will be closer to the limit with an HEQ5.

On 30/08/2021 at 08:51, wimvb said:

I don’t know about APT, but in Ekos it’s best to let the mount track to past the meridian (15 - 30 minutes for me), or the platesolving may flip the mount back. Happened to me a few times.

Good advice. Just make sure your mount limits allow it to track past the meridian by a few degrees.