DKNicholson

4 hours ago, Traceyh said:

I had seen a one in Jessops. It's the Celeston PS1000.  Is this any good as an entry level. Some of comments I've had is like double Dutch to me ...very confusing sorry 

It is difficult to know which comments are causing confusion, but I'll take a few guesses! 🙂

(1) A 'dob' is short for Dobsonian and in basic concept it is of a similar type of telescope to the Celestron PS1000 - they are reflectors. Dobsonians normally sit in a wooden 'cradle' that sits on the floor, whereas Newtonians normally sit on a 'mount' on a tripod. They are both known as reflectors because the light comes in through the open front and goes down to a curved (concave) mirror which reflects the light back up the tube to another very small mirror set at 45 degrees. This one redirects the light to a viewer/eyepiece that sticks out of the side of the tube.

(2) Refractors are the traditional style of telescope that have lenses at the front that focus the light to the bottom of the tube where the eyepiece sits. These lenses can be expensive to make and cheap refractors have only a small aperture at the front. Mirrors are cheaper to make because they do not rely on high quality glass for lenses.

(3) The aperture. The bigger the hole at the front of the telescope (the aperture) the more light is collected and focused to the eyepiece. Whilst stars are relatively bright and require very little aperture to be seen, some deep sky objects are very faint and require a large aperture to collect more light so there's a greater chance of seeing them.

Dobsonians (dobs) are the best value for money when it comes to aperture because the money goes in to making the telescope and not the mount that holds it. Olly Penrice suggests the SkyWatcher Skyliner 150P and if anyone knows what he's saying it's Olly Penrice! 🙂 This telescope has a 150mm aperture and would be a very good starting point. I can find very little information on the Celestron PS1000, apparently it has a 127mm aperture (but generally not a recommended telescope). A 200mm aperture reflector would be even better than 150mm but it also becomes more awkward and heavier to carry.

With a simple Dodsonian there are no directional adjusters, you basically push the telescope around on a low friction 'cradle'. This is not such a problem once you know your way around the sky, but you always have to nudge it to keep it looking at your chosen object - the Earth's rotation is the issue there. Newtonians are normally mounted on an EQ - equatorial - mount that has manual adjusters to move the telescope up/down and left/right. With Dobsonians/Newtonians it may be necessary once in a while to check the alignment of the mirrors, this is known as collimation - not really an issue with refractor telescopes.

All telescopes need eyepieces to look through in order to see whatever it's pointing at. Usually they will come with one or two and it is necessary to ensure this is the case or you will have to buy at least one - 24mm is standard and cost somewhere around £30 for an inexpensive one. The telescope should also come with what is known as a finderscope. This is normally a very small secondary refractor telescope that you use to look through when trying to point the main telescope in the right direction for the chosen object. Olly Penrice mentions Stellarium and it is a free piece of software for either PC/laptop or smartphone and it shows a detailed view of the night sky - what's out there and where to find it.

Finally I should mention 'GoTo' telescope mounts. These are computerised mounts that point the telescope at an object selected by you; they are the astronomy equivalent of vehicle SatNav. The SkyWatcher Explorer 130P ( https://www.firstlightoptics.com/az-goto/skywatcher-explorer-130p-synscan-az-goto.html ) is a good example of one and would be a good starting point, but it's £325 - but if you can stretch to that it would be much easier to use.

I do hope that some of this helps just a little and I wish you all the best and a Happy Christmas

OK - here we have my latest and greatest observatory set-up! 😄

The red signature 'scope is a William Optics GTF81 that has spent the last 3 years in my garage doing nothing. Then last night I had an epiphany - why not add it to the Altair Wave Series 115 and put the TS-50 guide 'scope on top of it! That way I can utilise the GTF81 without having to dismantle and store the 115 - I just have to swap the camera and filter wheel over!

It has taken so long to think of this as the mount is now an SW EQ6-R Pro, up from an HEQ5 Pro Synscan, and until recently I have been using an SW ST80 for guiding which was way too bulky for this set-up. Hopefully the load will not be too much for the mount as vibration may be an issue - just have to see!

I know that it's never nice to spend money if there's a cheaper alternative, but under the circumstances I should be inclined to bite the bullet and buy something like a QHY5-II that has been specifically designed for the purpose of guiding. It will also probably be quite a bit more sensitive enabling greater probability of finding a suitable guide star. Just a thought.

Imaged over three evenings but only just over eight hours integration (weather . . . !) with Flats and BIAS frames added. Taken using my spangly new Starlight Xpress Trius Pro SX694 CCD camera.

Telescope: Altair Wave Series 115mm - Camera: As above - Filter Wheel: Starlight Xpress SX-USB - Filters: Baader Ha, SII, OIII - Guided by: SX Lodestar x2 on a TS-50mm - Mount: SW EQ6-R Pro - Capture Software: SGPro with PHD2 and Platesolve2 - Process Software: DSS, Nebulosity V4, Photoshop CS3

I have this thing for Saturn and I have many videos I've taken over the years. This image is the result of one I took in July this year that I hadn't taken much time to process. It is 20% of 2,000 frames taken on a ZWO ASI120MC through my Meade LX90-8".

Using a 2" Antares x1.6 Barlow into a 1.25" filterwheel then camera, curiously led to noticeable vignetting where I had hoped it would help avoid it. So whether the vignetting was a result of that particular Barlow or just an inevitable result of using a Barlow, I don't know, but it is perhaps something to watch out for.

Have you checked how far past the meridian your system will go before it attacks the pier? If it is more than 20 minutes or so then try setting the meridian flip for as late after the Meridian as is reasonable. There is also a setting in PHD2 to reverse the guide camera after the flip though I have never found the need to tick that as it seems to do it automatically.

I wish you luck as this sort of error can be so frustrating. Yours aye . . . 

Copernicus through Meade LX90-8" onto a ZWO ASI120MC using Sharpcap. 20% of 3,000 frames processed using Autostakkert-3, Registax-6 and Photoshop CS3.

Impressive image - very nice.

This may be a useful article - http://www.wilmslowastro.com/tips/autoguiding.htm

and also this calculator - https://astronomy.tools/calculators/guidescope_suitability

4 hours ago, Rodd said:

imaging with a Barlow is success enough!  I have not had the courage to try my powermates.  It would be hard for me to justify it though as, except for the C11 Edge, I have the focal lengths I would get using the power mate (like a barlow) covered by other scope's natural focal lengths.  I would still like to try though.  But it gets complicated with guiding (guide scope may not be accurate enough) and the image circle may not be large enough for my self guiding filter wheel (they say its iffy). 

Rodd

The main issue I encountered was quite severe vignetting even with the 2in Barlow through 1.25in filters onto the small chip of the Atik. Using the Trius I think it would not be acceptable at all. When I can be bothered to mount it I have a Meade LX90-8" for very small DSOs, but I'll do with the 115 for a while until I get used to the camera. 

43 minutes ago, Rodd said:

That actually is very nice--so be proud.  Its a tough object to image well.  You have all teh details in teh core--more integration time will bring out teh faint pinks/reds.  Carful not to set you black point too low--the image is looking a bit dark on my screen (except for the core, which is perfect).  I struggle with this as well becuase of noise--but try and get a little more light into the outer regions and see if you can start demarking the dust.  So you know, the dust is lighter than teh background space in most locations.  there are a couple of dense dark regions, but for teh most part teh dust is reddish/blueish--a clay like mess in lost of my attempts--but recently i had some luck.  More data will help.

Rodd

There were quite a number of issues with this image.  The dust bunnies on the camera screen obscured some of the subtle detail - for some reason I had failed to clean the screen before installing.  As a consequence the flats struggled. Also I have been using an Atik 314L+ for the last 8 years so I have yet to become used-to the requirements of this camera - it's very different.  The integration time was not only too short but also affected by high, thin cloud for much of the time, so DSS showed that some of the frames were not of the best quality.  Altogether it was quite frustrating as I have had the camera for three weeks now and have only managed 4hrs 35mins in that period. 

Whilst it is fairly basic and far from perfect, the attached image is what I managed to achieve with the Atik through the same telescope but also with a 2" Antares Barlow x1.6 in the light path that I had been experimenting with.  Not a huge success it has to be said, but I may revisit it in due course.

This is the first object I've been able to image using my nice new camera - Starlight Xpress Trius Pro 694. It's not ideal and I plainly have a few things to learn before I can get the best from it, but I'm not too unhappy with this as a starting point! The total integration was just 4hrs 35mins, and with the weather we've been having I was lucky to manage that!

DSO: NGC7023 - The Iris Nebula

Telescope: Altair Wave Series 115mm

4 minutes ago, discardedastro said:

Sorry - I'll try harder, I'm not great at explaining things and this isn't my absolute forte!

Many thanks indeed for clarifying the process and associating it with the camera that I have - very helpful indeed.  SGPro does have a histogram function so I can certainly use that. As our weather is currently cr*p then I can do something about darks and bias frames, something else I hadn't thought of! As it happens I don't have PI but DSS will create master files so I should be able to use that functionality.

Thanks again, much appreciated.

22 hours ago, discardedastro said:

Not sure about SGP but Ekos/KStars lets you provide a target average ADU. The key thing is to avoid nonlinearity in pixels, but otherwise as high as you can manage. Depending on the bit depth of the camera that will vary and may be tricky to calculate. In general I've seen recommendations of around 30-40% of max ADU being a good ballpark; personally on my ASI183MM setup I target 10k ADU and that seems to work well.

As to the rest - if you can maintain your setup's state (including filter positions, etc) between sessions flats are reusable. I've gotten away once or twice reusing flats between nights even when taking the camera out to do collimation just by making sure I got the camera back in the same position by eye, but it won't be perfect. If you're running in an obsy then placing the flat panel on the wall somewhere and having the scope slew to point at it can achieve a pretty good result (just make sure the panel is "flat" in attitude with respect to the scope, as far as is possible). You need some way to turn the panel on/off, of course.

It's been a while since I played with DSS but are you making master flats and calibrating them with dark/bias frames? I think DSS can do this automagically, but worth checking. Using uncalibrated flats could lead to problems.

Thank you kindly for trying to explain. Sadly I feel none the wiser as, for some reason, I am not comprehending the terminology or how to measure/establish 'target average ADU' and 'non-linearity in pixels'. I concur with your comment 'may be tricky to calculate' as I have absolutely no idea how to do that.

I like your idea of positioning the flat panel in the obsy - I hadn't considered that and it would not be difficult to sequence that into SGPro so that all the flats were done at the end of the sequence.

The camera I have is renowned for not requiring dark frames - it's a high QE CCD. As for Bias frames I believe a library can be created which is periodically updated, so that is something I should do.

For some years now I have been very lazy when it comes to flats and have rarely done them. Recently I created a library of flats, but when added the files to the lights in DSS I lost not only the dust bunnies and other artefacts but also some of the details of the DSO and the 'sky' became very 'flat'. Plainly I was doing something wrong.

I had made a Flat Panel with variable output and put some opaque white sheets in front to ensure the light was even. The camera at the time was an Atik 314L+ with full-well of 19,500. I've now changed the camera and wish to make the best of it. Now I have a Starlight Xpress Trius SX694 Mono and the Full-well is stated as greater than 17,000 and system gain of 0.27 electrons per ADU.

How do I establish the correct exposure time for flats? I shall be needing LRGB and Ha, SII & OIII 1x1 binning and RGB 2x2 binning. I use SGPro and it has a Flats Wizard but it needs to know the exposure range to use - and thereby hangs the problem. How do I establish that range? For those who use SGPro, is it necessary to create flats during the imaging sequence, if so how? Besides manually placing the light panel in front of the telescope after each filter, I cannot see how to do it - particularly as I work remotely and a flip-flat is out of the question (£££)!

Any 'simple' help with this knotty problem would be greatly appreciated - not only be myself but by many others I suspect! 😁

4 hours ago, Cosmic Geoff said:

I picked up a copy of Philips' "2020 Stargazing month by month guide to the Night Sky" by Couper & Henbest at a discount & remainder store for £3 (reduced from £6.99)

It looks like a handy little book, especially for novices, and contains a sky map for each month, monthly objects of interest as well as a listing of the year's special events (conjunctions, etc) and a guide to astrophotography.

On Amazon.uk for £3.00 - surprising.

2 hours ago, david_taurus83 said:

I too balked at the cost of the WO rotator. The other issue with it is you would need to rotate everything from the flattener backwards. In my case I couldn't have the filterwheel pointed down as it risked hitting the altitude bolt on my AZEQ6.

So I got one of these instead. Just loosen the 2 thumbscrews and rotate the camera only. It adds 6.1mm though, not 5.5 as advertised.

https://www.365astronomy.com/TS-T2-Thread-360o-Rotation-Adapter-and-Quick-Changer-Extra-Short-5.5mm.html

Thanks for that, I've Just ordered one - seems like a reasonable solution.

13 hours ago, Paul M said:

It's only trying to help, where's the love?

But, true, after each update it does seem to help its self to my computer and something doesn't work the way it used to!

Not sure what's happening there as I have 3 laptops and a desktop which I always keep up-to-date and have never had a problem. I do wonder if perhaps that is more something to do with Internet Security software than with Windows 10.

6 hours ago, LongJohn54 said:

. . . . . .   Eeeek!   I wonder if my Win 8.1 will cope or will I have to make the change.

For what it's worth, Windows 10, that was much maligned when it was first released, is probably now the most versatile and stable version of Windows they have ever produced. That's probably not what a lot of people want to hear but it really has evolved to being a very good OS - and I don't even work for Microsnot! 🤩

On 08/11/2019 at 09:02, spikkyboy said:

So I have bought the book and already half way thru. Great book and good step by step guide for those of us with little or no imaging knowledge.

I have decided to keep the CPC for planetary imaging and visual observing.

I am going to get a totally new kit for imaging.

So we are now at this. A HEQ5 mount sounds great for the price and then a scope to match to it either SW80ed pro or the esprit 80.

My question really is that obviously the esprit is the better scope and a triplet but is 1000 pounds vs 500. Will somebody of my ability just be wasting 500 on the better scope? It all comes withing my 2000 budget but I can bring it to under 1500 and have cash for a field flattened and some towards a better imaging camera?

 

My first imaging 'scope was a William Optics Zenithstar 80 doublet and using it for Ha Narrowband imaging onto an Atik 314L+ (CCD) it was just fine - BUT (isn't there always) it had its limitations. Whilst it was a very good doublet there was still noticeable chromatic aberration when imaging particularly in LRGB. On that basis a triplet would certainly be advantageous if it will fit into your budget and you feel you may become enthusiastic over astrophotography.

As for the mount, personally I should recommend you acquire an HEQ5 Pro Synscan as that would serve you well for some time to come and it is easy to guide. Until very recently I was using one to image with an Altair Wave Series 115 with a separate guide scope. Whilst that was fairly close to its viable limit it performed very well.

It is quite easy to start with equipment with which you become quite quickly disillusioned. Buying 2nd hand is your best bet if you are thinking of dipping your toes in to see if it's an activity that may or may not interest you in the long term. It can quickly become a very absorbing interest - and then it can start to become expensive. Therefore if possible you want to try and avoid buying something new that you then may need to replace in the near future.

As you will soon discover - everyone in this 'hobby' has their own and differing opinions and that can either help or confuse the issue hugely. I only offer my opinion from my own personal experience and just hope it helps to clarify a little and not confuse too much! I wish you and your bank balance all the very best in this compelling activity. 🤩

Yours aye - David

2 hours ago, Thalestris24 said:

Sorry, I was confusing you with Calzune's OP. Not a problem. The 50mm finder will be fine. You really don't want a barlow on your guide scope - better off having the wide field of view to select guide stars. PHD2 is very good at sub-pixel guiding because it calculates the star's centroid. Currently running with Barlow in place as I was more interested in seeing how my new SX camera would perform and I spent a while calibrating PHD. At the moment the RMS Total error is between 1.0 -> 0.6 which is a significant improvement over previously. I shall certainly try taking the Barlow out and seeing how it goes. Because of the reduction in 'brightness', as a consequence of the Barlow, the stars are quite faint this evening and the Moon isn't helping much! As regards calibration and guiding, make sure you manually select a star with good snr and not clipped. Adjust guide exposure to be around 2-2.5s. All done already. The small pixel size difference between 8.4 and 9.8um won't make any difference, I don't think - lots of people use Lodestars.  When calibrating find a star at about 30 deg and in the region of the sky in which you are imaging. I calibrated just above the equator (in the South) as that was the instruction following an error message when I tried calibrating in the North (I'm imaging the Iris Nebula) - so I'll see how it goes, at the moment it's working well.   When guiding monitor the bullseye - if there's an offset to one side it's likely you are out of balance. I did check the balance again and adjusted it very slightly, so hopefully that will also help. If you can't get a decent calibration you'll have to investigate why that is. It calibrated surprisingly quickly with no error messages - so it is looking good. The Guiding Assistant can give you a lot of info.

Louise - thank you for your time and help - David

ps make sure none of your cables are dragging on the scope! That has always been an important consideration and I just slewed all over the place without any issue.

I'm using an Altair Wave Series 115 refractor with a Starlight Xpress Trius-694 camera. The guide camera is a Lodestar x2 through a TS-50 and Barlow x1.5. The image from the guide camera is very good and the ratio of guiding to imaging is 1:1.6 which I understand to be quite good for this set-up. I do have an SW ST80 where the ratio is 1: 2.2 which is OK, but the clarity of the stars is not particularly good. Using the TS-50 on its own pushes the ratio a bit far and the image through the Barlow and TS-50 is better than that using the ST80, so I've settled on that for the time being. The photosites (pixels) are the active cells on the chip and PHD2 seems to presume they are square as there is only one box available to enter the size. The Lodestar x2 has rectangular photosites (pixels) that are 8.4um x 9.8um. For some odd reason I had this set to 8.0um, but have now set it to 9.1um as the mean. I'm currently waiting for some clear sky to recalibrate PHD2 and run the guiding assistant. If I can get the RMS total error below 0.8 then I should be a happy bunny.

David

22 hours ago, Thalestris24 said:

Yeah, as I said, with a belt mod, you don't want or need East heavy. You want perfect balance in all three axes. People often forget to position the scope vertically and check it's still balanced ok i.e. stays in the vertical position without falling to one side. Of course, you also have to make sure your guidescope is rigidly mounted without flex - more critical with longer focal lengths.

Louise

Louise hi - That is pretty much as it is balanced at the moment and everything is absolutely rigid. I have found a couple of settings in PHD2 that may help a little. Whilst the image of the main camera and the image of the guide camera are similar, it is plainly evident that it is better if they are carefully centred on the same object. Also the photosite size of the guide camera was not accurate whilst the focal length of the 'scope and Barlow X1.5 is! I should also calibrate again and see if that helps - otherwise it's a bit of a mystery!

David