Owmuchonomy

Hmmm.. aside from other features I'm not familiar with yet I can't accept that a 35kg payload constitutes a 'Pro' label.

Sounds like you have a weird cable.  Mine is just a coiled cable that has the potential to stretch out a significant distance before catastrophe.  You could also just get the wifi dongle in place of the cable and run it from Synscan on your phone.  I believe FLO do some nice silicone upgrades too?

Good advice above.  Are you certain it's a focus problem with your images?  The pixel size of the 224 and your Mak's focal length are close to the sweet spot for the camera (f/15).  If you are using a barlow then potentially you will be over sampling a lot thereby degrading your images (among other possible reasons).  There is also little benefit in using an OSC for the Moon.  Much better results can be obtained using a mono cam. An IR pass filter combined with a good NIR camera such as the ASI290 will also combat to some extent the seeing issues in UK skies.

If you wish to use a DSLR for planetary imaging it is possible.  However, you will only get decent results if your Canon has video crop mode (my 60D had such a setting).  This crops the sensor capture down to something appropriate for planets for example 480 x 640.  Then you need to take video and use Autostakkert to stack the best of your frames.  I also got better results with eyepiece projection  (rather than prime focus) using a Baader adapter to connect the T ring adapter directly to the eyepiece.  The best results I obtained were when I used a 15mm plossl on my 102mm refractor.  I have moved on to using a 9.25" SCT and and proper planetary cameras, it's much less faffing around and gives you decent focal length and small chips.

By far the best telescope to buy is one that will be used.  We have a steady flow of disgruntled beginners who bring their gifted telescopes to the obsy to receive advice on how to set it up and get the best out of it.  Mainly, they are Newtonian reflectors on cheap and wobbly EQ mounts.  Simply put, the easiest one to use is as Robin describes, a refractor on an Alt-Azimuth mount.  Look no further than that.

Your issue is that you are trying to do two somewhat unrelated processes as one.  PA is to align the RA axis of your mount.  Star alignment is to set up your GoTo function.  They are not related.

Are you imaging or observing?

If you are observing, PA does not have to be accurate. Set the equipment to the home position. Do a rough PA using the polarscope then leave it alone.  Next do your star alignment.  If you think your set up is suffering from cone error then do a 3 star alignment using the handset routine.  If you are not so concerned about cone error do the 2 star routine from the handset.  You will then be good to go.

If you are imaging, repeat the above but do a TWO star alignment using stars on the SAME side of the meridian that you wish to image.  Next, run the PA routine from the handset.  It will take about 2 or 3 iterations to produce accurate results.  Then, repeat the 2 star alignment if it has moved somewhat during the PA routine.

I presume that's the IOS version.  As far as I know the MAC OS version is not yet released?

That’s an excellent scope choice for planetary imaging. The harder choice is to find a planetary camera in your budget. I have the same type of scope and choose from any three of my cameras. ZWO ASI, 290, 174 and 224, the latter being the colour option. You will need a couple of Barlow lenses to match your focal length to your camera’s pixel size. If you search for Chris Go and his planetary imaging lectures on You Tube they are very useful.

Looks like you have the EQ3 mount, if you wish to take up Astrophotography then a better mount such as the HEQ5 or better is required. Even that will require guiding with a guide camera for exposure lengths over 30 seconds or so. Tracking objects in the night sky for visual enjoyment is done much more easily as some error can be tolerated.

It's very nice to see that your children are so interested.  We have hosted 100s of events at the observatory for all groups.  We still get a buzz when a youngster sees Saturn for the first time.  Being very honest you will find it extremely hard, in fact virtually impossible to find an 'all rounder' solution.  Everybody will end up disappointed.  From experience and to occupy the children's imagination one should aim for a low maintenance, easy to use GoTo set up.  The children can then get involved in the experience.  A Newtonian on an equatorial mount does not fit the bill as pointed out above.  In your position I would purchase a decent small refractor (E.g., ED80), put it on an AZ-Gti mount and and upgraded tripod (like an EQ6 tripod).  You can then use a phone and iPad to open up the night skies for your youngsters.  It's also a portable system; ours runs from one drill battery for a couple of nights viewing. When you get the bug for imaging you then have a decent imaging scope and tripod ready but you'll need to go for a more sophisticated and expensive mount.  Enjoy!

The basics for planets in my view are:

1) Lots of focal length (hence the real need for a tracking mount, Alt/Az is fine).

2) A fast frame rate planetary camera (colour if you don't want to faff with filters).

3) Stacking software such as Auto Stakkert.

A DSLR is not really ideal because you need a very fast frame rate say 200 fps and you don't need a huge chip.  I have performed planetary imaging with a DSLR but it was a model with movie crop mode (rare) and I needed to use eyepiece projection. It's really not ideal.

For example, my setup is a C9.25 with an ASI 224 or 290 camera.  I adjust the focal length to get the optimum using a Powermate.  The simple formula is to times your camera pixel size by 4 or 5 to get the optimum f/. So for the 224 I use a 2x powermate which takes my scope to f/20 and a focal length of 4.6 metres.

It is also visible in the evening sky just before Xmas. Greatest elongation is on 21st December.

For planetary you require lots of focal length so bear that in mind. For example I use a C9.25 but the well known imagers are using such beasts as the C14. For cameras there is a lot of choice so do plenty of research first. I have 3 cameras, all ZWO. The 224 colour and the 290 and 174 mono.

On 06/10/2022 at 16:51, happy-kat said:

Do you use the ED80 for visual or imaging and if imaging in altaz or eq mode please?

For the public events it’s purely visual.

We have used the AZ-Gti and ED80 combination for 3 years at all the Observatory events so far.  It is the perfect combination for that purpose, quick to set up, user friendly, high contrast and can be wide field.  Look no further.

Just use a FOV calculator to help you choose too.  The objects you mention have vastly different angular dimensions in the sky.  For example, my image of M31 was taken using a fixed 300mm focal length lens attached to my Canon crop sensor.  My image of M42 was taken with my (0.63 reduced) C9.25!

On 25/09/2022 at 17:53, newbie alert said:

So if he had a C14 would that calculation still ring true? Christopher go uses a 290 with a pixel size of 2.9 so should he be using his at f11.6 or f14.6... so that calculation is abit vague and not really relevant

That information came originally from Chris Go.  Applies to all scopes as far as I know.

6 hours ago, vlaiv said:

Well, actually no. One can go up to 3-4 minutes with given setup. I'll explain.

Jupiter is ~440000Km in diameter and rotates once every ~10 hours. This means that point on equator closest to us moves at ~12.22Km/s. Given that current distance to Jupiter is ~591,000,000Km, this motion is 0.0042656"/s.

In 30s this point will travel ~0.12".

Given above setup at optimal sampling rate at ~0.258"/px, so fastest moving point will only move half a pixel in 30 seconds.

If everything was perfect, then yes, 30s would be sensible limit to prevent motion blur, however, we have influence of atmosphere, and due to seeing different parts of the image "jump around" for more than fraction of arc second. If seeing is say 1.5" on a given night - that really means that distribution of point position has FWHM of 1.5" or standard deviation of 0.637". That is your average deviation of point position from its true position over course of few seconds.

On average, seeing creates x5 larger motion of points on the image from frame to frame than rotation makes in 30 seconds.

Look at this gif from wiki from seeing article:

How much motion/distortion there is from frame to frame.

Stacking software knows how to deal with this - it uses alignment points and creates "counter distortion" (it can't undo blur, but can create opposite distortion, based on feature average position over time - that is how reference frame is created, alignment point deviations are averaged over period of time and that is taken to be reference position for that alignment point). It can correct for feature being out of place for several pixels (alignment point of 25px is often used so max displacement is 12px, but in reality it is more like 7-8px max).

Given this, software alignment of feature on order of 3-4px is not a problem and is easily handled by stacking software, so from above calculations we can see that there is really no need to derotate video for up to 3-4 minutes as stacking can handle any rotation.

Over my head but its all good and I believe everything you say. 😁

Good advice above.  Your FL is dictated by your pixel size and the best results are obtained at 4x or 5x that hence the advice to go to f/12 (4 x 2.9 = 11.6).  Use the smallest ROI you can get away with which will help get the frame rate up and limit the total capture time to 30 seconds for Jupiter otherwise you will need to add in a de-rotation step in your processing.

Good advice above.  You need lots of focal length, the smallest chip area possible and thus fastest frame rate possible.  For example I run my SCT 9.25 with a 2.5x barlow so fl around 5 metres with a ZWOASI174MM.  This gives me a f/ of about 25 which is close to the sweet spot of 4x to 5x the pixel size for that camera.

You may also benefit from an ADC but that's too fiddly for me.

What type of file is PIPP outputting?  Do you need to use PIPP?  I just put the original SER files into AS!2.  Have you tried that to see if the same problem occurs maybe.

The 400 will just restrict the image a little compared to the 600 but give it a go.  The big issue with the Lunt 50 is the terrible helical focuser.  I had one a few years ago and this let it down for imaging immensely.  Which focuser do you have on it?

What mount/software have you got?  If it's only visual you are doing you can use other methods and avoid polar alignment on Polaris completely.

Hi both, I was looking for the profile conversion as I recall doing that in PS, so thanks again.  I've quickly done a full disk test with Alex's method but I am familiar with the curves suggestion from Olly so will try that too.  Many thanks, Chris.

10 hours ago, Yawning Angel said:

Aye, easier to explain with pictures of a quick and dirty process

B&W image loaded, click levels

Select the Red channel and slide the gamma left to around 0.5 (Just as a starting point)

Green channel, right to 1.2ish

Blue much further, 1.8?

Twiddle to taste, or get close then use HSL to nail it

---Or---

You can use recolour to tint it, then HSL again to fine tune:

 

Hope that helps 🙂

Hi Alex, thanks again but it still remains greyscale when I follow your method and I make those adjustments in R, G and B.  I'm using the stacked TIF file from AS!2.