CraigT82

Depends on the scope too, the bigger the scope the more the dispersion will be visible in the final image, purely because the final image will be bigger itself. 

An ADC isn’t essential to produce images but if you want to produce the best images you possibly can then use one. 

Here is a couple of citizen science projects I know of:

https://hoys.space/ 

https://www.exoclock.space

Bothe require capturing your own images and submitting to the projects so not sure if you have some kit? 

Does anyone know exactly why the DR jumps when HGC switches on? 

JWST observing Pluto and Charon, should be an interesting image…

Great sketch…. I wouldn’t know where to start with sketching a big glob like that. Would love an Astro holiday in Namibia

5 hours ago, symmetal said:

The newest Sony sensors have a Dual-Conversion Gain mode which has two ADCs available for each pixel, so each pixel is converted twice simultaneously, one with a low gain and the other with a higher gain. The two ADC outputs are then combined to give a HDR, high dynamic range, signal output. Whether this is a HCG ADC combined with a LCG ADC, or two different 'normal' ADC gain settings, or a combination, I don't know

This is the thrust of Sony’s ‘Starvis 2’ (Clear HDR) technology. The sensor brackets an image simultaneously as you say in order to increase DR, but I’m not sure if that feature would be utilised at all by the Astro camera manufacturers?  I wonder if the thing with ZWO having different HGC switch point to Player 1 is something to do with this Starvis 2 tech.

The IMX662 and 678 also have the Starvis 2 tech and so will be interesting to compare how ZWO and other manufacturers use these chips too (once the other manufactures have caught up and released some cameras).

The Starvis 2 chips also have a different, ‘vertical’ photo well architecture which allows a greater charge build up, explaining why the full well capacity of these chips are much greater then their non Starvis 2 predecessors.  This is definitely something that the Astro cam producers can use! 
 

Yes there is… in the ‘Adjust’ section click on the ‘W-Balance’ button, then hit the auto button on the pop up

46 minutes ago, Astro_Nic said:

wow this is complicated!  So putting a 678 into the FOV calculator on the FLO website with a 2x barlow shows a very large square and a small jupiter.  Using a 585 with a 4x barlow shows a smaller square and larger jupiter.....or is a 4x barlow too difficult for manual tracking?  Or am I looking at the wrong thing to decide?

You won’t use the full sensor size of any camera for planetary imaging, you cut it down using the RoI function (region of interest). So don’t worry about how large the overall black square is. 
 

Manual tracking your scope with a 4x barlow would be something I’d really not want to try! 
 

And don’t worry about the size of the planet in the field of view calculators, when viewed at 100% on a display screen the planet will always be the same size whatever the camera, assuming you sampled appropriately with each camera. 

I’d recommend whatever camera has the smallest pixels.

With a 14” dob your focal lengths are going to be long which on an undriven dob makes things very difficult.

Going with smallest pixels means you can image with shorter focal lengths which should make things a bit easier. 

I’d be going with the 678mc with it’s 2um pixels, you would only need about 1.6x - 1.8x barlow power with that camera. 

If it helps anyone, which it probably won’t, but it might…. Here is one I made using a very simple design and using 18mm plywood. That doesn’t sound too sturdy but it copes well with my 100kg backside. The rear leg (bit of 4x2 softwood) can be set so that the chair back can be anywhere from nearly vertical to nearly horizontal (good for meteor spotting or bino usage).

Used a cheapo Titan router to make it.

Very nice with the gentle processing 👍🏼

8 hours ago, michael.h.f.wilkinson said:

Bigger scopes suffer far more from bad seeing than smaller ones, simply because the seeing disk is much bigger than the Airy disk of the optics.

Isn’t the Airy disk size related to the focal ratio only, rather than aperture size? Eg. 200mm f/10 scope will produce an airy disk the same size as a 100mm f/10 scope, and so the seeing blur relative to Airy disk diameter should be identical for both? 
 

Edit: Nope I’m talking rubbish. The diameter at the focal plane would be the same but the angular size subtended in the sky would be half for the larger scope. 

Yeah it’s annoying, there’s a clunky way which is to hit object info, the more, then show DSS image. Works on some but not on others.

These are really very nice images, wide field but super sharp and showing tons of fine features, and I love the colour, well done 👍🏼 

13 minutes ago, astrolulu said:

Thanks a lot. One of the questions I ask myself is whether F4 is a good parameter for a planetary-lunar telescope. Fortunately, it is not achromatic 🙂

Yes it wouldn’t be my first choice for a planetary scope due to the small diffraction limited field size but with a good focuser and confident/accurate collimation it should produce good high resolution images. 

Get sharpcap pro and run a sensor analysis and then the smart histogram tool, will give you good info on what’s best for your particular sensor

5 hours ago, davies07 said:

A good refractor is a lot less trouble

 

And a lot more money! 

Haven’t done myself but I think that should be fine. Why would a FW allow the use of smaller filters? I would have though the filters would be further from the sensor if placed in a wheel? (Assuming you normally put a filter on the nose of the cam)

Hi Ross, I know your predicament from your other thread about the ADC, I think something you could do is to sell the 2x barlow you’ve got now and get another one with a screw off lens cell, then you could screw it onto the nosepiece of the ADC and you can gain a lot of inwards focuser travel that way.

For example, the Baader Q 2.25x barlow is 2.25x natively and has a stated focal length of 44.5mm. 

The distance from the nose of the ADC to the top is about 84mm so putting the barlow cell on the nose should give you a barlow power of (44.5+84)/44.5 = 2.9x (roughly, this assumes your sensor will be level with the top of the ADC).

Just avoid Televue Barlows for this as although their lens cells screw off they do not have a standard m28 filter thread and so they won’t screw into anything else apart from their barlow body. 
 

11 minutes ago, deanchapman2705 said:

My worry with a 1" sensor is guiding. I'm used to shooting at 396mm focal length (A7iii has a 1.1x crop) and could maybe get away with 150s images with guiding although shoot 120s to be safe. With a 1" sensor, it has a crop factor of 3x so I would be shooting at roughly 1,080mm

Forget everything you know about crop factor… it’s irrelevant in astrophotography!  What is important is imaging scale - in AP this is what is generally meant by the term ‘resolution’ - it is how much sky is covered by each pixel and the units are arc seconds per pixel (“pp)

The guiding performance required is dependent on the imaging scale, which itself is dictated by imaging focal length and the pixel size of the imaging sensor. 

Ideally you want to be able to guide with an RMS error in pixels of half your imaging scale. So if your imaging scale is 2.5”pp the you should aim to guide at 1.25” RMS 

With your A7iii and a 360mm FL scope your imaging scale is 3.39”pp which is quite a low resolution. With the same scope and the 533 sensor it would be 2.15”pp. So the 533 would actually create higher resolution images with more detail. The trade off is a smaller field of view. Still the 533 is 9mp and will blow up for printing nicely as long as you don’t go crazy large. 

Your guiding would need to be a bit better with the 533 than with the A7iii (you’d need 1.07” rms Vs 1.7”rms) so you can check what your existing guiding figures are like to see if your mount can manage it.

It doesn’t shift the focal point so you will need the ADC’s body length of infocus travel (37mm I think) to be able to use it. I’m surprised you each focus with the barlow so far in as normally the barlow will shift the focal point outwards. On my newts I couldn’t use the ADC without the barlow but I could use it with a barlow as it shifted the focal point out far enough. 
 

As for the extra barlow power you get for putting the ADC in between the barlow and camera, you can work out what this will be using this formula:

Barlow Power = (Barlow FL + Distance) / Barlow FL

With distance being the space between the last lens surface of the barlow and the camera sensor. 

Really nice shots, nice clear view of the big rift in the NEB. 

18 minutes ago, MarsG76 said:

Brings a tear to my eye... a tear of shame... in 1969 they put a man on the moon... 69!!!... there was a sense of adventure, risk, courage, intelligence, ingenuity, purpose and true team work... today.. they can't even get the thing of the launch pad... I guess thats what greed, red tape and a broken education system delivers.

What a sad age we live in... Oh but they'll colonise Mars and have Moon bases by 2027... come on....  

Nostalgia ain’t what it used to be.

Really nice results, Mars is small but perfectly formed with plenty of detail, will be great to image later at opposition. Nice work with Uranus too, not easy with 8”. 

Here is a good one from our very own @MarkRadice