Xiga

@vlaiv is there any difference between software binning and just choosing to reduce the scale of one's stack?

Case in point - when i get my RC6 up and running with my 268M at some point, the image scale will be about 0.58" so obviously oversampled. My plan is just to capture as normal (Bin x1) but then in APP when the stacking process gets to the final stage (integration) I was just planning on choosing a Scale Factor of 0.5 (it uses Lanczos- 3 by default) to basically do the same thing as Bin x2 and bring the image scale up to 1.16".

Do you think this method would actually be better than capturing Binned x2 data at source? Apart from smaller file sizes, there shouldn't be much, if any, difference right? Although what about FWC? Wouldn't that be much higher if binning at source? 

KiThe results you get are amazing Richard, I really hope the LED lights don't have too much of an effect on your imaging. It's good that they will turn them down after midnight, that's something at least.

We bought our new house 2 years ago. My heart sank when we came to view it near the end and I saw the LED light literally smack bang right at the front (see below) 😥 Out the back (South) isn't much better, tall trees blocking everything below 60 degrees. Annoying, as my LP isn't too bad either, Bortle 5, not far off 4. 

I might try phoning the council to see if they can turn the light off after midnight. Not holding out much hope though

58 minutes ago, tooth_dr said:

I have that adapter. It comes with the ZWO filter drawer, it’s 100% solid as a rock.

 

 

 

 

Thanks Adam 👍

While I wait for my 268M to arrive, I've been ordering all the necessary bits to make up the 55mm of backfocus i need for the 80ED. I'm planning on using the 5mm M48 plate that comes with the camera, which I now understand brings the camera's backfocus to 19.5mm. My TS  filter drawer is T2, so I've ordered the ZWO M48-M42 adapter below. Has anyone used this before? It's fairly minimal looking, to say the least, but it only has to support the weight of the camera itself, so I'm hoping it's ok. I did think of going with the M54 plate, and ordering an M54-M42 adapter, but nowhere had any in stock. 

https://www.firstlightoptics.com/zwo-accessories/zwo-m48-to-m42-adapter-ring.html

As I have to pack away after each session, I just ordered a Baader T2 Dust Cap from FLO as well. 

I recently upgraded my guide camera to a ZWO 290mm mini. Haven't had a chance to use it yet, but I could immediately tell the 2m flat USB cable was pants, as it took an uncomfortable amount of brute force to get it to insert into my laptop's USB port, so not a good start, lol. It does at least seem to work,  but as soon as I verified that the camera could connect to Phd2, and made a few darks, the cable went straight into the big ol bag of cables (we all have one), eventually destined for the scrap heap. 

At only 2m it wasn't long enough anyway. Ordered a quality 3m Lindy one off Amazon. Job done 😀

Lovely Richard. Amazing amount of dust for less than 2 hrs. I did have to download and rotate it, because it was messing with my head looking at it upside-down lol. Nice use of Starnet too btw - the filename gave the game away 😁

How did you find using Gain 0 vs the more often used higher Gain (can't remember what it is for the 2600mc)?

I feel your pain on the weather front, this winter has been terrible! In my case, it's even worse, as even when the weather does play along, i can't image anything below 60 degrees South due to the large (leafless!) trees out the back of our house 😒

Curious - i wonder has anyone ever had 'Some fun between the branches'?! With CMOS subs being so short, i wonder if i just decided to let it rip for a night, what sort of percentage of the total subs would i end up actually being able to keep? Hmmmm...

Here's my attempt. Gradient reduction done in APP, everything else done in PS. 

Combined as SHO. Stars removed using Starnet, and then blended back in a lightly stretched Ha layer in blend mode Screen to add back the stars. 

Really amazing data, was fun to process, so once again thanks for sharing and taking pity on us poor folk who haven't seen a clear sky in weeks, if not months!

Edit - made a slight revision, with toned down highlights and slightly different colour palette. 

For anyone interested,  the 26C weighs just 620g. Pretty impressive when you consider the 2600mc weighs 700g and the 268c over 800g.

Ps - I got this piece of info direct from Altair over Fb messenger recently while researching whether to get an OSC or Mono. Their website lists just about every possible spec apart from the weight.

1 minute ago, tooth_dr said:

Cheers Ciaran. Can’t wait to see your images from the camera.  Weather is pretty dire. 

There won't be many, that's for sure lol. I will be hoping for more quality over quantity. 

ps - Yay for 1,000 posts for me! 😅 Holy moly, i've just noticed your post count 😳 

Congrats on the new camera Adam! Can't wait to see what you do with this and the 2600mc working in tandem. 

If all goes to plan, i am hoping to have one of these myself in the not too distant future. When i get a chance to use it.... well, that's anyone's guess 🙄 😋

2 hours ago, tooth_dr said:

Do you mean on the 2600 image in another post or the one above. For sure in the image above that’s the problematic 1600 microlensing effect.

Woops! I thought that was Richard's latest version, but I can see now it's clearly not. Thanks for keeping me right Adam!

That'll teach me for posting from my phone and not the computer 🤦‍♂️ Might be time to get a new phone. This S7 Edge is getting on a bit 😂

8 hours ago, Allinthehead said:

I actually find those small spikes quite attractive.

100% agree Richard. When I sell my Atik383l+ I will miss them. They make the stars so much prettier. I wish the CMOS sensors created the same effect! 

Ps - is there some slight micro lensing visible in your M45 image? I think I can see a reddish grid-like pattern around the brightest stars. Although, if it takes stars of this magnitude to show it, and only at this level, then it shouldn't be much of a problem I would think.

Someone over on CN has got their QHY 268M. It seems it weighs less than expected, 812 grams, and is 107mm long. 

So good news that it's almost 200 grams lighter than expected 😃

4 hours ago, Spongey said:

First batch of 2600MM finished! 

That photo should come with a XXX Warning! 🤤

I'm pretty much sold on the Qhy 268M now myself. 

However, i was doing a little searching online, and i came across this review of the early bird version of the OSC one. 

https://www.astrophotoygk.com/post/qhy268c-camera-review-best-astrophotography-camera

Look at the length of that monstrosity, it's 180mm long! I really don't like the thought of such a long camera hanging off the back of my scopes. Qhy's website has a drawing that states it is actually only 102.8mm, but then it says that's for the Photographic version, which hasn't been released yet (and which apparently will weight 780 grams). I've emailed Bern to see if he knows for sure how long this early bird version will really be. 

34 minutes ago, tooth_dr said:

I had 1.8kg on the focuser on my ED80, and I didnt really find any issues mechanically.  I never really scrutinised the star shapes, but felt they were ok also.  Perhaps your focuser could be tweaked a little?

Wow, 1.8Kg! I've adjusted mine a couple of times over the years, to try and tighten it up. Each time, i had to go and find the webpage to remind me of which screws to adjust, but tbh, it always felt like trial and error to me, even though i did see a small improvement. It sounds like i need to have another go and see if it can be improved further.

I just use the basic SW handheld auto-focuser. Hopefully it's up to the job too. What were you using to focus when you had that amount hanging off yours Adam? 

My next camera will definitely be an IMX571 one, but i haven't yet decided on whether it should be Mono or OSC. At the moment, I'm leaning towards Mono and pairing it with the D5300 for colour. 

Weight is an issue for me though. My wee 80ED's stock focuser is currently just about managing the Atik383l+ (at 750 grams). The ZWO weighs a similar amount, but the Qhy weighs just over 1Kg! which is just too heavy for me i think.Quite annoying really, as the Qhy is available now and at a very good price. In all likelihood, i'll probably just hold off until Autumn and see how things are looking then. 

I've recently picked up a used RC6. It will be some time before i get to use it, but when the time comes, the method i will be using to collimate is Dave's method below (2nd last post in the thread):

16 minutes ago, tooth_dr said:

Definitely not stating the obvious.

I would but am in a slightly awkward position.  When I bought the scope, I wasnt able to get a focal reducer or field flattener for the 94 scope from the same supplier.  I emailed about it, but they dont list it on the product range, and said it would take weeks or months to get it so recommended that I purchase elsewhere.  As the scope doesnt work without either I had to source it from another supplier.  I believe I can still return the scope, but will be left with a £328 focal reducer that wont be easily sold on.  I havent heard back from the focal reducer supplier, but they dont offer returns (14 days only) but they do offer a field flattener for this scope, that brings it to F5.5 also, but at a slightly shorter focal length than the esprit (517mm).  If it is to be believed, the field flattener delivers 'tack sharp stars' across a 44mm imaging circle, so this is a viable option to minimise loses, provided I can get an exchange.

Nothing's ever easy in this game Adam is it?! 

Hopefully the supplier steps up and offers the exchange. Offering only a 14 day return period is a bit of a joke, especially when we can wait 2 months for a clear night here in the UK. 

Good luck with the exchange and hopefully the FF works out better for you. 

Ps - I'm seriously thinking of getting an OSC IMX571 camera too. As you gather more data on various targets, I'd be interested to hear your thoughts on how it compares against 8300 data. 

Hi Adam, I'm sure you researched all the options, so apologies if I'm stating the obvious here. 

Have you thought about sending the SS back and just going for an Esprit 100 instead? Slightly slower, slightly more expensive and slightly higher FL obviously, but at least you know it will perform up to a 40mm imaging circle. 

Thanks Vlaiv, very enlightening as always! I use Astropixelprocessor for stacking, which I think uses Lanczos-3 and Mabula's own custom interpolation algorithm, which he coins 'Adaptive Airy Disc'. 

But I agree, I think we've veered just a tad off-topic here, lol, sorry Gerr! ☺️

13 minutes ago, vlaiv said:

In theory, Bayer drizzle when executed properly will provide 100% of resolution available from pixel size alone - or same as mono camera.

Problem is in the way that Bayer drizzle is implemented and if we go that route - in reality we open up a can of worms really .

Due to the way we image and process our images - even mono is not sampling at the rate pixel size suggests, or rather - our final image is not of given sampling rate. Main culprit for this is interpolation algorithm used when aligning images.

If you want perfect Bayer drizzle that will recover 100% of resolution - you want to dither by integer pixel offsets - so that final registration of subs is simple "Shift and add" - you don't need to use interpolation. This is by the way also best way to produce image in terms of resolution. Using any interpolation algorithm reduces detail further ...

Good thing is that it is really hard to tell difference between say 1" and 2" or 1.5" and 3" visually in astronomical images. This is because of way blur in astronomical images works. It is much easier to spot that in planetary images where limiting factor is aperture of telescope and extensive sharpening / frequency restoration is performed.

Here is screen shot of one of my images (btw taken in red zone with F/8 scope about 2h total integration time) here presented at ~1"/px. One copy was sampled down to 2"/px and then resampled back up to 1"/px.

Can you tell which one? Actually, you should be able to tell by noise grain - noise has just a bit larger grain and image is just a bit smoother - one that has been down sampled at 2"/px and then up sampled back to 1"/px

This is because detail in the image is not good enough for 1"/px - it is more for 1.5"/px - 2"/px sampling (seeing was not the best on particular night).

Btw, left image was sampled down and up again and right one is original.

Now, if I do that with 2"/px and 4"/px - you'll probably see the difference, but again, it won't be striking:

Here again - both have been reduced to 2"/px - but left one has been further reduced to 4"/px and then upsampled back to 2"/px.

First thing to notice - 2"/px is much more suited resolution for level of detail - image looks detailed and sharp. Second - now you can clearly see blurring due to sampling at lower rate - look at detail in bridge - it is clearly sharper in right image - but difference is not that obvious - you would not be able to tell unless looking at images side by side.

 

Thanks Vlaiv. I'll admit it's really not that easy to tell which image is which in your example, which I wouldn't have imagined. 

I suppose with an OSC one will always want to use Bayer Drizzle. I only really used it once myself, on an image of M31, and I recall there being a noticeable improvement. So maybe the true resolution when using Bayer Drizzle isn't quite the full resolution, but is probably a lot closer to it than twice the value, would you say? 

17 minutes ago, Gerr said:

Good points Vlaiv. My RMS error improves to about 0.6" RMS when I guide with the ED80 refractor. With the Newt being like a big sail it always is difficult to manage and guide accurately in anything more than a force 2 wind. 

The 6" Ritchey-Chretiens design reflector is lighter (approx 5kgs) and much shorter in length (391mm), so less of a handful for the HEQ5. This set-up should allow for longer guided exposures to off-set the higher f ratio (which converts to 6.75 with field reducer) so as you suggest a possible solution for me and my conundrum!

I will give this some serious thought.

Many thanks for your very knowledgeable input and guidance - much appreciated. 

Gerr

 

Hi Gerr

I also have an HEQ5-PRO. It's currently getting the StellarDrive treatment by Dave at DarkFrame. I've recently picked up a used RC6 for galaxy hunting. It's definitely at the high end of the scale for the mount, but as long as you don't aim for too high an imaging scale, it should handle it ok. 

Forgot to say, Mabula (the creator of Astro Pixel Processor, which I am a big fan of for calibration and integration) suggests not to use SuperPixel mode for over-sampled OSC images, as the lower resolution would affect registration. What's  your opinion on using Bayer Drizzle (with appropriate droplet size) and an integration scale of 0.5 instead?

https://www.astropixelprocessor.com/community/tutorials-workflows/does-app-support-software-binning-of-osc-color-images/

56 minutes ago, vlaiv said:

Ok, so here is quick break down of things:

- pixels are not little squares contrary to popular belief - they are just points without dimensions (they look like squares when you zoom too much and algorithm used to interpolate produces squares - this is simplest algorithm called nearest neighbor sampling)

- in that sense - no image will ever look pixelated if different interpolation algorithm is used

- there is limited amount of detail that telescope + mount + sky can deliver in long exposure photography  - and this is order of magnitude less detail then scopes are capable of delivering (in majority of cases) when there is no impact of tracking errors and seeing influence (atmosphere).

- if you are after most "zoomed" in image that you can get - above is the limit - you won't get more detail even if you zoom further in, if you are at the limit imposed by telescope + tracking + seeing.

- "zoom" can be defined as sampling rate or working resolution - it is expressed in arc seconds per pixels and represents how much of sky surface is recorded with single pixel. All the details within that pixel can't be resolved - since all of it will be recorded as single point.

This depends on pixel size and focal length. Your camera has 4.3µm pixel size and 200p for example has 1000mm of focal length.

http://www.wilmslowastro.com/software/formulae.htm#ARCSEC_PIXEL

(if you are working with color camera and not mono + filters - you need to factor your working resolution as twice the value - it has to do with how R, G and B pixels are spread over sensor - they are effectively spaced 2 pixels apart for each color).

So you were working at 1.77"/px with your 200p. That is "higher medium" resolution (this is really arbitrary naming).

Let's say that over 3-4"/px is wide field / very low resolution. 3"/px-2"/px is low resolution 2"/px-1.5"/px is medium resolution and <1.5"/px is high resolution

Most amateur setups and sky conditions simply don't allow for detail better than about 1"/px with long exposure imaging (there are techniques that can allow for higher resolutions but those are lucky DSO imaging with large apertures and such).

In order to achieve high resolutions - all there must be satisfied - larger aperture, excellent tracking and steady skies. In reality with Heq5 and smaller aperture scopes - I would say, stick to about 1.3"/px - in fact, if we enter focal length of scope that I linked - you'll get just that

Another rule of thumb is that your guide total RMS needs to be about half or less of working resolution. This means that if you want to go for smaller targets - you need to guide with 0.65" RMS or less.

How is your guiding?

I would not try 1.3" without at least 6" of aperture - as telescope aperture also goes into equation as well.

Another point - since you are using color camera - use super pixel mode in DSS - that will produce proper sampling rate for your calibrate images and stack.

Going higher resolution is just waste of resolution and waste of SNR - too small pixels are "less sensitive" pixels

Nothing wrong with going low resolution and in fact when doing wide field - you simply can't do wide field unless you go low resolution - but you won't capture all the detail available (that is ok for wide field).

True image resolution is when you watch it at 100% zoom - or one image pixel to one screen pixel - aim for your images to look good like that.

Hi Vlaiv

You say that for OSC cameras the true imaging scale is actually double what one might think it is, due to the Bayer CFA. But what if one were to use Bayer Drizzle rather than an interpolation algorithm?  Does this effectively bring the imaging scale back down to half the amount again? 

Richard Sweeney's recent amazing image of the HH Nebula comes to mind. He used a 2600mc camera with a Tak Epsilon 160, so roughly 1.5" resolution. I'll admit I am having a hard time accepting that it's really a 3" image it's that good. 

Ps - part of my reason for asking is that my next camera will be either the OSC or Mono version of the 2600. My head says go for the simplicity of OSC, but.......