oymd

1 minute ago, oymd said:

I think its VERY nice!

Well done!

 

Did you go by r*0.6*+g*0.4 in PixelMath, or did you change the values?

I think its VERY nice!

Well done!

Interesting read...

@vlaiv

@Martin Meredith

Thank you for your replies. 
 

After reading your replies, I’m left smiling. Honestly, thank you for the explanation, but I did not understand a word of it. 
 

Sorry, but this seems so so complicated. 
 

@vlaiv

with regards to your question about why would I want to drizzle, it’s just to know the process of how to do it. 
 

I’m currently imaging with my WO Star 71 only, which is 350mm FL, and have not yet got the right bracket for the ZWO EAF for my Esprit 100ED, but that is also 550mm FL. 

I realise that I will not need to bin or drizzle with my 294MC Pro camera on those 2 scopes, but I also have an Edge HD 11, and plan to give it a go at imaging in the near future, and according to that formula on over or under sampling, I will need to Bin and drizzle on that scope with my camera. 
 

So I just wanted to be prepared and have the knowledge to do it when I’m ready to cross that bridge. 

3 hours ago, Nik271 said:

Hardware binning helps dramatically with signal to noise ratio but any binning severely reduces the resolution of your sensor. So for example if the image was 500x200 pixels wide to start with on the sensor then after 2x2 binning you will end with an image which is only 250x100 pixels wide. So you will decrease the fine detail visible, but on the plus side the image will be much cleaner, as the new super pixels will collect 4 times more light.

The only way to get finer detail in the image is either get a longer focal lenth scope or a barlow, or a sensor with smaller pixels. But there is a price to pay, usually you end up with less light per pixel and need to expose for longer.

Actually there is another very popular method: drizzle. This works  when your images are moved a little bit by a few pixels (dithering). But others can advise on that as I'm not an expert.

2 hours ago, vlaiv said:

No, binning will not do what you want.

Like @Nik271 explained - binning works to reduce number of pixels image is composed of and in process increases SNR of that image at expense of detail. In some cases no detail will be lost - if your image is over sampled.

What you want in your case is to crop image.

First, let's address hardware vs software binning. Hardware binning is only available on CCD sensors that support it. There is very little difference between two methods and it concerns read noise. Everything else is the same - except for the fact that software binning can be performed after you gather data - in processing, which is good as you can decide to bin based on actual level of detail achieved.

You are imaging with ASI294mc and your only option is to do software binning. You can choose to do it in camera firmware (at capture time) - but I would advise against it as there is no real benefit in doing so (except for smaller image files). You can decide to bin your data in software if you want to improve SNR or conclude that no detail is present for bin x1 to be used (which is often case with today's cameras with small pixels).

In any case, I would advise you to take image at normal resolution, after stacking decide if you want to bin or not and then create two versions of the image:

1. Full FOV. This will show target at proper size if zoomed in at 100% zoom level

2. Cropped version - that will show target properly without need to zoom in at 100%

 

1 hour ago, Catanonia said:

Use dither on you guiding to move the image by a few pixels for each frame.

This means then you can use Drizzle in PI to double or triple the size of the image using approximations.

Using 2x or 3x bin will not increase your image size, it will reduce the image size and give you 2x2 pixels or 3x3 pixels for each pixel instead of one at 1xbin and therefore you will lose resolution, but gain signal.

 

Very informative replies, thanks...

Ok, let's say that theoretically I want to Drizzle.

@vlaiv You mentioned that I can choose to BIN AFTER stacking? How can I do that? Never saw that option? Either in DSS or in PI's WBPP? I never saw an option to change the images from the way I took the subs at 1x1 BIN to say 2x2 BIN?

In PI, in WBPP under IMAGE REGISTRATION, I always click on the box that says GENERATE DRIZZLE DATA, but I never see actual Drizzle files generated? I always DITHER after EVERY 300s sub anyways, but never saw the drizzle files? Do they get automatically added to the registered files during image INTEGRATION in WBPP in PI?

In my REGISTERED folder, I can see all the registered frames, and under each one is a 1MB file that looks like this:

2021-09-21_02-10-04__-4.90_600.00s_0020_c_cc_d_r.xdrz

Took this over the past 2 nights.

20x600s

60x300s.

L-eNhance

294MC Pro

WO Star 71 5 element Apo.

I was experimenting with the 600s subs. I was expecting SIGNIFANCT better SNR compared to the 300s. Just for the sake of exploring, I initially processed both sets of lights separately, but could see no real difference in noise and signal.

Please explain to me how binning would affect the end result image?

Say I want to image IC 63, the Ghost Nebula, with my WO Star 71 and 294MC Pro.

I had a look on Telescopius, and the target would be very small on my image.

I've only imaged at binning 1x1 in the past.

If I image at 2x2 or 3x3, would that help when processing the final image, as each pixel would be 4 or 9 aggregated pixels, and I can zoom in on the target when processing and crop accordingly?

here's what my FOV would look like if I imaged IC 63.

Lastly, I suppose the above is HARDWARE binning? What would SOFTWARE binning mean?

Many thanks

On 22/09/2021 at 23:23, Catanonia said:

Condensation on your sensor.

Happened to me this morning after a pretty dew wet night and took some flats and shat myself when I had a big black spot in the centre of a flat. 

I switched off cooling, switched it on again and it cleared itself up

Thank you for your suggestion.

I wrapped the camera and filter drawer with one of my extra dew heater bands over the past 2 nights, and the circular gradient is gone. I was imaging IC 1848 over the past 2 nights. No circular gradient!

On Cloudy Nights, the responses I got were very much suggestive its the Moon reflecting on my WO Star 71's objective, but I was imaging the last 2 nights with the full moon out in the same conditions, and using the dew heater bands eliminated the gradient.

So it must be condensation then!

Thanks again..

masterFlat_BIN-1_FILTER-NoFilter_CFA.xisf

6 hours ago, GoldTop57 said:

Were you running the cooler when taking your flats? You could cool in stages so go to 0 degrees leave for 5 minutes and then down to -10 etc.

Yes, same temp as the lights. All were at -5C

1 hour ago, Catanonia said:

Condensation on your sensor.

Happened to me this morning after a pretty dew wet night and took some flats and shat myself when I had a big black spot in the centre of a flat. 

I switched off cooling, switched it on again and it cleared itself up

Oh...never thought of that...

How can I avoid it happening in the future? Should I use a dew heater band on the camera and attached filter drawer?

Hi Everyone

Yesterday I imaged NGC 6960, and during processing I noticed a very obvious CIRCULAR gradient on my image?

I have attached a picture. I intentionally OVERDID the RGBK in Curves to highlight it more?

Is this from bad flats?

Is it from the filter?

Imaging setup yesterday:

WO Star71

294MC Pro

L-eNhance filter

65x300s

FULL MOON

These flats were taken 2 days ago, and did not produce any similar gradient on any of my Soul or Heart nebula images? Mount & OTA have not been moved or touched for the past 2 days, so did not take flats yesterday night?

The image on screen is after: DBE, background neutralisation, PCC, EZ DENOISE, HISTOGRAM STRETCH AND FINALLY STARNET.

I went back to the raw stacked calibrated Master Light unprocessed image, and just did a Background Neutralisation to remove the green cast, followed by a Histogram Stretch and RGBK curves. Did not do ANY postprocessing.

The circular halo/gradient is there, I think, but much less obvious?

Is it my processing?

Many thanks

8 hours ago, wimvb said:

The explanation I gave you is when you look due South. When looking due North (as in your images), the celestial equator is below the horizon, by the same amount it is above the horizon when looking South. Dec is the angle from the celestial equator towards the polestar. If you are 51 degrees latitude, the cel equator is 39 deg below the horizon in the North, and a star with declination of 69 degrees, will be 30 degrees above the horizon. The Polestar is your latitude in degrees above the Northern horizon.

Your 2nd image with HIP 47193 shows a declination of 81 degrees and an altitude of 21 degrees. The difference of 60 degrees is the amount that the cel equator is below your Northern horizon. This means that your location (latitude) is 90 - 60 = 30 degrees.

When you look due East or West, the celestial equator crosses the horizon, which means that DEC and altitude will be the same. From this it follows that the altitude of an object with a given declination depends on the azimuth angle (compass direction).

Did you do the phd calibration with your telescope pointing to the south and near the meridian (assuming you are in the northern hemisphere)?

Amazing information wimvb!!!

Ive learnt a lot from your answers!!
 

The south side of my garden had considerably higher bushes than the north side, so I always pointed and calibrated NORTH. Our neighbours are south of us, and they like to grow their trees really HIGH for privacy. The trees are about 3 meters high, so I always tried calibrating while pointing NORTH where I can see more of the horizon. 
 

Ok, I get your point. 
 

Tonight I will move my setup all the way to the NORTH of our garden, so that I can have a better and lower view of the SOUTH sky and try the calibration again. 
 

Ive also read on a thread in Cloudy Nights from 2018 that the possible cause of the error I get: Calobration failed. RA star did nit move enough, might be due to some setting in PHD2 where I should change the setting to move the mount MORE with every calibration step?

Thanks again!!

On 19/09/2021 at 16:11, wimvb said:

Yes. You can apply calibration at any declination, but PHD doesn't like it to be too high. There is a difference between DEC and Altitude. DEC is a number of degrees north of the celestial equator. Altitude is the number or degrees above the horizon. For me at 60 degrees latitude, the celestial equator is at an altitude of 30 degrees above the horizon (due south). This is also DEC 0 degrees. You can safely do your calibration some 10 - 15 degrees north of the celestial equator (for me this is an altitude of 40 - 45 degrees, when looking South). This may even be better, because if you calibrate too low (above your local Southern horizon), you well get a larger effect of the atmosphere and more seeing related problems.

Below your horizon sounds strange. in the Northern hemisphere, the altitude (degrees above the horizon) is always

(90 - your Latitude) + DEC

As I wrote before: for me an object is at altitude 30 + DEC, because I live at a Latitude of 60 degrees. If you live at a Latitude of 50 degrees, the altitude of an object is 40 + DEC. Normally you calibrate at or close to DEC = 0 (the celestial equator), which is at a local altitude of 90 - your Latitude.

Objects with a Declination (DEC) that is higher than your Altitude, are always North. Zenith (pointing straight up) has a declination which is equal to your local Latitude.

According to your Avatar information, you are located in or near London, which is at a latitude of 51 - 52 degrees. So, you would do your PHD calibration at an altitude of 38 - 39 degrees above the horizon. If you have bad local atmospheric conditions, you can calibrate at 45 - 50 degrees altitude, which is at a declination of 6 - 12 degrees.

Thanks wimvb for that...very informative.

Can you then please clarify why I see such VERY high DEC readings in my Stellarium.

Tonight I tried calibrating again, and I got the message: Failed, RA star did not move enough?

I think I need to sort my RA and DEC backlash. I will do that over next weekend, as there was simply no time today. I just loaded my existing calibration data, and I am currently guiding at 0.5-0.7rms, which is not bad.

Can you please clarify why those DEC values are so HIGH when my counter weight bar is HORIZONTAL, and the telescope is JUST FEW DEGREES pointing upwards from being also completely HORIZONTAL and parallel to the ground?

I was practically pointing at just above the treeline (basically tall bushes, not even real trees) pointing NORTH in my garden to try to calibrate. Pointing really low, yet DEC values are so HIGH?

P.S. I am currently away from London, at latitude 30.

12 hours ago, wimvb said:

That's actually a very valid question. East heavy implies that you need to adjust the balance of the scope/counter weights after doing a flip. When imaging towards the East, the scope is on the West side of the pier, and the counter weights on the East side. The counter weights should be slightly further out than perfect balance. After the meridian flip, you are imaging towards the West. The scope is on the East side of the pier and the counter weights on the West side. Now the scope side needs to be heavier, so the counter weights need to be shifted up the counter weight bar.

In practice, you try to get a good balance with as little backlash as possible. You then accept a small difference in guiding/tracking accuracy between East and West. Or you can just do your imaging on one side. If you decide to image just East of the meridian, you switch to another target when the first one passes the meridian.

oh, wow...really?

So, with the east side heavy thing, when imaging EAST of the Meridian BEFORE the flip, the counter weights should be ever so slightly heavier?

Then as the mount flips and starts to image WEST of the meridian the OTA should be ever so slightly heavier?

Which implies that someone has to be physically present beside the mount AFTER the flip, stop the tracking, and change the balance? Is that what experienced imagers do?

Or, if you just do not want to be near the scope so late at night, one would assume that we make the counter weight side ever so slightly heavier, and DO NOT image past the meridian?

So what do imagers do with regards to REMOTE locations? Is this weight shift done remotely?

Very interesting.

1 minute ago, wimvb said:

You can just see one RA allen screw near the bottom here (not indicated, but next to the cable).

Yes, sorry. I get it now. 
 

By the way, I never really understood what EAST heavy meant?

Does that mean that when balancing RA, with the counterweight shaft horizontal, the scope should be HEAVIER on the EAST (right) side of the mount?

But wouldn’t that still make the scope heavier on the WEST side of the mount as well when I swing the OTA around?

How can the OTA and all the imaging gear be heavier on just ONE side (EAST) of the mount?

Sorry, pretty sure it’s another dumb question, but it’s one I don’t understand. 

3 minutes ago, wimvb said:

They are the top screws in your own image, and indicated in @david_taurus83 first image

Oh, of course. Yes. Those are the DEC screws of course. The RA is on the back. Sorry. I’m an idiot!!

5 hours ago, wimvb said:

Yes. You can apply calibration at any declination, but PHD doesn't like it to be too high. There is a difference between DEC and Altitude. DEC is a number of degrees north of the celestial equator. Altitude is the number or degrees above the horizon. For me at 60 degrees latitude, the celestial equator is at an altitude of 30 degrees above the horizon (due south). This is also DEC 0 degrees. You can safely do your calibration some 10 - 15 degrees north of the celestial equator (for me this is an altitude of 40 - 45 degrees, when looking South). This may even be better, because if you calibrate too low (above your local Southern horizon), you well get a larger effect of the atmosphere and more seeing related problems.

Below your horizon sounds strange. in the Northern hemisphere, the altitude (degrees above the horizon) is always

(90 - your Latitude) + DEC

As I wrote before: for me an object is at altitude 30 + DEC, because I live at a Latitude of 60 degrees. If you live at a Latitude of 50 degrees, the altitude of an object is 40 + DEC. Normally you calibrate at or close to DEC = 0 (the celestial equator), which is at a local altitude of 90 - your Latitude.

Objects with a Declination (DEC) that is higher than your Altitude, are always North. Zenith (pointing straight up) has a declination which is equal to your local Latitude.

According to your Avatar information, you are located in or near London, which is at a latitude of 51 - 52 degrees. So, you would do your PHD calibration at an altitude of 38 - 39 degrees above the horizon. If you have bad local atmospheric conditions, you can calibrate at 45 - 50 degrees altitude, which is at a declination of 6 - 12 degrees.

wow, what a super informative post. 
 

The way I check for DEC is by reading the numbers when I am pointing at an object in Stellarium. Even when I am pointing the scope really low, just above the hedge in my back garden, the DEC reading on Stellarium of whatever object I am pointing at is around 50 or so. 
 

I must admit I think I don’t get DEC reading right. Stellarium shows many DEC reading and I think I’m confused about it. 

6 hours ago, david_taurus83 said:

You loosen the 4 allen bolts circled below, adjust the grub screws (arrowed) as per the guide, retighten the allen bolts and check for play. If your happy that removed the free play, start the check for binding. Readjust if necessary. As wim says though, you can only do so much by feeling by hand but it should improve things a lot.

Thank you so much for that. RA is clear. 
 

Sorry to be an absolute pain, but can you point out the 4 DEC Allen screws as well? 
 

And should I start with DEC then RA, or it doesn’t matter?

Lastly, when adjusting the grub screws and checking for binding, should I remove the scope etc from the mount, or do everything with the mount LOADED with the gear?

Many many thanks

 🙏 

Thank you for your rep[lies.

I will proceed with the above advice, but need to check a few points in my mount's anatomy, just to avoid messing up things:

@wimvb 

1- You mentioned: TWO different screws: Grub & Allen. By grub screws, are we talking about the tiny black holes on North & South sides of both DEC & RA axis? FOUR in total? If yes, then what are you referring to when you say: ALLEN screws? You did not reference the ALLEN screws in your steps 1-3? You only mentioned playing with the GRUB screws?

2- In step 2 you mentioned "apply guiding assistant and measured backlash"? What is that? Never did it? Is that in PHD2?

3- By calibrate in PHD2, I suppose you mean clicking SHIFT calibrate? I struggle always with calibration in PHD2 as it wants me to point somewhere at or below 20 degrees DEC, which is practically my horizon or even below!

@david_taurus83

You mentioned that the EQ6 strip down guides apply to my AZ-EQ6 Pro, but I recall seeing that the AZ mount has the freedom encoders, which make a significant difference in the strip down? Not sure.

I have attached a pic of my mount showing MY understanding of the GRUB screws and POSSIBLY the ALLEN screws you meant, but not sure??

There are 4 Allen screws on my RA body, but which Allen screws should I look at on my DEC?

Many thanks

On 16/09/2021 at 16:03, wimvb said:

Fyi, I just got guiding rms down from just below 1” to 0.5” (and down to 0.44”) by very carefully adjusting dec backlash. Previously I had improved RA by adjusting the belt tension. Just saying that a lot can be done to improve tracking without the need to disassemble the mount. But if you do need to take your mount apart, it’s good to have a guide like this.

Can you please share the details on what you did to minimise backlash on your mount?

I have a similar mount to the one above in the video. It’s fairly new, just a year old. 
 

I too have significant wobble on the Dec, and minimal wobble on the RA. 

I can’t see myself tearing the mount down as on good nights I average rms of 0.7-0.9. 
 

I read somewhere that the backlash on RA and DEC can be eliminated WITHOUT opening the mount, by just using a 2mm Allen key through the two tiny grub screw holes on either side of the DEC and RA axis on the mount?

is that possible?

Extremely nice image....

chapeau...

I struggled a bit to process this in PI.

Starnet leaves some artefacts over the BIG star just over the nebula, so played a bit with masks..

WO Star 71

294MC Pro + L-eNhance

L: 110x300s

D, DF & F: 50 each

PHD 2

NINA

WBPP

BTW, in Photometric Color Calibration, since I am calibrating a NEBULA, what option do I choose? The options available are AVERAGE SPIRAL GALAXY, or STARS? No option to choose a Nebula?

Hope you like it!

I welcome any feedback...

Western Veil3.tif

3 hours ago, Clarkey said:

 

If you connect you telescope mount through EQMOD and then open the tools you can set the meridian limits using the mount limits option.

 

Once open you can manually set the mount limits. From memory (it was a while ago), you can simply move the mount to the right position and add the limit. Then move the mount all the way to the other end of the meridian position to set the second limit.

 

Alternately you can uncheck the mount limits box but if the flip fails the scope could collide with the mount so I would not recommend this.

Hope this helps. 

Thank you for that. Very helpful.

So, I manually slew the scope to east and west, and when I am satisfied, I register a NEW LIMIT on either side of the mount?

But which button do I use to click?

The GREEN PLUS button? Press that to se the new limits?

18 hours ago, Clarkey said:

I had some issues with meridian flips (not with NINA but another one - maybe BYEOS or APT) and it was down to the settings between the mount control and EQMOD. I extended the range of the mount in EQMOD to a few degrees past the meridian on both sides which allowed the software to continue imaging just past the point of flipping. The mount then finishes the sub and flips without issue. Without this PHD and the imaging software was trying to move the mount but EQMOD was stopping it giving the star trails and errors. I would try to extend the range of the mount slightly in EQMOD and I think this will solve the problem. (You might be able to do this in NINA - in effect reducing the range of the mount, but the system will then need to wait until it reaches the meridian before filpping. Doing this wastes imaging time).

9 hours ago, The Lazy Astronomer said:

^that. EQMOD has a safety setting which limits the mount movement at the meridian (to stop scope and camera crashing into the mount).

If you'd just left it, NINA would have carried out the flip and continued as normal once the timer ran down. Personally, I trust NINA enough to just turn the meridian limit setting off completely in EQMOD - I don't particularly like the potential for software to be trying to do conflicting things.

thank you for your replies.

Can you please walk me through what steps do i need to do exactly?

I'm still unfamiliar with EQMOD and NINA, and still learning.

I watched a youtube video about this, by Cuiv the lazy geek, and am still confused.

How do I extend the mount's range in EQMOD? Or should I just UNTICK the box in EQMOD that says: ALLOW MERIDIAN FLIP?