Prolifics

29 minutes ago, wimvb said:

The new field flattener should give you round stars, once you got it tuned (correct distance to sensor). Further than that, you can experiment with longer exposure times. When you image R, G, B the sensor receives only about a third of the number of photons as compared to L, so in theory you can expose up to 3 times longer. In your Iris image, the L frames seem to have a good exposure time, but the R, G, B frames could then be exposed eg 2 minutes. If you aim at 2 x as much integration time for L than R, G, B, you'd need 4 x as many L frames as colour frames.

120 x 1 min L

30 x 2 mins RGB

Don't vary temperature and gain/offset too much, because you need darks for every combination of exposure time, gain and temperature. At low gain and longer exposure times, your camera has a larger dynamic range, and you'll need fewer subs to get to a certain level of signal to noise. If storage space and computer speed are a concern, you may need to factor this in.

The total integration time you need to get to a certain result (signal to noise ratio) depends very much on your sky conditions. According to an article by Jerry Lodriguss, you need 2.5 times more integration time for every magnitude of sky darkness/brightness you lose. Eg, if you image 1 hr from a dark site (magnitude 21), you need 2.5 hours to get an equivalent result from a magnitude 20 site, and 6.3 hours from a magnitude 19 site. It pays off to look for dark skies, if you have that possibility.

I played with "curves" after initial stretching to increase local contrast. I measured the lightness in two points where I wanted to increase contrast, then pinned one of those points and increased/decreased the other.

Good luck.

Thanks for explaining the exposure times for each filter. I was doing it half right. I always do double the Luminance amount but didn't relise about the RGB impact in light gathering. Now it all makes sense.

Regarding Backfocu I will have 56mm I need 57mm so I bought some 1mm 1.5mm 0.75mm etc Baader adjustment rings so I can play with that. What is the best way to test your Flatterner? Guessing I would say take a 3 minute exposure of Luminance? Check for elongated stars at the edges and adjust back focus from there?

My garden is a Bortle 5 site magnitude is around 20.27 for me.  So not terrible. I guess where you are is great because you get less daylight than anyone else  Plus the cooler conditions means less noise and I guess the northern lights or Aurora may hinder you at time?

I also have a friend who lives up there in the north of Sweden.

Kindest regards David

Hi Andy

I got one of these last month. I got fed up going out all the time to refocus for my filters.

Comes with many springy metal adapters to fit your scope took me about 30 minutes to install it.

Smooth as silk and can get better fine focus than by hand. Works flawlessly with APT. Make sure you downlaod the driver from their ZWO website and alter the ascom driver settings not on APT or SGP as driver overides it for me.

You do not get a PSU with it! Any positive centre 12v power supply will do with 1.5A rating or above.

If you want to go the extra mile go and fill in the backlash boxes you can determine backlash by movng the focuser until you see movement of your focus knobs one way then lower the amount from 10 to 1 and move the other way and record the Focus number just before it moves. This is your backlash. Mine is set to 8 units.

My HWFM and HDR values are just around 1.3 wasn't acheivable before by hand. 

Looks great on my scope (white). Would look great on black scope too, but not sure about bright red on blue or orange (Old Celestron).

A worthy addition to my setup that now I can not live without. Go for it! I left you some pictures...

Kindest regards David
 

Thanks Wim for that. You can see its like day and night compared to the one without darks.

You have even got some of the black nebulae out from it even with only 2.2 hours of data. Not sure what to try next. I think its expreminent with gain next. Raising the from 1 Min to 3 Min exsposures will help bring a sharper and more detailed image as my tracking is good. Plus my Focul reducer/Flatterner will improve things. I also took 3 minute dark frames today while I did the 60 second ones

Not sure what the white foggy stuff is? Did you set the black levels and grey and white levels? I know its zoomed in alot so will show a lot more noise and imperfections.

Looking forward to any tips you may have.

Thanks David

1 hour ago, wimvb said:

I've only downloaded the data, but I must say that it looks a LOT better. Just a slight vignetting effect left, no problem for PixInsight DBE.

I just finally spent out and bought https://www.365astronomy.com/ts-optics-photoline-2-0.79x-4-element-reducer-and-field-flattener-corrector-for-astrophotography.html

Cheaper than Pixinsight

I did speak to my friend Zoltan there and he said I may be getting Vigneting because of the backspace 2 inch going to a 1.25 cone and into back of my scope. Thats the adapters that came with my filter wheel and camera.  So not only will this fix that but is a matched flattener for my scope and 0.79 reducer. So the Flattener should stop the elongated stars at the far left and right of my shots.

Also the Reducer will lose 20% of my size because of the reduction of focal length but will gain x1.6 exposure time. Turning my F6.5 to a F5.13

I am away all of next week  so I will keep you updated somewhere on this forum with the results

Would be nice to compare the new data with the old if you get 10 minutes.

Have a good weekend.

Regards David

Hi Wim,

I managed to do the darks same temperature gain offset and exposure time as my lights. I may have found something else I was doing wrong. I was using the same master flat frame for each colour. This time I done them all seperate.

I have replaced the files and re-uploaded them. All with 30 frames of lights and 60 darks. I also saved them in 32 bit Tiff format as to not lose any data.

Hopefully you will have time to look at these and see if its the darks not being added has caused this problem or something else I need to work on.

https://www.dropbox.com/sh/skqoxrbe5huosg4/AAAdQ_UEP0XsX0S0b6oBPiiKa?dl=0

Kindest regards David

Thank you for that. My flats are taken with APT with an ADU of 25000. Using a lit flat panel and a white T-shirt. I am not using a flattener yet. Any suggestions?

I will take some darks tomorrow remake all the LRGB files again in Deepskystacker and see how that does. Then I will know for sure.

Regards David

Thats basically what I do when I stack. I don't use bias frames as apparently my Cmos camera dosn't need them. I have been doing 1 min exposures. I think it may be better aiming for 3 minute ones to bring in more stars. I still need to work with the gain and see whats best on certain objects.

Wish I could afford that program

My stars are not sharp and numerous like other pictures. I think it's more exposure time and gain settings that you were saying. Any good pointers would be appreciated but first I need to know if its my data or my post processing. I think its both

Cheers for looking at it for me! Oh by the way there are no dark frames yet only flats. I still havent took them

Kindest regards David

45 minutes ago, wimvb said:

Very nice. What camera do you use? If you get 0.4" guiding rms, you should increase the subframe exposure time. But if your camera has low read noise (modern cmos), you should be able to stretch your final image harder to pull out more detail and colour.

For example, this is what 3.6 hours of 30 and 45 seconds exposures got me.

https://www.astrobin.com/318629/C/?nc=user

Compare the different versions.

Hi Wim,

I think I am a little out of focus but here is a link to my stacked LRGB files it would be nice to see what you can get from it, to see if my data is any good.

https://www.dropbox.com/sh/skqoxrbe5huosg4/AAAdQ_UEP0XsX0S0b6oBPiiKa?dl=0

Regards David

32 minutes ago, wimvb said:

Very nice. What camera do you use? If you get 0.4" guiding rms, you should increase the subframe exposure time. But if your camera has low read noise (modern cmos), you should be able to stretch your final image harder to pull out more detail and colour.

For example, this is what 3.6 hours of 30 and 45 seconds exposures got me.

https://www.astrobin.com/318629/C/?nc=user

Compare the different versions.

Hi Win

All my equpment is in my signature. It's not far different from yours except the smaller scope

I only had half your data and don't think I autofocused before the session as I was just playing with my new hypertuned mount. HWFM and HDR normall around 1.3 when i focus.

I'm using unity game on my ZWO asi1600mm pro. 139/50 the 50 is so it shift the histogram to the right slightly and dosnt crop it. I was using gain 75/15 but saw a youtube video and decided to give the new gain a go.

Plus my post processing is just basics. Adjusting curves and levels. Removng noise and making an RGB layer and adding the Lum channel.

Thats about all I can do sa far. This is my 4th ever image

Regards David

Thanks everyone!

It worked and with my rubbish post processing I got this in 10 minutes with very limited data. This .jpg so very low detail. Iris Nebulae of course

8 minutes ago, wimvb said:

In dss you should be able to set one subframe as alignment reference. Always use the same sub for this, eg one L sub, even for R, G, and B subs. Just exclude that sub from the stack.

From the dss faq

How do I align the resulting images of 4 stacks (red, green, blue and luminance)?
To align the resulting images on the same reference frame just add the reference frame to the list even if it is not from the same stack, force DeepSkyStacker to use it as the reference frame (using the context menu) but left it unchecked. 
This tells DeepSkyStacker to use it as the reference frame but to not add it to the stack.

http://deepskystacker.free.fr/english/faq.htm

 

 

Thanks Wim I am going to try that shortly. I had already used a reference frame but one for each colour now I see the problem. I will let you know if it works for me.

Kindest regards David

Also using deepskystacker to register LRGB. darks and flats all togther as one lump works fine but not sure if I can work with that in photoshop. So if it can align is there an option to compare frames from each stacked colour?

Cheers David

Hi Sean

Thanks for your reply. Each colour is stacked and aligned by itself. But each colour has drift like you said of a few millimeters. Isn't there a program that aligns your LRG and B data after they are stacked?

For an example say I take 30 exposures of Lrgb 1 night then decide to finish it in 2 months time. They are going to be slightly different.

Here are examples of my RGBL data as you can see the stars have rotated slightly. My mount has just been hyptertuned and was guiding at 0.40 average in PHD2. Polar aligned with Sharpcap to 00.08 on each or better.

L 60x 1 Min
R 30 x 1 Min
G 30 x 1 Min
B 30 x 1 Min
30 Flats of each 
60 Darks

Finally RGB when put in there channels without luminance. Now you can see the green and blue where we arent alligned with each other.

Regards David

Hi guys

I am suffering to being able to understand something as a new imager.

I imaged an object that went past meridian and my mount done a automatic meridian flip but from then on the pictures were upside down. Using APT
I put them in deepsky stacker and made a reference frame for each of LRGB images and got them all to stack fine and saved them as L.tiff R.tiff G.tiff and B.tiff. Each colour are aligned fine. (now each colour are all the same way up)
However when i put them in photoshop when I make an RGB channel and paste each one in I get red and green dots in the RGB master which shows although each colour are aligned they are not aligned with each other.

So question is when I have stacked each LRGB although individiually they are stacked fine how do I get them to stack with each other. Stars are slightly missaligned in each colour to each other.

Very hard to describe but hopefully you understand.

Thanks in Advance David

On 10/07/2019 at 18:29, michael8554 said:

If your camera and guidescope aren't separated between sessions the focus and hence HFD shouldn't change, and 2.2 is great. 

If you're not separating them, then are you guiding on saturated stars sometimes (flat top to star profile).? 

Auto selected stars don't do that. 

Michael 

Hi Michael Found 20 minutes of gaps between clouds tonight done all the things you mentioned and with hazy clouds was getting between 40 and 90 snr on quite small stars. Thats a big improvement and I think will solve the issue and be even higher without clouds. I also loaded up sharpcap and turned on polar align. I have never had more than 9 stars detected it was at 19 tonight

Oh and that was on gain 1x using the ascom altair driver. Did not get chance to up the gain clouds rushed in fast!

Thanks for all your help in this matter

Regards David

Just a note been looking through my last PHD2 logs and my HFD is beween 2.2 and 7 averaging 3.8 which i guess is not good?

21 minutes ago, michael8554 said:

It's HFD, and below 3 would be great, but minimum might be higher and would be the best you can get.

You can check your current HFD in a PHD2 guidelog, search the text file for HFD. 

Michael 

Many thanks that was the next question  I have been focusing on objects about 40 m away and it works fine so not sure what the problem is. I am using the adapter that came with the guidecam so you can get focus.

17 hours ago, michael8554 said:

What are your issues.? 

Michael 

Hi thanks for the advice. My guide scope is listed in my signature. Only thing I havent tried is the HDR below 3 I will check it but cloudy skies here for a while and get back to you.

Regards David

15 hours ago, michael8554 said:

What are your issues.? 

Michael 

Hi Michael I am struggling to get a snr of more than 15 mostly around 4 to 8. Guiding stars are sometimes lost. 

Regards David

Hi having a few issues with my guiding and focus.

Just a couple of questions especially if you have one of these guiding scopes.

1) Which driver should I use Altair or ascom altair? I am using eqascom setup.

2) What gain should I use on the guide camera as a ballpark? Some say gain 1x (lowest) if you can set in ascom if using the Altair Ascom driver.

Finally a link to my actual guidescope. I have also in phd2 software set the noise reduction to 2 x 2 mean as recommended by several people.

https://www.altairastro.com/Altair-GPCAMv2-130-Mono-Guide-Imaging-Camera.html

Many thanks

Managed to get out last night. Spent alot of time getting the autofocuser working as I wanted it. I ended up with only a couple of hours so I tried M13. With the filter wheel the right way around

I have no photshop skills as you can see. Took me about 10 minutes to get something that qualifies as identifiable. Flats seem to have worked a lot better this time. Be pleased to have some input please as this is a minefield in learning which I love.

Guiding averaged 0.85 in PHD2
HWFM 1.37 and HDR 0.50 using ZWO EAF 

30 x 1 min Luminace
15 x 1 Minute Red
15 x 1 Minute Green
15 x 1 Minute Blue

20 Darks
20 Flats @25000 ADU

PS. I have some slightly oval stars to the edges are these caused by not having a Flatener/Focul reducer? I should have cropped the picture but left it as is.

Another major fix I have just made which I would have not picked up on if I wasn't scouring the forums. My EFW zwo wheel was on the wrong way. Which means the gap between the camera lens and the filter was 8.5mm instead of 2.4mm approx. Plus it also meant the filters were on the wrong way. I reversed it all and the camera is on the correct side of the filter wheel now and the screw threads on the filters are facing the camera.

Which accounts for those big black reflection filterwheel size circles on my images  Should also reduce vigneting sigificantly!

 I just purchased and installed the EAF ZWO Auto focuser and is working like a dream. Can't wait to get back out hopefully this weekend for another try. Will post end results. 

Regards David

On 05/06/2019 at 20:40, Adreneline said:

Good luck with the light panel - at least it should provide consistent and repeatable results.

Thanks not been a clear night since I last spoke to you. Looking better for next week. Its because I bought a light panel :)

Weather been aweful no clear skies for last 8 days and not looking good for bnext 5 days either :(

I received my light panel so wikll check it out as soon as I can.