Marmo720

On 26/04/2020 at 23:42, jjosefsen said:

Hi,

I doubt this is vignetting, your images should be getting darker not brighter around the edges.

Try calibrating without flats, does your issue persist? I'm going to guess that they are - because I have the same problems with the same camera.

It seems to be in the dark frame calibration and for me it is only a problem with broadband filters..

But I would love to see what happens if you try to calibrate without flats and compare, and without darks and compare.

Thank you for the response. Happy to know it isn't something specific to my setup - gives me hope

I have attached the same data but without flats (with darks + bias), and without darks (with flats + bias), and lights only (no calibration).

I do have some Ha data from tonight and will do same with that to see what the results look like.

How do you overcome this issue with your camera? What settings do you use for gain, offset, ADU for flats?

Thanks again!

Hi all,

I have made the jump to mono with altair hypercam 1600m, combined with 36mm filters and ZWO 7 EFW. I have the train setup to the spacing given for the altair 1x flattener on my Wave 80 ED. To the best of my ability anyway...

The link below shows a DSS stack of:

60 x 60 sec lumi at gain 500

50 x 60 sec darks 

58 x 0.3sec bias 

50 x flats at 2000 ADU

All are at -15 deg. The camera is 12 bit and I thought 50% would be 2000 ADU. Equivalent to about 30K on a 16 bit camera. 

I have tried half the number of flats. I have tried ADU ranging from 800 to 2000. All give me very similar results to the below image. 

Stuck for what to do so appreciate any advice.

https://we.tl/t-pA4rzIxaMb?src=dnl

As always, thanks for the advise Roland

I have gone for the Altair hypercam. Hoping for clear skies!

Hey all,

Hope everyone and their families are well. 

I am now considering going mono from my current astromod Canon 600D and would appreciate any advise and guidance. My imaging telescope is the Altair Wave 80 ED APO (with 480mm FL). I came across the sale of a set of ZWO 7nm narrowband filters (36mm) with the matching ZWO EFW for a reasonable price. Before I commit to buying that, I also wanted to check which camera to get at the same time or whether worth waiting.

The 3 cameras are all around the same price used from different locations (ABS, Facebook etc). They are the Altair Hypercam 1600m, Atik Horizon and Atik 383L+. All have similar FoV with my telescope (slightly smaller than my Canon 600D) and I believe all have similar back focus, which should work with the 36mm filters. Any advise with those cameras? The 383L+ is a CCD vs the other two CMOS. If age matters, the Altair is the newest and I am not sure how old the other two are yet.

The other alternative is to wait for the ZWO 1600mm Pro to be on sale (or used) and get that then. Would mean the smaller filters would be cheaper too in the long run.

For reference, I am imaging from Bortle 8 skies. 

Thanks in advance for any advise  

I have very similar scope and guidescope setup to you @oymd and the dew straps and controllers I linked to in your Wanted thread are the ones I use. Work very well and I forget they are there when imaging. I got the quad channel just in case as the price difference was minimal.

I was also in same boat as you in terms of getting a controller or not but considering how cheap they are and that it can always be sold on if required meant I just got a controller anyway. Make sure you read the small instructions that come with them and they are very easy to use. 

The straps come with long durable leads and so can be moved to the side and away from other cables.

17 minutes ago, wuthton said:

My Zotac has 4gb of ram which is plenty for long exposure image capture but I'm not sure about planetary, it's well over 12 years since I've tried it.

Thank you. Glad 4GB at least works for long exposure imaging. At the moment the price of n4100 mini pc with 4GB ram is about same as raspberry pi 4 4GB once everything is bought so not saving anything long term besides time! 

I did consider that a windows mini pc could always have a Linux distribution installed if I wanted to do ekos etc route. 

1 hour ago, wuthton said:

Marmo,

The Zotac with Windows 10 Pro, PHD and Sequence Generator Pro is superb, it's never skipped a beat, bomb proof but comparatively expensive. I haven't used the Raspberry Pi (Kstars and Ekos) in the wild yet for various reasons but it does look very, very promising for a portable rig that I'm planning. You do need to be semi-confident with Linux command line to run the install scripts but it's not particularly difficult. I'm sure if you start a topic plenty people will chip in.

I've only .... so far.... touch wood.... sacrificed one PC to the gods of unexpected snow. I have painted some tin foil black and taped it over the vent holes in the top of the Zotac, just in case.

Thank you very much for getting back to me. I am relatively comfortable with Linux and command lines (use some python at work) so can figure things out but I also don't want to spend heaps of time trying to figure it all out when my Windows setup works fine.

Is the Zotac the 4GB or 8GB ram? I am concerned if 4GB is too low or not future proof enough or am I over thinking it? I am mainly focused on DSO imaging but will want to do planetary when the opportunity comes. 

Thanks again.

Posted multiple times for some reason - sorry!

Posted multiple times for some reason - sorry!

On 22/11/2019 at 17:35, wuthton said:

I've used an on mount mini pc for years and I couldn't recommend it highly enough. My personal choice was a Zotac CI320 but there's now much newer models available in the CI series.

I chose it purely because it had 6 usb ports and therefore I could wave bye bye to hateful usb hubs. A secondary bonus was a massive improvement to guiding as the number of cables going to the floor is a fraction of before resulting in less cable drag and less chance of a snag.

They are barebones so you need to cost in an SSD, ram and a Windows Pro license key.

Edit: Have you looked at a Raspberry Pi 4 with Indi, Kstars and Ekos. I'm just starting to have a play with it but I'm yet to find a weakness?

Hi - how did the Raspberry Pi 4 setup work? Was it stable and how does it compare to your mini pc experience? 

I have been considering either option for about a month now as my current laptop is high end gaming rig that I don't want to wreck. Last night was so cold that I could barely stay out long enough to get everything setup, which can take half hour if I don't need to do focusing!!

Can you advise on your experience with both as I am ready to pull trigger on either Raspberry Pi 4 or with Beelink S2 that has N4100 processor and 4 GB ram (I was hoping for 8gb Ram but can't see that model in the UK).

Thanks,

Marmo

I am going on Saturday and would be great to meet forum members. I am meeting Carole there too and plan to spend on a few things for my astro imaging setup. 

Will be my first astro event so excited to see everything

Just to update on this - it seems my issues with the imaging train and flats are fixed and I can finally do some astrophotography!!

I spent all of Friday night capturing the Rosette Nebula and I was able to get nice tracking for 3 mins and then 4 mins. My only attempt at 5 mins shows some star trails but didn't want to spend the cold night trying to fix that. The attached is auto save from DSS with 45 mins at 3 min subs and 40 mins at 4 min subs. I didn't need darks it seems either so only used lights, flats and bias. Flats I had to do manual instead of the auto setting on APT. 

Unfortunately, the rest of the nights imaging and also Saturday night are wasted as dew covered my lens and guidescope lens too so will be buying dew heaters at the Astrofest in 2 weeks.

Just wanted to say thanks to everyone who gave advise and helped with this. Excited to do some more imaging!! 

Thanks @RolandKol and @carastro for showing me what a processed image looks like too so I can practice on this data while the skies are cloudy.

Clear skies all.

Autosave_NGC2237.tif

4 hours ago, tooth_dr said:

Although this isn't really applicable to this thread, I'll just add my view.  Carole is right about the temp - I assumed you had a set point cooled camera.  Doing your DSLR flats at any temperature close to your lights will be ok - they will be so short that there will be no thermal current building up anyway, and the same with the bias frames.  With darks it really does matter.  I wouldn't bother with darks with a DSLR, because no matter when you take them they wont be temp matched, and you wont get an accurate representation of the thermal noise.  Instead try dithering between frames.  If you do a search on this, it's be covered quite a bit.

Thanks for the advise. I have been dithering for a couple of months but continued to do darks anyway as I didn't want lack of them to be reason for why I kept having issues with my stacked images. 

Now that flats issue is fixed, I will try experiment stacks with and without darks. If there is no difference, then I can save myself time or use the time for lights if clouds are clear. 

28 minutes ago, carastro said:

Mo, darks can only be re-used if they are the same temperature as the chip when capturing.  It might be worth keeping darks so long as you record the temperature and note the temperature when you are capturing.   DSLR's though are difficult for doing this as the temperature will vary through the night, but some people say they have been successful doing this.

When you have a cooled camera with set point cooling like Tooth Dr and I have life becomes a whole lot easier from the darks point of view.  Plus there is little thermal noise anyway. 

Carole

Ah - thanks for the clarification. I haven't kept an eye on temperature as I always do flats on the same sessions anyway. However, I have noticed for example winter temperatures are about 18C while summer is obviously higher so can't use same flats.

Since I do all my darks at the end (and normally after bias and flats), if the temperature has changed a few degress, it should be fine? Or should I be taking darks straight after lights to be as close as possible in temperature and then take flats/bias last?

Thanks,

Mo

9 minutes ago, tooth_dr said:

Darks last a whole season so no issues there, do it once and it’s done 👍🏼. Flats - if you are setting up each night I’m not sure how much benefit it would be to setup just to taken them.  My scope and camera does not move between sessions so flats last me several sessions or longer. 

Good tip on darks  I didn't realise you could keep darks for a few months like you can with Bias frames? 

My flats are relatively quick so I take them at the end of the session. However, I have had so many issues with flats since the summer that I have had to setup several times with the aim of just testing flats and no imaging. Think I am almost there though with getting the issues resolved.

13 minutes ago, tooth_dr said:

Both with the luminance filter.  I normally take dark flats too so I dont think it really matters too much on exposure time.  I take my flats at night when it's cloudy in the obsy with the roof close, to avoid light leakage in the rear of the scope.  I set it to run over night.  Thanks Carole.

 

 

Adam.

I suppose that is an advantage to having an observatory in this country with all the clouds. I don't currently have one and the thought of going out on a cloudy cold night to set everything up and only image darks and flats is not appealing at all! I don't mind if I have a few hours of clear sky to collect lights and then do flats/darks once the clouds come in on the same evening.

49 minutes ago, tooth_dr said:

Thanks Carole. I was just hoping for a more elegant solution, but paper seems to work so I’ll shall have to stick with it!

 

 

 

Would another piece of acrylic work? With potentially fewer papers if needed to further diffuse? Then you can stick both acrylic together (super glue the edges?) And have less to manage every time you need to take flats? 

15 hours ago, RolandKol said:

Plenty of time to clean the glass!
Once cleaned, do some flats to check if that major one has gone away....
I do recall you had it previously and it was on the sensor....

P.S.

Happy to see, things have much improved and you actually are very close to create the nice and clean image

Thanks Roland! Getting closer with every clear sky

It is similar dust bunny to last one and not sure if on sensor or CLS filter but either should be easy to remove now as done it before. 

@carastro, thanks for the video. Will practice on my old images while waiting for clear skies.

I am using Gimp as I can quickly check the images. I also have Photoshop CS2 to see how I get on with Photoshop but not used it before.

Rosette is a good idea and I considered it last night but as I only had a short time to test, I went for M31. Now that things are working again, I will commit to one target and try get as long exposure as possible. Rosette is also in a good spot for me in the sky right now.

Thanks

Edit: Now that everything is working well - the clouds have decided to take over. No clear skies for over a week and half according to Yr   

Thank you very much @carastro! So glad to see the manual flats working and I also don't have that darkening of the bottom right that I have seen in previous images. I knew that dust bunny wasn't going to be removed by the flats as it was very dark even in single lights. I will clean it off the lens at the next opportunity but now everything seems in order for me to start imaging properly  

I noticed that with your CLS filter on, the 60sec was about 1/6 of the way to the left in the histograms so I know I can do longer exposures. Without your filter, the 60sec histogram was pretty much in the middle or slightly to the right. Looking forward to seeing what 5min exposures with total >2h integration looks like!

Quick question - so I know the longer single subs are very useful for targets without cores but what would be the suggestion for bright targets with cores such as M31/M42? 5min subs for the fainter outer parts and shorter subs for the core? Using same ISO or do people change that depending on target brightness? Just checking as I am practising on M31 and don't want to waste any nights by not imaging correctly.

Thanks,

Mo

Seems to have worked! I only had just over an hour last night to get everything setup, polar aligned and image so went with M31. There is a deep dust bunny which I could have cleared but didn't have time and wanted to check if flats would work on such a dark bunny. 

I took these images with your cls filter Carole and didn't have time to do without filter but it is setup for next time. I took the chance to take 60sec and 180sec subs. I think I can go for 300 seconds next time with your cls filter!

I also had issue that my neighbor forgot to turn off the garden security light so it kept coming on hence why top left corner looks brighter once stacked. I didn't have any of the bottom right vignette that I kept seeing in all my previous images.

Here are the calibration files:

https://we.tl/t-IIhgwbAvqm?src=dnl

Lights:

https://we.tl/t-mpw3PPaTSA?src=dnl

Thanks,

Mo

21 hours ago, carastro said:

Mo came round to my house last night to collect the CLS filter I am lending him, and also I got him to bring his camera, scope, lightbox and laptop, and sat next to him while we tried out flats.  I was happy to see the manual method in APT seems to work at 1/100 sec with his lightbox at maximum brightness with the histogram approx 1/3 across, so I sincerely hope we have got to the bottom of his flats problems.  This was done using the CLS filter so he is set up for future imaging from S London. 

But he now needs to do an image using this flats plan, to double check as all the recent tests have been done after the camera was moved.

Fingers crossed.

Carole 

 

Thanks Carole! Lovely home and nice seeing your setup.

I got all the gear setup now and just waiting for that clear night to test it all

32 minutes ago, carastro said:

Yes 300secs but use a LP filter.  I've got a CLS LP filter I hardly ever use now if you want to give it a try.  It's a clip in filter for DSLR cameras.  However I am not sure with the Advent of LED lighting whether the CLS filters are still any good and there may be better ones around, see what others think but as I say you are welcome to borrow it. 

These are images I have done from home some years ago with a Modified DSLR camera, all 300secs with CLS filter from Bromley (scroll down for the specs and click on image for larger version without the platesolving):

https://www.astrobin.com/2113/B/?image_list_page=6&nc=&nce=

https://www.astrobin.com/2150/?image_list_page=6&nc=&nce=

https://www.astrobin.com/2160/?image_list_page=6&nc=&nce=

https://www.astrobin.com/2164/?image_list_page=6&nc=&nce=

https://www.astrobin.com/15802/B/?image_list_page=6&nc=&nce=

Carole 

 

 

Lovely images. I would love to borrow your CLS filter as I have seen a few on sale here and on ABS and would be good to know if it works or if I need to look elsewhere. 

So glad the flats look better and thank you for the manual advise. Excited for the next clear night

4 hours ago, carastro said:

I just tried out 5 of the 1/100sec manually done flats, and 5 subs of the original images, and am pleased to report there is no vignetting.  As I suspected the APT flats plan does not seem to work.

Of course the dust does not line up  because the camera has been moved, but the main problem here was the vignetting and we are all aware of dust not lining up if you move the camera. 

I tried the 1/160 of a second sub flats but they did not seem to work.  

Attached is the stretched image using 1/100 sec flats showing no vignetting.  (remember I only did 5 subs of lights and flats just to save time and no darks, so it is noisier than it needs to be.

Also below is the same image after gradient exterminator and a further stretch.

Assuming we have now sorted your flats, further improvements can be gained from:

a) Longer exposures (are you guiding yet? If so take 300secs).  

b) Gradient Exterminator will be a very useful plugin for Photoshop since like me you live in a LP location.

Meanwhile I am stacking the 1/160secs all light and full calibration.  = RESULT - THE FLATS DID NOT WORK ON THESE. 

Carole 

 

 

Thank you Carole - very happy to see the results. I could tell straight away that doing the flats manually was better as the dust bunnies stay in same place.

I am guiding but I assumed anything longer than 60 secs at our locations would result in higher noise and not much signal gain? You recommended going up to 300 sec at iso 800 even at our locations and on a dslr? I guess I could do trial run on next clear night with 180sec and 300 sec. 

Happy new year all. Hope you all have good health and clear skies.

I took some flats last night which are linked to below. I don't have any matching lights, darks or bias so I have attached selection from different night. The camera was moved several times in between and so o wouldn't expect a nice image. Just checking if the flats are done correctly.

I started with automatic plan that I have used in the past where the exposure is calculated by the camera/APT. The dust bunnies jump around a lot as previously observed by @vlaiv. I then did 2 sets of manual exposure settings as suggested by @carastro and the dust bunnies don't move around as much/at all which was good to see. I did one manual with same exposure as the automatic so they can be checked side by side and also one at 1/100s so I can reach 75% on the histogram.

Any advise and help is much appreciated.

Lights, darks and bias from same night but different to flats date:

https://we.tl/t-Fkdf2TYAId?src=dnl

Automatic flats produced by APT plan:

https://we.tl/t-xr6A1hoQIQ?src=dnl

Manual flat plan at 1/160, which is same exposure length as the automatic plan:

https://we.tl/t-0AF8llWMZd?src=dnl

Manual flat plan at 1/100, which puts histogram at close to 75%:

https://we.tl/t-SQYlCTBRSe?src=dnl

Thanks,

Mo