Starwiz

This was my first image with the CLS filter in place.  It was captured in the UK six years ago.  Orion was low down in the sky and there was an orange street lamp just below where I was imaging, so it shows how good the filter is.

John

On 02/02/2022 at 10:17, Kenboy said:

https://www.highpointscientific.com/astronomik-cls-canon-eos-xt-clip-filter-cls-eos-xt

On this website it says this filter is designed for use with lenses of all apertures, operating at f/3 and above

does this mean I can't use it for my canon 50mm f/1.8 lens? 

I'm no expert on this, but logic would tell me that you should be OK if you change the aperture to 3 or above on the lens.  This would obviously let a little bit less light in, but you'll be exposing for much longer anyway.

John

On 02/02/2022 at 12:48, Shibby said:

However, to me it looks like a bit too much noise reduction may have been applied to the nebula? I feel it could be far more detailed with a gentler touch.

Yes, perhaps.   The noise in the SII channel was very bad for some reason.

John

I actually acquired the data for this one back in August, but due to some challenges with the processing, I've only just got round to finishing it.

Imaged from Malta.

24.25 hours total integration time in SHO plus an hour of RGB for the stars.

John

10 hours ago, Kenboy said:

Hi guys 

thanks for your advice 

can I just check

my 550d is astro-modified (rear filter removed) 

so is this the one to go for -> Clip filter for Canon EOS APS-C £116 (https://www.firstlightoptics.com/light-pollution-reduction/astronomik-cls-filter.html) 

I've got the Canon 1200d (also astro-modified) and the clip in filter does the job.  When I used my DSLR with the CLS filter I was doing up to 15 minute exposures in a Bortle 4.5.

It looks like this:

https://www.astroshop.eu/broadband-filters/astronomik-filters-clc-canon-eos-clip-filter-aps-c/p,16744

John

1 hour ago, barbulo said:

But remember that filters will imply longer exposures.

The Astronomic CLS filter has a loss of about 8%, so you would need to expose for about 8% longer to collect the same amount of the target light you want to collect.  However, the main reason for longer exposures with a light pollution filter is that now you CAN expose for much longer without being swamped by the light pollution.

John

1 hour ago, BobJC said:

I'm thinking of going with the Optolong L-ENhance clip-in filter which I believe will instantly solve all my light pollution, red cast and extended processing woes

A light pollution filter can make a big difference if you're in an area polluted by sodium lighting.

Two images from some years back when I was using a modified Canon 1200D.  The Orion Nebula, an easy target was without the CLS filter.  The Horsehead, a much fainter target, was my first image with the CLS filter and I was amazed what a difference it made.  Previously when I'd tried the Horsehead, it was washed out by the light pollution.

John

On 03/11/2021 at 11:31, MartinT said:

I think I'll be mainly viewing, but I'd like to try astrophotography

A way to get started with astrophotography is to start by imaging the moon and planets.  You can use your DSLR for this when you have a scope to attach it to.  Planetary imaging involves taking a video of the object, then using post processing software to stack only the best frames when the atmosphere is at its most stable.  This is how I started, using an EQ5 (not motorised at the time), before the bug bit me and I bought an NEQ6.  Deep sky astrophotography becomes somewhat more expensive.  🙂

John

Imaged from Malta in SHO over several clear nights during the past couple of months.

John

On 21/07/2021 at 22:16, powerlord said:

And is that with the 200p ?

Yes, the 200P.

On 21/07/2021 at 22:16, powerlord said:

very nice. i can only hope to get something similar as I'm doing the same just now. Can I ask - were you using 139 gain ? And is that with the 200p ?

stu

Hi Stu,

For the NB I used Gain=200, Offset=50.

For the RGB stars I used 90s exposures with Gain=0, Offset=10.

I've since reworked the stars which I think look a little better now.

John

On 19/07/2021 at 00:38, rnobleeddy said:

I was unfamiliar with that software - but I guess it suffers the usual issue that it doesn't work with diffraction spikes. I'll give it a go anyway!

Yes, there's still a lot of unwanted artifacts left by Straton to clean up after the stars are removed.  It's important to take it slowly to avoid destroying any of the scientific data and it probably took me a few hours on this one.

I'm not totally happy with the stars on this one.  I think they could look better but not sure how to improve it further, so any advice is very welcome.

Just over 30 hours integration from Mellieħa, Malta over several nights during the new moon period using 15 minute exposures in SHO.

The stars were captured separately with a couple of hours of RGB.

Stratton was used for star removal from the SHO data.

Thanks

John

Imaged from Malta over the new moon period.

John

36 minutes ago, powerlord said:

Hi chaps, I noticed today that my darks I was taking were blown out. Which explains why they didn't work yesterday in processing! duh. should have checked histogram.

I traced the light leakage into the ring where the focuser tube moves in and out of the bottom of the OTA. This is an ED72.

Is this a common thing with a simple fix, or is it either a dismantle and try and trace and try to fix ? washer/oring ?

alternative, is insulating tape around the tube there - that works as it's how I found the light leakage, but hardly ideal.

I doubt it was making much difference during shooting at night, but can't help.

stu

Yes, it's common.

I have the same with my SW200P.

I found light leakage at the focuser and at the primary mirror.  I use dark cloth shrouds.

The best way to find where it's getting in is to have your camera running in a dark room, then go around with a torch or mobile phone and note where the image changes.

John

Can anyone tell me how I go about recording a PEC curve.

I can find tutorials on how to use the curve, but not how I get it in the first place.

I'm using PHD2 and EQMOD.

Thanks

John

2 hours ago, wimvb said:

simbad and aladin

https://aladin.u-strasbg.fr/AladinLite/

Enter M101 in the target field en hit enter. Then move the fov to the suspected quasar. Activate SIMBAD on the right hand side of the display.

Use the bulls eye (left hand side of the display) to get more information on any target. Or click the small boxes that are activated with SIMBAD. Other than that, just play with it.

Thanks, that's great.

Here's my contribution:

Quasar [VV2006] J140354.6+543246

Magnitude:  20.69

Redshift:  3.258

Lookback distance:  11.8 billion years

Indicated by the yellow markers in the image.

I think I've found a quasar in one of my images from last year, that is near M101.  I only know this based on a post I saw on CN.

What is the best way to validate this if I don't know the name of the quasar?

John

A useful explanation for anyone who needs it.............

Link:  Understanding offset

Note:  The last histogram is a short video, so you have to click on it to see the results.

John

SHO post-processed in Gimp then finished off in PS.

John

While doing some more processing this morning, I noticed another artifact, but this one occurs at 90 degrees to the other and is smaller.  This also occurs at multiple places throughtout the image.

I'm thinking that it might be some sort of alignment feature added by the stacking program, but not cleaned up.

OK, this is rather weird.  Ha, OIII and SII stacked in ASTAP.

See the two 'stars' at the end of each of the yellow lines.

This isn't visible in the individual lights, so I can only think it is some sort of stacking artifact?  It appears in all channels.

John

20 hours ago, happy-kat said:

I prefer the DSS image the other looks too heavy and lacking detail/depth

It doesn't look that way on my screen.  Differences in displays & settings, perhaps.

On 14/03/2021 at 15:35, Seelive said:

I assume an identical stacking method was used in both programs? Is the apparent difference significant for all equivalent stacking methods?

Yes, I used the 'Average' method and used stars for alignment in both programs, although ASTAP has other alternatives.

Having been a user of DSS for several years, I've recently had a look at the stacking feature in ASTAP.

The two images were both stacked using the same lights, darks, flats and dark flats.   

Ha = 17 x 360s, Temp -10 deg C, Gain 200, Offset 50.

30 x matching darks.

30 x flats

30 x dark flats.

The images were stretched to about the same level in Gimp.

I then zoomed to 250% and cropped, to show the comparison better.

To me, the ASTAP stacked image looks a lot cleaner and a bit sharper too.

Has anyone carried out a more extensive comparison between the two stacking programs?