david_taurus83

Why do you want a premium mount for planetary imaging? Seems a bit overkill? 

I have to admit I've never even heard of this phenomenon let alone seen it. There's some amazing pictures on Google! One to look out for! I've seen bright rings or halos around the moon sometimes but never the sun.

1 hour ago, alacant said:

 

Perhaps best to use a master bias as a master bias. We've not seen any benefit using dark frames of any type, be they dark for flat or dark for light.

Just our €0.02  but HTH anyway. 

Cheers

That's what I meant. I use Pixinsight to manually calibrate. I remove the bias from the flats prior to creating a master flat.

2 hours ago, Neil27 said:

Delivered yesterday by Bernard, in several boxes. As the missus said looks like a few boxes of scrap metal 😂

Before and after assembly. Installation documents and PSU to arrive in the next few days.

Managed to get it assembled by looking at various pictures on the internet and the ‘simple assembly guide’ on Mesus website. 

 

Even I'm excited looking at that! Hopefully next year!

3 hours ago, powerlord said:

thanks - good info there.

I assume you also use flats though ? if nothing else, to minimise dust/lens marks, etc?

Yes flats are always a necessity. I just use a master bias as a flat dark.

I've made a couple of DSLR cooler boxes and created quite an extensive dark library for my 6D by 'matching' EXIF temps by controlling the ambient temperature around the camera. I can't see any real difference between using darks versus not using them. The 6D is very low noise already. It produces very clean stacks though I have only ever used mine from my light polluted back garden so when I remove the LP it does look noisy in areas of low signal. I would concur that not using darks and to dither is more beneficial. You must use a master bias though. The 6D bias is a whopping 2047 ADU out of a possible 16k ADU. It gives the impression that your lights are more washed out than they actually are so I try to expose until the histogram (in software, not on camera) is around the halfway mark.

I refer to them as the H-Alpha moon or red moon or the even rarer Luminance moon

Sadly nothing will be done about space junk until there's a serious incident with loss of life. 

Hi. Have you done the common wrap around of PTFE tape to tighten the threads?

Wish I'd never let mine go. My CEM25 punches above its weight but its a delicate little flower that needs careful balance. The AZEQ6 was solid. Wind, dangling cables, slightly off balance was no problem for it and could even manage a dual rig.

What camera are you considering for mono? Are you using a coma corrector? If so, then you'll still need to space the camera back 55mm if that's the case, and the drawtube will come into focus in the same place.

I could take darks on my old WO GT71 during the day. Never an issue. Now though, with my Altair Starwave scopes, the one time I tried it looked like there was light leak getting under the dew shield. It's appeared to get worse when I shined a torch on the shield.

Yes it's SkySafari but you can use Stellarium or Carte du Ciel. So if you want to frame like I showed above with top and bottom of the sensor aligned with 44° and 45° then yes, turn the sensor on its side!

If your using a refractor then if your camera is 'upright' in the home position, then the top and bottom will be parallel with the right ascension grid lines. And if you rotate the camera 90° so it's on its 'side' then the top and bottom of the sensor will be parallel with the declination grid lines.

Camera upright with RA lines top to bottom

Camera on its side with declination lines left to right

Don't ask me how it works with a Newt!

I've not seen a CEM70 in the flesh but I did have an AZEQ6 and I would have lumped them together in the same weight class? Not sure you'll see the performance increase your looking for? I have the CEM25 and only have 6kg on it and balance is really critical. If its slightly out in Dec and RA it guides all wonky but get the balance just right and its great. I wouldn't like to try and balance a 250P on a CEM mount! The 120 might be better suited though. 

Did you calibrate the darks with bias?

Ah sorry, I had gotten 1.25" in my head. 

If you can stretch to £179 I can recommend the Astronomik OIII 6nm. No halos when I tested on a bright star. (Despite my recent issues with halos and reflections which I suspect is my flattener, but that's another thread)

Looks great Steve!

Its the reducer. The last piece of glass to check. I just stuck a nosepiece on the camera tonight and into the back of the scope. No glass or filters between objective and camera. No halos or reflections. Oddly enough, apart from 2 corners I appear to have better stars across the field at the scopes native F7.

This is a 300s sub I took of M45 last November. If anything is going to show halos, it'd going to be this, right?

Looks good to me. That's with the IDAS D2 on front of the flattener and through the Lum filter in the wheel. No visible issues.

So last night I done some sanity checks. Took another series of subs on the Beehive, this time with no filter at all. No IDAS D2 and Lum filter removed from the wheel. Here's the calibrated stack.

Halos still present and a new one left of sensor. So I can safely rule out the IDAS D2 and Astronomik filters.

Also took a couple of shots of Arcturus. These show another strange artifact. Reflection? It moves when I set Arcturus off centre.

Reflections in the camera? The sensor needs a good clean. I spoke to Atik a while ago as it has these small dots which I thought was dust but Atik say it looks like the sensor had frost on it the once and left some marks behind. See typical master flat.

Or could it be electronic? Here's a cropped gif of last night's subs showing a close up of the new halo in M44. There's no halo in the first few subs but it suddenly blinks on the same time as that little chevron type artifact appears. The same artifact appears in the bright star above right at the same time! Anyone ever seen anything like this?

I done some testing the other evening on M44. I removed the LP filter from the flattener for this. Took half an hour on each filter, 60s subs on L and 90s subs on RGB. Each filter showed some halo on the brighter star on the right.

M44 LRGB

L filter

Red filter

Green filter

Blue filter

There's a strange artifact on the brightest culprits on all filters. It's on the centre star and right one with halo in LRG and on B its more so on the right one, despite the star to the left looking brighter with no issues! Checking on Sky Safari they are both practically the same magnitude, around 6.5. (39 Cancri - halo, 40 Cancri - no halo)

I just don't understand why it's not on all the brighter stars? Perplexed!

On 11/04/2021 at 15:21, ollypenrice said:

Thoughts:

- Are you refocusing regularly?

- As you approach the zenith the full weight of the camera/FW is hanging on whatever is locking your drawtube at its present extension. If it's going to slip, the zenith is the place where it will do so.

- As you approach the zenith the atmosphere's tendency to induce blue bloat is at its lowest so your problem is contrary to that.

- In thinking about this, don't forget that luminance passes blue, so bloat in L and bloat in B can have precisely the same origin.

- I'd check for dew on the lens, the filters and, above all, on the chip window. That's where it gets me on the rare occasions when it does get me.

Olly

 

Hi Olly

Yes, have an autofocuser set to focus if temp changes by 1°C or star HFR changes by 10%!

The focuser is R&P and the AF holds it solid.

I added another dew strap the other night, cleaned the objective and checked the sensor window on the Atik after a while of running the cooler. Couldn't see anything obvious..

Do you have the correct focal length selected in APT? 

A bit odd. I know with a DSLR you can use flats with a different ISO value to the lights so I wonder why DSS is asking that? You haven't done what I did the once and collect an entire library of darks only to find out later that they saved to png format?!?