Are these clouds?

[TiffsAndAstro]

because there's none (i can see) i my subs

the shady hollows only appear after background extraction and sky looked clear....

 

[alacant]

Hi

Perhaps post a -link to- the image before extraction along with details of any calibration...
Cheers

Edited May 19 by alacant

[Elp]

Looks like a flats issue to me, clouds don't image like this.

[TiffsAndAstro]

21 minutes ago, alacant said:

Hi

Perhaps post a -link to- the image before extraction along with details of any calibration...
Cheers

Sorry didn't have time for more detail.

The above is 60% best images stacked in dss to check my siril stacking. I did darks flats and biases and stacked in both siril and dss with those.

My guiding was decent (for me) around 1.3"

Hfd in phd2 was above 4 mostly, snr around 13

 

[TiffsAndAstro]

1 minute ago, Elp said:

Looks like a flats issue to me, clouds don't image like this.

I'll have a closer look at my flats, it's not impossible though I did then as usual.

[Elp]

Whenever I've had a slight shift or rotation mine look similar. Or it could be dew formation on the lens.

Due to long exposure clouds would streak into smooth forms usually, and you'd see a distinct contrast change or brightening of the background and also dimmer stars in the subs from ones which don't have cloud.

[TiffsAndAstro]

27 minutes ago, Elp said:

Whenever I've had a slight shift or rotation mine look similar. Or it could be dew formation on the lens.

Due to long exposure clouds would streak into smooth forms usually, and you'd see a distinct contrast change or brightening of the background and also dimmer stars in the subs from ones which don't have cloud.

Didn't seem to be any dew last night my gear was bone dry. To be fair my dew heaters isn't directly around the primary, it's a little higher up the dew shield. But it was switched on.

I'll have a look at my flats and lights a bit more. I can also test stack  with less recent flats see if any difference.

It's only an hour of subs, so not earth shatteringly vital. Would just like to figure it out to avoid repeating same mistake.

But because you said it looks like dew, it does indeed look like dew

Also they only appear after a background extraction 

Edited May 19 by TiffsAndAstro

[TiffsAndAstro]

1 hour ago, Elp said:

Whenever I've had a slight shift or rotation mine look similar. Or it could be dew formation on the lens.

Due to long exposure clouds would streak into smooth forms usually, and you'd see a distinct contrast change or brightening of the background and also dimmer stars in the subs from ones which don't have cloud.

im a bit surprised, but it was my flats. not sure what happened, as i did them as i usually do. using a set of flats from a few days ago and the dew seems to not appear after a background extraction.

ty again, again.

[TiffsAndAstro]

just for the curious bit less than an hour on m106 and almost 13 minutes on m94 (had issues finding veil nebula, i remember now but its high enough after 1230 so will try again tonight).

i think the m106 is ok considering one hour, full moon, clouds and my gear.  m94...well i at least i've proved it exists...