At a loss here

[Anthony1979]

ive been trying for days to sort this image out but still not getting any where.. i just dont no where the problem is.. ive tried different settings in dss.. it only seems to be when i add my flats but was told my flats were fine.... this is lights,flats,darks and bias

Any ideas please

[alacant]

Hi

Tell us what you did to get to this stage.

Go through all the light frames and reject any with cloud, haze and any other imperfections.

Link us to an example of each type of frame you used.

Restack and post a link.

Cheers

Edited April 25, 2020 by alacant

[Ant]

I used to get exactly the same issue, but only occasionally. I  never really got to the bottom of it.

In the end I used to take three sets of flats. One at my normal ADU count (which from memory was around 20K (1/3rd full saturation)).

But because of this issue, I used to take another set at 15k, and another set at 25k. 

Then if the usual set went a bit Pete Tong, I'd use one of the others, which usually worked OK.

Also how many Flats are you using in your stack? If its an even number, remove one... I was always told that it needed to be an odd number for flats, darks and bias frames (never understood why).

Ant

 

[Freddie]

If it only happens when you use your flats, obviously the problem must be with the flats. What does your master flat look like?

[Anthony1979]

I will put the tiff files on tomorrow... Ive shutter laptop down starting stressed me out

I used level and curves in gimp then got frustrated and messed about with everything...  Im near enough given up on it all.. Its driving me nuts

[FaDG]

I've had a lot of grief with my flats too! 

I tried different exposures, different methods to acquire them. Then, recently, I found the solution.

How did you shoot those flats? 

If not already done this way (in which case I don't know how to help), try taking then again tomorrow, in full daylight with a white T-shirt on your lens and pointing opposite side of the sky wrt. the sun. Head for 1/4 ADUs of your full well. 

It was really the one and only way I solved my flat problem. 

Edited April 25, 2020 by FaDG

[Anthony1979]

I cant take the flats now because ive took the camera off the scope

[Anthony1979]

single flat frame

_DSC0001.NEF

Edited April 26, 2020 by Anthony1979

[Anthony1979]

single light frame

_DSC0007.NEF

[Anthony1979]

master flat

MasterFlat_ISO400.tif

[Anthony1979]

stacked lights

 

Edited April 26, 2020 by Anthony1979

[Anthony1979]

28 minutes ago, Anthony1979 said:

stacked lights

M101 TEST 4.TIF 276.49 MB · 2 downloads

Sorry this is a full stack of lights,flats,darks and bias... The pic above

[MarkAR]

Just done an extreme stretch of the stacked lights and it looks like it might be light pollution.

[Anthony1979]

23 minutes ago, MarkAR said:

Just done an extreme stretch of the stacked lights and it looks like it might be light pollution.

Ive never had this problem from my back yard... Ive done all my imaging from my back yard and this is the first problem ive had... 

[Anthony1979]

2 minutes ago, Anthony1979 said:

Ive never had this problem from my back yard... Ive done all my imaging from my back yard and this is the first problem ive had... 

The one i put on saying stacked lights was with flats darks and bias. Its not just lights sorry

[Anthony1979]

I will do a stack of just lights

[alacant]

Hi

The single flat frame shows off centre optics. The master-flat less so. the dust has been removed so in that respect, the flat frames are working. The stack shows intense gradient which is not present on the -quite nice- single frame. It looks like there was a change in orientation and /or light leak into camera or telescope when you took the flat frames.

It's rescuable, but it needed a big hammer to remove the irregularities. I fixed the stars whilst I was at it; there seems to be coma toward the edges.

Anyway, HTH and stay safe.

 

 

 

 

 

 

[Anthony1979]

So it is down to my flats being bad

[david_taurus83]

The flats dont match the lights if this is the set that I had a play with. So they can cause all sorts of issues, gradients etc

[Anthony1979]

29 minutes ago, alacant said:

Hi

The single flat frame shows off centre optics. The master-flat less so. the dust has been removed so in that respect, the flat frames are working. The stack shows intense gradient which is not present on the -quite nice- single frame. It looks like there was a change in orientation and /or light leak into camera or telescope when you took the flat frames.

It's rescuable, but it needed a big hammer to remove the irregularities. I fixed the stars whilst I was at it; there seems to be coma toward the edges.

Anyway, HTH and stay safe.

 

 

 

 

 

 

I did accidently remove camera when i was packing everything up forgetting i had to take flats then put it back on.... So is this where i went wrong ( bad mistake) 

[david_taurus83]

What software are you using to process after it's been stacked in DSS?

[alacant]

4 minutes ago, Anthony1979 said:

is this where i went wrong

We can confirm or otherwise with a stack of just the light frames.

Cheers

[Anthony1979]

8 minutes ago, david_taurus83 said:

What software are you using to process after it's been stacked in DSS?

I use GIMP 2.10

[david_taurus83]

1 minute ago, Anthony1979 said:

I use GIMP 2.10

Does it have a method to deal with gradients? Unless you are imaging from a pristine dark sky location and your optics are spotless then you will nearly always have some sort of gradient to sort out. Have you had a look at any of the dedicated astro softwares?

[alacant]

3 minutes ago, david_taurus83 said:

nearly always have some sort of gradient

Hi

The single frame looks pretty good to me.