294MC Pro, L-eXtreme and a bunch of flats......

[vlaiv]

@scotty38

What scope are you using here?

Can you try something? Shoot your flats in different way with L-eXtreme a bit differently. You need a room that you can make completely dark (if you need laptop / computer in that room - shield it somehow to produce the least light) and place flat panel on the far wall of the room.

In essence - shoot normal flats but with flat panel say 3-4 or more meters away from the scope (have scope pointed directly at flat panel and flat panel squared with aperture of course).

I suspect that we have some sort of angle dependence at play here. Both ASI294 and L-eXtreme filter have quantum efficiency that depends on angle of incident light. Larger the angle - less light goes thru. If you have fast scope and light is placed right at aperture of scope - it can produce some strange angles on filter and sensor.

Ideally - things will even out and we have working flat systems even if flat panels are right next to aperture.

[scotty38]

23 minutes ago, Jamgood said:

@scotty38 Have a read through this thread and see if you can find anything helpful. @vlaiv helped me solve my problem when I got my 294mc. There's quite a bit of info in there, if you haven't read it already. 

 

Yes I have read that post but thought it was a "fix" for APT issues but will have another look at it, thanks.

[scotty38]

3 minutes ago, vlaiv said:

@scotty38

What scope are you using here?

Can you try something? Shoot your flats in different way with L-eXtreme a bit differently. You need a room that you can make completely dark (if you need laptop / computer in that room - shield it somehow to produce the least light) and place flat panel on the far wall of the room.

In essence - shoot normal flats but with flat panel say 3-4 or more meters away from the scope (have scope pointed directly at flat panel and flat panel squared with aperture of course).

I suspect that we have some sort of angle dependence at play here. Both ASI294 and L-eXtreme filter have quantum efficiency that depends on angle of incident light. Larger the angle - less light goes thru. If you have fast scope and light is placed right at aperture of scope - it can produce some strange angles on filter and sensor.

Ideally - things will even out and we have working flat systems even if flat panels are right next to aperture.

It's a GT81 with 0.8 flattener/reducer so making it roughly f4.7 so not uber fast. I'll see what I can set up to give this a try though, thanks

[scotty38]

@vlaiv Here you go. I created flats from a tv running notepad on the screen, not perfect but just need to see if it's different really. I used 5 frames of lights, flats, flat darks and my usual master dark.

I think there is a clear difference......

[vlaiv]

3 minutes ago, scotty38 said:

I think there is a clear difference......

There seems to be, but I'm not sure how can this help you get proper calibration though.

What was the distance between TV and scope and were there other sources of light in the room?

Never mind that - I just saw your post where you calibrated with darks only - there is still very uneven background in that image.

What is your imaging train like? Describe places of components, will you?

In particular, if L-eXtreme is placed before or after reducer. What size is the filter? 1.25" or 2"?

I'd try following - placing filter in front of reducer so it is in slower beam - F/6 and maybe combining it with UV/IR cut filter just in case to see if it makes difference.

[scotty38]

Thanks @vlaiv The filter is in a filter wheel right in front of the camera and it's 1.25". The reducer is an adjustable Flat 6AIII, I've just set up to do some imaging and I will check but I am not sure where else in the train I could put it, I think it's too small to go anywhere else.

 

[vlaiv]

Just now, scotty38 said:

Thanks @vlaiv The filter is in a filter wheel right in front of the camera and it's 1.25". The reducer is an adjustable Flat 6AIII, I've just set up to do some imaging and I will check but I am not sure where else in the train I could put it, I think it's too small to go anywhere else.

 

Yes it is, I was hoping it is 2" version and that you can put it in front of reducer.

[scotty38]

12 minutes ago, vlaiv said:

Yes it is, I was hoping it is 2" version and that you can put it in front of reducer.

At this rate the only place it's going is the bin 🙂

I might get out now and just buy a 1600MM bundle 🙂

[scitmon]

Well this concerns me, I just bought a L-eXtreme and minifilter wheel for my 294MC pro, but haven't had chance to use it yet.

[scotty38]

31 minutes ago, scitmon said:

Well this concerns me, I just bought a L-eXtreme and minifilter wheel for my 294MC pro, but haven't had chance to use it yet.

Not all seem to suffer though so don't worry. There's always a good chance it's all my own fault somehow anyway....

[scitmon]

I guess I don't have to wait for clear skies to take some flats, I'll see if I can do some this weekend.

[scotty38]

1 minute ago, scitmon said:

I guess I don't have to wait for clear skies to take some flats, I'll see if I can do some this weekend.

Very true. I took more lights last night and I still have the flats issue but as @vlaiv mentioned earlier in the thread the issue is there on my lights HOWEVER I revisited some IC1396 I took last month and the issue is not on the lights. It would appear it has become a problem rather than being there all the time. Of course I have no idea why and I have gone through every permutation I can think of with settings and versions of drivers etc.

On one hand it feels like it's something I've done but on the other hand other folk have the issue so I think I need to examine my IC1396 lights carefully to see if the issue is there or not.....

[PadrePeace]

8 hours ago, scotty38 said:

Very true. I took more lights last night and I still have the flats issue but as @vlaiv mentioned earlier in the thread the issue is there on my lights HOWEVER I revisited some IC1396 I took last month and the issue is not on the lights. It would appear it has become a problem rather than being there all the time. Of course I have no idea why and I have gone through every permutation I can think of with settings and versions of drivers etc.

On one hand it feels like it's something I've done but on the other hand other folk have the issue so I think I need to examine my IC1396 lights carefully to see if the issue is there or not.....

I hate to prolong your misery but was IC 1396 taken with the same scope and flattener, exposure, gain etc? I can’t see how it wasn’t there but is now. The general consensus seems to be long (> 3s) flats exposure.

I tried sky flats and that made my issue (very bright glow left and right sides) worse.  Whilst I know you’ve tried almost every option already is it possible you have your filter fitted in reverse which might give reflections back into the sensor. I fit mine to the scope side of the 1.25” adapter ring that then screws inside of the 11mm extension that comes with the camera?

 

Edited January 12, 2022 by PadrePeace

[scotty38]

1 hour ago, PadrePeace said:

I hate to prolong your misery but was IC 1396 taken with the same scope and flattener, exposure, gain etc? I can’t see how it wasn’t there but is now. The general consensus seems to be long (> 3s) flats exposure.

I tried sky flats and that made my issue (very bright glow left and right sides) worse.  Whilst I know you’ve tried almost every option already is it possible you have your filter fitted in reverse which might give reflections back into the sensor. I fit mine to the scope side of the 1.25” adapter ring that then screws inside of the 11mm extension that comes with the camera?

 

Yeah everything is the same, nothing has been taken apart since I put the filter in and I agree on it cannot be there now and wasn't before - That's why i need to double check IC1396 as the issue must be there.... It's perfectly possible the filter is in wrong but I did look how others had them fitted blah, blah before I did it but I could have been mistaken. I will probably have a check tomorrow and see how it compares with what you've said.

Thanks for the info!

[scotty38]

18 hours ago, PadrePeace said:

 Whilst I know you’ve tried almost every option already is it possible you have your filter fitted in reverse which might give reflections back into the sensor. I fit mine to the scope side of the 1.25” adapter ring that then screws inside of the 11mm extension that comes with the camera?

 

ok, my filters are 1.25" and are screwed in to the filter wheel and the way I have that oriented means the screw thread side of the filter is facing the camera. Is that correct?

[The Lazy Astronomer]

52 minutes ago, scotty38 said:

ok, my filters are 1.25" and are screwed in to the filter wheel and the way I have that oriented means the screw thread side of the filter is facing the camera. Is that correct?

Threads facing camera is the way mine are.

[scotty38]

17 minutes ago, The Lazy Astronomer said:

Threads facing camera is the way mine are.

ok thanks, I had watched a few videos and just done the same again so yep looks like I've done it correctly. Oh well I was hoping I'd made a mistake and had an easy, if somewhat embarrassing, fix 🙂

[PadrePeace]

11 hours ago, scotty38 said:

ok, my filters are 1.25" and are screwed in to the filter wheel and the way I have that oriented means the screw thread side of the filter is facing the camera. Is that correct?

That’s the same as me.
For what it’s worth I have just stacked four hours of extreme dual band Ha and OIII in the California Neb with exactly the same flats system I used before and the flats just failed, adding rather than subtracting from my subs. I have however successfully processed this work by using just dark frames and the LP tool in APP to clean up what little additional colour (greyscale) the flats should have dealt with. Completely confused by this now and won’t be bothering with Flats for extreme subs. They just don’t work. I’ll post the split Ha and OIII subs pre and post LP removal below. I’m 

there was some bight stuff down the RHS and you may be able to just make out some shading in the top left hand corner. This is the way ahead as I just don’t think this sensor is compatible with the extreme filter and flats. I think both channels need to be dealt with in a different way by flats and a single common flat for both just isn’t possible. 
Finally, when it comes to OSC or RGB flats work a treat. Just stacked 9hrs of OSC to go with my ‘no flats’ California Neb NB and though it took most of this evening to crunch the 28GB of subs it worked a treat. 

Edited January 14, 2022 by PadrePeace

[scotty38]

That's very interesting, maybe I should have a bit more of a play in APP too...

[PadrePeace]

11 hours ago, scotty38 said:

ok, my filters are 1.25" and are screwed in to the filter wheel and the way I have that oriented means the screw thread side of the filter is facing the camera. Is that correct?

That’s the same as me. For what it’s worth I have just stacked four hours of dual band Ha and OIII in the California Neb from my extreme with exactly the same flats system I used before and the flats just failed by adding rather than subtracting from my subs. I have, however, successfully processed this work tonight by using just dark frames and the LP tool in APP to clean up what little additional colour (greyscale) the flats should have dealt with. Completely confused by this now and won’t be bothering with Flats for extreme subs. They just don’t work. I’ll post the split OIII subs pre and post LP removal below. 
 

In the plus side, just stacked 9hrs or 28GB of OSC to go with the above and all calibration frames worked a treat though it took most of the evening to do it. 
I now firmly believe that a single master flat won’t work with the extreme NB. I think both channels need different flats treatment and on flat is never going to work for both. I’ll be splitting my NB channels from now on and just use darks and APP’s light pollution tool as above. 

Edited January 14, 2022 by PadrePeace

[PadrePeace]

11 hours ago, scotty38 said:

ok, my filters are 1.25" and are screwed in to the filter wheel and the way I have that oriented means the screw thread side of the filter is facing the camera. Is that correct?

That’s the same as me. For what it’s worth I have just stacked four hours of dual band Ha and OIII in the California Neb from my extreme with exactly the same flats system I used before and the flats just failed by adding rather than subtracting from my subs. I have successfully processed this work by using just dark frames and the LP tool in APP to clean up what little additional colour (greyscale) the flats should have dealt with. Completely confused by this now and won’t be bothering with Flats for extreme subs. They just don’t work. I’ll post the split Ha and OIII subs pre and post LP removal below. 
 

Flats work fine for OSC but are a liability for my extreme dual NB. I’ll not be using flats for E- NB  going forward. Just darks and a friendly LP tool.

Edited January 14, 2022 by PadrePeace

[Flamidey]

13 hours ago, scotty38 said:

ok, my filters are 1.25" and are screwed in to the filter wheel and the way I have that oriented means the screw thread side of the filter is facing the camera. Is that correct?

According to this Optolong document, the side that should be away from the sensor is actually towards it when you use it in a ZWO camera (at least it was like that in mine). You can't reverse the assembled filter because it doesnt fit in the train BUT you can reverse the glass itself with a rather simple disassembly. You need to unscrew the ring (it has a small notch in it). Careful not to scratch the glass or even touch it with your bare hands.
To be honest, I didn't notice any difference after doing it.
I don't have a filter wheel, so I'm not sure if you can reverse it there.

Edited January 14, 2022 by Flamidey

[scotty38]

6 hours ago, Flamidey said:

According to this Optolong document, the side that should be away from the sensor is actually towards it when you use it in a ZWO camera (at least it was like that in mine). You can't reverse the assembled filter because it doesnt fit in the train BUT you can reverse the glass itself with a rather simple disassembly. You need to unscrew the ring (it has a small notch in it). Careful not to scratch the glass or even touch it with your bare hands.
To be honest, I didn't notice any difference after doing it.
I don't have a filter wheel, so I'm not sure if you can reverse it there.

Thanks I'll have a look at the document. I don;t think the filters can go in differently so it would mean messing about for sure.

[scitmon]

The ZWO mini filter wheel that I'm using can be reversed.

[PadrePeace]

2 hours ago, scitmon said:

The ZWO mini filter wheel that I'm using can be reversed.

Not the case if you mount a 1.25” into the ZWO adaptor that comes with the camera. There just isn’t enough thread left to mount the camera to the scope. Just found my filter to be ‘the wrong way around’ so not sure how to fix that without turning the glass around and I’m not doing that on a £180 filter. It will likely go back to FLO if it’s a factory mounting issue.