Quark Chromosphere - Uneven field illumination

[Mark_C]

Hi all,

I purchased my Quark from FLO last October and was just wondering if this is normal for a Quark Chromosphere to have uneven field illumination such as in the flat that I've attached to this post? I find that without taking these flats, my solar images are totally unusable when I start stretching the curves in imppg. I realise that taking flats is good practice anyway, but ideally would have liked to not have these inconsistencies to begin with.

The unevenness is consistent regardless of whatever OTA I attach the Quark to so I assume this lies with the Quark itself.

I'm just wondering is it worth asking FLO to look in to this being a warranty issue or is this normal and to be expected?

 

 

 

 

 

[Stu]

I would certainly speak to @FLO to check whether there is a problem or not. I’ve tagged them, so hopefully they will reply here but if not, do get in touch to get it checked.

[Mark_C]

Thanks Stu, I think that's definitely good advice. Hopefully @FLO will see this, if not then I'll get in touch!

Edited April 9 by Mark_C

[Nik271]

I use my Quark visually and I can definitely see there is uneven illumination of the field. In solar chat forums there is a lot of discussion of uneven illumination, both of Quarks and of Lunts, so my guess is that it is a very common issue with these filters.

[Franklin]

1 hour ago, Mark_C said:

I'm just wondering is it worth asking FLO to look in to this being a warranty issue or is this normal and to be expected?

I think these Ha solar filters all exhibit this to some degree and it's a consequence of their design. My Chromosphere Quark had it but it wasn't obtrusive, not visually anyway.

[LukeTheNuke]

There are some (downsized) flats below from two of my Quarks. I'm not 100% sure, but I think the second flat below is from my best Quark (which went faulty, alas, and was replaced). My advice would be to see what the end result looks like applying the flat, and if it looks good, don't worry about it. You could possibly get a flatter Quark, but it might also be one that shows less detail.

My favourite Quark wasn't the one that was the most even. It was the one that showed the most detail.

 

Edited April 9 by LukeTheNuke

[Steve Ward]

Perfectly normal for a Daystar product and perfectly acceptable as far as Daystar are concerned ... 

Their customer service and T&Cs are pretty appalling so good luck dealing with them should the unit have to go back to them.

This recent long-running thread over on Cloudy Nights should give you an inkling into their attitude and the reason why I will never go down the Quark route ... 

https://www.cloudynights.com/topic/909154-daystar-filters’-sr-127-‘qt’-dedicated-hydrogen-alpha-solar-telescope-chromosphere-model/

[Mark_C]

Thanks for the responses all! Really appreciate the feedback. I guess it's comforting to know that I'm not the only one who has these uneven illumination issues with this filter. To be fair with the flats taken and subtracted within Sharpcap the results are fairly good (i think) although I'm no solar expert.

I've attached a picture - this was taken with an Evostar ED120 and UV-IR cut filter. I've not had a proper chance to test the different dial settings of my quark because the weather has been so rubbish over the past 6 months that it clouds over before I get a chance to try each setting! This picture has been taken with the dial set at 0 from a set of 1000 frames.

16 minutes ago, Steve Ward said:

Perfectly normal for a Daystar product and perfectly acceptable as far as Daystar are concerned ... 

Their customer service and T&Cs are pretty appalling so good luck dealing with them should the unit have to go back to them.

This recent long-running thread over on Cloudy Nights should give you an inkling into their attitude and the reason why I will never go down the Quark route ... 

https://www.cloudynights.com/topic/909154-daystar-filters’-sr-127-‘qt’-dedicated-hydrogen-alpha-solar-telescope-chromosphere-model/

I've just read through this thread and this is very dissapointing to see, had I known this beforehand I probably would have avoided buying this filter, as the CN thread does not represent Daystar in a good light.

 

I think the attraction of being able to put this filter on a long FL scope such as the ED120 to get close in details drew me in more than the risk of getting something that may not have worked properly!

 

[Steve Ward]

7 minutes ago, Mark_C said:

Thanks for the responses all! Really appreciate the feedback. I guess it's comforting to know that I'm not the only one who has these uneven illumination issues with this filter. To be fair with the flats taken and subtracted within Sharpcap the results are fairly good (i think) although I'm no solar expert.

I've attached a picture - this was taken with an Evostar ED120 and UV-IR cut filter. I've not had a proper chance to test the different dial settings of my quark because the weather has been so rubbish over the past 6 months that it clouds over before I get a chance to try each setting! This picture has been taken with the dial set at 0 from a set of 1000 frames.

I've just read through this thread and this is very dissapointing to see, had I known this beforehand I probably would have avoided buying this filter, as the CN thread does not represent Daystar in a good light.

 

I think the attraction of being able to put this filter on a long FL scope such as the ED120 to get close in details drew me in more than the risk of getting something that may not have worked properly!

 

 

I've seen a lot worse than that , as far as I'm aware FLO send their Quarks to be checked over by Gary Palmer before they're released into the wild so it should be one of the better ones.

I think you need to give it a proper session running right through the temperature settings visually before jumping into imaging so that you can find the sweetspot.

And remember that your local seeing will ultimately determine the image quality , more aperture is not necessarily better .

[Zakalwe]

Nothing wrong with that Quark at all IMHO. I wish that mine was that flat!

Solar flats are an essential piece of the imaging workflow and are very easy to create- either stretch some clingfilm over the aperture or de-focus the heck out of the image.

 

For example, here's a flat from one of my Quarks....and this is after correction with a tilt adapter to get rid of the Newton's Rings. You'd have a conniption if you saw the image without the tilt adapter!

[Mark_C]

56 minutes ago, Steve Ward said:

 

I've seen a lot worse than that , as far as I'm aware FLO send their Quarks to be checked over by Gary Palmer before they're released into the wild so it should be one of the better ones.

I think you need to give it a proper session running right through the temperature settings visually before jumping into imaging so that you can find the sweetspot.

And remember that your local seeing will ultimately determine the image quality , more aperture is not necessarily better .

Ah yes when I queried FLO about my concerns about Quarks and their QC before purchasing, they did say that they are checked by Gary, hence why I bought it from them as I didn't want to take the risk elsewhere, plus I'd be backed by FLO in the event there are any problems.

I did not realise there was such a wide variation with these devices, and it sounds like mine may actually not be a bad copy after all. I did not realise how bad they can be.

 

38 minutes ago, Zakalwe said:

Nothing wrong with that Quark at all IMHO. I wish that mine was that flat!

Solar flats are an essential piece of the imaging workflow and are very easy to create- either stretch some clingfilm over the aperture or de-focus the heck out of the image.

 

For example, here's a flat from one of my Quarks....and this is after correction with a tilt adapter to get rid of the Newton's Rings. You'd have a conniption if you saw the image without the tilt adapter!

Oh wow, that really is rather bad! How does your images look once the flat has been subtracted?

Edited April 9 by Mark_C

[Steve Ward]

36 minutes ago, Mark_C said:

Oh wow, that really is rather bad! How does your images look once the flat has been subtracted?

Fair to middling I'd say ... 😉

https://www.astrobin.com/search/?q=Zakalwe&d=i&subject=&telescope=&camera=&date_published_min=2011-11-09&date_published_max=2024-04-09&sort=-published

[Grant]

It is essential to use flats with the Quarks to ensure a nice even field of view - DayStar themselves recommend their Flat Caps which work really well to diffuse the sunlight and get a good flat alternatively, just move your focuser so you are fully out of focus and take your flats that way - Sharpcap has a great tool for doing that.

If that example image is from your Quark then it's working A-OK and you are getting some lovely results, don't be concerned - enjoy! 🙂

 

[LukeTheNuke]

Your Quark image looks good to me.

Wowsers, Zakalwe's flat is lively! Which I think just goes to show, it's about the end result!

[Stu]

2 hours ago, Grant said:

It is essential to use flats with the Quarks to ensure a nice even field of view - DayStar themselves recommend their Flat Caps which work really well to diffuse the sunlight and get a good flat alternatively, just move your focuser so you are fully out of focus and take your flats that way - Sharpcap has a great tool for doing that.

If that example image is from your Quark then it's working A-OK and you are getting some lovely results, don't be concerned - enjoy! 🙂

Thanks Grant.

@Mark_C incase it’s not clear, Grant is FLO so hopefully that is reassuring 👍

[Zakalwe]

6 hours ago, Mark_C said:

Oh wow, that really is rather bad! How does your images look once the flat has been subtracted?

I've had my moments.....

 

[Stu]

43 minutes ago, Zakalwe said:

I've had my moments.....

 

Errr, wow! V nice 👌 

[Mark_C]

6 hours ago, Grant said:

It is essential to use flats with the Quarks to ensure a nice even field of view - DayStar themselves recommend their Flat Caps which work really well to diffuse the sunlight and get a good flat alternatively, just move your focuser so you are fully out of focus and take your flats that way - Sharpcap has a great tool for doing that.

If that example image is from your Quark then it's working A-OK and you are getting some lovely results, don't be concerned - enjoy! 🙂

 

Thanks Grant, I suspected this was the case and it is great to have confirmation from yourself and other users of the Quark that what I'm experience is perfectly normal, it gives me reassurance. 🙂

 

3 hours ago, Stu said:

Thanks Grant.

@Mark_C incase it’s not clear, Grant is FLO so hopefully that is reassuring 👍

I suspected it was, thanks for the heads up Stu! 🙂

 

1 hour ago, Zakalwe said:

I've had my moments.....

 

That's incredible! Very sharp and detailed. It's impressive how excellent results can be achieved even when you have to fight against challenging equipment, well done!

Edited April 9 by Mark_C

[Zakalwe]

13 hours ago, Mark_C said:

That's incredible! Very sharp and detailed. It's impressive how excellent results can be achieved even when you have to fight against challenging equipment, well done!

Thank you.

I wouldn't really describe it as fighting against challenging kit, more it's just a necessary step in the overall process. Achieving sharp focus and trying to beat the seeing (I use a 120mm Espit refractor with the Quark) are much, much more difficult than spending 2 minutes taking some flats.

[ollypenrice]

On 10/04/2024 at 09:41, Zakalwe said:

Thank you.

I wouldn't really describe it as fighting against challenging kit, more it's just a necessary step in the overall process. Achieving sharp focus and trying to beat the seeing (I use a 120mm Espit refractor with the Quark) are much, much more difficult than spending 2 minutes taking some flats.

Never having taken solar flats I just watched a good video on how to do it. The extreme defocus method was the one I didn't understand. How can this correct vignetting if the chip is sampling a smaller or larger diameter light cone?

The case for using flats is certainly overwhelming, as it is for DS imaging.

Olly

[Zakalwe]

2 hours ago, ollypenrice said:

 How can this correct vignetting if the chip is sampling a smaller or larger diameter light cone?

Vignetting isn't really the problem here, it's uneven lighting across the whole image.

The way I do it is to centre the image on the disc so the whole field is illuminated. Then either use a bit of clingfilm across the aperture and defocus, or just defocus without any film (depends if there is cloud cover or not). Dunno if it the correct way, but I know that it seems to work for me.

 

 

[Mark_C]

3 hours ago, Zakalwe said:

Vignetting isn't really the problem here, it's uneven lighting across the whole image.

The way I do it is to centre the image on the disc so the whole field is illuminated. Then either use a bit of clingfilm across the aperture and defocus, or just defocus without any film (depends if there is cloud cover or not). Dunno if it the correct way, but I know that it seems to work for me.

 

 

Very nice!

Regarding flats, I also do the same, I use an A4 ring binder wallet that I've separated in to one single sheet then wrap it around the OTA dew shield with an elastic band. I then higher the exposure so that it's at around 60% in the histogram, then get SharpCap to take the flats, seems to work just fine and the results seem to be decent. I think this is the way DayStar advise to take solar flats, or use one of their dedicated flat screens (that do pretty much the same thing but more convenient.)

[Hughsie]

On 11/04/2024 at 20:09, Mark_C said:

Very nice!

Regarding flats, I also do the same, I use an A4 ring binder wallet that I've separated in to one single sheet then wrap it around the OTA dew shield with an elastic band. I then higher the exposure so that it's at around 60% in the histogram, then get SharpCap to take the flats, seems to work just fine and the results seem to be decent. I think this is the way DayStar advise to take solar flats, or use one of their dedicated flat screens (that do pretty much the same thing but more convenient.)

I use a crumpled up sandwich bag over the front of the scope held on with a lacky band. Beats paying what DayStar charge for their flat panel!