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Annoying "bloom'" spoils a rare clear sky!


assouptro

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I recently Plucked up the courage to modify my canon 6d

I opted for a Baader mod as I use a refractor and wanted to avoid star bloat.

The mod went reasonably well apart from damaging the microswitch on the cameras ad card door, I have managed to leave this switch in a permanently on position which will do for now. 

Anyway, first light, I chose the veil, C33 as it was high in the sky and I wanted something with a lot of Ha. I forgot to mention I am using an Astronomik CLS clip filter, the full frame version. 

The first results were encouraging. I chose 5min at 1000 ISO as a starting point and here is the result 

IMG_1797.thumb.PNG.4fe115fd8bc0be7dcf50831b10c53825.PNG

 

Two nights later and clear skies allow me to "play" again.

Nothing has changed, the scope and camera have been left connected, there isn't any dew, all optics appear clear but I ended up with this annoying "bloom" effect.

IMG_1796.thumb.PNG.835c21f2eecdd106b3d223863192ab60.PNG

Can anyone shed light on this? 

I'm annoyed. Clear skies are a rare thing here in the NW and I feel I've just wasted one. I just want to avoid wasting another.

thanks for looking and thanks for any help 

Bryan 

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20 minutes ago, Dr_Ju_ju said:

Have you taken\subtracted darks\bias etc. ? I personally wouldn't go over 800 iso, also, try taking shorter lights & stacking them.

Hi Doc

thanks for taking the time to input.

I have taken flats but not processed yet, nothing had altered since my last session where I was using 1000iso and i was going to add to the last batch hence sticking to the same parameters.

i just don't see why this time I end up with this effect?

however, I may start again at a lower ISO thanks.

Bryan 

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21 minutes ago, Astrobug said:

Could be some local reflection from your pc monitor or whatever light source.

Did you turn off the screen of your 6D?

Hi astrobug.

at first I thought it was a reflection from a neighbours house lights but when I moved on to the heart neb, the effect was still there.

the laptop was closed and the camera screen was off. 

I can only think it's something to do with the CLS filter. 

I may try with and without tonight, although without it my skies are pretty bad. But I may be able to eliminate the filter? 

Thanks 

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Well to me it looks like the second image is a longer exposure, if you look st the object it’s actually a bit brighter as if it has been exposed for slightly longer, and that might be why you have the extra brighter patch...

Blow them up and you will see why I mean.. :), so have you used exactly the same exposure time... ?

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4 minutes ago, LightBucket said:

Well to me it looks like the second image is a longer exposure, if you look st the object it’s actually a bit brighter as if it has been exposed for slightly longer, and that might be why you have the extra brighter patch...

Blow them up and you will see why I mean.. :), so have you used exactly the same exposure time... ?

I've just double checked 

both images, 308s ISO 1000

just different nights.

the seeing may have been different, but not that much.

cheers

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I just noticed that your 'first' image filename is IMG_1797.PNG, and your 'second' one is IMG_1796.PNG. So, unless you've done anything special with the filenames, they would seem to have been taken in reverse order.

Wondering if, in fact, you've been looking at the wrong image?  (I'm probably not the only one make this kind of mistake, so perhaps you did too?)

 

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46 minutes ago, carastro said:

On first glance it just looks to me like the effect of longer exposure being stretched more without having used the flats yet.

Carole 

Hi Carole

I would agree however the images haven't been processed in any way they are straight out of the camera

all parameters were the same (as far as I could tell) apart from it being a different night.

I will try put it through DSS with flats and see what happens.

Thanks

Bryan

  

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39 minutes ago, AKB said:

I just noticed that your 'first' image filename is IMG_1797.PNG, and your 'second' one is IMG_1796.PNG. So, unless you've done anything special with the filenames, they would seem to have been taken in reverse order.

Wondering if, in fact, you've been looking at the wrong image?  (I'm probably not the only one make this kind of mistake, so perhaps you did too?)

 

You had me wondering there.

I have double checked.

The reason the files have the numbers they have is because I just downloaded them in the reverse order to my phone from the camera via wifi. the phone gave them the numbers.

Cheers

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The images don't look unstretched to my eye but I don't know your setup so it's hard to say.

Moon not in play here at all?

Might it not just be the sky on the night? We're having an annoying thin high haze at the moment.

I'd say that the colour gradient would be well within the range of DBE to sort out.

Olly

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46 minutes ago, ollypenrice said:

The images don't look unstretched to my eye but I don't know your setup so it's hard to say.

Moon not in play here at all?

Might it not just be the sky on the night? We're having an annoying thin high haze at the moment.

I'd say that the colour gradient would be well within the range of DBE to sort out.

Olly

Thanks Olly 

no moon, to the naked eye the sky looked similar on both nights.

im convinced it's something within my image train, but all looked clear!?

infact, here's a single sub of the heart taken on the same night IMG_2218.thumb.JPG.c2930dc41ad4ca28f14e9896b89de8e5.JPG

You can see the same effect in the same area.

i have a astronomik xl CLS filter and I'm not impressed as it leaves bad banding top and bottom. I have also read they can cause some colour cast. 

I will have to replace it I think with a good quality 2" screw on Lp filter methinks

oh! And with regards DBE

I will eventually buy pixinsight and then learn to use it! 

I just always seem to have another piece of equipment to buy! 

It's  a crazy hobby!

 

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1 hour ago, assouptro said:

Thanks Olly 

no moon, to the naked eye the sky looked similar on both nights.

im convinced it's something within my image train, but all looked clear!?

infact, here's a single sub of the heart taken on the same night IMG_2218.thumb.JPG.c2930dc41ad4ca28f14e9896b89de8e5.JPG

You can see the same effect in the same area.

i have a astronomik xl CLS filter and I'm not impressed as it leaves bad banding top and bottom. I have also read they can cause some colour cast. 

I will have to replace it I think with a good quality 2" screw on Lp filter methinks

oh! And with regards DBE

I will eventually buy pixinsight and then learn to use it! 

I just always seem to have another piece of equipment to buy! 

It's  a crazy hobby!

 

Understood.

However, software is equipment. Honestly, the contribution of processing software to the success or failure on an image can easily be greater than that of the hardware, depending on your sky.

Olly

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As Michael suggests make sure the viewfinder is blanked off. But on a dark sky, low light, high gain on the chip stray light finding it's way in is likely to cause a patch. You mention laptop, was that with the screen towards the DSLR ?

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I have discovered the fault!  

The only difference between the two nights was..... night 1 the wind was blowing a bit so I didn't need the dewshield on the lx200gps which was guiding  with a qhy and a 3.3 focal reducer as this catches the wind and creates a bit of wobble. Whereas night 2 it was still and there was the possibility of dew so I put the dewshield on. 

This has never caused me problems in the past but it would appear the dewshield has reflected a neighbours light and the camera has picked it up! 

The 6d is a more sensitive camera than my 450 and in fact way more sensitive as I have modded it.

Why do they insist on having lights on dawn to dusk sensors? 

I need to move to a house in the middle of nowhere!

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14 minutes ago, happy-kat said:

Have you flocked the inside of your dew shield, that might help.

Hi kat

It's the outside of the dewshield on the 12"lx200gps that is protuding beyond the dewshield of the imaging scope, a revelation Astro 100ed. The dewshield is mat black on the outside by maybe i should flock it externally? 

Cheers

Bryan

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On 17/09/2017 at 19:24, ollypenrice said:

Understood.

However, software is equipment. Honestly, the contribution of processing software to the success or failure on an image can easily be greater than that of the hardware, depending on your sky.

Olly

Can't argue with that Olly! 

As soon as I've decided whether to get a new laptop or just upgrade my hd to ssd I will be purchasing pixinsight.

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  • 2 months later...

Just a quick update....

the fault was nothing to do with my dewsheild it is a fault on the camera.

if I use live view and go straight into imaging I end up with the same “amp glow” effect on all subsequent frames.

If i disconnect power between using live view and shooting all is well. 

It can also appears when i change iso unless I disconnect power before the next batch of exposures.

it may be as a result of me modding the camera? Who knows? 

The main thing is I can get round it and have finally found out what’s going on!!

thanks everybody for your input.

 

bryan 

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This is interesting! I had a similar but much more marked problem the other evening.

Here are four 10-minute darks taken on my cooled Canon 450D, just screen grabs of the unprocessed RAW thumbnails. Can you spot the difference?

Between the first two and the second two I enabled live view:

image.thumb.png.1732aee1795509aac921a2cf9581629e.png

The marks are exactly the same as the ones that spoiled my lights.

 

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7 hours ago, Stub Mandrel said:

This is interesting! I had a similar but much more marked problem the other evening.

Here are four 10-minute darks taken on my cooled Canon 450D, just screen grabs of the unprocessed RAW thumbnails. Can you spot the difference?

Between the first two and the second two I enabled live view:

image.thumb.png.1732aee1795509aac921a2cf9581629e.png

The marks are exactly the same as the ones that spoiled my lights.

 

Thanks for your input!

 

I never had this problem with my 450 but I have a neighbour who was using a 450 that was given to him and occasionally he would end up with the green banding your subs display here

It would appear there is a connection with live view?

It reminds me of amp glow my 350d used suffer from.

I have learned how to avoid it with the 6d, if I change iso or after using live view I have to disconnect the power from the camera for 5 seconds before continuing the shoot and that solves it.

clear skies

Bryan

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