Physopto

I might try a figure closer to that next time out. I am at The Galloway Star Camp next month. So a few more hours spent trying out different levels would not come amiss.

OOPs Something went wrong there Just noticed that I should have said 25,000/2 for the flats and that is the minimum I use.

Hi Vlaiv Yes I can see your argument. I always use around 50% FWD for my CCD (QSI 683), ( what QSI recommended I believe). So I aim for around the 25,000e ish. It is a long time since I did any maths/statistics on shot and thermal noise. So I just aim for what seems to work. I would guess it may be different for the various makes of CCD depending on how they work. Things have changed greatly in the last 25 years or so since I did my first degree. All I was pointing out is where carastro may have seen or gotten the 33% figure from. I use Maxim DL but have never tried their auto routine so far. I get too little time to waste messing about with experimenting. I beleive in" if it ain't broke, then don't fix it!" Derek

Hi Vlaiv Yes I can see your argument. I always use around 50% FWD for my CCD (QSI 683), ( what QSI recommended I believe). So I aim for around the 25,000e ish. It is a long time since I did any maths/statistics on shot and thermal noise. So I just aim for what seems to work. I would guess it may be different for the various makes of CCD depending on how they work. Things have changed greatly in the last 25 years or so since I did my first degree. All I was pointing out is where carastro may have seen or gotten the 33% figure from. I use Maxim DL but have never tried their auto routine so far. I get too little time to waste messing about with experimenting. I beleive in" if it ain't broke, then don't fix it!" Derek

Hi Vlaiv Yes I can see your argument. I always use around 50% FWD for my CCD (QSI 683), ( what QSI recommended I believe). So I aim for around the 25,000e ish. It is a long time since I did any maths/statistics on shot and thermal noise. So I just aim for what seems to work. I would guess it may be different for the various makes of CCD depending on how they work. Things have changed greatly in the last 25 years or so since I did my first degree. All I was pointing out is where carastro may have seen or gotten the 33% figure from. I use Maxim DL but have never tried their auto routine so far. I get too little time to waste messing about with experimenting. I beleive in" if it ain't broke, then don't fix it!" Derek

People who mention " get some water repellent for the small tent leak I had in the torrential Thursday night at last years autumn camp." Can be shot you know 😂

This is part of a page from the Maxim DL manual Sky Flats Assistant MaximDL Application This app for use with MaximDL allows the user to take a series of sky flats while automatically compensating for the changing sky brightness. It is also useful for users with light boxes since the exposure duration will need to be adjusted There is some common setup between the two modes - you need to enter the initial, min and max exposure durations, the target ADU level and error range The initial exposure duration should be chosen to be reasonable for the desired target ADU count – this reduces the iterations required to get to the starting level. It doesn’t need to be accurate though, the app will iterate to get to the correct value. The target ADU selected should be about 33% of the saturation level of your camera. This will give the most accurate and noise free raw flats which will result in the best master flat once stacked. Going too high can result in pixels outside the linear range of the CCD and too low can result in poor signal-to-noise in the flat. The allowable error percentage allows you to control how close to the target ADU count the flats must be - exposures outside this range will not be saved, rather a new exposure time will be calculated and the exposure retaken. Making this too restrictive may result in a lot of exposures being thrown away. The ideal target number of flats somewhat depends on the noise characteristics of your CCD, but after stacking about 10 flats the signal-to-noise ratio in the flat drops to a level which will generally be insignificant once applied to the light image.

I don't know if it is somehow my down load but the Flat in Maxim under stretch shows 3 distinct peaks very strange! Derek

Yes they are flimsy but sandwiched between the flat field panel and the white dispersion cover they are fine. Easy to do. My flat field generator is fitted into a cut down an old plastic plant pot fitted with cut out foam so it fits over the scope dew shield. Derek

I have the same Gerd Neumann flat field generator. I have never tried altering the voltage as I suspect it is better to use neutral density filters with it. I use 2x filter sheets (2 off) and vary the timing of the exposure. It can also be done with a white t shirt but again I don't think it is the best method. Just my opinion! You could try this anyway. # Best of luck Derek

Really nice image. Colours look amazing and well balanced. Derek

Beautiful image. Well done. Derek

Well that is a pity missing you and Dawn. But good news for the Autumn event. 😀 Derek

Yes Jim, we will be there from Sunday 23rd. Can't before that as van taken by Lynn and Kev. So at least a few days to catch up and chat with everyone. I am as others are, hoping the weather plays ball! Two chances and one of them means downing a good few drams 🤣 Derek

2 days is better than NOWT ! 😁 Be good to see you both. Derek

I don't think you could easily beat the clear skies found in Galloway at: Scotland's Premier Star Camp 😺

No Mike, we have to reverse this "liberal attitude" to wrong doers that has become the norm these days. Especially anything to do with the dreaded, 🤔(whispered) "😡rain". 😂 Derek

More the merrier John. I'm sure there will be room. Derek

Hi James, Great! Just what we need more dedicated Astronomers and Scottish to boot. 😃 Derek

Great that looks as though it is around 🌚🌚🌚🌚🌚🌚🌚🌚🌚 + 👩👩 so far... Just need to hear from some of our northerly Scottish contingent as well. 😀 And as Mike will be there that should take care of the Pie ordering situation😂 Derek

I have just finished talking to Lesley on the phone. She has agreed that there is no objections setting up tents on the hard standing/field edge. Cars can be parked around the back of the house in the storage area if need be to allow motor homes parking on the hard standing area. Obviously this is all dependent on the field being overly sodden come the Star Party start as no vehicles will be allowed on the grass if it is that bad. BUT it is still some way off as yet and the weather could improve with luck. So as of the present information known even if the field is very wet -------- The 2020 Spring Galloway Star Party is a GO. I hope that this is welcome news for all attending and/or for those awaiting more news on what is happening. Please book at, your earliest convenience to avoid any disappointments. So hoping for good clear skies. 😂Rain dancers will be shot!😂 Hoping to see regular and new attendees. Derek

Excellent news! I just tried calling Lesley but I think she is still occupied elsewhere. So I will try again in the morning if I can to check on a few things. Derek

Excellent news. I think that now makes about 👨‍🦰👨‍🦰👨‍🦰👨‍🦰👨‍🦰👨‍🦰👨‍🦰👨‍🦰👩‍🦱👩‍🦱 of us and Mike has confirmed that he will be attending the Autumn camp as well 🙂 Derek

More the merrier 🔭🔭🔭🔭🔭🔭🔭 I am sure that Lisa will enjoy the atmosphere and company. I will be talking to Lesley, probably tomorrow. I was supposed to today but things happen! So hopefully I can find out a wee bit more information to share with everyone tomorrow. Derek

Not my fault you canna appreciate a bl... awful whisky !