Hardware and software advice needed for upgrading to guided imaging

[ianpwilliams]

Would it be this one:

http://www.astronomik.com/en/clip-filter-system/clip-filter-eos-mit-astronomik-cls.html

Not that I am going to buy it until I actually get out there and get some good images, because I still don't know for sure if this guided imaging is going to work out. But it could maybe be something for later. I just wish it wasn't the case that there always seems to be something else that you need to buy...

[wxsatuser]

Would it be this one:

http://www.astronomik.com/en/clip-filter-system/clip-filter-eos-mit-astronomik-cls.html

Not that I am going to buy it until I actually get out there and get some good images, because I still don't know for sure if this guided imaging is going to work out. But it could maybe be something for later. I just wish it wasn't the case that there always seems to be something else that you need to buy...

Welcome to AP.

Yes, and I have bought loads that I don't need and have tried various things.

I'm now only interested in imaging with DSLR and decent camera lenses.

There is only one big purchase I want to do but will no doubt sell a lot of gear to get it.

[Thalestris24]

Hi Ian

Re: lp filters

A lot depends on the type/source of lp that you have. Unfortunately, white street lights are becoming more common and a filter doesn't much help to alleviate broad spectrum light. If most of your lp is caused by yellow sodium lamps and mercury lamps then a lp filter will help greatly. Again, it also depends how bad your local lp is. I live in a city and the lp is dreadful. It works against me trying to pick up faint objects i.e. nebulae and galaxies, even using lp filters. There's nothing I can do about it other than live in hope the local authority really will improve things... If your lp lies predominately in the bands associated with mercury and sodium then the Hutech IDAS P2 is probably the better filter. However, sodium and mercury lamps are being phased out in favour of the more efficient LEDs. If your lp is broadband and very bad then narrowband imaging might be the way to go! I would see how you get on without a lp filter first and see what your max sub length is and whether simply imaging in a different direction helps.

Louise

[ianpwilliams]

For star alignment it seems that I slew to target star in Stellarium (CTRL 1), centre the star in APT live view using EQMOD, then Sync in Stellarium (CTRL 3) to move the Scope reticule to the target star and Sync it, correct? And do I need to align with 3 stars near the target or will 1 do?

[salas]

Ian, that's correct basically teaching the mount where it is. I think you are meant to choose stars say in the east and then the west of the sky, I've found the more you do the more accurate it gets. Usually 3 for me and it's pretty much bang on.

[ianpwilliams]

Yeah I've read various things, some saying 1, some saying 3, some saying east and west, some saying 3 stars creating an area around the target. My guess is any of the above will probably do the trick.

[salas]

Yep best thing really is to go and and play around with it and see what works best for you, you will develop your own routine.

[ianpwilliams]

My EQMOD time is still wrong (2:25pm instead of Windows 1:25pm). Is this going to be an issue? 1:25pm is what it should be. I've checked regional settings in Windows and it seems fine.

Also, I can't change the settings in EQMOD Site Information. When I load the program the Lat/Lon/Elev are all fine and Edinburgh for location. So I don't understand why the Pole Star HA time is an hour out. Surely that would screw up polar alignment, and also slewing to targets?

[ianpwilliams]

Here is the screen.

[ianpwilliams]

Also, will Edinburgh be enough for Stellarium location settings? For Edinburgh it says:

N 55o 57' 7.42"

W 3o 11' 47.33"

Altitude 66m

I am apparently N55.96, W3.14, and 21m alt. But I'm not sure what that would be in Stellarium.

[ianpwilliams]

More questions:

A guide I'm using says to set the mount to sidereal tracking in EQMOD in order to test the North/West/South/East commands in PHD2 Manual Guide, which I've done (it works fine). My question is do I need to be in Sidereal mode in EQMOD for the rest if the session, as I'm not sure it defaults to that?

Taking Darks in PHD2 - what should I use for minimum and maximum exposure time? And how many Darks should I take? Also, am I able to do this in the daytime seeing as the cap will be on?

Also, will it be worth trying to get rid of these dust bunnies (which are annoying me)? I think they may be on the guide cam rather than the guide scope, so I would have to remove the guide cam. I have focussed the guide cam for the guide scope using a distant daytime object, put I've tightened the ring on the guide cam so I could still put it back where it was afterward. The only question is whether I will be able to get rid of them or not. Should I try the lens pen?

[ianpwilliams]

Also, why is it that my program says EQMOD at the tope when everyone else's window says EQASCOM? I was under the impression that EQMOD is the program which is run by EQASCOM. So why would some programs say EQASCOM at the top instead of EQMOD?

[ianpwilliams]

So to some up, these are my current outstanding questions...

1 - Polar Alignment in EQMOD - Do I need to remove the scope and weights if using EQMOD when Polar Aligning? The YouTube tutorial suggested possibly removing the scope, which surely would also mean removing the weights to avoid slewing with weights and no scope. So do I need to remove both, or neither? Will it really get into such an odd position? Should I just polar align the old fashioned way I.e. By rotating the RA to match the constellations in my PolarFinder app and then using the Alt Az to move Polaris to the small circle?

2 - EQMOD time display - the time is wrong in EQMOD, despite being correct in Windows (5pm in EQMOD was 4:03pm in Windows), and I can't see a way to change it. At the moment I have 55.96N, 3.14W, 21m elevation, and just the time seems to be wrong.

3 - Setting location in Stellarium - will just putting “Edinburgh” be enough for Stellarium location settings? For Edinburgh it says:

N 55o 57' 7.42"

W 3o 11' 47.33"

Altitude 66m

I am apparently N55.96, W3.14, and 21m alt. But I'm not sure what that would be in Stellarium. 

4 - EQMOD Sidereal Mode - does EQMOD default to this mode when loading up? I’m not sure it does, but I don’t know if I need to switch to this mode when StellariumScope opens up EQMOD

5 - Taking Darks in PHD2 - what should I use for minimum and maximum exposure time? And how many Darks should I take? Also, am I able to do this in the daytime seeing as the cap will be on?

6 - Dust Bunnies - Will it be worth trying to get rid of these dust bunnies (which are annoying me)? I think they may be on the guide cam rather than the guide scope, so I would have to remove the guide cam. I have focussed the guide cam for the guide scope using a distant daytime object, put I've tightened the ring on the guide cam so I could still put it back where it was afterward. The only question is whether I will be able to get rid of them or not. Should I try the lens pen?

7 - Why is my program called EQMOD at the top of the window, but the program in the tutorials is EQASCOM?

[ianpwilliams]

Sub lemgth is easy with a dslr.

The correct length for your sky brightness is when the camera histogram peak reachs at least 20% but no more than 40%.

Does'nt matter what other settings you have, iso etc, just expose for around at least 20%.

Depending on sky brightness this could be 30secs or 10minutes, or more.

You will have to do test exposures to find your optimum exposure.

I would suggest taking a 30sec exposure and see where the histogram peak lies.

For example if it lies at say 10% you could double it to 1minute and it will be near 20%

I normally as a rule expose to 25%.

Here is the histogram on my 60Da, a 10minute exposure for around 25%, this was with an LP clip filter.

We are looking at the white luminance one at the bottom, ignore the RGB ones.

I would hopefully be using the histogram in APT (bottom-left corner of attached image). How would that compare to the camera one? There seems to be four lines in APT which is the same, so in the attached screenshot I guess I would be looking to just cross the next line to the right? Mightn't there even be an easier way in APT to find out where the peak ended based on a number?

[Thalestris24]

Hi Ian

I don't know anything about hour angles and polar scopes... I just use PHD2 to drift align with the built-in tool. I find a bad pixel map works quite well in PHD2. Say 20 exposures of 10secs. You can only either use darks or a bad pixel map - not both at the same time! Don't worry about the dust bunnies/marks. There's plenty of room left for guide stars! I don't think lat and long is critical. 55.96 = 55 deg + 0.96 deg = 0.96 x 60 mins = 57.6 mins = 57mins + 0.6 mins = 0.6 x 60 = 36 secs so 55.96deg = 55deg 57mins 36 secs.

With using eqmod and guiding, I suggest you just jump in and do it! It's the only way to learn

Louise

[ianpwilliams]

Yes I'll have to get out there eventually. I'm just trying to do what I can to prevent from getting outside and getting everything set up, only to come across something which I know how to fix and then having to pack up again. But I'm getting closer now.

[salas]

So to some up, these are my current outstanding questions...

1 - Polar Alignment in EQMOD - Do I need to remove the scope and weights if using EQMOD when Polar Aligning? The YouTube tutorial suggested possibly removing the scope, which surely would also mean removing the weights to avoid slewing with weights and no scope. So do I need to remove both, or neither? Will it really get into such an odd position? Should I just polar align the old fashioned way I.e. By rotating the RA to match the constellations in my PolarFinder app and then using the Alt Az to move Polaris to the small circle?

2 - EQMOD time display - the time is wrong in EQMOD, despite being correct in Windows (5pm in EQMOD was 4:03pm in Windows), and I can't see a way to change it. At the moment I have 55.96N, 3.14W, 21m elevation, and just the time seems to be wrong.

3 - Setting location in Stellarium - will just putting “Edinburgh” be enough for Stellarium location settings? For Edinburgh it says:

N 55o 57' 7.42"

W 3o 11' 47.33"

Altitude 66m

I am apparently N55.96, W3.14, and 21m alt. But I'm not sure what that would be in Stellarium. 

4 - EQMOD Sidereal Mode - does EQMOD default to this mode when loading up? I’m not sure it does, but I don’t know if I need to switch to this mode when StellariumScope opens up EQMOD

5 - Taking Darks in PHD2 - what should I use for minimum and maximum exposure time? And how many Darks should I take? Also, am I able to do this in the daytime seeing as the cap will be on?

6 - Dust Bunnies - Will it be worth trying to get rid of these dust bunnies (which are annoying me)? I think they may be on the guide cam rather than the guide scope, so I would have to remove the guide cam. I have focussed the guide cam for the guide scope using a distant daytime object, put I've tightened the ring on the guide cam so I could still put it back where it was afterward. The only question is whether I will be able to get rid of them or not. Should I try the lens pen?

7 - Why is my program called EQMOD at the top of the window, but the program in the tutorials is EQASCOM?

Will try answer some of these - 

Q1 - I align without scope and weights - less strain on the alt / az bolts adjusting, then add scope and weights, never had a problem doing this.

Q2 - The time in EQmod is correct - your PC is showing daylight savings time - simplistically the sky doesn't care if we put our clocks back and forward 

Q3 - Will probably be fine but if you want t be super accurate you can use google maps to give you precise info for your location

Q4 - Yes this is default (on mine anyway!)

Q5 - I let PHD run its default Darks routine - it's not tremendously important for the guide cam to be honest

Q6 - See how you get on first, as if the dust bunny is obscuring something enough (which I doubt) as Louise says there will be plenty of other stars to guide on

Q7 - Doesn't matter so long as it works 

[ianpwilliams]

Great, thanks for that. Definitely going to get out there soon. I just wish I'd bought the guiding upgrade equipment a couple of months back, it's cold out there!

[ianpwilliams]

Looks like I'll be giving this a go tomorrow night if the weather forecast stays as it is.

I've read in various places about how the mount should be "east-heavy" when balancing, but that's dependent on where the scope is. How does that work exactly? It almost seems like you have to balance the mount after the scope is pointing at the target (which can't be right), unless you pre-empt where the telescope is going to be and where it'll be pointing, which would surely be very hard to do. Is it going to cause any major problems if I just have the mount balanced i.e. weight and scope balanced when the RA is on it's side and the scope and weight are level, and DEC balanced when in the same position, and with the scope is on it's side and parallel to the ground?

Also, assuming I manage to get to the imaging stage and that everything goes according to plan (unlikely!), how many subs should I be looking to take? At the moment I have no idea how long my subs will get (under reasonable light pollution I would guess maybe 5 minutes?), but I don't know how many I will be wanting to make the most of the extra data gathered by the longer subs. And of course whatever sub length I reach I will then have to also use for my darks (how many darks do you think?), and I'll have to do flats too (which at least are quicker, if a complete pain). I think I should probably be thinking about this in advance, because I won't have all night, nor will I have enough battery power in the laptop to do a huge session. Any thoughts?

[D4N]

The East heavy thing is so that the gears stay meshed, the mount will always lean on the RA gears as it is weighted that way.

I really wouldn't bother about it on your first guided imaging session.

There is a bit of contention surrounding darks, if you have a temperature controlled camera then great, you can make a library and keep it. For other cameras it is more of a problem, even if you take them on the same night the temperature may have changed appreciably between the light frames. Now if you consider you may only have 2 hours of data total do you want 1 hour of lights and 1 hour of darks or 2 hours of lights?

Personally I think that it would be better to take more light frames and use a bad pixel map and dithering to reduce the noise.

Dithering by the way is intentionally slewing the mount slightly between light frames, there is a function in PHD t do this. This will move hot pixels in the image allowing the stacking software to reject them.

/Dan

Sent from my iPad using Tapatalk

[ianpwilliams]

OK I'll give the east-heavy thing a miss for now.

Would it be enough to just take as many lights as possible and do a Bad Pixel Map, or would dithering be required as well? I'm not too confident on the dithering thing, it sounds like it could go wrong if done incorrectly.

Also, how do you do a Bad Pixel Map for the DSLR? I know how to do one for the guide camera (well I say that, I don't know what settings I would go for for a Bad Pixel Map for the guide cam, but I plan on use Darks for the guide cam anyway), but I don't know how I would do it for the DSLR. Would it be something that I would do in APT? And if so, what settings would I go for?

The weather forecast has changed for tonight anyway, so I'm hoping that tomorrow's forecast will stay reasonable.

[ianpwilliams]

Also, how do I set up a schedule in APT to take, say, fifteen 5-min subs with 5-sec gaps? Do I create a "Plan"? I had a look at the user guide but I couldn't find out how to set up a plan.

Also, do I need to change any settings in APT, other than the obvious BULB mode, exposure length, ISO etc? There are lots of recommended settings in the user guide but I'm wary of playing around with them.

Incidentally the weather forecast is now better for tonight and bad for tomorrow, so hopefully I'll be going out tonight, so I could do with help ASAP if possible, especially if I'm not taking darks.

[ianpwilliams]

Well that was interesting. I got outside and got everything set up, and managed to get polar aligned. Then I struggled to see anything in APT, although I eventually discovered that it was because the focus was way out. So then I fixed that using the Bhatinov mask, and slewed to Mirach, although I couldn't see Mirach. So I decided to slew straight to M31, and managed to find it. Took a couple of 30-second subs to centre it, and planned on attempting to set up PHD2 for guiding, but then the clouds rolled in, and soon after that the laptop battery died.

The battery only lasted 2 hours. When I bought the laptop second hand it had a 9-cell battery with it, so I bought a new 6-cell, which is what I used tonight. I'm not sure if using the 9-cell will help or not really, given that it's the one that came with the laptop. I could buy a new 9-cell battery, but even that might not cover me for a whole session. So I may have to look at other options. Is there any way that the laptop could be powered by the Tracer battery while it powers the mount? It's 22Ah so I wonder if it might hold enough charge for the mount and laptop, if I had some kind of splitter.

The other alternative could be to have some kind of car battery in the shed with a power cable running from that, and maybe a plastic sheet on the ground should the power cable need to run along the ground. I'm currently waiting for my landlady to empty the shed, so I could put my tripod and mount in there which would help a lot anyway, but then maybe I could put a car battery in there too. What do you think?

[ianpwilliams]

I think maybe a leisure battery in a plastic box, which I would keep in the shed and bring out for each session, has to be the way to go, assuming I can get some kind of converter do that it can power the laptop.

Either that or I could try using an Android tablet, but I guess the battery wouldn't last for that either.

[Tinker1947]

My Samsung 7" runs Sky Safari 4 Pro for 5 hour before  the low battery warning kicks in, this is with the program set to stay live, does the shed have mains electricity  a leisure battery will need a trickle charge, if its goes flat it will die, they also need a better charger that a car battery charger, if there is mains power than a suitable 13.8v would be a lot better to supply mount/dew heaters ect....