jacko61

I have a Sky at Night subscription but it expires next month and I think I'm going to let it lapse in favour of an Astronomy Now subscription. Because it's a BBC magazine I think the S&N content is aimed at a wider audience so sometimes the articles feel 'dumbed down' slightly. There usually seems to be more depth to the AN content.  Purely a personal opinion of course. 

Graeme

17 hours ago, iapa said:

I was more moaning about the fact all my darks are at -20˚C

 

Ah, gotcha.  My ASI533 dark library was all at -10 but I've gone to -15 for the ASI2600. I hadn't considered it might get so warm I can't cool to that temp. 

Graeme

@iapa

I'm at pretty much the same coordinates as you give or take a minute or two and I had no problem last night cooling my ASI2600 to -15 which seems cold enough for my purposes. I crank up the camera first and start it cooling straightaway in APT. By the time I've aligned on my target, run a couple of test shots and got guiding sorted it's almost always cooled enough. 

Graeme 

On 07/08/2022 at 14:28, Iem1 said:

The dove tail of my Z73 is short, too short to balance the DEC without having to shimmy the scope up to the end of the EQ6's clamp. So it is only being held by one of the grips instead of two. It's not massively unbalanced, but definitely not ideal. I chose safety of the rig over perfect balance atm. Need to get that sorted ASAP so both grips hold the bar AND i can balance it properly. Could also be not helping.

 

This statement has me worried.  If you only have the dovetail effectively held by a single clamp then there will always be flexure between the scope and the mount no matter how tight you have the clamp.  I have the same scope and before I bought a losmandy plate I had issues with the supplied vixen interfering with the focus lock screw. Easiest thing was to turn the scope upside down in the rings so I could slide the rings back a bit.  Can you post a photo of your setup please?

Graeme

Those are interesting results @Richard_  Everything I've read tells us that the sensor is too close if the edges look star-treky but your image at 10mm TOO FAR shows just that. Very odd.   I did notice some play in the focus tube so I've tightened the 2 screws to take that out although they only address the vertical movement - it would be better if they had adjustments at 120 degrees around the tube.  This last image is the first I took with the new camera - 20th July.  Same scope but it has the Flat73A - i.e. flattener, not reducer.  In this one I paid very close attention to getting the backfocus exactly on spec i.e. 11.4mm (ish) on the adjuster and the edge stars don't look too bad at all. I think I'll have a play with the focuser and make sure the reducer is set to exactly 1.8mm next session. 

Graeme

8 hours ago, SoftwareDeveloper said:

JackO, I took the liberty of downloading your images, and since you specify what camera you used- I had my plate solver measure the images and give the measured focal length for the images. Assuming the ASI2600 was used for both images: The measured focal length for the Andromeda image is 346.2mm, and for the westveil it is 347.6mm. That is a 1mm shift in focal length between the two, one possibility is one includes a filter in the optical path that the other does not. But the focal lengths should be almost identical when the images are in focus.

So what SHOULD the focal length be with the flatner and without it? You did not specify what optics train was involved in each case. I thought the results worth sharing as they may help suggest adding or removing spacers until the design focal length matches the measured value.

 

Thanks for this. Sorry, but I have no idea what your plate solver is telling me.  The Western veil was indeed taken with an l-enhance filter. I'd removed the filter for the M31 image but I also adjusted the reducer out another mm.  I should have stated that I was using a William Optics ZS73 with the Flat73R 0.8 reducer giving a focal length of 344mm.  For last night's attempt on the north american nebula I set the reducer adjustment to 3mm instead of the 1.8mm advised and overall the blobbiness has gone down apart from down the left hand side. (there's still a tiny bit in the right hand corners but nowhere near as prominent as earlier.   Next clear night I think I'll swap the reducer for the flattener and see if the problem is restricted to the reducer. 

Graeme

I've just started imaging with my recently purchased ASI2600MC and I'm noticing what I first thought might be a backfocus issue but I'm starting to think might be tilt.  Up till now I've used an ASI533Mc camera and haven't seen this before. I'm pretty certain the backfocus is right - I'm using the WO flat73R which has a backfocus of 56.8mm so the 17.5mm from the sensor to the camera front plate plus the 21mm and 16.5mm extensions give me 55mm to which I then add 1.8mm adjustment on the adjustable reducer.  This measurement has always worked well with the ASI533 but I'm getting eggy stars with the ASi2600.  The thing is, these eggs look much worse on the top left and bottom right corners although the right hand side also shows some distortion.  

I've attached two subs below, the first - of the western veil - looks pretty bad in all 4 corners.  I adjusted the reducer out a millimeter before I took the second image (andromeda) and some of the distortion has been reduced but it's still there AND it still looks worse down the left hand side (at least to my eyes).    

So, what do you think?  do I simply need to wind the reducer out a bit further or do I have a tilt issue?  

Graeme

On 27/07/2022 at 19:49, Stuart1971 said:

Great image I have to say, but maybe reduce the amount of stars and the Nebula will pop even more…👍🏼

Took your suggestion to heart and downloaded starnet. This is my first attempt (and my first attempt at blending layers in GIMP. So a totally starless version blended with a 50% opaque copy of the original.  I'm not sure this is the way to go about it - the stars in the blended version look a bit grey but it's a new skill that I'll be looking into.  The version with no stars at all does make the nebula look incredible but it's not for me

Graeme

Night of 26th July. The perfect end to a birthday. We had perfect clear skies above Lanarkshire for a change.  This is thirty five 240 second subs plus Darks, Flats and Dark Flats. ZWO ASI 2600MC pro, William Optics ZS73 with 0.8 reducer, L-Enhance and Skywatcher EQ8R-pro.   Captured and processed in APT, DSS and Startools.   I've had to crop this  quite a bit as the corners were looking a bit star-treky. I think I need to move the sensor a millimeter or so further away from the reducer to compensate for the thickness of the l-enhance.     

Graeme

On 13/07/2022 at 08:21, Giles_B said:

so perhaps I've found something else to spend money on (*sigh*)

The fact the 'what did the postman bring' thread runs to 463 pages should have told you that you'll be spending money for a long time yet

Graeme

Maybe light leaking into the filter wheel?

Graeme

First light with my new ASI2600MC pro.  Only managed 24 minutes of 3 minute exposures last night before the clouds rolled in. This was taken though my William Optics ZS73 on a skywatcher EQ8R-pro. 

Managed 30 minutes imaging last night between getting dark and the clouds rolling in.  I had the 10m active usb3 cable direct from my laptop to the ASI2600MC.  It was recognised in device manager straightaway and didn't miss a beat through half an hour setting up / platesolving / testing exposure times plus half an hour actual imaging so I reckon the fault must lie in the internal wiring and hub of the EQ8R-pro.  A bit of a shame as the cable management through the mount is one of the main selling points. 

Graeme

27 minutes ago, Tomatobro said:

My understanding of the EQ8 usb hub is that it has to be powered by 12 volts so do you have 12 volts plugged in at the input side?

yes. two 12volt power supplies going into the mount, one for the hub and one to power the mount itself. When I switch on the hub supply the asi2600mc  cooling fan comes on straightaway even when the usb isn't plugged in so I know there's power going through it. 

My imaging set up till a month ago consisted of ASI533MC camera - 1m USB 3 cable into the 'hub' on the Skywatcher EQ8R - pro mount then via a 6 metre passive USB 3 cable to my laptop. Never had an issue with connectivity or downloading 13Mb files from the camera during a session. 

Now, however, I have an ASI2600MC pro which sends 51Mb files (per sub!!) . I'm having a problem keeping this camera connected.  I've replaced the passive long cable with a 10m Lindy active cable which works fine if I connect it direct to the camera. Unfortunately if I plug that cable into the mount and then take the 1m cable to the camera it continuously connects and disconnects in APT (although it seems to stay connected in device manager). 

I'm now thinking I need a powered hub at one end of the long USB3.0 cable but which end ?  does it matter?  It would be easier powering it if it was at the laptop end but it's not an insurmountable problem to have it at the mount - I have several 12volt power splitter cables. 

Any thoughts?  Please don't suggest a  wifi hub  or ASIAIR etc. 

Graeme

17 hours ago, Varavall said:

Because I like to sleep. NINA does all the work whilst I sleep, so taking flats that same night is not feasible.  

I guess, because you're in Spain you don't have to worry too much about the weather suddenly changing through the night. I'm in Scotland so I don't have that luxury Regardless of what the BBC weather might say it's best to anticipate some rain through the night.  Anyway, I like to have a 'hands on' approach to my astronomy so I'll sometimes sit and watch the subs coming in and even if I've gone back into the house for a while I'll be back out to the observatory well before the end of a plan to check how they're looking. Means I can take my flats and dark flats straight after the session before I pull the roof back over my scope. 

Graeme

1 hour ago, ONIKKINEN said:

Cant tell you an exact reason why this is the case, just the way i have noticed it with my flats.

But to guess a few: Temperature differences deforming the tube differently each night, focuser maybe in a slightly different position (also depending on the tube length - which is dependent on temperature), perhaps collimation was 1/10th of a turn of a knob different than last time. Many reasons with not-ideal scopes why flats suck. I have solved many issues, but not all of them so its a safe bet to just take the flats each night. With a modern camera it shouldn't take more than a few minutes anyway.

And every time you take off the lens cover you're attracting new dust particles. As you say, 2 or 3 minutes to run a flats plan in APT so why wouldn't you take new ones every session?

Graeme

Why not generate your flats after each filter run? 

Graeme

On 03/07/2022 at 11:36, Laurieast said:

But is there a way of avoiding the drilling part? Like suspending the bolts above the hole by sky hooks, and filling in around them? or is epoxy a known better way of doing it? I have no building knowledge.

 

Yes.  Many of us have created a former to lay on top of the wet concrete in which the bolts are fixed. The concrete then hardens around the studs.  There's a very good pictorial guide on this thread (page 2)... 

I think so. (others might not).  These were taken with the 533MC through my ZS73 (the heart is with the reducer and still too big so I've just got a 2600mc so I can fit the knobby bit in  ). All these are from quite short sessions and I'm still learning the processing so not perfect by any means.

Graeme

You need a WO ZS73 with both the flattener and reducer. Alongside your existing collection you'll be able to image just about anything in the sky.

Graeme

A number of folk have said you need a special EQDIR cable.  This is no longer the case.  You've said you have the EQ6-R. That means that if it's a more recent one there's a USB-2  type B socket on the mount below the ST4 port.  You can use a standard USB 2 printer cable from this to your laptop and connect to EQMOD without needing the EQDIR cable.  I found the EQMOD set up to be fairly straightforward but the com port needs to be set at 115000 baud rate in EQMOD.

Graeme

18 minutes ago, Craney said:

 

If I had 'spangled' the carpet as a kid, I would have got a clip around the ear......  and made to Hoover it !!!

Things I wish we still had.

Graeme

11 hours ago, Greymouser said:

 I said I was going to Nottingham to get another scope at a bargain price, only to be told over her dead body!

A new patio would solve that problem (in a Brookside manner if you know what I mean 😉).

Graeme

I've only looked at this once a month or so ago and only managed 45 minutes between trees and clouds.  The Forestry commission are due to start felling south of me sometime this year so I'm hoping to get much better access to some of the lower objects. 

Graeme