smr

I bought this Table yesterday for £12, reduced from £40! Well chuffed  It's absolutely ideal for astro. 

It's a High Gear camping table, on sale at Go Outdoors if anyone is interested.

I would image DSOs which aren't close to the Moon. I'm imaging the Soul Nebula at the moment as it's on the other side of the Sky from the Moon, although I don't think I'd bother if I didn't have my L-eNhance filter.

Partly the reason why I jumped over to Cooled OSC from DSLR instead of straight to Mono. I thought there would be a learning curve with OSC and there is. There's nothing wrong with jumping straight into Mono, and if forgoing the filters it's essentially the same process, that said I have found a jump between going from DSLR to Cooled OSC, and more of a jump than I expected.

I spent the first night expecting everything to be really easy and get some good hours of M42 for first light. No, instead I spent the night trying to understand why I couldn't see any stars to focus on whilst watching M42 sail on by, in good skies and with no Moon. Frustrating? Yes.

By the time I had kind of figured out how to focus and see bright stars ... clouds.

Next night I decided to shoot the Soul Nebula, the subs were horrible, severely elongated stars in all corners and stretched / bloated stars near enough across the entire frame. Seems I hadn't tightened my flattener after rotating it, and I still hadn't properly managed to focus, or at least go through the focus routine smoothly.

So yesterday I decided to take a step back from it all and reassess my whole imaging set up. I decided that rather than try to capture images, I'd try to focus on my work flow. So I decided to to reset and recalibrate my guiding, and I spent most of yesterday understanding how to focus in APT with a dedicated astronomy Camera and why Live View was poor in ZWO native driver mode.

So I uninstalled PHD2, installed the latest version, went through the calibration of my Mount and it tracking speed, at night I calibrated my Guide Camera with Sharp Cap for focusing it and Calibrated on a good guide star 20 deg of the Celestial Equator. 

I realised that with APT you have to left stretch the histogram to see Stars in Live View

ZWO native driver live view for whatever reason doesn't work very well and so I set the Camera to ASCOM in APT, live view worked much better. 

Focused the Camera.

Plate solved over to the Soul Nebula and started imaging. Good guiding, much better stars. And this was with the attitude of expecting to use the night for testing, I wanted to be sure I had everything dialled in and couldn't care less about imaging last night, but from being pragmatic and methodical and not trying to jump straight into imaging I was able to sort everything out.

What I'm trying to say is, do everything in steps slowly but surely and go through them with a checklist to make sure you have done everything as well as possible and try to eliminate power or connection issues during the daytime. Things like USB hubs/ports can be diagnosed during the day and once you've established where the weak links are you can fix them one by one until everything is working as it should.

Thanks for the comments, they are appreciated.

I set up earlier and was using the ZWO native driver with APT, it's really really sketchy with Live View - I just can't get it to expose the sky properly despite trying different settings - gain and exposure length, auto mode on or off for both, and unticking video mode, tried loads of of things and I just get a washed out image.

So eventually I disconnected the Camera, and shift clicked connect, chose ASCOM instead, set the Gain, Offset etc. in the pop up dialogue and then clicked on live view, slewed over to Capella and saw a very nice image, black sky with nice star spikes (via Bahitnov mask) and was able to focus easily. 

So it seems my problem was insofar as using the ZWO native driver in APT to control the 2600 instead of ASCOM. Annoying, but I'll stick to ASCOM now. I just thought that ZWO would have finessed their software and drivers for APT but obviously not, unless I am not choosing the right settings. Just strange how instantly after using ASCOM and clicking Live View I saw the images coming in how they should be.

Hope this helps anyone else if you're having similar problems..

8 minutes ago, Spaced Out said:

I use a Lacerta Flatfield box, it's not the cheapest but I think the build quality is good, it's dimmable and it has worked OK for me so far !

https://www.teleskop-express.de/shop/product_info.php/info/p8241_Lacerta-LED-Flatfield-Box-with-240-mm-usable-Diameter.html

Thanks, looks like a good bit of kit. 

3 minutes ago, Paul M said:

I don't have the filter but have spent some time with an OSC in APT using the native driver. How about using a bright star, gain set quite high (250?) and a 5 sec exposure in live view and have histogram stretch on. I guess the Bahtinov mask attenuates the star also. I don't use one but find diffraction spikes from my big newt or just star size are good enough.

APT Live View with a CCD works differently to when using a DSLR. So you can select any exposure time you like. It just keeps updating the image. 5 seconds isn't to long to wait between focusing tweaks and if that isn't long enough increase it at will.

Thanks Paul,

Will try with those settings.

I've recently upgraded to my first dedicated astronomy camera - the 2600MC-Pro. All of my experience with APT prior to this has been with a DSLR.

I've been having difficulty trying to focus - which is the best way to do this ? I have the Optolong l-eNhance filter which probably doesn't make focusing easier than without.

With my DSLR I would just take an image, zoom in, check the lines from my bahitnov mask and then readjust, take another image, until focus was as good as I could get.

With my OSC I was thinking that because it's more sensitive than my DSLR that I might be able to do focusing in live view, but I have not had much luck trying to do this.

So is it possible to do in live view (I'm using the ZWO native driver), and if so what settings do I need.

Thanks for any help,

Joel

15 hours ago, Budgie1 said:

I cleaned up the WO Back Focus diagram to make it a bit clearer.

It looks like you've got it correct, you're just 0.2mm long and the 15.70mm is part of the train.

Thank you Martin.

25 minutes ago, Clarkey said:

Assuming that the additional extension of 15.7mm is part of the flattener then 54.8 looks right. Just looking at your image, have you made any allowance for the tilt adjuster or is that part of the distance to the sensor of 17.5?

With regards to the question of whether 55mm will be OK, I would try it and see. You might need to reduce it a fraction if you are very fussy about star shapes, but equally it might be acceptable.

I don't know, I'm confused. That 15.70mm part is a spacing ring, which does come with the flattener, but the glass in the flattener ends here:

Hi,

Can anyone recommend a good flats panel ? 

Just trying to verify whether I have got this right if someone can help...

I have the 2600MC-Pro which has a 17.5mm back focus from the sensor to the Camera flange. Added to the Camera is the 21mm spacer, then a 16.5mm spacer (55mm) according to the diagram below I need 54.8mm of back focus with this flattener. It's the first Z73 (non adjustable) flattener. 

Is this right for back focus? If so, is it ok if I am out by 0.2mm?

Presumably the required back focus for me is 54.8mm.

I had a look at my scope last night and realised that I could easily turn the whole camera (with all spacers attached, and the flat 73 field flattener quite easily, even though the thumb screw for the flattener was tight. 

Not sure why this is, I think I may have a faulty flattener, anyway the fact that it felt loose probably had something to do with the elongated stars when imaging the Soul Nebula.

I'm going to buy the updated Flat 73A (Adjustable) Flattener so I can do away with the spacers and get exact back spacing much more easily, by just adjusting the drawtube on the flattener.

I recently bought the Flat 73R, which is the 0.8X Reducer/Flattener so I'm going to test out the stars with this combination over the next few days, looks like we've got a clear spell from Friday - Sunday! Only problem is, as typical it coincides with full moon.

But I'm grateful anyway because I can try and dial in my back focus and hopefully get better stars, and sort out / recalibrate my guiding.

Will keep updating this thread if anyone else is having similar problems so that it might help. Should probably change the thread title now though as it's gone off on a proper tangent

8 hours ago, vlaiv said:

Sure, I'm 100% for proper calibration. In this case - darks matching lights in every respect (temp, time, gain, offset, ....) and flat darks matching flats in the same way.

Do be careful to use appropriate algorithm when mixing long and short subs as they don't have equal SNR and simple average (or sigma reject) is not the best way to do it. PI offers weighted average - so go with that if you use PI.

From quick inspection - I'd say, check connection to the camera.

My guess is that you are not using threaded connection or there is some play in focuser.

Try to compare first and last sub of the session for star elongation in the corners. If they are the same - you have some sort of tilt issue - but if they are different - then you have some play in your connection (gravity will tilt stuff in different direction depending on where scope is pointing and it is pointing in different parts of the sky in the start and in the end of the session).

Thanks for the advice vlaiv. 

I've attached an image of actual first light a couple of weeks ago, spent most of the night adjusting to the Camera, coming from a dslr there were a few things to learn. 

This is an image of the Elephant's Trunk Nebula at the end of the night, about a half hour integration, conditions weren't great during this imaging as I was shooting through high clouds but I just wanted to see what my stars looked like.

In this image the stars aren't anywhere near as elongated as the previous image of the Soul Nebula above, which would align with your theory about possible tilt? The Elephant Trunk was a lot lower in the sky whereas with the Soul Nebula last night the scope was almost vertical.

Having said that the stars in the Elephant Trun aren't great either, but I'm trying to diagnose where the problem is, with some stars towards the corner in the Trunk being more round, but certainly not tight, I'm wondering if it is something to do with tilt as opposed to back spacing ? 

Curiously ( I don't know why ) the stars in the top left of this image are very elongated, but in the bottom left, whilst not round, don't have nearly as much elongation ? 

Apologies if this is getting rather long winded, probably deserves it's own thread as I really want to be able to take images with tight stars across the field now!

So this is the image, a very quick stretch.

Elephant Trunk with severe elongation top left but bottom left not half as elongated:

Soul Nebula (with severe elongation in each corner)

11 minutes ago, Mr Thingy said:

What was the target, by the way?

 

The Soul Nebula

13 minutes ago, vlaiv said:

It is just because data is not color balanced / color transformed like in DSLR - which has this transform applied by default (although you can also get pure raw data from DSLR as well - and it will also look funny).

 

Thanks vlaiv, do you recommend I calibrate with darks as well? I'm sure you've mentioned before that this is one of the advantages of having a cooled CMOS? 

If so I would need to take darks for 180 seconds and 320 seconds at -10. 

I started off last night imaging at 180 seconds, but then thought the histogram looked bunched up to the left too much so started 320 seconds, but on reading what you've said above, with the histo looking fine... well that was at 180 seconds, so I may as well go with that to reduce guiding errors... as my stars for whatever reason do not look great at all.

I don't think my back spacing is correct, although according to ZWO's diagram it should be at the desired 55mm....  it's either my back spacing or guiding anyway, not sure which.

L_2021-02-22_21-19-51_Bin1x1_320s__-10C.fitIn this sub you can see the stars in the middle look oblong, but then look really elongated at each corner..

However here's a sub taken on the 10th, where there isn't the same severe elongation, and same imaging setup.. not sure why my stars were so elongated last night - the only thing I did differently last night was rotate my camera 90 degrees with the camera rotator of the flat 73 field flattener.

L_2021-02-10_22-55-39_Bin1x1_180s__-10C.fit

27 minutes ago, tooth_dr said:

There are x2 as many green pixels as red of blue so maybe this is the reason. 
Offset 50 seems ok too 

Can you post your flats here?

Yes although it was just a green cast I'm not used to seeing with my DSLR. Maybe it was the Moon brightness I don't know.

Here's 3 flats, I ran the flat wizard in APT and had to lower the brightness down on me LED panel all the way down for the wizard to accept the flats.

My flat panel has always been fine for my DSLR but it's one of those cheap LED panels from amazon... https://www.amazon.co.uk/Dimmable-Bi-color-3200-5600k-Battery-Camcorders/dp/B07QL8WHRV/ref=sr_1_5_mod_primary_lightning_deal?dchild=1&keywords=led+panel&qid=1614083961&sbo=Tc8eqSFhUl4VwMzbE4fw%2Fw%3D%3D&smid=A90RIP9U5D1UK&sr=8-5

So I probably need to look at buying a dedicated astronomy flat panel? Any recommendations ?

F_2021-02-22_23-08-18_Bin1x1_0.2125s__-10C.fit

F_2021-02-22_23-08-24_Bin1x1_0.2125s__-10C.fit

F_2021-02-22_23-08-31_Bin1x1_0.2125s__-10C.fit

Yes gain at 100 is just what I ascertained from various threads on the 2600MC Pro as a good setting. 

My offset was 50.

Just had a look at last night's stack of 3 hours, I took some flats but not sure I took them correctly as they seem to have made the image worse. 

Haven't used any calibration files, I should build a darks library.

There's a big green cast in general on a lot of the images, presumably Moon glow.

Anyone? Or is that simple it's not worth answering?

Hi,

Finally started imaging with my new 2600MC Pro, my first dedicated astronomy camera, so there have been a few things to learn coming from a DSLR.

I'm currently imaging and have just opened a sub in Fits Liberator... Do I need longer subs? Looks like the Histogram is stuck on the left hand side even though I'm imaging at Gain 100 and 3 minute subs, optolong l-enhance filter, bortle 5, 78 percent Moon.

This is the histogram ( I think ) in APT, basically I'm not really sure how to view the histogram in APT, with a DSLR it was fairly obvious. Presumably it's the window with the auto-stretch function, in which case it appears to be off the left hand side?

It's my Birthday tomorrow, a few hours of clear skies tonight is all the Birthday present I want! Hopefully first light with my new 2600MC-Pro.

Just now, bomberbaz said:

Absolutely outstanding science, amazing landing.

I loved the technology of the landers data and accompanying graphics, felt like I was almost there watching it land in person. 

I filled up a little as the emotion was so powerful on touchdown, the release of emotion was palpable. 

Well done again all the teams involved, truly inspiring result for all your dedication. 

I agree, I thought it was excellent how immersive they made the presentation of it all, and I found it amazing how quickly the rover sent back photos after landing! Brilliant, really enjoyed it.

I didn't get a ticket, but I got the T-Shirt

Fantastic!!

 

5 hours ago, kirkster501 said:

We've had no proper clear skies at all other than the odd 20 mins here and there.  Certainly nothing suitable for astrophotography.  I got in a bit of time with the Dob but seeing was rubbish.

It has been brutal for astronomy since last summer.  Utterly terrible.  Winter is now the off-season in astronomy in these parts.

In 2020 I managed about 4 images with my DSLR, and that was with no other commitments, so anytime it was clear skies, I was ready. 

So far this year I've managed to get one image.

47 minutes ago, vlaiv said:

What you can conclude is that imaging at F/4.7 will bring you more FOV and will also bring in a bit more SNR for same imaging time than imaging at F/5.9. Exact numbers vary from situation to situation and from target to target, so that is not something that can be easily stated.

This is the part that I was thinking about with total integration time., if using the reducer brings more SNR then total integration time doesn't have to be as much compared to without the reducer.