SteveBz

1 hour ago, Wyvernp said:

Without spending any extra money;

 - Dither if you aren't already.
 - Can't think of anything else

Other than that a cooled CMOS/CCD is a fantastic upgrade in a lot of ways but it is an expensive one, more so if you decide on mono. But you'll be able to have a dark frame library so will save time not having to take them every time as well as greatly reduced noise.

Actually, possibly QHY too. I've tried both manufacturers and they both work eventually.

1 hour ago, Wyvernp said:

Without spending any extra money;

 - Dither if you aren't already.
 - Can't think of anything else

Other than that a cooled CMOS/CCD is a fantastic upgrade in a lot of ways but it is an expensive one, more so if you decide on mono. But you'll be able to have a dark frame library so will save time not having to take them every time as well as greatly reduced noise.

Thanks for that.  I guess that's what I was worried about.  I was planning to fix my dithering, sometimes I do, sometimes I don't but I had difficulty sorting out the settle time.  I also thought of going OAG, but the cost of a new camera like a zwo asi290 is also quite high.

But I've been thinking about getting a cooled camera for a while, it's just out of my pocket at the moment.  Which one in the ZWO range would you recommend?  (I'm raspberry pi based, so it has to have a linux driver.).  I do think that's really the correct choice.

I was also wondering if there was some post-processing I could do to help, like splitting into layers and using despeckle, or high-bandpass filters etc, before recombing?

I've seen this stuff done, getting great results, but I don't really know what the method is.

Regards,

Steve

Hi Guys,

I didn't expect to be able to take photos at this time of year, but in fact it has been fine.  Just seems a bit warm for the poor old DSLR, which is pumping out noise.  I'm writing to get some suggestions on what to do next.  Here is an image of M101 taken over two of the last three nights (22nd and 225th June) at ISO400 on a Nikon D5000 DSLR with coma correction and light pollution filter. 

It's 63 3-minute lights (3h9m), plus darksx40, flatsx100 and biasx100.  Scope is Celestron 200mm f/5 Newtonian with goto EQ5 mount.  Guiding is QHY5 + guidescope + PHD2.  The nights had different temperatures by about 10 degrees (12C and 20C).  I took darks both times, but my DSLR does not have a sensor temperature indicator so I had to use the ambient temperature, which is only approximate.  The second night was warmer and noisier.

Processing is as follows:

1. Stack RAWS from each night separately with matching darks (pls flats and biases) with DSS to get calibrated files for the whole period.
2. Stack calibrated files from all nights to produce single .fts image.
3. Apply ARCSINH stretch and colour balance (from SIRIL package) and save as .tif
4. Import into GIMP.
5. crop.
6. Use 'Curves' to stretch everything upward in a single arc.
7. Use 'levels' iteratively to balance colour and darken sky.
8. Use 'Curves' again to apply an S-curve, to darken sky and stretch Galaxy and stars further.
9. Export to .png and .jpg for posting.

So I can still see a lot of noise, much of which is fixed pattern. 

So my real question is, how do I take this to the next level? 

Thanks in advance.

Steve.

Hi Pavolg,

It looks fine.  What is the board attached to D4, is it some sort of weather sensor?  I didn't use the driver board you are using, just an opto-coupler chip with four gates, two in the positive direction and two in the negative, but otherwise pretty much the same.  I also added a manual over-ride (a switch for direction and a cheap PWM board for speed) so that I can still focus manually when I am outside.  My only real comment is that you don't show the double connection at the motor.  It's quite important that you get it right, otherwise you can burn out your driver board.  The motor will be fine with 12v.  I have 2 speeds, 90% PWM and 10% PWM, and in fact I mostly use 10% on the micro control knob, so in fact its 1% normal speed and I love my focusing.  Really tight.

Good luck.

Steve.

On 30/04/2015 at 11:04, MikeODay said:

Hi

Does anyone feel able to recommend an OAG + Coma Corrector combination that achieves the correct spacing and good reliable results when connected to a Nikon DSLR?

Cheers

Mike

Hi Mike,

Did you ever get this sorted? My main camera is a Nikon D5000 (ie about 10 years old) but I do have a Canon 350D (15 years old) that I could use if I needed to. It might be easier all round.

It would be great to have an update.

Regards

Steve.

On 13/05/2015 at 03:21, kalasinman said:

BTW my Nikon camera adapter is only 1mm and fits very nicely.

Sorry this is such an old thread, but do you remember where you got this?

1 hour ago, Robindonne said:

There must be other thin adapter options.  I also use a 1,5 mm eos/t-ring   And it has a normal thread i quess

But eos is Canon I think. I do also have an old Canon 350d, which I could back up to. I don't know whether that's better or stick with the Nikon D500, wwhich at least has live view, not that I use it much any more.

Regards

Steve.

Hi Guys,

I'm thinking of getting an OAG. The problem seems to be that if I want to continue to use my coma corrector, the OAG needs to replace my t-Ring. Sadly all the OAG plus thin adaptors seem to be for Canon Eg TOAG. I did find a 1 mm thin adaptor for Nikon on Aliexpress, but sadly it has the wrong m42 thread  (1mm instead of 0.75).

Any thoughts?

Regards

Steve

3 hours ago, pavolg said:

Hi,
I plan to make a similar Arduino focuser using my DC motor from SkyWatcher motor focuser. I don't need any buttons etc. I can't see from the video how it's connected motor driver to RJ11 socket and also to Arduino. Could someone help me?

 

Here's some photos and a video. The yellow cable tie is so I can see it remotely through a webcam. Actually it looks as though the connections are antiparallel. I hope you can make out the colours through the RJ11 plug.

Hope that helps.

Steve

3 hours ago, pavolg said:

Hi,
I plan to make a similar Arduino focuser using my DC motor from SkyWatcher motor focuser. I don't need any buttons etc. I can't see from the video how it's connected motor driver to RJ11 socket and also to Arduino. Could someone help me?

 

I did exactly that and it works perfectly.  You can even do your own auto focus routine.

You can easily slide the black cover off to check, but as I recall there are only 2 connections wired in parallel.I'll check properly later.

Just make sure it's all tight or it won't work well using AF.

Good luck.

Steve.

22 hours ago, sloz1664 said:

Hi Steve,

I have the 2.1M mk1

Total height 2.3M

Dia 2.1M

Slit width 0.52M

Wall height 1.2M

Door 1.05M high x 0.75M wide

 

Steve

Great. Thanks very much.

Steve.

8 hours ago, Jkulin said:

Mines a MkII and I haven't collected it yet, but the measurements I have been given the following: -

"The dome walls have a diameter of 2100mm +/- about 5mm. At the bottom of the walls, there's an approx. 80mm flange on the inside - so the internal diameter of the flange is 2100 -(2 x 80) = 1940mm +/- about 10mm. "

I hope this is correct as I have had the concrete and brick wall erected to take it.

Great. Thanks for that. Do you know its height?

Steve.

Hi Guys,

I've been offered one of the old pulsar 2.1m observatories. Does anyone have the other demensions of it. Eg height, slit width, door etc.

If you have diagrams that would be even more amazing.

Thanks very much.

Steve.

3 hours ago, iapa said:

The ARO130 ( II have both mono and colour btw)

Piggy back guiding, but will be going OAG once Dalèkъ regeneration is complete and the cloning starts from the cast offs.

Well I think the ASI174 will do OAG as far as I can tell.  My QHY5 won't unless I chase each guide star individually.  Cant really do with that.

I was thinking the ToupTek cam with the imx290 chip should do it.  But I'm still investigating.

Steve.

18 hours ago, Shimrod said:

I can't give you an answer to your question, but I am envious of your wide open sky! I am hemmed in by houses.

Me too.  Houses and high trees and petrol stations and roundabouts with lights and neighbours with security lights.....

If I ever can upgrade from my trusty Newtonian C8-N, it'll be a RC with 250mm diameter.  But before that I need a cooled camera!

Steve.

20 hours ago, iapa said:

I recently replaced Touptek mono with an ASI174

the toupteck mono worked well with PHD2 as guide camera in StartTravel 80 piggy backed on 8” SCT.

i did put in a USB3 hub so there was no port sharing

i found if the guide camera was on the ASI1600 USB hub I got timeouts

Hi Iapa,

Thanks for that.  Which one did you have?  There seem to be 2, the 1200 and the 2000, one uses the AR0130 chip with 3.75 um pixels and the imx290 which has 2.9 um pixels.  Were you doing OAG?  Which is really where I want to go.

Regards

Steve.

So has anyone got this device working? It looks like very good value for money. The zwo asi290 which I understand uses the same Sony imx290 chip is hundreds of pounds more expensive, but then it works!

I was thinking of buying it and installing it using the zwo driver, but only if someone has managed to get it going.

I'm on Linux, so it'll probably be even harder.

Regards

Steve.

13 hours ago, michael8554 said:

My Canon Master Flat is saved as a TIF and happily reloads along with the Raw Picture files, showing as a TIF in the list.

But that's in 4.2.4, ver 3.3.4 may be different.

Michael

OK, thanks, I'll try it.

Although I have to say, I've just reinstalled Siril.v.99 and it's amazing. I'm no longer so drawn to DSS.

Regards

Steve.

8 hours ago, wxsatuser said:

All RAW files are gray scale it's the colour filter array that turns them into colour.

Do not worry about the fact they are reported as gray.

Ok, great I understand.  Thanks for that.  I'm running a session now.

What about master calibration files?  If I put in 100 flats, for instance, in .NEF form, it creates a MasterFlat, what format should I store this in, so I can use it again (tif or fit).  The issue for me was, if I store it in tif, then it comes back as being RGB and incompatible with the monochrome raw files?

Regards

Steve.

Ok, there's a bit of weirdness here.  It seems that version 3.3.4 of DSS can't handle Nikon NEF files correctly - it describes them as 'gray' - at least on Linux.  For that reason I have been using ImageMagick or ufraw to convert to .tif files first for DSS and I used the same mechanism for convertying to .fits for Siril.  However, it appears that ufraw, imagemagick and rawtran (which I also used) all used dcraw under the hood (and DSS uses libraw - based on dcraw).  So all of my files have been having some conversion issues, maybe a bit of non-linearity when there should have been linearity, or brightening or something, which has caused the above effect.

When I started with .NEF files directly in Siril, demosaiced (debayered) in Siril, stacked my calibration files and then calibrated and stacked my lights in Siril and displayed in kstars, I get this:

Not a perfect image, but no vignetting and no walking noise.  Still need to do biases.

Amazingly, this has been going on since I started!!! Up until now I just cropped heavily and turned the brightness down.

I just need to work out how to turn it back into tiff without encountering any of these problems so I can edit in gimp (which uses RawTherapee under the hood), to edit.

Regards

Steve.

Hi Guys,

I seem to be having ongoing calibration problems with my calibration whether I use DSS or Siril resulting in uncorrected vignetting and camera noise, which seems to be compounded by flexure in my guiding giving me traveling noise - if you look carefully the noise has a texture to it appearing from right to left and small 'worms' in it (there's one due South of the main subject, M106), which I guess correspond to hot pixels in the original data.

Here's the output using fits as an intermediary file and Siril to stack which gives a good idea of the problem (but I get the same issues with DSS and .tif).  This is about 3 hours from last night 5mins x 36 frames, 100 flats, 100 biases and 16 darks:

Here's an unstacked original:

Plus 100 stacked flats, converted to monochrome (in case that was the problem - it wasn't):

I feel I've tried everything, and I'm at a bit of loss as to what to do next.

Regards,

Steve.

10 hours ago, almcl said:

Sorry, that's gone way beyond my knowledge level!  

There's a thread about colour gamuts and spaces (I think) here:

and some more here:

There isn't universal agreement about all the statements made in the two threads.  I use sRGB.

Morning Al,

Nice articles.  After some thought and a lot of experimenting I find 2 things.  1)  ufraw-batch (which is the Linux raw converter I used to use) had a terminal bug and is being discontinued.  I think my past use of it meant I didn't have to worry about colourspace. So now I need to actively select sRGB.  2) I'm going to revert to my previous SkyWatcher light polution filter.  UHC is just too hard at the moment with its vastly reduced red response.  When I amplify the red component, I get a huge amount of red noise (as you did too).

I might also experiment with an OAG to stop those little maggots wandering around my images.  What is the model you use, please?  I might guess that the size of prism is important for light capture.

Regards

Steve.

Well since neither is raw, i'll give sRGB a try.

Tx

Steve.

Hi Al,

Do you have a view about colour spaces? When I convert from NEF to TIF I get a choice of raw, sRGB, Adobe, Wide, ProPhoto, XYZ, ACES and I choose raw.  Is this a good choice, do you think?

Regards

Steve.

Yes, I looked it up, demsaic and debayer appear to be synonymous.  But what you have done is amazing.  I think I don't understand 'stretch' yet.  I'll look it up some more.  I might download a version of StarTools, it appears that you can get an evaluation version.

Tx.

Steve.