SilverAstro

A very interesting topic, (I also have just read it end-to-end ) because I have from time to time moved to Linux since before there was a Windows ( DOS > Linux ! ) and promptly moved back again !! (to DOS & Windows) because of allsorts ! The nearest I came to completing the task was a few years back with a Live Mint, which was the first to almost do what I wanted !
So, it sounds as though Lubuntu may be worth a new excursion I wonder if there is a Live version yet ?

As for the learning curve - yep fallen off the steep Linux one more than once ! The thing is with Windows it just works at the shallow end of the curve and one can happily remain there (if printing birthday cards is all one wants ): one can tackle the steeper parts of the curve later. With Linux there was no shallow end, it was just steep jagged mountain tops and fisures the whole way from getgo (time was you had to be a geek just to print "Hello World" ) so I agree with the Red bits
It got easier with the advent of the internet, but was a bit silly all the time having to boot to Windows to get connected to learn why one's Linux wasnt !!!

Kstars sounds interesting, goes looking for a Windows Portable demo muwahhah !>>>>

The effect of ISO on a RAW ( if any !) and the result in stacks, is the cause of much debate across the interweb ! I think a new topic ex-this EQ topic may be a good idea cos I suspect this will run and run ? !

My experiments so far are with Filroden, ie. any ISO setting is a post RAW developement feature but ymmv depending upon camera manufacturer and if or not a true RAW  ( or true-ish) is being presented from the sensor for the user. Most third-party softwares like DSS and I believe Startools and Pixinsight (but I dont have these latter two) all use Dave Coffin's DCRAW. Thus it would be a good idea to view one's RAWs in DCRAW first before getting hung up on which ISO is best, to eliminate the possibility that DSS etc. are doing things under the covers before showing the "raw".

Ummm, another imponderable ?, are gradients better removed before or after ! I expect a batch command could be concocted in some softwares to do it before ? but anyway, yes, they are all low frequency components, , ,   but frame-wide nebulosity is a lurking problem !!

25 minutes ago, Filroden said:

A quick eyeballing of Hercules between 5pm and 10pm shows it rotates about 45

That's a neat trick in Somerset today given the wet stuff that is current !

28 minutes ago, nicks90 said:

 Look at the overall angular rotation of something like Leo over 2 hours by watching it move in stellarium in fast forward... few degrees maybe?

But but , a quick point of order ( as it is raining and nowt else to do ! ) the angular rotation in Stellarium is not the same as the field rotation between tracked frames to be stacked.

and the bow-tie effect is somewhat reduced when you superimpose the outline of the final, crop, frame.

and both a linear gradient and a stacked bow-tie, or even a round vignetting, can be quickly reduced (to greater or lesser degree) with a high-pass filter, or failing one of them in your image proc. of choice (eg. freewares !), a high-pass can be made in a layer with a gaussian blur of large-ish radius + an inversion + 50% opacity then a black level clamp. It is quite interesting to play with on a rainy day

3 hours ago, Nigel G said:

but I had to find out.

I'm not going to post it here it might spoil our reputation hehehe.

I do like a good experiment, well done Nige ! Awwww go on, heheee.

Actually I am going to propose another experiment, Ian and me and no doubt many others were surprised at how those 5x90 made such a difference, so one wonders if the other 85x45 were needed ! perish the thought !! So, experimentally, what do the 5x90 look like by themselves stacked alone ?

So many variables so many foundations to wobble

1 hour ago, happy-kat said:

Edit: Can't recall if you changed the mirror bolts.

 I think the mirror bolts are radial not longitudinal/ (/ co-linear?), somewhere on the forum there was discussion about elongating the holes to allow movement along the tube ? Well into voiding warranty now !

4 hours ago, LeeRich said:

I couldnt get prime focus when using my dads SLR hence adapting my webcam. But it was almost there so maybe the removal of this upper collar could work ?

Thanks for the info Lee. You raise an interesting point there, we are ( I am !) used to thinking about parfocal issues with eyepieces but I didnt extend the thought to different cameras.

4 hours ago, wxsatuser said:

I took the liberty of a quick ABE in PI just to see.

Remarkable what you have pulled out there !   What is ABE please  Edit, found it ! automatic background extraction.

4 minutes ago, happy-kat said:

I thought the GSO unit looked shorter to start with then the kit focuser.

Yes I thought so too,  , , @LeeRich

32 minutes ago, happy-kat said:

What might improve the practical side what about a better focuser unit. Lee fitted a single speed GSO one to his Discovery 150p.

But he has only used a webcam on his so far, so we dont know if the GSO would get prime focus for a DSLR  like wot Nige has*, so may also need modifications with a hacksaw !!?

( *and like wot I would want,,, having started out thinking I want only a visual portable setup like the Discovery, but  have been so impressed by the results in this NoEQ topic that it will be all you folks fault if I now go imaging iyswim lol! )

2 hours ago, SteveNickolls said:

The sky to the SE was much more agreeable and I was able to take 50 second exposures of M13

Nicely done Steve, in fact  "Wow" , I had to download the full size and go pixel peeking !

So even at 50sec it is still sky background that is the limiting factor ? not field rotation in the 'rotation friendly' direction

4 hours ago, SteveNickolls said:

I have come across this site-http://daltonskygazer.com/alt-azimuth-mount-tracking-movement-and-field-rotation/ which also explains things and has tables for each 20 degrees of latitude.

Thanks Steve, interesting and that is a good link.

I found the one I was thinking of, a pdf by Bill Keicher :- http://www.autostarsuite.net/forums/storage/19/4981/Field Rotation V3.pdf

has some neat pics/charts for various lattitudes and the varying regions of the sky, written for CCDs but I guess the proportionality would be similar for DSLR etc.

8 hours ago, Nigel G said:

M42 1x30s

Interesting to see what single exposures on AltAz are like , thanks for showing.

I have read (somewhere on the interweb !) that the problem of field rotation varies depending on where in the sky one is pointing and so with M42 now in the west and in one of the 'better'? directions (a little)longer exposures for the subs may be ok ?

On 08/03/2016 at 19:51, nicks90 said:

first effort at using an az mount to the thread

then a quick mess with levels in Gimp, but i have no idea about how to do anything else with it. I really need to sit down and watch some processing videos, but its just finding the time!

and poor focus and horrendous light pollution - you can spot the flame neb!

Great first effort ! Thanks for showing.

I also have been messing and learning with GIMP ( sadly I dont have any AltAz of my own yet , only camera on a tripod stuff so not on-topic for this one !)

So, if you will forgive me I have borrowed your pic and played with a light pollution tool in GIMP (well actually it does not seem to be called that in the GIMP sites, but from a previous life in electronics I sussed that it was a useful thing in the frequency/FFT domain, this message will self destruct in 1/2hr ) )

(I dont know what the netiquet is in using other peeps pics so I wil show just a cutdown jpg of your original to show the effect but not steal the intellectuals ! ) ( and it was cloudy/raining outside so it gave me something to do, thanks !)

The light pollution is spread across the frame [ and is (in data speak !) called a low frequency signal] and can be got rid of with a suitable filter [ a high pass filter in other speak ] to leave only the sharpish stuff like the stars and condensed nebulosity

The tool you want is in Filters > Generic > High Pass Filter (if it is not there in your version of gimp then go to the addons repository and look for high-pass.scm and put in your scripts folder/directory)

PS Edit ,, if that is all gobbldygook I'll happily do a blow by blow account how-to get it installed but didnt want to teach eggs if a hint is all you need about the high-pass tool

So, I did this, with a bit of increase in hue>saturation as well :-

32 minutes ago, The Admiral said:

The keen-eyed should see a faint galaxy on the RHS; will need to identify that.

IC4263, see my post in your other topic,

great AltAzing , amazing.

13 hours ago, LeeRich said:

thinking about a DSLR now lol

    "slippery" and "slope" are words that come to mind 

Nice beginning, was that with the barlow and is it a full frame or a crop ?

7 minutes ago, LeeRich said:

 i figure SkyWatcher glue it thinking the collimation will stay set...trouble is mine was set wrong before the glue dried.

once the glue is released the cell can move freely around the elongated holes for collimation.

Yes I think you are right, that is what they expected !

Good explanation, thanks Lee, I was hung up on expecting the screw ( and the pitch of its thread) to be doing the micro-adjust in the classical manner before glueing , and had missed the implications of the elongated holes and tightening the screws up against them ! All is clear now. Thanks

On 12/02/2016 at 23:09, LeeRich said:

I released the glue and managed to collimate it with ease even though a little unorthodox as the mirror holder is held in with 4 screws around the tubes outer edge.

Hi Lee, brill topic, nice mods. looks good now, Black is Good at night.

as you know I am contemplating the Discovery ( not yet made up my mind !, it takes a while !! ) but I am curious about 'releasing the glue' operation,,, was this solvent or brute force with a chisel ?

And : "4 screws round the edge", does this mean that they are shifting the mirror laterally or are there wee levers inside to tilt the mirror ? Normally one would expect screws round the base ?

Just idly curious is all, at this stage ! Thanks.