Gerry Casa Christiana

The way I resolved this issue on my Canon 550d (almost) is by removing the SD card out of the camera. Someone on here Carol if I remember correctly suggested I try. Since then I don’t keep a SD card in. I believe it’s a electronic signal being picked up in the frame. Give it a try

Gerry

On 03/09/2019 at 18:37, alacant said:

Hi

I'd tell PHD2 860 and make sure I recalibrated with the guide camera binned. Make a new profile.

Cheers

Hi Alacant 

Whats the benefit of the guide camera being binned?

Thanks 

Gerry

I think the issue is more the length of your exposures. 20 seconds is not enough to get the detail you need. The background in the first picture is too bright. In photoshop try to get the black levels to around 30 that will help to see more detail in the galaxy. 

Kind regards

Gerry

22 minutes ago, ollypenrice said:

I might add luminance or simply more RGB as a first step.

The colour to luminance ratio which I use depends very much on the target. If we are trying to capture faint dusty or other broadband signal it's the luminance which will find it so I'l shoot lots more luminance than colour, as in this example. https://www.astrobin.com/335042/?nc=user  The luminance found the difficult tidal tail. However, this makes the processing harder because you need various techniques to stop the luminance bleaching out all the colour. If keeping the star sizes down in a nebula shot is the priority then I might shoot no luminance at all and use the RGB as a vehicle to carry OIII and Ha and give naturally coloured small stars. There's no one answer but the great thing is that the mono camera gives you the flexibility to choose your approach.

The easiest processing comes from equal amounts of L and R and G and B.

Olly

I'm still on dslr and if price is no option God willing I would probably go mono there is still a temptation there to go one shot though. So even if you don't have a permanent setup you would say it's still faster? So using Ha on red and Oiii on blue and normal green for improving star colour and size? Learning a lot 

Thanks

6 hours ago, ollypenrice said:

I'm going to argue the other way but first let's get one thing sorted out: monochrome CCD with filters is faster than both one shot colour CCD and DSLR imaging. I did this image of the Heart nebula in only two hours and processed it quickly and simply. Each colour had 20 minutes and the H alpha had 1 hour.

This compares with the same equipment on the same target done 'properly' with well over 20 hours of data and complex processing:

I do not believe any one shot colour camera in an F5 system could match the first image in 2 hours.

In this case the speed in the first image came from the use of the Ha filter but it can also come from the luminance filter which is at least three times faster than a colour-filtered image whether that's from OSC or RGB filters. (OSC and RGB are pretty much equivalent.)

Personally I think that using the right tool for the job is always easier than using a multi-purpose tool or the wrong tool. I went straight into astrophotography with a mono CCD and almost no computing skills at all. It is often argued and assumed that you should go via DSLR into CCD but I don't agree with this. A number of people whom I've taught on my courses have said that they found DSLR to be a blind alley. Their words, not mine.

The big argument against CCD was cost, which is fair enough, but there are now dedicated and cooled CMOS cameras which are far cheaper than CCD and in my view they have introduced an exciting mid-cost alternative.

Olly

 

 

 

Love it when people go against the flow  I have to say it's quite convincing just a quick question if I may. With the first picture if you needed to improve on it would you increase time on rgb or spend more time on luminance or h Alpha? Is there a sound ratio to colour and luminance that you follow? 

Thanks

Gerry

2 minutes ago, andrew s said:

Yes I study star spectra with a home built echelle spectrograph. I have a guide head on a telescope which feeds the starlight into a fibre optic which guides the light to the spectrograph. This allows the spectrograph to be stable as it does not move as the telescope tracks the star.

Regards Andrew 

Wow fascinating. Love to see what kind of results you get. Anyway for another thread. 

2 minutes ago, andrew s said:

The reflective version should be ok with any camera. A prism adds aberrations when off axis.

I use  mine as the input to a spectrograph. 

Regards Andrew 

A spectrograph. It's a area I know nothing about. Could I ask what you use it for?  Related to spectral analysis of stars etc?

Regards

Gerry

19 hours ago, andrew s said:

The second coloured diagram is not correct. The blue prism is the wrong way round. No  known material could deviate the light at a right angle in this configuration.

Regards Andrew 

So that's where all the confusion is. Types of prism  looks like one is reflective another transparent. As you say we live and learn. Wonder what works best in practice. Good to know actually because later if like for me I decide to get a cmos then i might need a different oag. 

All the best

Gerry

Ah yes it is quite different. Looking at the picture looks like a clear prism? No matter as long as it works. With mine which I also bought from there but made for dslr you cannot adjust the mirror like yours but it works fine for me  let us know when all is working. 

19 hours ago, andrew s said:

I think the first was correct. The light undergoes total internal reflection at the 45 deg face. The light path in the coloured diagram is impossible. 

Regards Andrew 

Actually looking a little closer probably both are correct  it's just the angle of the prism that threw me.  Regardless of the pictures. Thanks google! The idea is light comes down the telescope to both the camera and the guide camera in the same direction one small part gets refectled up by the prism towards the guide camera. That's the principle which is clearer than pictures obviously in this example. Apologies for any confusion. 

Let us know when it's all working otherwise one of us will pop over to fix the mess I've created  

Actually the picture above is incorrect the angle of the prism will be going towards the focuser not the camera  

Kind regards

Gerry

Looks awesone but how is it balanced  mine has something similar with a USB hub on the scope. Powered like yours. What do you put the better guiding down to? Losmandy? 

Gerry 

Woooo guys and girls. Your putting me right off the star adventurer! I think a pier project might be more suitable instead. Let's hope the wife agrees! 

No I didn't want to go to the maximum weight but I just wondered how these tripods would cope with a small scope and guiding. If they are both up to the job great. 

Gerry

Thanks to everyone. Can I ask what are the differences in weight capacity for Neewer and FLOs tripod. I'm certainly going to be putting a small scope on mine and probably auto guiding etc. 

Do they both work ok for that? 

Cheers

Hello all

Can someone tell me what I need for star adventurer apart from the mount.  

A long shopping list. I would like to do this setup but not sure what I need. Also would like to add guiding. 

Can people explain what tripods etc. 

I can order everything from FLO if they have it  

Gerry

13 hours ago, Atreta said:

You got a lot of Ha too, great image.

i'm considering to mod mine, but i don't like red overwhelming the entire picture. 

Hope you can get it. I wanna see

I have already modified the same camera. Huge difference! Wouldn't go back. Couple of comparisons below but the also guiding was added as I didn't have that before  

12 hours ago, Atreta said:

Last one, the good old m8 lagoom nebula 

I'm focusing more on this is target to see how much detail i cam get out of it.

This is about 5 hours of integration time from different nights taken with iso 400 and 4 minute exposure and with flats. I found that iso 400 works best for me. 

The camera is a t5i unmodded and i still can't use the coma corrector,  I'll try to have a friend to help me with it. 

Great shot. Here is mine on my T2 unmodified last year. Mine has even worse HA than yours!

On 26/06/2018 at 17:48, Gerry Casa Christiana said:

I turn off guiding and use PHD2 to create log file (there is option in PHD2 to disable guide commands). I usually create about hour / hour and a half of log file. While doing that - at some point I press time stamp button in EQMod. EQMod auto PEC is also turned off. Next I load PHD2 log data into PecPrep and create PEC curve.

So just so I understand. In PHD2 you set up guiding on a star near the equator leave that going for a hour and a half then create a log file. Then load that into Eqmod pec prep? Sorry never done this but would like to try. So PECPREP is part of Eqmod right? I'll have to google this maybe @chrisshillito has already done this as I know he designed it. 

Gerry

2 hours ago, Stub Mandrel said:

The Rowan Belt Mod looks well thought out...?

Actually was guiding low and with the scope on the on the east side last night, wasn't as good at about 1.03" Took a bit of fiddling  with settings to get that - mainly reducing the aggression as it was overshooting.

I think problem was that it was west heavy making the RA tracking 'jumpy'.

In my limited experience I think it does improve things but it might be easier to get a pole master and get the improvements that way? Rowan mod isn't easy by the look of it. 

4 hours ago, vlaiv said:

My experience is with EQMod (there has been some debate if PEC helps or whether guiding is fighting PEC, but for EQMod it seems that PEC helps quite a bit) and here is how I do it:

I turn off guiding and use PHD2 to create log file (there is option in PHD2 to disable guide commands). I usually create about hour / hour and a half of log file. While doing that - at some point I press time stamp button in EQMod. EQMod auto PEC is also turned off. Next I load PHD2 log data into PecPrep and create PEC curve.

After that I just tell EQMod to use that PEC curve and work "normally" from then on. I usually recreate PEC curve on significant change in system, or if sync is lost (HEQ5 does not have absolute encoders, and one must park each time after session to preserve mount position to PEC synchronization - if there is power failure or something and sync is lost - PEC curve needs to be generated again).

In general PEC is meant to be recorded on "raw" mount data / motion - so don't have anything running that will disturb this - like guiding or whatever.

 

That sounds like a plan. Great. I'll certainly take the principle that PEC needs to be created raw. Unfortunately at the moment I don't have a permanent setup but I could in theory set up early let it record what the mount is doing and apply the curve once I start guiding?  

On 14/06/2018 at 01:32, vlaiv said:

PEC in place and mount is not suffering any short period PE

I've always been unsure about PEC. Do I need to record it during guiding and then apply it or create a PEC file before in guiding and then apply it when I'm actually guiding. A little tweak extra towards better guiding. 

5 minutes ago, vlaiv said:

No, I have not heard about that one, but I'll have a look.

I don't have a particular place for images (yet, I'm sort of working on it), but to tell you the truth I don't have much to show off. I started using RC last summer, and managed to get just a couple of images with it - most L channel (no NB or color taken with RC yet - I did combine color data from other scope on one of images but it did not turn out that great). Weather is just not cooperating for at least past 6 months (only one session, and that was short one).

I post most of my images here in DSO imaging section, but to save you trouble, I'll link in ones taken with RC:

http://serve.trimacka.net/astro/2017-07-18/

http://serve.trimacka.net/astro/2017-07-21/

http://serve.trimacka.net/astro/2017-08-27/

http://serve.trimacka.net/astro/2018-05-07/

Just open links and click on png. One of ngc7331 has a lum only (that is pure RC) and color one - mixed with data from another scope and another camera (TS80 F/6 apo and ASI178mcc - so not much color data and it is not that good).

You can use search here on SGL for my posts in DSO imaging to see capture details for above images.

 

Your way ahead of me I'm still learning dslr so luminance etc is not something I have tried. I imagine that at the resolution of those pictures it's going to be tough although it depends on the mount I guess. Great pictures. 

Here is the link

http://www.goldastro.com/

Gerry

I'm not sure if you have encouraged me to stay away from RCs  still sounds quite complicated. I guess it isn't. I think I have enough problems with my F5 newtonian although its getting better. Have you heard of the gold star collimator? Works with its own software and looks great. I think that's what it's called if I find the link I'll let you have a look. You probably already know it. I was tempted to get one for my scope. Comes with a special type of Bahtinov mask depending on what type of telescope you have and the software with it. 

Do you post any pictures anywhere from your RC? I'd be interested to see. 

Gerry

3 hours ago, vlaiv said:

First thing that I've learned related to above is importance of collimation on RC scopes - you don't collimate it well you will end up with stars that don't look nice.

Do you use a Howie Glatter collimator? Or the fail safe star test. I think it's always put me off a RC because they seem pretty difficult to get them right. 

Thanks. 

Gerry

21 hours ago, vlaiv said:

Although recommended distance is 85mm, I think you will find that your combination of equipment is not going to work well on "default settings".

I have same gear (TS RC8", x0.67 reducer - ccd47 variety from TS, and ASI1600).

Main problem with this setup is FOV. 8" RC has fully corrected field less than the size of ASI1600. If you have well collimated RC and use ASI1600 at native - you should get round stars up to the edge with slight field curvature showing - stars close to edge will be a bit larger / slightly out of focus. Best to focus about 3/4 from optical axis - if you use Bahtinov mask or measure FWHM when focusing - place star somewhere around 2/3 to 3/4 between frame center and one of the corners. This way you will "spread curvature" over sensor (stars at the edges will be closer to focus, and stars in center will be slightly out of focus, but almost impossible to tell). This is of course in case you will be keeping whole FOV. If cropping out - focus closer to center of FOV.

Now, back to star shapes and reducer - With RC8" it is advertised as being able to do 30mm without corrector. I would say that is probably pushing it and corner stars will suffer. ASI1600 has about 22mm diagonal. When you apply x0.67 reduction, you are squeezing larger field on smaller surface. Equivalent to this is using larger sensor. How much larger? 22mm / 0.67 = ~32.8mm. This way you are imaging out side of corrected circle. Edge stars will surely suffer because of this.

I would say that going up to 28/29mm imaging circle would be appropriate (even then, prepare for very specific focusing - finding focus place that gives best focus over FOV). This reducer acts as slight field flattener - but not proper one, so field will be a bit flatter but you will still have to deal with field curvature. Now let's see what sort of magnification one should get to cover 28/29mm "imaging circle". Again some math 22/x = 29 -> x = 22/29 = x0.75.

If you do a search on web about this combination - RC8 / x0.67 you will find that people often say - best results are not at x0.67 but x0.72 - x0.75 (above is the explanation why it is so, some will even say it works good with "native" x0.67 - but that is simply because they are using small sensor - 11-17mm, for APS-C that is larger than ASI1600 they probably need to go as low as x0.75 or lower).

What would be proper distance for x0.75? Go for distance of 55-58mm (correct distance will not be of big importance, just use spacers that you have) . You can actually experiment and start with 55mm and then move reducer further and further until you reach point where things start to fall apart.

So to reiterate:

1. Well collimated scope.

2. Check that there is absolutely no tilt in imaging train and focuser is well collimated as well. I had to switch to threaded connection because of slight tilt.

3. Reduce distance to 55mm and work your way up from there - try to find sweet spot (best reduction with the least star distortion) - experiment with focus position for best results.

4. Understand that you introduced another optical element in optical train and that it is not perfect - so star shapes will suffer (just how much depends on optical quality of item).

HTH

Where did you learn this stuff! Is there a book somewhere I can buy and study this? 

Gerry