Mr niall

Hi all

I was wondering…

in AS!3 or Registax, I was wondering about setting alignment points before stacking. Mainly:

1. Where do I put them?

2. how many do I use.

3. is more better or..l does it depend?

4. Is a small alignment box a benefit over a big alignment box?

many thanks, sorry probably a daft question!

Not very good but… 

svbony sv905, sky max 127 no Barlow

about 3000 frames

On 05/10/2021 at 22:12, vlaiv said:

You want this line:

190 1,742364914 0,501801095 446,0454179 30,71525639 29,7470829 8

This gives ~0.5e of read noise - lowest. It is gain of 190 or "relative gain" of 30.71 (whatever that means)

There is no relationship between gain and frame rate. You want lowest read noise and that is to some extent controlled by gain. Just simply select gain that provides lowest read noise.

Exposure length is related to frame rate in certain way.

You want your exposure length to be such that it freezes the seeing. That is in most cases around 5-6 ms. In very good seeing it can be as high as 10ms. You'll recognize such seeing as image being quite steady on preview - no jumping around or fast blurring of features.

Exposure length limits max fps that you can achieve and relationship is as follows 1000/exposure = max fps.

If you set you exposure to say 5ms - max FPS that is theoretically possible is 200FPS - you simply can't have more than that as there is only limited amount of time in one second .

Real FPS will also depend on your camera and computer USB connection and also how fast computer can save those frames. Choosing smaller ROI will help there.

Amazing - thanks again 

On 05/10/2021 at 21:15, vlaiv said:

This part is fine

This part - I'm not really sure.

What does 25m/s mean? If you mean that you used 25ms exposures - than that is definitively not fine. You want your exposures to be around 5-6ms. Don't look at histogram values - don't try to get them to certain percentage of maximum. That is not important. Important bit is freezing the seeing and you can only do that with short exposures.

Gain needs to be set as to minimize the read noise. Do you have any graphs - Gain vs read noise or similar for this camera? If not - then use high gain settings like 90% or so. Usually read noise goes down when you up the gain.

Use Raw8 color space and save movie as ser, and then later select RGGB debayer in AS!3.

3000 frames is very low frame count - you want something like x10 or more. Try to get high FPS if you can (USB 3.0 connection, SSD, and fast capture mode / turbo USB - what ever you have available in SharpCap). 640x480 ROI is good - you can even go smaller if that will help with FPS

Image for 4 minutes or so.

Stack only 5-10% of the best frames.

Thanks Vlaiv that’s a great help,

the only reference I can find for gain:read noise is 1:15.37.

And this pinched from cloudy nights;

Gain Value e / ADU Read Noise (e) Full Well (e) Relative Gain Rel. Gain (db) Plage dynamique (arrêts)

1 53,51718504 15,41294929 13700,39937 1 0 8

1 53,49988682 15,4079674 13695,97103 1,000323332 0,002807972 8

1 53,2706365 15,34194331 13637,28294 1,004628226 0,040107519 8

1 53,24938755 15,33582362 13631,84321 1,005029119 0,043572895 8

2 26,30033128 7,574495409 6732,884808 2,034848325 6,170640859 8

3 18,00270287 5,184778427 4608,691935 2,972730563 9,463110964 8

3 17,99257615 5,181861932 4606,099495 2,974403698 9,467998248 8

5 10,687864 3,078104832 2736,093184 5,007285369 13,99204686 8

6 8,996134626 2,590886772 2303,010464 5,948908867 15,48874632 8

7 7,585126959 2,184516564 1941,792502 7,055542423 16,97060815 8

9 5,919660762 1,7048623 1515,433155 9,0405831 19,12392885 8

12 4,491903321 1,293668157 1149,92725 11,91414445 21,52125723 8

15 3,534253406 1,017864981 904,768872 15,14243007 23,60391153 8

19 2,786607465 0,80254295 713,3715112 19,20513948 25,66834931 8

25 2.087201755 0,601114105 534,3236493 25,6406382 28,17857661 8

29 1,840842201 0,530162554 471,2556033 29,07211983 29,269534 8

190 1,742364914 0,501801095 446,0454179 30,71525639 29,7470829 8

200 1,766410019 0,508726085 452,2009648 30,29714759 29,62803485 8

400 1,767016897 0,508900866 452,3563255 30,28674211 29,62505119 8

890 1,76654012 0,508763555 452,2342707 30,29491628 29,62739513 8

900 1,766020558 0,508613921 452,101263 30,30382902 29,62995014 8

To be honest I’m following a guide that’s a few years old now and then copying the workflow of someone who has used this camera and posted their results. I was struggling to get my head around the relationship between frame rate and gain, but I will definitely follow your advice and push the frame rate down to 5/6 ms.

I’ll go back to Raw 8 and use SER too.

I will report back!

Many thanks!

Hey all

I’ve been having fun imaging Jupiter and Saturn recently, but I’ve got to the point where my image quality seems to have hit a plateau. 
 

I’ve included my most recent Jupiter and Saturn for reference - I think the biggest things I would like to improve are;

1) Sharpness (although I am aware atmospheric conditions may play a part)

2) They seem “thin” - as in… lacking in depth, it feels like they go mottoes or pixelated very quickly when processing (if you see what I mean)

I haven’t managed to get a really defined Cassini division yet and that’s my next target.

Equipment - Skymax 127 on AZ GTI

Svbony 305pro (Sony imx290 2.9um pixels) shot at F12.5

Sharpcap for capture - around 25m/s 50% gain for Jupiter and around 70% for Saturn. Colourspace is RGB24 (tried raw8 and raw12 but seems really pixelated). 3000 frames, 640x480.

Processed using Autostakkert and Registax, best 20% kept.

Just to wrap this up; RVO kindly sent me a 12v adapter to try. It was immediately and noticeably different which is interesting.

But still erratic - for example couldn’t get from Altair to M29 without help.

But before that it got from Polaris to Saturn perfectly!

Anyway RVO have agreed to replace mount. Thanks for your advice all fingers crossed for next one!

As a side note the OTA is absolutely fab.

Thanks for your comments everyone and information. It certainly does sound like a plausible explanation; particularly stuff like the weird behaviour of sometimes being right and sometimes quite off.

Believe it or not I actually owned it for more than 30 days before I got to try it in anger due to our wonderful weather, so I've had it about 6 weeks. RVO asked me to fill out a big engineer report for the distributor but I've emailed them again with the thoughts from you all in case that helps. I'm really really hoping I don't end up having a battle with the retailer over this... they say they almost never get problems with them. I cant afford powerpacks or external power systems unfortunately (well... I can technically afford one but the accounting department would never authorise additional purchases for "telescope stuff"!).

Eugh I'm having horrible flashbacks as to why I gave up on this hobby the first time. 

Ach, onwards and upwards.

9 hours ago, adyj1 said:

Do you have a 12v DC plug-in transformer with a 5.5mm/2.1mm barrel plug (min. 750mA ouptput)? If you were able to temporarily try the mount with a 12v supply - maybe with a mains extension lead from the house - it would be a good way to establish whether  power is causing you a problem.

 

No I wish I did that would be handy, good idea though thx.

8 hours ago, Gfamily said:

I find that targets near the zenith are more easily 'missed' than lower targets.  What's your mount like when trying to find targets lower down  ? 

It’s fairly hit and miss at all altitudes, but I think it is actually even worse at altitude now I think about it…

35 minutes ago, ScouseSpaceCadet said:

I meant to add the below;

Besides the leveling and pointing true north missing from the AZGTI manual, the below is also crucial and missing:

 

Rules for choosing alignment stars:

•  It is recommended that the altitude of the two alignment stars are between 15 and 60 degrees and the deviation in altitude is between 10 and 30 degrees.

•  The azimuth deviation of the two alignment stars can be between 45 and 135 degrees, it is best to be close to 90 degrees.

That’s interesting, I think Mizar / Altair fits pretty well in that range though?

42 minutes ago, AstroNebulee said:

Hi, Do you keep the 4mm ep in when slewing to a new target or swap to a wider field one 

Deffo a top choice of external battery pack and small lightweight and power your mount absolutely ages, I've one I used before going to an asiair pro, cost £47 from amazon. 

Thanks buddy - sorry yes I should have said, I am changing to a 40mm plossl after alignment not sticking with the 4mm

But I’m still not sold on the power pack idea, I really don’t think I should have to spend an extra £50 on top of the purchase price just to make it work when it says it should run on batteries! 

58 minutes ago, ScouseSpaceCadet said:

To be fair my first unit what feels like a long time ago now just would not align and was replaced. The second was replaced due to internal tapping while tracking. The third that's over a year old now works great. Inadequate power does cause issues. I had random slews etc until I picked up the Talentcell battery.

Anyway, Niall reading your list you seem to have all bases covered except two specifics.

1. Do you start with the telescope level and pointing north before the alignment process?

2. Before finishing each star alignment do you finish with up and right arrow presses?

Thanks buddy, yes to both of those 👍

28 minutes ago, GoldTop57 said:

An alternative power source is definitely worth exploring. Also when you've got both clutches completely undone do both axes move fairly freely are do they bind or feel tight?

On the altitude it moves perfectly, on the azimuth it moves anti-clockwise perfectly but when turning clockwise there is a little bit of what feels like stiction or flex before it starts moving. If I just lean on it it’ll flex a couple of mm then bounce back if I let go. But no resistance.

40 minutes ago, Shimrod said:

 

I know you've changed the batteries, but I've read quite a few posts on this mount that behaviour with batteries can be a bit strange. There is a discussion in this thread about external battery alternatives. The picture in the  @ScouseSpaceCadet is a particularly neat solution!

Thanks Shimrod, I had wondered about that. But ultimately I came to the conclusion that if that is the problem then it’s a faulty unit. If it doesn’t work using batteries I’m not sure I should be expected to pay at least another £70-100 for a bespoke power supply just to make it do so. And I can’t really afford the gamble anyway to be honest!

thx buddy thats the one!

Hi all

I was hoping somebody may be able to help me or give me some advice for my AZ Gti (with Skymax 127) if at all possible? This is my second AZ GTi in 12 months and the second time I'm having issues. I haven't ruled out the possibility I'm doing something wrong but I'm struggling to see how I'm so far off using a really intuitive system that people seem to rave about!

Basically I cant get it aligned.

I've tried every alignment method available with broadly similar results - insomuch as every time an alignment is completed the resulting slew takes me some considerable distance (between 5-10 degrees) off target. Also it isn't consistently off, it can be off in any direction so I haven't been able to pin down if its going consistently "too far" or "not high enough" or whatever. I've also used a variety of stars for alignment - Jupiter / Saturn / Altair / Vega / Deneb / Dubhe / Mizar. For example I've used stars near each other like Mizar / Vega / Polaris and stars really far apart like Polaris / Altair / Jupiter, but the results are the same. I should note I have no access to anything from the North East to the South East.

Maddeningly when I manually centre it on a target, it is usually (but not always) able to find that target again no problem. Sometimes it is still miles off re-finding the alignment stars. For example, after setup (using Altair as one of my stars) I sent it to M27 - miles off. Centred it - then tried M29 - miles off - then sent it back to Jupiter which I had previously centred and BANG perfect. Back to M29 - perfect, over to a new star - Vega - miles off.

I've been recreating this for the last few nights and I really don't know what to do next. Basically unless I already know exactly where something is, it is fairly useless. It seems to be tracking ok, but I haven't done an extended test.

For the record

• Mount is levelled and everything is tight.
• Scope is perfectly balanced.
• Scope is mounted the correct way round
• Targets are centred using a 4mm eyepiece so pretty close to perfect at alignment stage.
• Have changed batteries 3 times, even different brands.
• Alignment is completely re-set every time, app is forced closed and reconnected between alignment attempts.
• Time / date / location are correct.
• Auxiliary encoders are off.
• I've updated the firmware twice - once to the AZ/EQ version, then again to the standard (.32) current version.
• The mount doesnt feel slack or wobbly in any direction. The motor does not sound like it is struggling.

For the record I'm definitely aligning using the correct stars (!) and I've read the cloudy nights forum on this subject from one end to the other but I don't have any ideas.

So yeah, can anyone suggest where I am going wrong? Honestly I'm so depressed by the whole experience.

Many thanks.

Hi all

ive updated the firmware on my az gti to the most recent (32?) az/eq firmware but can only find the right hand version so my finder is upside down now!

is there a left hand version anywhere?

thx

1 hour ago, Louis D said:

I wonder if they're from the same line reviewed on CN in 2006.

That's a great price.  The best I could find for them was $186 on ebay.

Yeah similar I think.

This was them

https://www.aliexpress.com/item/32962028327.html

like you say, the don’t seem to be available anymore. I only bought them 12 months ago too!

I’ve tried for years to find eyepieces that I really like - although being a bit of a funny OCD kind of person I kind of like all my eyepieces to be of the same brand!

I’ve tried BST Starguiders, Vixen NPL, Baader Hyperion… there are others.

In the end I bought a full set of “Series 500” plossls (all 9 of them) from China for £85. £ for £ none of these little guys compares with the mid range ones I’ve used before (The Vixen NPL 30mm and BST 15mm are particularly good). 
 

But I’ve done enough observing to know I’m not “missing out” on anything and my eyepieces definitely aren’t holding me back. They’re solid, sharp in the middle of The FOV, I’ve got every focal length I could ever need and they’re compact and I’m not terrified of breaking them. I can’t see myself replacing them ever.

Whatt I’m saying is sometimes you have to try out better eyepieces to know what you want. But it’s so subjective, half a million people could have told me when I started out “the stock EPs are fine just stick with them” and I would have ignored them all! So much of it is down to weird things like aesthetics and personal attachment.

But the amount you spend doesn’t necessarily dictate the potential pleasure you will derive. 

1 hour ago, jetstream said:

Except when referring to that supplied 10mm MA IMHO. Cooling and collimation are very high up like you say John, along with the other things. The 25mm Super plossl easily shows the Horse Head in the 15"+ scopes here.

Skywatchers don’t come with plossls anymore. They used to, way back in the day. But now they come with a “Super” but it isn’t a plossl, it’s a MA.

Still not a bad eyepiece, but a little bit cynical on the part of Skywatcher if you ask me.

5 hours ago, Located said:

I also want to know how much difference they make if I buy them as currently I can see Jupiter decently as a 'dot' kind of but with a bit of colour along with small 'dots' being the moons (Which constantly blasts me away with joy 😂)  though wondering if I can push the limits and see a bit closer, honestly I want to push my SW130P to its full performance if that's possible with these BST eyepieces and stuff, will be glad to hear a response, thanks guys and gals!

Eyepieces make a sort of incremental improvement. It wouldn’t be a totally transformative experience or anything - like opening up a whole new world of viewing pleasure and detail or anything like that. 
The eyepieces that come with the scope really aren’t too bad but combining a really budget Barlow with a really budget eyepiece does cause a bit if a “double dip” in quality. You will never need to use a 5x Barlow with your scope.

The biggest advantage with BST starguiders I would say is probably the wide field of view and the long eye relief. Those two things really do make a difference to viewing enjoyment and justify the price tag alone.

As a side note - you really should be easily able to see clearly defined bands across Jupiter even on a relatively murky night at anything above 75x. If you can’t then maybe need to think about why (it won’t be a fault of your current eyepieces)
 

The easiest way to get the most performance from your scope is good collimation, no eyepiece can overcome a badly aligned mirror!

If you want maximum performance from your scope then by far the biggest factor is viewing location and dark skies, closely followed by collimation. 

1 hour ago, Louis D said:

They why not remove it when calculating the true cost of the item before taxes for resale purposes since end consumers seem to be unable to recoup VAT taxes paid?

I think we’re just arguing semantics now.

edit. I did write a big long post but… meh. It didn’t add anything really!

Well there’s two points to consider; the first is - it depends on the Mak. Many come in a package with a mount and the position of the dovetail is relative to what works best with the type of mount. Relatively speaking even a 6 inch Mak is fairly compact so it’s not a massive issue generally.

The second thing I would say to consider is the fact that they’re rotatable so you can mount them however you like! You might need to adjust the mounting for the RDF but that’s it. So if you want to mount it differently it’s never a big deal. 

2 hours ago, Louis D said:

Thus, the UK seems to use the 78% rule instead of the 65% rule that the US uses.  Keep this in mind if you ever do cross Atlantic sales.  Alternatively, the US uses the 54% rule if a 20% VAT is assumed on new sales in the US to level the playing field.

No that’s not right. I mean your maths is correct but the application of logic isn’t. Everything has VAT applied to it - every single piece of astronomy equipment and over 90% of all other products with some weird exceptions like postage stamps and children’s clothes. Therefore that amount is integrated into the purchase price. I can understand in the states - where you have a system of adding tax at point of sale - that you may see it differently.

But it’s a static rate that applies to everything, everywhere. So much so, that the price of items without VAT isn’t advertised anywhere separately. The price - with VAT - is the price. So when selling an item, we aren’t “trying to recoup tax” as you put it, we’re recouping a portion of the price paid. The amount we pay in VAT is irrelevant to us as a consumer, all we care about is the total amount we paid. 

Hi all

Ive been away for a while (after finding out I had what turned out to be severe depression, but had some good treatment!)but am hoping to get started again. Managed to scrimp and save enough to get a Skymax 127 on an AZGTi. Good to be back, wish me luck!

Niall