Anthonyexmouth

28 minutes ago, davidc135 said:

For the basic star test, aim the collimated scope with a 5mm or similar eyepiece at Polaris and allow time to cool.

Firstly, the optics can be checked for astigmatism by racking through focus, the out of focus blurs being distorted into ellipses the major axis of each at 90 deg to each other as you pass from intra to extra focus.

To then check for correction the size of the 2ndry shadow should be compared at exactly equal distances either side of focus. Its usual to check at +/-10 waves defocus which, for an F/5 optic is 1.1mm. It's not too crucial so long as it's the same either side. You might even try 1p pieces which are 1.5mm. You'll need two spacers.

Pull the ep out of the drawtube by the thickness of one spacer.

Find focus with the focuser.

Now pull the ep further out from the drawtube by another spacer to give the extra focus image. Note the size of 2ndry shadow.

Now push the ep back into drawtube to give the intra focus image and compare the two shadow sizes. 

If the inside f shadow is larger the scope is under-corrected and if it's the outer that's larger then over-corrected. I think a maximum reasonable error of 1/4 wave corresponds to a 3:2 proportion. Hopefully it'll be better, even 1/10 wave can be spotted.

A still cooling mirror adds over-correction.

A perfect mirror would look exactly the same either side. Zone and edge imperfections will affect the strength of the rings that surround the shadow.

David

 

Ah, ok, no eye pieces or mounting rings and the original focuser is junk. 

2 hours ago, ollypenrice said:

What was your uncropped image? To do DBE you need background markers distributed across the frame. One in each corner would be a minimum, I think.  When I don't have that available I generally use ABE. This target tends to be full of nebulosity with dark sky conspicuosly absent!

I'd certainly try SCNR green as well.

Olly

Uncropped was a mess as it was a stack of 3 nights and a camera rotation i'd forgotten about, thats why its that shape. 

2 hours ago, davidc135 said:

+1 for the star test.  David

What do I need to do that? 

11 minutes ago, ollypenrice said:

I agree with Vlaiv that there's real OIII in there. However, I think you may have a red-green gradient (red left, green right.) This is common on OSC data, I find. Compare the dust patches in the lower part of the image. Those on the right are distinctly green. What we can see of the background (top left and top right corners) also confirms a greener right hand side.

Lower levels of green will turn things magenta and that, too, might be going on just left of centre. 

What do you use to neutralize gradients? My guess is that Pixinsight's ABE would sort this out, and/ SCNR green.

Olly

I used DBE, is it worth running ABE too?

Just trying to migrate from APT to NINA. I cant seem to get the scope position reticule to show up in stellarium. I've added the port number and when i clicked get position from stellarium for a target it did that but it doesnt show the scope position in stellarium anymore. 

CANCEL... Its working now. 

27 minutes ago, vlaiv said:

If you have one - then yes, give it a go. That is emission region and good dual band (or more bands) filter will eliminate sky glow / LP background and improve SNR substantially (if you have significant LP).

I dont have one at the moment,  hopefully picking up a Sharpstar 76 in a week or 2 and planning on pairing that with an asi533 mono but thought about keeping my 294 and maybe adding a dual band filter. 

1 minute ago, vlaiv said:

I think there is real OIII glow in that region.

If you look NB images of that region - you will see that it is mostly dominated by OIII (but this is due to processing, OIII is usually fainter than Ha in "normal" light as there is much less O vs Ha).

 

Ah cool, so not anything i'm doing. Do you think that region is something a dual band filter might help with on a OSC or best to live with it and wait for another go when I move to mono. 

Is this blueish area real or something to do with my optics or processing? Cant see it in anyone elses images. If it's me or my optics, how would I get rid of it. 

28 minutes ago, Merlin said:

Personally, I don’t like waste, I’d renovate the ‘scope. The optics might turn out to be better than a newly-acquired one.

 

That's what I'm thinking. I always heard good things about Orion optics UK quality. Just hoping someone has some concrete knowledge as to whether it's worth it. 

1 hour ago, newbie alert said:

If you're changing the bearings then you don't need to add more.. you can easily over grease a bearing, and white lithium cakes up and dries.. 

There sealed ones don't need it but the 2 tapered bearings do. Also white lithium certainly doesn't dry out. Well not in the 40 years I've been using it. 

11 minutes ago, The Admiral said:

If I recall correctly the ASI294 has peculiarities when taking flats. The recommended exposure time is 2-3 secs. There are numerous posts around on taking flats with this camera.

Have you successfully taken flats before with this camera?

Ian

Yeah, over 2 secs for the 294 and matching dark flats. It's a great camera but you have to get the calibration frames right. 

I've got an old mid 90's Orion optics 6" f5 europa n the loft, my first reflector. Is this a mirror worth recoating? It'd need rings and probably a new focuser if I want to use it for imaging but wondering it it might be better to get it back in good order or just buy a new 150 pds if i ever want a reflector again.

20 hours ago, Adam J said:

You may not need to, but if you did I would use a rocket blower on it first, then once i was sure that no debris was on the surface that i could end up moving about and causing scratches I would then move to a 100% pure cotton but along side some Baader optical wonder fluid. You then need to keep swapping the cotton but out and repeating until no residue remains. 

Adam 

 

tried the blower, it's just such an odd pattern. guess it might be where it may have iced up at some point. its not evident in images. My flats do look terrible but not due to that, everything in my optical train looks clean and dust free but got huge shadows in my flats. they calibrate out but i'd love to be able to see where they are coming from. 

31 minutes ago, m.tweedy said:

There is also this

https://www.rothervalleyoptics.co.uk/geoptik-equatorial-mount-grease-kit.html

Damn, £18 is more than the bearings cost. I think that'll stay on the Shelf . Lol

53 minutes ago, Bizibilder said:

If you have just bought bearings are they not already greased?  If so you could ask the supplier which grease it is.  Many bearings are greased for life and should be OK as they are.  If you want to change the grease you need to ensure that you have removed ALL the old grease before greasing with the new grease.  

Oh the sealed bearings are greased. I mean the tapered bearings, those will need grease. I only use quality white lithium, I buy it by the bucket for use on my commercial fishing boats. 

As my guide cam is gonna be away for a while being repaired I've decided to strip down my Heq5 and change the bearings, is a standard white lithium grease ok for this? Hoping it is as all of my grease guns are full of it and just spent £70 on bearings so don't wanna spend much more. 

Well, I've emailed all the main players I can think of with no luck. Got some cheap ones from eBay but that are rubbish, keep falling off. 

12 minutes ago, iantaylor2uk said:

Not sure why you want such a long exposure time for flats. I use the auto exposure function in the ASI Air Pro and use a flat panel with no paper. With just an IR/UV filter the exposure time is around 30 milliseconds or so, whereas with the L-enhance filter the exposure time is around 300 milliseconds. The flats used from these short exposures seem to work fine for my ASI 071 MC Pro camera. 

I'm using a 294. They need long flat exposures. 

2 minutes ago, ollypenrice said:

The ADU value is tolerant but you might need a lot of paper to get up to 3 seconds...

Olly

6 sheets of printer paper. 

How important is ADU for flats? Just made an el flat panel and added enough paper to get the right adu with the flats wizard in Nina. It's something like 2.87766s , I made that up but you get the point. Can I for ease of taking flats and dark flats just use 3s subs or is accurate 30% adu more important? 

21 minutes ago, teoria_del_big_bang said:

Always two sides to an argument. Well almost always, I can't argue that black is white. 

I cannot comment on the PI developers attitude as never had any dealings with them, and I totally agree if the case is as said then they should listen to their customers, or potential customers, like any other business.

But from the software side of things I tried to get into PS for a year and just could not get to grips with it, couldn't do a thing with it without following a tutorial religiously, watching the tutorial on one monitor whilst pausing then doing the processing on another. I just really struggled.

I put off trying PI because so many people of SGL said it had a steep learning curve and that it was just so difficult to use. But then when I tried PI it just made sense to me and once I understood the ethos behind it I just took to it and like I said it made real sense.

Why one and not the other, not sure, maybe the more Arty amongst us, or those already familiar with photography find PS so straight forward and whether it is that those with a more mathematical or logical approach take to PI  and prefer that path I am not sure.
I know that I tried photography in my younger days, all the gear (before digital SLR) even all the darkroom stuff so was keen, but I was pretty useless at it, I could take the images and develop them no problem , but they were poor to look at, just didn't get what made a good photograph. Also I was never good at drawing or art, struggle to even write legibly. But, maths and logic I was much more at home with.

 I think it is just a matter of horses for courses.

But, without going on about it it does worry me about your comments, and Olly's, about the developers attitude, and although I said I could not comment on that I just thought about  a recent issue regarding what I thought was a great third party script, called NSG, which when I did the latest major update of PI I found the script and all my settings had disappeared and no idea why, until I read on the PI forum that the developers had a disagreement with how the script handled weighting of images and decided there way was right and the script was wrong so just removed it from the repository of anyone who did the update.
That did really annoy me to say the least.
The script is still available but PI made it really harder to install and use it as the script could no longer then call an instance of a PI process. Luckily the script developer did find a way around the problem and thankfully I can still use the script but took me several hours to find out what had happened and how to reinstate it and get it working again.

So sounds like the attitude issue is true. Shame because (for me and I think so many others) the software works for us.

Steve

 

I gotta say, between Adam Blocks free videos and Mitch's videos PI has certainly started to become much easier to understand. Much more so than GIMP or APP, I wish I'd bought PI before spending money on APP. 

1 hour ago, bomberbaz said:

Thanks @vlaiv for the above explanation, I get it all until the last (underlined) equation. However rather than mash my brain trying to really get my head around it, I will accept that you are right and they are not really needed.

However I am one of these people who will go out now and run comparisons because I want to see for myself. I guess that is the scientist part in me. I can accept what someone tells me is right but I won't fully believe it until I prove it right. 

Anthony, now I know what WBPP is (google is ace), I shall watch this as I really do want to get my head around calibration frames fully. As above vlaiv's explanation is very detailed but lost me at the last minute.  Maybe this video will help a few pennies drop.

Cheers guys.

Steve

The video, well a little series explains it really well with diagrams. The wbpp series is quite long but worth watching and there are 3 or 4 that cover calibration frames but some are about DSLR so may or may not be of any use. 

3 hours ago, wimvb said:

Fyi, if you load a sub and have it as the active window, you can use that to get the astrometry solution (get from image). You then apply the process to the integrated image. But do use the sub that was the reference during image registration. If you plate solve the integrated image, you can still get the data from (any) sub and use that as a starting point.

Thats what I was doing, hoping that would give a more accurate position to the manual search box but it still wouldnt work, claimed platesolving failed even though it was the same image, clicking ignore metadata seemed to work.

I wonder if it might have lost it after the flip, if there was one, I was asleep and my plan puts the mount back to the home position. I'll have to be more careful with the reference image.

6 minutes ago, teoria_del_big_bang said:

which one was the reference image, or did you leave it on auto ?

Steve

Auto.