Priesters

Great capture.  Did you use any filters to get this image and if so which one(s) if you don’t mind me asking?

Deleted

Great picture, hoping I can get to that standard one day 👍.

 I’m just trying to get to grips with an Altair 183C and an Optolong L’Extreme dual band filter.  Would you mind telling me what black level, gain and exposure you used for this photo?  Not sure if the scales are the same for black level and gain for 183C and 26C so maybe confirm the max values as well.  So far my histograms have all looked like a ski slope coming from the left hand side and I’m not sure that’s right.  Any help much appreciated. 

36 minutes ago, teoria_del_big_bang said:

Lovely Image 🙂  

I wonder what BlurXT would do for this image

Thanks Steve, much appreciated.  Have to say that if I'd have produced your image of the JellyFish I'd be printing it up and insisting it goes on my Living Room wall 👍

Unfortunately my post processing is currently limited to DSS and GIMP so the BlurXT experiment will have to wait 🙂. 

Bit noisy and had a problem with pinched optics but I was quite pleased with my M33 taken an couple of weeks ago with an Altair 183C and WO GT81.  1hr 45mins of capture time.  Still a lot to learn about processing 🙂.

11 hours ago, Ratlet said:

I'm happy with their after care and I'm happy with the new one.

I’d echo this wholeheartedly.  I bought a used 183C and noticed some dust spots on my subs which I think originate inside the sensor chamber.  They offered to clean it for me (no mention of a charge) which really surprised me as I wasn’t the original purchaser.  Think I’ll wait till the summer to take them  up on the offer as they calibrate out pretty well with Flats.  Anyhow, very impressed with Altair 👍

Not tested yet but I think I may have discovered a contributing factor.  Forgot about this as I’d hidden the gap underneath the OTA 🙄

Response below from Flo in case anyone else experiences the same issue.  Great service, as always 🙂.

It is pinching of the lens caused by the lens cell radial adjustment screws when the cell contracts in cold temperatures.

We can slacken them off slightly, but only by so much otherwise when the temperature increases the lens cell will be too loose and the scope runs the risk of falling out of collimation.

We recommend using a dew heater band, placed as close to the lens cell as possible which often cures this, as a first step and if that does not eliminate the pinching we can have the scope back and adjust the lens cell for you

Great news - what should I spend the money on instead then 😂

4 hours ago, AstroMuni said:

EDIT: And some stats on the tilt : Stars: 965, Truncated mean[FWHM]: 2.83, Sensor tilt[FWHM]: 0.08 (3%), Off-axis aberration[FWHM]: 0.13

I’d suspected tilt before so it’s useful to have that confirmed.  What software did you use to ascertain that?  You may have gathered I’m still on the lower slope of the steep learning curve 🙂 I was also wondering what my next Astro purchase might be so that’s the tilt adaptor added to the list. 🙄

3 hours ago, scrufy said:

Is it an inherent problem with that scope design or just some particular samples?

Hopefully not 🤞.  Some of the threads I’ve read ended with a satisfactory resolution, usually by slackening the collimation screws, other threads with less satisfactory conclusions.  That said,   I don’t think this is unique to WO optics.  

1 hour ago, The Lazy Astronomer said:

I'd look to have a professional sort it out, personally. 

Thanks for the advice and yes I’ve learnt the hard way in the past about fiddling with stuff I don’t understand.  Looking back at previous images I can see the effect, but to a lesser degree, when the weather was warmer.  I bought it from Flo in Feb so I’ve emailed for their advice.   However, I am a little worried as after Googling ‘WO GT81 pinched optics’ there seems to be an unnerving number of threads!

Hi,

if you decide to go down the USB over Ethernet route I still have this gear for sale @ £50.  If it’s any use to you, I’d happily throw in the 15m Cat 6 cable for outdoor.

Cheers

Andrew

StarTech 4 Port USB 2.0 Extender over Cat 5 (40m) or Cat 6 (50m) - Price Drop!

7 hours ago, The Lazy Astronomer said:

evidence of pinched optics.

6 hours ago, ONIKKINEN said:

pinched optics and so on.

I suspect it is pinched optics as this is the first time I’ve used this scope (WO GT81) in such cold weather.   Only other change has been a new camera (Altair HyperCam 183C).  Is there anything I can do about pinched optics?

Hi,

Just wondering if anyone could have a look at these images and work out why the stars have a square-ish appearance.  One image is the stacked and stretched version from SharCap (no further processing done) and the other is a single sub frame.  I might be being paranoid but I wondered if I had a problem somewhere in the imaging train.

Any help appreciated.

Andrewframe_00010.fits

@Gary Clayton thanks, that’s v useful.  I don’t use the ASI Air Pro so not an issue for me.  

Hi,

I’m looking for a camera to go with my WO GT81 for wide field and the 183 sensor with its tiny pixels seems like a good match.  There’s a second hand Altair HyperCam 183c pro tec in the classifieds at the moment so I’m quite tempted.  Thing is, throughout my short AP journey, I’ve always been a ZWO man.  Is there any material differences between the ZWO and Altair variants or any other factors that may make me regret going for the Altair?

Thanks

Andrew

12 minutes ago, Pixies said:

Well, at the moment it's a lot less relaxing than visual!

Sounds like you’re on a similar journey to me.  I found EEVA became a lot more relaxing once I got Plate Solving set up.  Quick photo of the stars and the mount moves to bang on target.  Not tried it with my AZGTi in AltAz tho as mine’s on a wedge and works in EQ.  I was a bit worried about polar alignment before I converted to EQ but SharpCap made it super easy and very accurate.  Obviously a wedge is extra cash but I think it’s worth it once you’ve got it all set up.  I didn’t fork out for the ASI Air like many people do with the AZGTi in EQ mode and just use a wired set up with a USB hub.  There’s a really good AZGTi owners thread on SGL if you want more info on all this.

nice pics btw 🙂

Sorry, there’s also a field flattener for it.  I’d recommend this one rather than the SW version.  I appreciate I may be getting carried away here.  

7 hours ago, SmokeyJoe said:

Not sure if the extra 100 quid is worth it.

I use the SW ED 50 as a guide scope and it works really well.  I also use it as a very wide field imager as the glass in it is very good (too good tbh for just using as a guide scope).  However, to use it as an imager you’ll probably also need a guide scope 🙄.  I have the Flo Astro Essentials Mini Guidscope which is the same spec as the ZWO and just as good.  The only other bit you’d need is a mounting bracket as per attached pic.  I use the ZWO 120 as guide cam too btw.  

Thanks Olly, very useful as always.  

At the risk of making myself look like a total idiot - is it possible to get to a more realistic sampling rate through binning and achieve a better outcome?

52 minutes ago, ollypenrice said:

As I'm sure you know, you have no hope of resolving detail at 0.47"PP.

Yes I am aware of that.  I like shooting at F10 to get close up to small objects.  Technical question for you - if I used a reducer and cropped to get the same ‘close up’ image as the native focal length would there be any beneficial effect on clarity or would it be just the same?

1 hour ago, ollypenrice said:

And, after all that, where is this egginess? I struggle to see it. If you have to pixel peep to see it then your problem is... pixel peeping! Don't do it. Its only purpose in life is to spoil your enjoyment of a good image.

I shall definitely take heed of your very sage advice and stop pixel peeping.  

4 minutes ago, michael8554 said:

Seems reasonable to me.

I’d read somewhere that there was a 4x rule i.e keep the guiding resolution within 4x the imaging resolution.  Interested to know if that’s not a thing and people successfully use set ups similar to mine.

7 minutes ago, michael8554 said:

Guessing from the pixel scale it's the SCT.

Yes, that’s right.  It could well be tilt or similar optical train problem as the attachment to focuser is not threaded.  
 

Next time out I’ll take a single short sub as you suggest and post it.  When you say short though, roughly how short do you mean?

thanks for the response btw 👍

@Borderline Bob thank you, that’s much appreciated 👍.

Hi,

I think I know why I’ve got eggy stars on this image but thought I’d just check.  For this session my guiding RMS was averaging between 0.5 and 0.8” and I was taking 10 min subs.  I think my problem is that my imaging set up resolution was 0.47”/px and my guider resolution was 2.97”/px.  To my eye the eggs all seem to be pointing in the same direction which makes me think it’s a guiding issue rather than an optical one plus the fact I know I’m breaking the conventional wisdom of what constitutes a good set up.  However, would appreciate any thoughts on this.

Thanks

Andrew