Ratlet

15 minutes ago, Rob said:

Took a punt and bought my first Aliexpress item. Really like it too. Nice long handle for my Bresser 127L.

aluminium fully anodised. 
 

 

There's some good gear on AliExpress.  Often get some stuff that is hard to find elsewhere (I'm currently waiting on some M54 Extenders for my 130PDS) and some stuff that is just cheaper all round.  My biggest complaint is the prices are like a rollercoaster on some of the shops.  SVBONY, I'm looking at you.

Thank you for the help.

I think for now I will put it on the shelf and give the takumar a try for the next run.  I've marred a couple bits on the Tair 3 already and I don't fancy dismantling it as from what I've read it is not an easy task and I tend to be a bit rough when it comes to mechanics.

Alas the astigmatism remains.

I managed to get the ring to move and after a few tap and tests the astigmatism remains.  It does appear to have rotated somewhat though, probably due to the front element rotating.

What I have noticed is that there does appear to be an difference in the level of astigmatism.  When defocused with red halo you get a very marked oblong, however defocused with a blue halo is very nearly circular.  The colour fringes is also greatly reduced.  When focused you get the worst of both worlds and get both atigmatisms.

I think testing on stars, slightly out of focus with blue halo could be a winner.

On the plus side, I tested my takumar 200mm and it is much better.  Even fully open.

Attached crop of F5.6 from the tair 3 slightly defocused with blue halo

I love the short focal length telescopes.  They look like you're getting a long one in installments.

Could you rotate the scope so the focuser and camer hang down to offset the weight of the guidescope being on the rings up top.  

Alternatively just get 2 vixens and screw them to the losmandy plate to they extend our and then attaché the guide scope to that.

Personally I would go for sticking it on the top.  Things sticking out to the side in my experience quickly become things that got snapped off.

My Tair 3 has astigmatism.  Testing with an artificial star has also been interesting.  Airy rings at F8 and F22, but nothing at faster ratios.  Going to attempt to fix that this evening (hopefully just the retaining ring is too tight).

Or I'm about to put an epic scratch on it.

14 minutes ago, AstroNebulee said:

Very nice for your first dso attempt and a good process too👍. 

I wouldn't worry about using dark frames with the 600D just do bias instead and use the time saved to take more light frames. 

As astromuni said if you want to post your stacked file, I reckon there's more to pull out of the data. 

Lee

I think you can get away with using a constant bias with the older canon DSLR.  2048 I think.

In siril, instead of putting an address to the bias file, just type in

=2048

1 hour ago, Pixies said:

- are we not going to see the sketches?

You can see on M32 I got very excited after watching refreshing views and used my blending stump.

North is marked incorrectly on M27 as well.  Good job it's in pencil

There were rumours of cloud last night, but looking at the satellite imaging it looked to be tracking right over the glens and missing us completely.

M32 - I was actually wanting to try the 8mm BST on M31 but as my eyes got dialed in I could swear there was some fuzzyness around the stars.  Decided to attempt a sketch of it as I wasn't sure.  Checked in the morning and the sketch matched up for M32.  Pretty chuffed with that.  First observation of M32.

M103 - practice at star hopping again.  I really need to do the charts more zoomed in or try and figure out a decent magnitude range.  Wasn't sure what I was supposed to see and since I didn't want to blow my dark adaptation so I just sketched the tight little triangle of stars and some of the surrounding area.  Turns out it was M103!  Nice wee cluster.  First observation of m103

M33 - I tried to observe it but I'm not sure I did.  I probably should have sketched the area...  Nothing distinct.  Just a faint brightening in an area.  Possibly.

Sketching is awesome.  They don't have to be fancy, but I know with absolute certainty that I'm nailing some of these objects because of my sketches.

4 minutes ago, alacant said:

Ah, OK. Yes, indeed. I should have mentioned.

Sorry. You need one of these. No idea in English.  Is this a lens spanner?

Yes, I think lens wrench is more common.  I think there is probably a technical difference, but I have no idea.

I will say that I have no regrets buying the lens.  For the cost it is brilliant and gives me something to practice with and learn and even with the astigmatism and my shoddy focus it is making decent results.  Approximately 40 minutes of M33 last night at F5.

I am almost disappointed.  I thought it would be difficult and involve some serious work.  The ring with all the writing can be easily unscrewed by hand.  The retaining ring is below and having attempted to move it with a screwdriver, it is stuck harder than the amount of pressure I am happy to apply without the correct tools.

I have ordered a lens spanner which should be here tomorrow.

2 minutes ago, alacant said:

Hi

You were unlucky as your Tair has astigmatism. As related previously, this is probably just a case of the front element being distorted by too tight a retaining ring. Loosen, then in a vertical posición, shake to re-seat the glass. Next, re-tighten until the glass just stops rattling when agitated. With this adjustment, and  your 72 to 58 step down ring, it should all but disappear at focus. If still intrusive, try 72 to 55; still affording a respectable f5.5.

Otherwise and as Tairs are quite common, they rarely reach their reserve price at (on-line) auction, so another alternative would be to just get another:)

Cheers and HTH

For £40 I am learning a lot about optics so it is not a complete bust.  Fortunately we have lots of clouds so plenty of time to play with it.  I shall update when I have attempted to fix.

9 hours ago, Magnum said:

They just got back to me saying i was correct and they have now gone in and recalculated everywhere. But i just had a look and both cams are still showing the same price lol.

Just checked the prices.  Looks like they've increased them all 🤣.  The Saturn is looking a bit less alluring now.

Did a test on M33.  Got sewed out after and hour but focused as best as I could.

When focusing I used live view without guiding on focused on deneb without a bahtinov mask.

As I moved the lens through focus the stars went from having a horizontal bloat to a vertical bloat.  Odd.  I will need to try stopping down the lens some more next time

23 minutes ago, happy-kat said:

Sorry, good luck in the retest later

I'm grateful for you summoning them.  Alacant is usually correct. 

I didn't want to bother alacant 🤣.  The guru of the tair and the 130pds.

I checked the hot shoe bracket after the post and it had worked itself loose through the evening.  I'm going to try and jury rig it for this evening but I'll sort out a more permanent solution in the morning.

I'd wait to see what starfield say.  It looks awfully like someone has messed up the pricing and put the satru notice on the other sensor.

Just don't get the Saturn-C.  I want that lol.

On second thoughts it's fairly even across the whole image and there is a less severe vertical component.  To me this does suggest guiding as the issue.

I'm wondering if it could be because I'm using a hotshoe mount for the guide camera and it could be a small amount of flex.

I'm using a Tair 3 and stock canon t3i for imaging mounted on a GEM 28.  One thing I've noticed is that whenever I image my stars have a tendancy to show a horizontal smear to them.  I'm certain it's not guiding as it appears to be aligned with the sensor of the camera.  I've attached a snip from an autostretch from siril.  The tair has the ability to rotate the lens on its mount and this was done with the sensor and lens vertical relative to the mount but I've seen similar in my images on M31 here the lens was horizontal relative to the mount.

The lens was stopped down to about F5.6 in this case, but was broadly similar when fully open.

Is this just because of the correction of the glass?  It seems odd that the effect is worse aligned with the sensor.  I've attached a stack and autostretched image as well.  This is only about 21 minutes of data.  I'm not really attempting to produce images yet, just working my way through nina, guiding, etc to figure everything out so any usable data is a bonus.  Crescent nebula was selected because it's a dense starfield and a bit of nebulosity (quite chuffed there is anything as the dslr is stock)

Another night of figuring out how things work.  Setup the Tair to do the crescent nebula (not the ideal target for an unmodified DSLR but I wanted a fairly dense starfield for testing) and left it cooking.  Probably one of my more successsful evenings with that.  I finally got everything to work together.

M27 - as much a test of star hopping as anything.  Managed to find my way from Albireo (great place to start).  Managed to find it surprisingly easy.  Pleased to note that my observation matched sketches by other people as well.  Attempted a sketch but it was a bit guff and I wasn't really setup for it.  First Observation of M27.

M31 - meant to be another star hopping however I could see the stars either side of M31 visually so it was largely point and shoot.  Dew was becoming an issue here, so largely only saw the core and the condensation.

M13 - At this point I was getting horribly dewed out.  All my eyepieces were getting fogged up and the Starguider as basically useless.  Managed to basically just point and land on it.

Pleiades - Had basically given up at this point, but could just about make it out through the trees about 20° up so waited for it to clear a bit more and framed it up quite pleasant, but the cold and damp was getting to be a bit much.  Still worth it, this marks my first observation of the open cluster!

All in all a good night, learned a few things (I need bigger finder charts than what I've been making, the mily way is amazing from my back garden; I should get some constellation binos, dew is a killer and it will be much colder than you think lol).

37 minutes ago, The Lazy Astronomer said:

Absolutely gorgeous! These RASAs almost seem like they have - to borrow a term from the auto industry - forced induction (for photons)

Maybe I should get one - how much do I really need two kidneys I wonder... 🤔

The good news is that if you sell the one kidney for the RASA you won't be able to afford to drink so it works fine 🤣

Been going through this myself.  You might need to loosen one first before you can tighten the others. Just don't loosen two at once too much as the mirror might rotate and you'll have an extra step (rotate the secondary to the correct position).

Good luck.  It's not too bad once you get going.  Bit of a steep learning curve but levels out pretty quick.

1 minute ago, Knighty2112 said:

Nah, JWST needs a good collimation performing only!  

I bet @FLO would get a Cheshire eyepiece out there in 2 days.

Another Scot here.  Welcome to the forum.  The craic is top notch.

You are in for a treat

I desperately hope these are still available at Christmas.  They are fantastic!