Ratlet

53 minutes ago, Don Pensack said:

One thing to remember about field curvature, whether it comes from the scope or eyepiece, and that is, "always focus on a star 50% of the way from center to edge".

If you have any accommodation left in your eyes, you will be able to focus the entire field that way.

If you focus solely on the center, the edge will be out of focus or vice versa.

This probably explains why it is only an intermittent bugbear for me.  Sometimes I focused on something dead centre other times something further out.  It'll be a while till I get the funds for a Morpheus, so I'll have plenty of time to play with my existing line up.

58 minutes ago, PeterStudz said:

I agree with this. When I put the primary back in my Dob I initially used a credit card in order to set the distance. However, when I tried to collimate the primary was so slack that I spent at least 45 frustrating minutes chasing the donut (it was impossible to collimate) before I worked what the problem was. 

I then used some thick/stiff paper which did the trick. 

I used card for the mirror clips.  I suspect that the popular opinion got morphed from a business card to a credit card as business cards fell out of favour.

For the supports round the side I shimmed it out slightly so that it has slightly less freedom.  I got the scope in and left it for 24 hours so the mirror was warm.  Measured the gap at about 2mm with the mirror warm.  Shimmed it down to about 0.5mm whilst warm.

7 hours ago, bosun21 said:

It can prove to be an expensive learning curve. I did the journey in incremental steps before settling on a full set of Baader Morpheus eyepieces and several orthos along with a low power eyepiece. This was a costly mistake and I wish I had just went straight to a quality eyepiece. Once I tried one Morpheus I had found what I was looking for, so I just added another and another over a period of time. This is just my thoughts on the matter, you may have an entirely different outlook.

Managed to spend a bit of time this afternoon looking at FOV and Ernests reviews and the Morpheus is pretty much bob on for what I'm looking for.  Being critical of the FOV, the 15mm uff is a bit too close to my 12mm BST.  The 17.5mm gives me a nice fov that slots in between the 30mm superview/30mm uff and the 12mm BST whilst also being highly corrected which is what I'm looking for in the next eyepiece.

Cheers for making the push for the Morpheus. 

I had a look at some of the other posts discussing the uff eyepieces.  They are quite informative.  There was a link to Ernst's eyepiece reviews where he quantifies the amount of aberration in the eyepieces.  The 15mm seems to be a better performer than the 18mm, although the 17.5mm Morpheus is better than both. The 16mm nirvana is nowhere near as well corrected as any of the others.

I think I need to take my existing eyepieces out and get a feel for what I consider acceptable correction with what I've got already and try to relate that back to Ernst's tables.  I think the 15mm to 18mm would provide a decent framing for a lot of DSO in the dob.

Also need to get a better bead on how I feel about the wider FOV in general.  It's nice for panning about but I'm trying to make a push with my sketching and I found the 82° FOV was quite challenging, especially with the distortion.  I suspect that about 70° is about the sweet spot.

Quite enjoying this mucking about with eyepieces.  It's interesting to see the differences they make to the experience beyond magnification.  Really appreciate the help and feedback.

So having bedded in with the Nirvana 16mm I'm finding that at the edge of view the image quality is quite poor and the stars are pretty out of focus/smeared with my 10" F5 dob.

Is this likely to be something I'm doing, such as my collimation or scope cooling? Or is it just the nature of the eyepiece?  Would it be helped if I tried focusing on a star midway on the FOV rather than dead centre?  I've got mild astigmatism (0.75 diopter) but I'm getting contact lenses to correct this but haven't had a chance to try them out yet so possibly that is a factor.

It's still a great eyepiece, and has provided wonderful views, but sometimes it feels like the outer edge distortion is really apparent for some reason.

I'm currently just playing with eyepieces mostly to figure out what works for me and I was thinking the next would be an ultra flat, initially looking at the 30mm Stellalyra UFF to replace the 30mm superview.  I'm now thinking it might be an idea to try a 15 or 18mm ultraflat instead if anyone has experience of them.  I tend to mostly observe with the 16mm so it does kind of make more sense for comparative purposes.

Feedback greatly appreciated.

1 hour ago, Captain Scarlet said:

Forecast looks good for this evening. First combination of low wind, no Moon and no cloud for a couple of months. So in anticipation:

 

You should post this to that thread asking what nothing looks like.  Pretty sure it looks like the inside of your scope!  That is dark.  What size tube is that monster?

6 minutes ago, bosun21 said:

Yes that’s the one I was looking at as well. I have a cheap one from Amazon that works okay, but it’s shaky and a real pain in the proverbial to align properly.

You can also have it delivered from their Spain warehouse.  Quicker but costs $6 more (I think).  I'm working for the next 2 weeks so expedited delivery isn't critical for me.

12 minutes ago, bosun21 said:

Did you buy it from the US? The ones on Amazon are £90!

Ordered it from their store:

https://www.moveshootmove.com/collections/move-shoot-move-rotator/products/msm-xyz-phone-mount-for-telescope

Free shipping and customs cleared for $69

Would that be the Accuview phone mount?  Hope so cause I just ordered one lol.  The wife is out of the house.  It's easier to ask forgiveness than permission.

Got to say, it was £58 and that seems like a bit of a bargain compared to the NeXYZ.

Been living in fear of you posting about that phone holder and to make matters worse you also used it to take pictures of doubles and a planet!

Looks like I'll be entering prolonged negotiations with the financial controller.  Again.

Cracking pictures.  I wonder could you use the video mode with a phone with stacking software?

Hope you are feeling better soon and glad it wasn't worse.  It still must have been serious, I can tell because you didn't say whether the mount was okay or not 😉.

With any luck it we'll have back to back clouds until you are back out observing.

1 hour ago, Franklin said:

I've got one of those Nadira chairs and it's great, but you're right it does need a cushion!

They're fantastic.  It makes it so much more comfortable.  Not thrilled by the strap arrangement, but it works.

I'd say that an observing chair is so good that I wish I bought one before I went off the deepend with eyepieces.

Did a cheeky wee session at 0400 with the dob. Managed to get M57 and my old favourite M27 in and another quick look at M13.  It was already getting light by this point with it being nautical twilight/dawn and the scope didn't have any time to cool so no sketching.

Not a complete waste though, the views were comparable to the 5" in brightness in ideal conditions.  Bodes well for moving in to summer as darkness becomes a rare commodity.

Also learned that the setting circles are pretty much useless if I don't properly level the dob lol.

37 minutes ago, Paz said:

I drove out to a spot to observe venus this evening. The clouds roll over and I had a Hamlet moment thinking to get back in the car and go home. In the end I set up anyway and had a look through thin cloud.

Clouds can make great filters.  Only filter I've not managed to get a thumb print on too.

1 minute ago, Earl said:

Well the question in my mind, outside of theoretical models does the state nothing actually exist or is there always bit of something be it virtual or not.

 

I'm onboard with this.  Can an observer observe nothing, since in order to observe you must observe with something (em field, gravitational field) which implies the existence of something (the fields themselves).

I'm not sure if nothing makes sense.

As an alternative, if your library does an online thing you might be able to get the digital version for free.  My library uses Libby and I can 'borrow it' each month.  Weirdly they also get Australian sky and telescope but not the regular one.

1 hour ago, wookie1965 said:

How big is your dob and can you post a link to where you got it as I want one for my 10" please.

Mine is a 10" Dob.

I ordered mine from here and bought an 18" Bearing.  I could have got the 19" as the base of my dob is 22" in diameter, however I don't think it will improve performance enough to justify nearly double the cost!

https://www.ebay.co.uk/itm/141742604866

I've not had a chance to take it out and use it in anger yet but it seems pretty smooth.  It moves easily but doesn't do the windmill thing that the standard bearing does and doesnt have that ever so slight rocking thing going on.  @Mr Spock has used ones from simply bearings which he has been very happy with.

https://simplybearings.co.uk/shop/p187448/600mm-Round-Lazy-Susan-Rotating-Aluminium-Turntable-Bearing/product_info.html

I did try teflon (carpet gliders from Wickes rather) without any melamine but it was a disaster.  I did however end up taking two of them without the stick backing and putting them together so the gliders face outwars and putting them in the middle of the lazy susan just loose.  This means when I tighten the bolt I get a wee bit of extra friction so I can change eyepieces without the dob moving but still move it freely.  As I said though, not tested it out yet.

Stunning images Mark.  I really like the stuff you've been doing recently like this and the tracking of the orbits of Jupiter's moons.

Thanks for the feed back folks, glad you enjoyed it.  I might scan and reupload the sketches in a bit as my phone has made them a bit blurry.

Any other newbies out there, I highly recommend you get yourself a couple pencils and a pad of paper and go out and sketch.  Tremendous fun and it's not often you can get so much enjoyment in astronomy with something you get from home bargains!

1 hour ago, jetstream said:

@Ratlet These are excellent sketches, great observing!! Out of curiosity how dark are your skies you think? A 10" dob can be one of the best scopes to have, nice choice.

Gerry

According to Clearoutside, it's Bortle 4.  I suspect looking North it's more towards Bortle 5 as that is more into town.  I keep meaning to do the SQM check with NINA (as well as some acutal astro imaging) however everytime I go out I decide I'd much rather do visual lol.

Forgot to mention that Actual Astronomy Podcast have a great episode yesterday on M51.

https://music.amazon.co.uk/podcasts/9f2f6454-5577-49a2-8744-4ae169f000b3/episodes/8dbc9111-b89d-4e06-82e3-113918799970/the-actual-astronomy-podcast-314---m51-with-alister-ling?ref=dm_sh_7Qtj2dpqPKjE3MzXStPMilBeH

Bit lastminute with this session.  I'd tried fitting furniture sliders on the dob earlier in the day but they didn't really work well and I couldn't get them off.  Made small adjustments challenging, but probably save the session as there were some strong gusts.  

I did a 1 star alignment on Arcturus with my 10" Stellalyra Dob and set both my altitude and azimuth on my setting circle and inclinometer.  This was sufficient for the whole session and everything ended up in the FOV of my 16mm nirvana.

Seeing was initially poor, or the scope hadn't cooled sufficiently (M3 looked atrocious) but after a while it was acceptable.

I started of with sketching M63 I have no ide what it was supposed to look like before this.  It was quite nice though.  Not too happy with the star placement, but it was a bit of a learning process with the dob.

Next up was M94.  This was very nice to sketch.  The core was quite bright with fainter nebulosity extending out from it.  Not quite as bright as my sketch shows but pretty bright.

Finally I moved up to M51.  I had checked it out earlier but the seeing wasn't up to it.  It was much better by just before midnight.  I couldn't say for absolute certainty that I saw the bridge between the two galaxies but it might have been popping in and out.  I need to have a bit of a dig as there was something bright to the left of the core but I'm not sure if it was a field star or what.  I managed to see some of the dark lanes which I was well chuffed about.

It was getting late and cold so I thought I'd have a look at M92 maybe do a sketch of it.  Immediately decided I just don't have the skills.  It was incredible.  It was noticeably not circular which I found surprising.  Bright chains of stars sort of wandering to the centre and dark areas in between.  Just stars upon stars.  Where there isn't stars there is granularity like gubby sugar grains on black.

Based on this I cast my eye at M13 which was one of the first objects I observed.  From my memory of it last year in the 130pds, it might have been a different object entirely.  Incredible.  Faint fuzzy is not how I would describe it at all.  I think M92 might be the nicer of the two in a larger scope though.

I concluded with M3.  This was a great idea as the view was much better than earlier.

A fantastic night.  Globular clusters are incredible.  I think taking in the 3 of them gave me the best idea of the benefit of the bigger dobsonian compared to the 130pds.  Sure faint things get a bit brighter, but the resolving power with the bigger tube just transforms globs into totally different beasts.

Lazy Susan bearing for the dob.  Tried tefom pads, well furniture sliders but it was way too stiff.

Also contact lenses so no mor passes on and off.

An unexpected treat.  Met office had it clear after 2200.  Setup but seeing was pretty poor.  Improved massively as the night went on.  Sketched M51, M63 and M94.  Got a good look at M92, M13 and M3.  Lack the skills to know where to begin trying to sketch them!  M92 was phenomenal, a literal WOW! Moment when I looked through they eyepiece.

I know people go on about the aperture of dobs being great for nebulas, but on globs it puts them into another realm of existence.

1 hour ago, Zermelo said:

... but with eypieces that already have generous eye relief, adding a Barlow may test your "floating" skills, hence the telecentric.

Not likely to happen on the Svbony zoom, though.

My 32mm plossl has spades of eyerelief.  Took me a couple sessions to figure out why I was struggling to use it sometimes (glasses off Vs glasses on putting my eye in the perfect place).  Tried it in a Barlow once and gave up.  Needed to put my head in next doors kitchen.

Keeping on topic, I used the 3-8mm with my BST Barlow and it Barlow's very well.  I get reflections (from eye to eyepiece) with my 8mm BST in the Barlow but the svbony didn't have that and the image quality was just as good with the Barlow as without on the zoom.  In both cases it absolutely stomps over the starguider.