Observation report 13/08/18

[Dave1]

Well what can I say, the night sky never ceases to amaze me. Even when the seeing is bad, maybe I'm easily pleased? 

So I set up my Skylight 4" F15 telescope tonight. With the intention of primarily viewing Mars. To begin with I viewed Saturn. And oh dear seeing is not good at all. I'd say a 4 or 5 on the Antoniadi scale. So I viewed Saturn for quite a while. I could at times just make out the Cassini division, I could barely make out the equitoral band. I could see the shadow of the ring on the sphere. 

So Mars made an appearance. The conditions whilst viewing Mars were worse than for Saturn. I could make out dark patch very occasionally which were probably a mare. 

Tonight I decided to look at some double stars, whilst I was waiting for Mars to show. I looked at and split easily for the first time The Double Double, which I was very excited to find, as up until now for some reason it had eluded me. I then looked at the double star Almach, which I think is very pretty, nice colour combination. I then went looking for the Wild Duck star cluster. Which I didn't find this time, but hopefully will next time. 

Dave

[Paz]

Nice report, you will enjoy M11 the wild duck cluster when you do see it.

[Kn4fty]

A bad night of observing is still better than a good day at work!

Congrats on the double double. 

[Knighty2112]

Nice work Dave. Good report.  

[Demonperformer]

Nice one, Dave. Have to agree about Almach.

[Stu]

Good session Dave. The planets are certainly challenging this year, but glad you managed the Double Double, an old favourite that I often return to.

M11 is great, I'm sure you will track it down sooner or later

 

[Dave1]

Thanks everyone. Finding objects with my telescope is quite hard, especially as the finder scope is really a small 40mm telescope with a very narrow field of vision. 

Most of the time I just look down the skylights long body and point to where I think an object roughly should be, then check the eyepiece. My finder eyepiece is a GSO 32mm plossl. To help me on my double star and star cluster quest I have ordered a 2" eyepiece which is 50mm 52° field of vision erfle. Which will make a huge difference. 

Dave

[Special K]

9 hours ago, Dave1 said:

Thanks everyone. Finding objects with my telescope is quite hard, especially as the finder scope is really a small 40mm telescope with a very narrow field of vision. 

Most of the time I just look down the skylights long body and point to where I think an object roughly should be, then check the eyepiece. My finder eyepiece is a GSO 32mm plossl. To help me on my double star and star cluster quest I have ordered a 2" eyepiece which is 50mm 52° field of vision erfle. Which will make a huge difference. 

Dave

Good report Dave!  I'm curious what mount you're using as I can't see it listed in your equipment list. In reading the list I could see that all your scopes are very long focal ratios which are great at magnification but restrict field of view. I'm not surprised you could be having trouble landing on targets if you are eyeballing it.  I do the same with my large frac, so I'm not being critical!  Using the f/5.9 scope with a low power, wide field EP, I have about 3 degrees to play with and can land in the vicinity nearly all the time. But at high mags this can get tricky, and I'm assuming this is equivalent to your situation. 

There are quite a few options to help find targets easier, such as a really wide angle EP of 82 degrees or more for finding objects and would also come in handy for large objects. There's also the Go-to mount option.  I'm an old timer who insists on finding stuff by star hopping and blundering around in the dark, but the electronic option is always there!  I use an equatorial mount which makes hopping at high mags easier for me, which is why I ask about your mount.  Also, if the finder scope is too narrow, you could get something wider to work with.  Finders should generally be giving you about 5 degrees TFOV which should be more than enough for dead reckoning. Of course there are more sophisticated finders like a Telrad!!!

[Dave1]

Hi special K, 

Like you I like to try and keep things low tech. I started off with manual equitorial mounts, which didn't take me long to set up as I aligned them to magnetic North. Which is more than good enough for visual, and super quick to set up, that way. 

I much prefer azimuth mounts. So I currently have a Altair Sabre V2. Which is buttery smooth, especially since I greased it on the azimuth axis. Admittedly my 4" F15 Skylight really pushes the Berlebach and Sabre to its limits. I don't think it's the mount more the tripod, I have a few ideas to try to improve it. I have given goto series consideration I might bite one day. 

Because all my other smaller long focus telescopes have proper finder scopes on them it's not as bigger problem. The 4" Skylight came with the original finder scope which isn't a finder scope, it's really a small 40 mm telescope. With a focuser, diagonal, and changeable eyepiece even, even though the eyepieces are proprietary. I'm reluctant to change it, as I would have to use a different mounting strategy. And I want to keep it original as its the first 4" F15 Richard of Skylight telescopes built. So collectable. 

Ah yes I spent a good while yesterday comparing rich field eyepieces. My criteria was it had to be an eyepiece that was fairly cheap, as it will only by used as a finder eyepiece. The eyepiece had to be designed when long focus achromats was one of the telescopes that reigned supreme. So that I had an eyepiece that was optimised to that telescope design. It also had to have a wide as possible field of vision. And maximum light transmission, so minimal amount of glass. It also had to give me the biggest exit pupil possible. 

So that left me with the classic ERFLE eyepiece. 

Below is a chart showing the Peleides. 

The red line is a TS rich field erfle 50mm 52°.

The green line is a OVL 2" aero ED SWA 40mm 82°.

The yellow line is a Explore Scientific 82°series eyepiece 30mm 82°.

As you can see the TS Rich Field erfle has the biggest exit pupil. Which is why I went with that eyepiece. 

[Special K]

Hi Dave, I'm amazed by the TFOV of that ERFLE compared with the other EP's and it frames the Pleiades very nicely!  Thanks for posting the comparison.  The mount sounds much nicer than mine ?  I only use the AZ4 on my travels but have thought once or twice about a sabre or Giro so that I can get the ED80 into play.  However, with my F/5.9, I think I'd rather have one of your f/15's as the twin as they can really zoom in!  Happy hunting!

[Dave1]

On 15/08/2018 at 19:11, Special K said:

Hi Dave, I'm amazed by the TFOV of that ERFLE compared with the other EP's and it frames the Pleiades very nicely!  Thanks for posting the comparison.  The mount sounds much nicer than mine ?  I only use the AZ4 on my travels but have thought once or twice about a sabre or Giro so that I can get the ED80 into play.  However, with my F/5.9, I think I'd rather have one of your f/15's as the twin as they can really zoom in!  Happy hunting!

Hi SpecialK

Yes I thought the picture showing the TFOV might be of help. I think the ERFLE gets as good as it gets for long focus refractors. 

Well I must admit the Altair Sabre is pushing the limits of grab and go. Especially if still attached to the Berlebach tripod with counter weight. The Sabre would easily be able to handle an ED80 telescope. For grab and go though I'd choose the giro, much lighter I think. 

Aye long Fracs can sure zoom in alright