Help with star hopping

[popeye85]

So but I'm still a bit bamboozled about how to find out the afov.

[Stu]

45 minutes ago, popeye85 said:

So but I'm still a bit bamboozled about how to find out the afov.

That's actually the easy bit

Eyepieces always have three specifications, the focal length, the afov and the eye relief.

A plossl for instance will generally have 50 degrees afov, a Panoptic 68 degrees, a Nagler 82 degrees and an ethos 100 degrees.

As has been said, divide the afov by the magnification and you have the actual fov. As Shaun mentions, using the field stop method is more accurate, but the field stop spec is not often quoted so using afov is easier, and generally accurate enough.

[Ruud]

Much of this thread (at least my contribution) may be based on a misunderstanding. You see, when I read the title "Help with star hopping", I thought the OP was asking about finding targets in the sky using the old-fashioned way, like it was done before GoTo telescopes existed. 

This of course involved maps and true field of view circles. But why would popeye85 be interested in that? He has a GoTo telescope! So, in retrospect, I think Popeye wants us to do suggestions about nice targets to find with his GoTo, for a good night's observing.

Am I on the right page now, popeye?

[popeye85]

11 hours ago, Stu said:

That's actually the easy bit

Eyepieces always have three specifications, the focal length, the afov and the eye relief

Ah of course! Look online! What else? Think I might finally be getting to grips with with it all! Thanks for the help!

8 hours ago, Ruud said:

This of course involved maps and true field of view circles. But why would popeye85 be interested in that? He has a GoTo telescope! So, in retrospect, I think Popeye wants us to do suggestions about nice targets to find with his GoTo, for a good night's observing.

Am I on the right page now, popeye?

Almost Ruud!

I do have a GOTO but me thinks it would be no bad thing to learn 'the old skills'! Which as you say involves maps and FOV circles. I'm also getting a Dob in a couple weeks so will need to know how to star hop for that.

[popeye85]

On 23/10/2016 at 15:41, N3ptune said:

 

To the right, the infos to roughly measure with the hand pointing the sky really useful to memorize.

The text is impossible to see for the right part but the distances are: 1 - 5 - 10 - 15 - 25 degrees, with the arm extended towards the sky.

Basic theory on Degrees minutes and seconds, (just in case)

http://zonalandeducation.com/mmts/trigonometryRealms/degMinSec/degMinSec.htm

Sorry n3ptune! Don't know how I missed this earlier!

Think I have seen this beforeHow accurate is it?

[N3ptune]

@popeye85

Hello! I would say it's accurate enough for the little things I have to do.

For example, I have high trees on the side of the house,  can use the hand technique to measure the angle from the floor to the top of the trees then check on Stellarium if the item I want to see will be above or hidden behind the trees. (Using a compass also and it's working fine)

For the eyepieces, knowing the TFOV of them all and being able to take rough measurements on the paper atlas, I can anticipate which bright stars will be visible on the EP.  For example in Lyra, I know with my 2" will almost show both Sheliak and Sulafat. Now that these 2 are located at the edges, also know the ring nebula is hidden inside the same FOV no doubt about it. With harder to find objects I always end up measuring things. (It's working so far)

That's the fun part of the whole process, getting good at searching for stuff and memorizing the sky.

(;

[popeye85]

Next choice  to be made is wether or not I get a finder scope, at the minute I have a telrad and just got a ep which should get me a 2° FOV, money's tight at the minute so hesitate at having to fork out another £60 for a finder. 

[Stu]

1 minute ago, popeye85 said:

Next deacon to be made is weather it not I get a finder scope, at the minute I have a telrad and just got a week which should get me a 2° FOV, money's right at the minute so hesitate at having to fork out another £60 for a finder. 

Hmmm, spellchecker playing havoc with your post?  

[popeye85]

Tee hee! Oops, sorted now, should make a bit more sense!

[Floater]

The Telrad should be enough, I think. It's a finder tool. (Although I don't have one so ready to be corrected.)

No need to splash out cash unless you have a specific requirement that the Telrad doesn't satisfy.

[StarryEyed]

Popeye85

I will add this. I personally find having the telescope in AZ much easier to star hop with than EQ. When I use my mount in EQ mode the eyepieace can get rotated which can make working out star fields a bit more trick as they can be mirrored flipped and rotated. I also like to set it up in AZ mode by lower the elevation on it to zero. Its an EQ5 so I turn the drives of like this.

SkySafari is your friend you can add scopes and eyepieces at the very bottom of the settings menu under equipment you just need to scroll down that list. It will work out the field of view for you just entrer all the numbers for telecsope and eyepieces.

Cartes is great but at the scope a smartphone or tablet is much more practical.

Just remember than even though you need to take some time finding things by start hopping you are still looking at the skies and I cant tell you how many times I saw something I never expected that was a surprise whilst I was star hopping.

Most importantly stay relaxed.

regards.

[popeye85]

Starryeyed- great post. I totally see where you are coming from regarding the new vs alt-az, lucky I am using a Dob so don't have that issue but it prices how many factors to take into account.

I have sky safari on my phone which I use but can't seem to find the function with ep's. I have the v4 so it might not be available on that one-still a great wee all though.

On a side night I have been trying to get a answer to the question about whether it not you can bring up telrad circles on the app version of stelarium. Can't seem to find it.

[billyharris72]

When using  a finderscope with a printed atlas I find it helps to know the field of view and to cut a circular hole of the correct size in a sheet of paper or card. Helps to frame the map and give you an idea of what you are expecting to see.

[Davesellars]

It's easy to star-hop using an EQ mount.  Just use the equatorial lines on the star atlas.   SkySafari and a RACI along with a RdF or Telrad to point to the starting point is a great combination.

[StarryEyed]

Popeye.

I have sky safari 4 pro.

Under settings scroll down to equipment. see image. in there is were the settings are assuming you have them. For what its worth you could upgrade to a full copy of sky safari. which when you can pick up a windows 7 inch tablet for ￡60 I also use one of these for image capture for a DSLR webcam and charts. 

You have options.