Eyepieces (eventually for DSLR)

[bishbosh]

Hi,

Apologies in advance as I am only just starting out, so bear with me if I can't explain myself very well.

Since getting my scope a month ago I've sadly only had occasion to use it a few times because of the lack of clear nights recently. However I did finally manage to successfully polar align my scope - Polaris was following the circle in the reticule nicely and I managed to do a 3 star alignment.

Anyway, the first question: what do people use to accurately centre an alignment star in the telescope? I only have one eyepiece at the moment - a Skywatcher 28mm LET which doesn't have crosshairs, the finderscope has cross hairs though. I think I've aligned the finderscope to the telescope but I'm assuming it would be better to accurately align the scope to the star, or does it not matter too much for GOTO purposes?

I guess I have the beginner mentality of wanting to view everything in the heavens, nebulae, planets, DSOs, etc

My next question is more of a i'm-not-sure-what-I-should-do-as-I-don't-want-to-waste-money type. My scope is a SW Explorer 200pds on a HEQ5 Pro mount, I could have bought a lighter mount but I knew I would want to be imaging at some point so did not want to have to trade in a mount in the future for one that would be more suitable. I also know my shortcomings and did not want anything too complicated either, therefore the HEQ5 Pro sits nicely with me and I haven't really had any issues using it.

At some point I would like to add an eyepiece or 2 to my collection. Although this is where I stumble. At the moment I am mainly a visual observer but would like to do imaging in the future with my Nikon D7000 - I've been looking at the Baader Hyperion/Morpheus line as they allow a DSLR to attach to the EP. For deep sky stuff I know I can attach the camera to the focusser directly. I like the fact that the Baader line allows a camera to be attached. It's probably a case of you get what you pay for but I wouldn't want to buy something ok-ish and then have to upgrade later if I outgrow it, with my Nikon, I bought decent lenses as and when and I've yet to feel I've outgrown them. I suppose I just don't know what the upgrade path would be, am I better getting a decent EP first, maybe a coma corrector later? I just don't know.

Sorry for the essay, any info greatly appreciated.

Dave

[laudropb]

Hi Dave. It is not usual to have a crosshairs in your eyepiece. They would rather get in the way of the view. It is possible to buy eyepieces with cross hairs or reticules but these are generally used for specialised purposes rather than viewing.

I am a purely visual observer, but as far as I am aware you do not attach a DSLR to an eyepiece. Imaging with the eyepiece in the telescope is usually done afocally and the camera is not attached as such.

[Pompey Monkey]

I am a purely visual observer, but as far as I am aware you do not attach a DSLR to an eyepiece. Imaging with the eyepiece in the telescope is usually done afocally and the camera is not attached as such.

Eyepiece projection (afocal) is perfectly feasible and adapters are made and sold for the purpose. I am thinking to try it myself next year when Jupiter rises at a more civilised hour

http://www.firstlightoptics.com/baader-planetarium/baader-hyperion-eyepiece-t-adaptor-m43-t.html

[salas]

Firstly you've made a good choice with the HEQ5 which has helped "future proof" if you get in to imaging.

I don't have any experience attaching my camera to eye pieces but generally imaging is carried out by most folks at prime focus, which involves attaching the camera directly to the focuser. It seems counter intuitive when you want to get as close as possible to what you want to see, but for galaxies, clusters nebulae etc, this is the best way to do it - you get a wider field of view which is necessary.

You do get illuminated eyepieces with a cross hair, these are usually about 12mm. I had one for imaging thinking I would need it but eventually realised I would be using my camera and software to centre on my target.

I may be complicating things, but have you thought about using a lap top running Stellarium or similar connected to your mount to take you to your targets? You have the mount for it. I personally couldn't be bothered faffing about with the HEQ5 "Pro" hand held unit and went straight for a basic HEQ5 with Stellarium controlling the mount via a laptop and USB cable.

Just do your research before you buy stuff, but if you buy anything you find out you don't need you can sell it on without too much loss. Astro stuff seems to holds it price pretty well.

Cheers,

Steve

[John]

You can go wild on eyepieces.   Since you only have one I would suggest a zoom and a 2X barlow for now.

I just purchased the Celestron 8-24 Zoom.  LOVE it!  FLO does not seem to carry it.

http://www.amazon.co.uk/Celestron-1-25-inch-8-24mm-Eyepiece-x/dp/B0007UQNV8/ref=sr_1_1?s=electronics&ie=UTF8&qid=1449085368&sr=1-1&keywords=celestron+zoom+eyepiece

And a 2X barlow - doubles the magnification of any eyepiece.

http://www.firstlightoptics.com/celestron-eyepieces/celestron-2x-universal-125-barlow.html

I've just sold one of those Celestron Zoom's. Optically it was quite good for it's price but it struggled at F/5 which is what the original posters scope is. When I say struggled, I mean that there was quite a bit of distortion of stars in the outer 50% of the field of view. Not surprising for a low cost eyepiece perhaps but it's there none the less.

Incidentally these Celestron Zoom's are the same as the Skywatcher 8-24, Seben 8-24 and a number of other brandings. I'm not knocking them because for under £50 you can only expect so much but it's worth being aware of their limitations in faster scopes.

Mind you, Hyperions are also mentioned by the OP which are also none too well corrected at F/5. The Baader Morpheus also gets mentioned and those are a lot better I'm sure. For which you pay of course !

I still feel that the general rule of thumb holds good:

Wide Angle / Low Cost / Sharp across the field in fast scopes = pick any two

The ES Maxvisions are perhaps the nearest I've used to breaking the above mould though.

[Ruud]

If you defocus an alignment star so that it becomes a nice large circle of light you can centre it with ease.

Try it. You'll find that you won't need an eyepiece with cross hairs.

[Owmuchonomy]

I purposely bought Baader Hyperions so that I could attach my DSLR directly to the EP. This set up works well for long focal length work on planets. It is extremely easy to set up. Examples of the results can be seen on my Flickr page. It is also the only way I can currently capture solar images with my Lunt 50. If you wish to do shorter focal length imaging of DSOs then you attach the DSLR directly at prime focus without an EP.

[YKSE]

I totally agree with your "pick two". 

My total experience with this eyepiece is an F5 refractor and an F6 reflector scope.   As you zoom to shorter FL you do get a dark area around the edge which could be described as distortion. 

The darkening around the edge is called vignetting, all zooms suffer this (to a different degree though) because of moving field stop, even some fix-focal eyepieces vignette too (milder than zooms).

I would like to think that more appropriate terminology for distortion mentioned about is aberration, even though the word distortion feels right in beginners ears. Here's a link about common aberrations we see through a eyepiece:

http://umich.edu/~lowbrows/reflections/2007/dscobel.27.html

My guess is that stars will be crossed in the outer field(astigmatism) in a f5 scope with the zoom when proper focused, it's more obvious with brighter stars.

[bishbosh]

Thanks for all the comments, they are appreciated. I should add that I also wear glasses so EPs with a decent amount of eye relief would be beneficial.

@ruud, that's a good tip about defocussing a star to centrally locate it in the EP, that hadn't occurred to me, I shall try that.

@Ed, thanks for the video, just been watching it now. Yes, I did think about the Baader zoom, will keep that in mind.

In the meantime, as I don't want to rush into buying anything too soon, I've since found a neighbour down the road who is into astronomy, he has offered to lend me a couple of EPs to try out - this should give me an idea of what is available. 

I have Stellarium on a laptop, but I haven't yet thought about using it to control the mount. That might be something to consider - at the moment though I'm just getting used to the SynScan handset - there's so much to learn!!

I'm just waiting for a clear night, possibly around midnight tonight - I want to get out there!

[baggywrinkle]

For their money, the Baader are good and as has been pointed out there are a complete rnage of spacers and adapters for them. I have used them with my Canon650D with reasonable results.

They are big ep's so once you add the length and mass of a camera you need to watch for balance and flexure. If things are not firmly (but not overtight) screwed together flexure will creap in and add to focus issues.

The 8-24 zoom is very good but at higher powers below 12mm setting the outer 80% of the FOV through a camera shows distortion.

Welcome to SGL.

[LukeSkywatcher]

I have the Baader 8-24 zoom and love it apart from the 8mm which i think is a bit soft on focus (so i use a separate Vixen NPL 8mm EP for observing planets). 

Baggy~nice bodhran you have there. Do you actually play or is that just a tourist photo of you posing with one?

[Yearofthegoat]

I have Stellarium on a laptop, but I haven't yet thought about using it to control the mount. That might be something to consider - at the moment though I'm just getting used to the SynScan handset - there's so much to learn!!

I'm just waiting for a clear night, possibly around midnight tonight - I want to get out there!

I've only just got round to setting up my HEQ5 Pro with Stellarium via EQMOD and the requisite serial-to-USB cable.  It works fine* but took a bit of computer faff to get it going. When (note the positive outlook!) the clouds clear I'll be sticking with my Synscan handset for now.

I found that once I'd done a 3-star alignment, putting the star in the middle by eye, the GoTo accuracy was good enough, certainly for visual, and found subsequent objects absolutely fine.

Good tip above about de-focussing the star to put it in the middle - hadn't considered that!

The 28mm LET is okay, but loses quality at the edges. That said, I use for 'orientation' as I'm not great at recognising the stars etc. yet,  I since got a 15mm BST Starguider which is great, and a 3.2mm which is perhaps a bit short but I got great (stunning really) views of Jupiter with it back in Feb in the freezing cold! Both EPs are fine with glasses (I'm shortsighted to about 6 diopters).

Hope you get clear skies soon - it's overcast here darn sarf at the moment

(*Apparently there is an issue with clock timing in Stellarium - search for 'BIOS clock' but AIUI that's more important for imaging/tracking - there are others on here who are better placed to comment on that).