Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_imaging_challenge_banner_30_second_exp_2_winners.thumb.jpg.b5430b40547c40d344fd4493776ab99f.jpg

Recommended Posts

Having been sorting out my perfect travel scope for some time, I looked at what other people decided to go with and nearly everyone, it seems, goes for a small refractor. Why?
I have settled on a Celestron C5, ( even though I was considering a small refracotr too at first, ) which is light; very compact; seemingly robust and has a larger useful aperture than a small refractor. So why do most seem to go for the small refractor? I know it has a larger field of view than a SCT, but I can step the C5 down to F 6.3, which gives  what is too me a decent field of view, so I am finding it hard to understand. I have been very impressed with the C5 so far and do not regret it's purchase at all. 

I am sure I will get a small refractor at some point, when I can afford it that is, because I will have to spend a lot more than I did on the C5, to get a similar, or better performance. So what am I missing? ?

I will not even mention a Mak option here...

  • Like 2

Share this post


Link to post
Share on other sites
4 minutes ago, Greymouser said:

I can step the C5 down to F 6.3

I'm sure this is elementary - how is this achieved?

Share this post


Link to post
Share on other sites
Posted (edited)
7 minutes ago, iPeace said:

I'm sure this is elementary - how is this achieved?

The Celestron f6.3 focal reducer/field flattener as shown below... and attached to my 're-modded' ETX105...

PIC025.JPG.cefae6dd0a831f1a44b582b1544d904c.JPG

Edited by Philip R
  • Thanks 1

Share this post


Link to post
Share on other sites

The description mentions that the focal reducer is for imaging. Do you use it for imaging, or (also) for visual? If for visual, does it affect the quality of the views at all?

I'm not at all knocking your perception of affairs, just thinking along the same lines...if this works without drawbacks, surely we all should...

:happy11:

Share this post


Link to post
Share on other sites
Posted (edited)

I have not yet ventured into the " darkside " and use it for visual only. Until I win the lottery that is and can afford to do imaging properly! So many of the images here put me off joining such a steep; expensive and difficult learning curve. Not to mention my light polluted skies and lack of opportunity to travel at the moment to truly dark skies.

On my C9.25 the view is improved with the reducer, over no reducer, which I found odd to be honest... ?

Edited by Greymouser
  • Like 2

Share this post


Link to post
Share on other sites
Just now, Greymouser said:

visual only

Excellent.

1 minute ago, Greymouser said:

On my C9.25 the view is improved with the reducer, over no reducer, which I found odd to be honest... 

Well. Fascinating. Never tried an SCT. Did the Mak thing for a short while. Now it's refractors and newts. Will follow with interest.

?

  • Like 1

Share this post


Link to post
Share on other sites

The F/6.3 focal reducers work well for visual observing. I used to use on with my C5 and later with a C8 SCT. There is a more extreme reducer that takes the focal ratio down to F/3.3 and that one is for imaging only.

 

  • Like 1

Share this post


Link to post
Share on other sites

I went for a small refractor as a travel / grab and go scope simply because it is quite a bit smaller and lighter than a C5, it's not prone to dewing (a dew shield adds to the SCT package size) and the cool down time is very fast. Nothing wrong with C5's though - they are small and capable. NASA used to take them up to the ISS so they must be OK  :icon_biggrin: 

 

  • Like 3

Share this post


Link to post
Share on other sites

Various reasons for me. I prefer the star images through a refractor, and also love observing with a widefield (3 or 4 degrees) for scanning the Milky Way or taking in the Veil or NAN for example.

I've taken refractors around all over the place and guess I just enjoy the simplicity, minimal cool down and less dewing.

Nothing wrong with your choice though, a little more aperture helps with resolution and if you enjoy it, that's all that matters!

  • Like 4

Share this post


Link to post
Share on other sites
Posted (edited)
2 hours ago, John said:

I went for a small refractor as a travel / grab and go scope simply because it is quite a bit smaller and lighter than a C5, it's not prone to dewing (a dew shield adds to the SCT package size) and the cool down time is very fast. Nothing wrong with C5's though - they are small and capable. NASA used to take them up to the ISS so they must be OK  :icon_biggrin: 

 

Smaller and lighter than a C5? My C5 weighs in at about 2.36 KG and is about 30 cm long, both without diagonal or eyepiece. Though I am aware that  refractors are narrower. The Astrozap dewshield wraps around the OTA. which seems to take up little extra space, or weight.
But OK, I get where you are coming from, but is your tiny refractor better than the extra aperture? I am not arguing, I am trying to understand. Also how much did your refractor cost, if you don't mind me asking?

@Stu I guess I need to get a look through a decent refractor now, just to see how different the view is. I suspect it is mostly just preference, unless I want to spend a huge amount of money on a 4" apo, but perhaps I am just justifying my decision. As you say I do like it so, it is all good. :icon_biggrin:

Edited by Greymouser
  • Like 1

Share this post


Link to post
Share on other sites

My travel refractor cost around £200 pre-owned. The scope weighs 1.6kg and the travel tripod / mount around 1kg. The whole lot needs to be able to be fitted into a smallish soft bag for minimal impact on our travel baggage.

A C5 will show fainter objects and more resolution of course but my little refractor will show a 3 degree true field and go up to 150x which is the sort of versatility that I find useful when under other skies.

I don't do serious observing when on holiday - my other half would get annoyed because I can do that at home !

 

 

 

  • Like 1
  • Thanks 1

Share this post


Link to post
Share on other sites

Another quick thought - I can use my Herschel wedge with my refractor for white light solar observing which is often a nice way to spend some daylight time on holiday. An over the front end Baader film filter or similar would be needed for an SCT of course.

 

Share this post


Link to post
Share on other sites

I've often taken a 127 Mak on holiday when we've been driving.  I guess that's much the same size as the C5.  Last year when we were going on an aeroplane however, I took a TS 72ED because I could easily fit it along with everything else I wanted into my hand luggage with room for plenty of padding.

We're driving again this year, and I'm not sure which I'll take.  If there's room in the car perhaps I'll sneak both in when my wife isn't looking :D

James

  • Haha 2

Share this post


Link to post
Share on other sites
Posted (edited)
4 minutes ago, John said:

An over the front end Baader film filter or similar would be needed for an SCT of course.

That is something new to me, I was told elsewhere not to try using a SCT for solar observing. Everyday a school day I guess. :icon_biggrin:

@JamesF I did consider the 127 Mak, but it is a little heavier and takes even longer to cool. I will be driving mostly with it, or maybe backpack if I can get past a couple of problems, but certainly whilst driving, I like your idea of getting both and sneaking both into the car! :biggrin:

Edited by Greymouser

Share this post


Link to post
Share on other sites
3 minutes ago, Greymouser said:

That is something new to me, I was told elsewhere not to try using a SCT for solar observing. Everyday a school day I guess. :icon_biggrin:

I see no reason not to.  More recently I've used my ST120 and a wedge, but before that I used to use my 127 Mak with a Baader film filter over the front.

You can't use a wedge with an SCT or Mak that I'm aware of though.

James

Share this post


Link to post
Share on other sites

I’ve used solar film at the front of my Mak. It’s fine but compared to a wedge, no comparison.

Steve 

Share this post


Link to post
Share on other sites

An interesting thread with many excellent comments. I suppose when it comes to travel you can base the discussion on two areas - UK and Aircraft travel.

I owned a Celestron 5" SCT and it was an excellent lightweight scope and it had the 6.3 reducer to obtain a wider FOV. I had an Orion glass solar filter which gave excellent visual and photographic performance and in fact the images it produced was part of the winning video produced for the ESA competition for the 2004 Venus Transit.

If I was choosing a scope to take on holiday using an aircraft I would take a small refractor mainly for a wider FOV but also to use as a solar scope. Using a Herschel Wedge would be so convenient.

My main travel grab and go scope is a Heritage 130P but its disadvantage I cannot undertake solar viewing.

So in conclusion nothing wrong with C5 for travel and together with a solar filter, dew shield and a 6.3 reducer covers must observing requirements.

IMG_4493.JPG

  • Like 4
  • Thanks 1

Share this post


Link to post
Share on other sites

I've had several C5s over the years (all C5+ versions), and have fond  memories of a fantastic three weeks in Crete with a C5+.  This was in May 1995, blimey, 24 years ago!   My love affair with this scope lasted for many years off and on.  I can remember how good the three spokes of the Triffid Nebula looked in my C5+, much better than most view I'd had in UK skies at that time with larger telescopes

Now I use a small refractor  for grab and go and travel.  Mainly for the reasons others have mentioned, better optical quality (an apo) wider field views, robustness, takes less room and is easier to mount, easier solar viewing  etc.    I'll always have a soft spot and fond memories of all those C5+s I had the pleasure of using though.  :smile:

  • Like 1

Share this post


Link to post
Share on other sites
Posted (edited)
14 hours ago, Greymouser said:

 

@Stu I guess I need to get a look through a decent refractor now, just to see how different the view is...

At your peril. When I did that, and it was in fact @Stu‘s refractor I looked through, I ended up subsequently considerably poorer? 

Edited by Captain Magenta
  • Haha 3

Share this post


Link to post
Share on other sites
Posted (edited)

I've used a Skymax 102 and an ST80 as travelscope (in fact they are my onlyscopes 😀) and they both worked fine. The ST80 is easier to use and seems to gather just about as much light as the mak, but it comes down to why you are traveling. For example, I went south for the Mars Opposition last year, so naturally i took the mak (and instead it gave me great view of the Rosette Nebula, while Mars itself was hidden by the huge dust storm 😡). If I am going to a dark location, I'll take the ST80 as I need the wide FOV to find anything. I'd like to have a C6 for traveling though 😮

Edited by Ags
  • Like 1

Share this post


Link to post
Share on other sites
On 08/05/2019 at 12:51, Greymouser said:

Having been sorting out my perfect travel scope for some time, I looked at what other people decided to go with and nearly everyone, it seems, goes for a small refractor. Why?
I have settled on a Celestron C5, ( even though I was considering a small refracotr too at first, ) which is light; very compact; seemingly robust and has a larger useful aperture than a small refractor. So why do most seem to go for the small refractor? I know it has a larger field of view than a SCT, but I can step the C5 down to F 6.3, which gives  what is too me a decent field of view, so I am finding it hard to understand. I have been very impressed with the C5 so far and do not regret it's purchase at all. 

I am sure I will get a small refractor at some point, when I can afford it that is, because I will have to spend a lot more than I did on the C5, to get a similar, or better performance. So what am I missing? ?

I will not even mention a Mak option here...

To go back to why?

I would suggest the the main reason for small refractors is that they rarely require collimation - alignment of mirrors and optics.

For SCTs and reflectors as they get jostled around the mirrors move slightly.

Do you need to collimated - if you look at a star with high magnification eyepiece and bring it slightly off focus, you will see s series of rings (Airey disks)  - if these are concentric, you are fin, i the centre of off set you are miscollimated.

A couple of reference:

https://garyseronik.com/a-beginners-guide-to-collimation/

https://www.ozscopes.com.au/guides/telescopes-guide/caring-and-collimating-your-telescope

 

  • Like 1

Share this post


Link to post
Share on other sites
On 08/05/2019 at 22:04, John said:

the travel tripod / mount around 1kg.

Wow! Could you tell me the make and model of this little setup please, that sounds great? Also, I guess would it take the weight of a C5? If so I wonder just how light I can make my setup? 

@Mark at Beaufort I am unlikely to need to take a scope on a plane any time soon, so car or backpack are the only considerations, hence I had more choice I suppose. I did not even know that Orion made a filter, never mind a glass one. I was assuming the baader film was the best available, or better yet the wedge. I was toying with the idea of getting a wedge, but know so little about solar observing, except back in the day with my first little scope: a 50mm Greenkat and projection. I did also use the dreaded little eyepiece solar filter that came with it too. ( Yes I know, but I was only young, about 8, so there... ) I was surprised that some scopes still come supplied with this, why are they allowed to be sold? I got away with it as a kid, but they should probably be banned. 
I have so far kept my ST102, because of the thought of getting a wedge to use with it, at least until I can afford a better Refractor. How good would a wedge work with a ST102?

@Captain Magenta I doubt I will be bumping into Stu anytime soon, ( probably a good thing since he is obviously a scope pusher! :shocked: ) but it was always my intention to get a decent refractor, but as money is not as good as I would wish at the moment, I considered the C5 to be a cheaper option, especially when considering performance. I will get something like Takahashi FC 100 at some point, I have heard such good things about them, but they were just too expensive for now, 4 times + the price of a C5, never mind being quite bulky, so not sure about how mobile. Before I got my C9.25, I was considering the Skywatcher 150ED, but that is in now way a travel scope! Even less so than the C9.25.

@iapa The collimation on my C5 seems to be spot on in fact, No fettling needed so far, but I am sure that could change. In fact it is very sharp, sharper than my C9.25, which means now I will have to check to see if that needs collimating, next time I get it out. I cannot compare the C5 to a Tak or similar, but certainly it is far better than my ST102, which has left me wondering if I should push that on. :unsure:

Share this post


Link to post
Share on other sites
5 minutes ago, Greymouser said:

I will get something like Takahashi FC 100 at some point, I have heard such good things about them, but they were just too expensive for now, 4 times + the price of a C5, never mind being quite bulky, so not sure about how mobile.

My FC100 DF travels regularly with us as Cabin Baggage... So far it's been taken to La Palma 4 times, Namibia twice and Zambia from the UK. With no issues. I had tea recently with Es Reid and for interest took the scope with me just to see whether all those hours in an overhead bin, on light aircraft and in numerous overland vehicles had shifted anything... Es couldn't fault anything. So don't be fearful of travelling with the scope... This is my travel set up... The way the scope comes to bits is shown at the bottom of this thread
 

 

  • Like 1

Share this post


Link to post
Share on other sites

@Greymouser Afaik, you can't use a Herschel Wedge with a Catadiatropic telescope, you have to use front-mounted solar film. Otherwise your secondary mirror will take 100x the power of the sun.

https://en.wikipedia.org/wiki/Herschel_wedge

Not sure if you were thinking of a wedge with the ST102 or C5?

  • Thanks 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.