STAR DIAGONAL?

[bmc]

i'm looking to upgrade the star diagonal i got with my scope. but i'm not too sure what kind of upgrade i should be considering. should i stay with a mirror type or go with a prism?

keep looking up

[YKSE]

You can have a look at this page about the diagonals:

http://www.astrosurf.com/luxorion/reports-stardiagonal.htm

It's not very common that people upgrade diagonal of your scope, I would recommend you to check your scope's collimation first, or maybe you are using too high magnification for viewing? The stock 9 mm EP .e.g. can be challenging for you F12 scope in many occations when seeing is like our usually light-polluted skies.

[ronin]

It will have a mirror diagonal in it so replace with a mirror. A prism will have a different optical path length.

[bmc]

thanks. the reason for thinking of upgrading, is that i got some new ep's and i noticed that in comparison the quality of the ep's provided wasn't as good. therefore i have come to the same conclusion of the provided diagonal,  the scope's collimation is fine. 

as for the high mag. i've tended to not use any ep lower than my 12mm. as it is a struggle with as you say our glorious lit night sky.

thanks for the advice. i'll have at the web link.

keep looking up

[bmc]

what would suffer more loss of light though? a mirror or prism?

[YKSE]

The prism type will suffer more, 99% dielectric is among the best, as I understand it.

[bmc]

thanks. do you know if stock diagonals that come with the scope are dielectric? or just plain aluminium coated mirrors?

[YKSE]

I don't know that, but I doubt it, since many higher-end scopes don't have 99% dielectric diagonal, reflectivity around 90% are more common ones, i.e. about 10% difference.

[Teslar]

The WO dialectic is a lovely upgrade. Made a huge difference to the stock SW one that came with my Mak180. It's a very worthwhile upgrade

[michael.h.f.wilkinson]

I replaced my stock diagonal with a dielectric (WO, 2" type which would not make much sense in a SkyMax 127) and the difference is quite clear to see.

[bmc]

WO dialectic? as in William optics? 

[YKSE]

Yes. William Optics. All the 99% dielectric Diagonal perfom more or less the same opticallly, maybe the build quality in cheaper ones are not as good as premumium brands. I seems to recall that John(Moderator) mentioned in some threads that he cannot tell optical difference between Televue's and a revelation(?) 99% Diel Diagonal.

[michael.h.f.wilkinson]

There are concerns that the smaller 1.25" dielectric diagonals have issues in edge quality due to strain caused by so many layers of coating, but I have not personally seen this

[rwilkey]

The stock diagonal will not be dielectric, however, the longer f-length of your scope may mean the improvement in the quality is less obvious to the untrained eye.  Longer f/length telescopes tend to disguise imperfections in optics.

[AstroJOE]

Yes. William Optics. All the 99% dielectric Diagonal perfom more or less the same opticallly, maybe the build quality in cheaper ones are not as good as premumium brands. I seems to recall that John(Moderator) mentioned in some threads that he cannot tell optical difference between Televue's and a revelation(?) 99% Diel Diagonal.

The Revelation 2" quartz diagonal (currently on offer at Telescope House) has been an excellent upgrade to the stock 1.25" diagonal that came with my CPC1100. I did quite a bit of research before purchasing it and found many positive comments when comparing it to the more expensive 2" diagonals including the WO and Televue ones.

For the money I think the Revelation would be a worthwhile buy, cheaper than the other ones I've mentioned as I've said. As I understand it in order to get any meaningful difference over and above what you'd get from this price range you'd need to enter the realms of 'silly money'. 

Hope this helps!

[bmc]

thanks for all the advise .from all accounts, i think the revelation dielectric seems to have the edge.

[Naemeth]

thanks for all the advise .from all accounts, i think the revelation dielectric seems to have the edge.

I have this as my 1.25" diagonal:

http://www.telescopehouse.com/acatalog/Revelation_Dielectric_99__Quartz_1.25__Diagonal-1.html

I honestly don't think there is any point in spending anymore on a diagonal, as it makes very little difference optically. I've read numerous reports that even having a premium diagonal makes next to no difference (apart from the differences in build quality).

HTH

[fondofchips]

The Revelation 2" quartz diagonal (currently on offer at Telescope House) has been an excellent upgrade to the stock 1.25" diagonal that came with my CPC1100. I did quite a bit of research before purchasing it and found many positive comments when comparing it to the more expensive 2" diagonals including the WO and Televue ones.

For the money I think the Revelation would be a worthwhile buy, cheaper than the other ones I've mentioned as I've said. As I understand it in order to get any meaningful difference over and above what you'd get from this price range you'd need to enter the realms of 'silly money'. 

Hope this helps!

+1 for the revelation diagonal this diagonal is a good fit on the scope & the eyepieces slot in nice & secure.

[John]

+1 for the revelation diagonal this diagonal is a good fit on the scope & the eyepieces slot in nice & secure.

Yep, the 1.25" Revelation is a nice diagonal and holds even heavy eyepieces pretty well.

[bmc]

Hi astrojoe, can you clarify, do you use a 2" diagonal converted to a 1.25"? Does that not blurr edges?

[Tinker1947]

+1 for the Revelation feel s a solid bit of kit....

[AstroJOE]

Hi astrojoe, can you clarify, do you use a 2" diagonal converted to a 1.25"? Does that not blurr edges?

Hi bmc

The Revelation 2" diagonal  also comes with a 1.25" adapter so you can use either 2" or 1.25" eyepieces in it. 2" eyepieces will give you the maximum FOV your scope will allow and the 1.25" a bit less. But even when using the 1.25" it still allows you to use the 'sweet spot' of the diagonal mirror so the views are still as good as they can be.

I have a selection of 1.25" eyepieces and 2" eyepieces and they all work well in this diagonal. Obviously my more expensive ones perform better but to be honest even the stock 1.25" eyepieces that came with my scope(s) are okay. My Baader Aspheric 36mm gives the best views of DSO's as you'd expect as they have a pretty good reputation. The Baader 8-24mm zoom performs well through the Revelation diagonal as well and whilst I use it with the 2" eyepiece adapter, it is effectively a 1.25" eyepiece.

I've only used the Revelation diagonal it in my CPC1100, haven't yet tried it in my 127 Mak but I have no reason to believe it wouldn't perform well in that either.

Upgrade to a decent 2" diagonal and you'll get wider FOV's and brighter images to look at, particularly on faint DSO's. Only a little bit brighter admittedly but nevertheless a significantly 'little bit' brighter

Don't expect Hubble images though!!!

Hope this helps

[bmc]

Sorry if this is a stupid question, are you using a 2" diagonal on a 1.25"  ota? Therefore using two 1.25" converters? One for the scope & one for your ep? 

I understand if you were using a badder, you would get the fov related to a 2" ep, (I`am thinking of picking up a badder hyperion in the near future), but would you not loose that fov due to using a 1.25" converter for your ota? Or the fact that your ota is 1.25"? (If that's what your using). 

Sorry again if I'm talking gibberish.

[YKSE]

If you OTA is 1.25", then it 1.25" diagonal you use, it doesnot make much sense to use two converters(if there's i.e.) to use a 2" diagonal.

The hyperions are essential the 1.25" EPs except 31mm and 36mm aspheric, their performce deriorate if used as 2" EP by what I've read.

[AstroJOE]

Sorry if this is a stupid question, are you using a 2" diagonal on a 1.25"  ota? Therefore using two 1.25" converters? One for the scope & one for your ep? 

I understand if you were using a badder, you would get the fov related to a 2" ep, (I`am thinking of picking up a badder hyperion in the near future), but would you not loose that fov due to using a 1.25" converter for your ota? Or the fact that your ota is 1.25"? (If that's what your using). 

Sorry again if I'm talking gibberish.

I'm not entirely sure I know what you're asking - do you mean am I attaching my 2" diagonal to the 1.25" visual back? If so then the answer is no. You can either replace the 2" visual back with a 2" adapter and attach the diagonal that way or you can do what I've done and buy the SCT version of the 2" diagonal which attaches directly to the back of the SCT. Telescope House sell both versions at the same price. Sorry if that's not what you mean!

Using a1.25" eyepiece in a 2" diagonal will restrict the maximum FOV that can be achieved although the images do still appear brighter compared the stock 1.25" diagonal that came with the scope. I'm in process of upgrading my eyepieces to 2" ones as CPC1100 does have a limited FOV. I've read a focal reducer can help to increase this further, quite how much I'm not sure but I'll probably get one of these in the not so distant future.