Altair Astro Starwave 152mm v2 f5.9 refractor

[Davey-T]

Losmandy dovetail for mine despatched by FLO, probably won't arrive in time for the weekend though 

Dave

[DRT]

A tip for anyone with sausage fingers like mine

I find the knurled screws that secure the diagonal to the focuser a bit fiddly as they are quite short. I replaced them with these and it is now much easier to get a good amount of tension in the compression ring to hold everything securely...

http://www.amazon.co.uk/Lathe-Black-Round-Thumbscrew-Knurled/dp/B00W8YFQD2

 

[Anderscn]

If they just would build an f/10 or longer for some decent planetary views around 200x, I would get one immediately.

BR,

Anders

[Neil27]

58 minutes ago, Anderscn said:

If they just would build an f/10 or longer for some decent planetary views around 200x, I would get one immediately.

BR,

Anders

Problem solved?

http://www.rothervalleyoptics.co.uk/altair-starwave-102mm-f11-achromat-refractor-telescope-with-2-crayford-focuser.html

 

[Anderscn]

5 hours ago, Neil27 said:

Problem solved?

http://www.rothervalleyoptics.co.uk/altair-starwave-102mm-f11-achromat-refractor-telescope-with-2-crayford-focuser.html

 

Not really. This thread is about the 152mm f/5.9 - so I was asking for a 152 mm f/10 or longer.

 

BR,

Anders

 

[Neil27]

Hi Anders,

apologies mis read your intentions.

I would also be interested in such a scope.

[Fozzie]

Nothing wrong with the F11 gents.. lovely scope.. However if its a 150mm F10 your after.. then look up Istar Perseus Range

http://www.istartelescopes.co.uk/page_2413941.html

Probably as good as it gets, but you feel for your wallet afterwards!

Ta

Fozzie

[Stu]

h

1 hour ago, Anderscn said:

Not really. This thread is about the 152mm f/5.9 - so I was asking for a 152 mm f/10 or longer.

 

BR,

Anders

 

That would be a big old scope, not easy to get mounted solidly

[Anderscn]

Thank you gentlemen for the good comments. I already own 4" f12 and a 5" f12 achro's - both with Istar optics , and I struggled quite a lot in the beginning with vibrations from those long cannons. I think that I in the meantime have cracked the code of how to tame them without spending a fortune on a ton- heavy mount. And I think that my current setup may even be able to handle a long 6 inch'er. I am not too happy with Istars own scopes, though being fantastic craftmanship, they are a bit too heavy to my taste. So coming back to the Altair 152mm f5.9 - really like it from what I hear of build and optical quality. If they just could make similar one - in f10 in stead..

By the way - I am sorry if I somehow have stolen the thread?

 

BR Anders

Edited April 22, 2016 by Anderscn
spelling

[Commanderfish]

Nice review and very interesting scope. Has anyone compared the views in one to a 5" (127-130mm) Apo?

[John]

35 minutes ago, Commanderfish said:

Nice review and very interesting scope. Has anyone compared the views in one to a 5" (127-130mm) Apo?

There are some posts from folks who have done such comparisons in this thread from the Cloudynights forum:

http://www.cloudynights.com/topic/491788-152mm-ar-vs-102mm-apo/

[Commanderfish]

Thanks John. It was that thread that lead me to buying my ED127!

I also have a C9.25, and this has lots of aperture and is a good scope, but doesn't have them sharpness of an Apo or the contrast, especially in mild light pollution.

I'm wondering whether a 152 F5.9 will be as good or better on galaxies and clusters as the C9.25. Anyone ever compared the two?

Edited May 18, 2016 by Commanderfish

[John]

I guess it will depend on whether the high contrast of the refractor can bridge the 55% increase in aperture of the C9.25. If the difference was just 1 inch it could be close but I think my money would be on the C9.25 for galaxies at least. I've not actually compared them though.

For really large objects, seeing objects within the context of the starfields and object groups the faster refractor would have a marked advantage in true field size.

They are very different scopes really - the sort that complement each other rather than compete perhaps ?

 

 

Edited April 26, 2016 by John

[Commanderfish]

Yes I think that's right John. I had the ES ED127 and 9.25 SCT out side by side last night. Viewing M81 and M82 was interesting. The ED 127 gave a decent image; the C9.25 produced a larger image but the contrast was no better, partly due to LP (no moon at the time though), so I wasn't making out any extra details. I'm 3 miles outside Kingston, 16 miles from the centre of London, but I have a grazing field to the east and a golf course to the south so the LP isn't overly terrible.

This is why I wonder about a large achro, the 5" doesn't seem affected by LP but the C9.25 definitely suffers.

 

You're right about the SCT serving a different purpose, its the best planetary scope I have.

 

Does anywhere sell a 7" fast achro?

[Arminovski]

Hi

If you could compare your scope with a standard doublet, which focal length would roughly equal it?

What's the focal length of the front lens?

 

Thanks

 

Edited August 17, 2016 by Arminovski

[John]

1 hour ago, Arminovski said:

Hi

If you could compare your scope with a standard doublet, which focal length would roughly equal it?

What's the focal length of the front lens?

 

Thanks

 

I'm not the original poster here but I can say that the objective lens of the scope (which has 2 elements like all achromatic objectives) has a focal length of 900mm and a focal ratio of f/5.9. You multiply the aperture of the objective lens (152mm in this case) by the focal ratio to get the focal length.

I've seen reports the colour correction of this scope is actually slightly better than that of one of the chinese 150mm F/8 achromats such as the Skywatcher Evostar and the Meade AR152. Thats quite an achievement for an F/5.9 achromat 

Edited August 17, 2016 by John

[DRT]

3 minutes ago, John said:

I've seen reports the colour correction of this scope is actually slightly better than that of one of the chinese 150mm F/8 achromats such as the Skywatcher Evostar and the Meade AR152. Thats quite an achievement for an F/5.9 achromat 

I have the Altair 152 and the SW Evo 150 F8 so I  might point them both at the full Moon tonight and test that theory, John

 

[DRT]

4 minutes ago, DRT said:

I have the Altair 152 and the SW Evo 150 F8 so I  might point them both at the full Moon tonight and test that theory, John

 

Question: in order to make this a fair test should I try to equalise the magnification by using different EPs (e.g. E8mm in the Evo and E6mm in the Altair) or would it be more accurate to use the same EP to avoid contaminating the result?

Edited August 17, 2016 by DRT

[John]

14 minutes ago, DRT said:

Question: in order to make this a fair test should I try to equalise the magnification by using different EPs (e.g. E8mm in the Evo and E6mm in the Altair) or would it be more accurate to use the same EP to avoid contaminating the result?

I'd probably go for getting the magnification about equal Derek. Eyepieces of comparable quality would be good to but I guess they don't need to be exactly the same.

When I was comparing a Skywatcher 150 F/8 with a minus violet filter, with no filter and with a chromacor, I tried to put some order of magnitude of the amount of CA that was being shown around the moons edge by finding a lunar crater that was appeared about the same size as the CA halo was wide, if that makes any sense. It's not exact of course but it did help me to quantify the differences to some extent

 

[DRT]

19 minutes ago, John said:

I'd probably go for getting the magnification about equal Derek. Eyepieces of comparable quality would be good to but I guess they don't need to be exactly the same.

When I was comparing a Skywatcher 150 F/8 with a minus violet filter, with no filter and with a chromacor, I tried to put some order of magnitude of the amount of CA that was being shown around the moons edge by finding a lunar crater that was appeared about the same size as the CA halo was wide, if that makes any sense. It's not exact of course but it did help me to quantify the differences to some extent

 

Thanks, John. The Ethos 6mm and 8mm will give me identical magnification with these scopes so I will use those. Now all I need to do is identify the name of a suitable crater, which is not one of my strengths

 

[John]

45 minutes ago, DRT said:

Thanks, John. The Ethos 6mm and 8mm will give me identical magnification with these scopes so I will use those. Now all I need to do is identify the name of a suitable crater, which is not one of my strengths

 

I find the Virtual Moon Atlas useful and it's free !!!:

https://www.ap-i.net/avl/en/start

[DRT]

I have just had a quick look at the Moon through the Altair 152 F5.9 (Ethos 17mm x53) and SW Evo 150 F8 (Ethos21mm x57). The viewing was awkward as the Moon is barely above my neighbour's roof. My initial impressions are that the Altair 152 provides a sharper view and marginally less CA than the Evo 150. If the Moon rises a bit higher in the sky I will spend a bit more time on this tonight and report back.

[Davey-T]

Had a look at the Moon through my Tecnosky version a few weeks ago and the CA didn't appear at all bad.

Dave

[Arminovski]

Thanks to all.

But doesn't petzval design mean that the front lens has a longer focal ratio and that's one of the reasons for better correction? I've seen their claim that this scope is better corrected than an equivalent f8 doublet (conservative maybe?) and on google groups I've read long time ago how to build your own big petzval. If I remember correctly the suggestion was to have a longer focal ratio front lens and that the corrector lens would then half the focal ratio.  Using the same reasoning I thought that this scope maybe has f12 front lens 9and that the correction would end up in that neigbourhood when compared to simpler doublets. Wrong?

Btw I would love to see how this scope compares to istar doublets.

[DRT]

This scope is not a Petzval.