Solar Max Coronado 70mm Scope

[Grotemobile]

https://www.telescopehouse.com/coronado-solarmax-iii-70-bf15-doublestack.html?utm_source=Telescope+House+Newsletter&utm_campaign=846fd65bc0-EMAIL_coronado_SMIII_2017_08_10&utm_medium=email&utm_term=0_2ccd288edb-846fd65bc0-29660141

This looks very good for the price.

[Stu]

I saw that, does seem good.

I'm interested to know what the basic refractor is once the Ha filters are removed, is it just an achro or a decent app?

[Moonshane]

Did I read somewhere that the ds  unit is in fact 60mm?

 

[Ibbo!]

3 minutes ago, Moonshane said:

Did I read somewhere that the ds  unit is in fact 60mm?

 

I read the same thing

[Moonshane]

From one of the suppliers

The SolarMax III is a 70mm F/5.7 refractor equipped with 60mm external hydrogen alpha (H-a) filters.
 

[xtreemchaos]

that kinds defeats the 70mm objective or am I missing some thing ?, but still id love a look through one, the price tag makes my eye water a bit, it has to be a apo base. charl.

[Stu]

52 minutes ago, Moonshane said:

Did I read somewhere that the ds  unit is in fact 60mm?

 

That's a bit off!

[Moonshane]

I'd expect a doublet achromat as I am pretty sure most solar scopes have that. They don't mention it's an apo and I am sure they would if it was.

 

[Stu]

1 minute ago, Moonshane said:

I'd expect a doublet achromat as I am pretty sure most solar scopes have that. They don't mention it's an apo and I am sure they would if it was.

 

Sure you are right Shane, seems like they are making a bit too much of the fact that it can be a standalone refractor too...

[spaceboy]

1 hour ago, Moonshane said:

From one of the suppliers

The SolarMax III is a 70mm F/5.7 refractor equipped with 60mm external hydrogen alpha (H-a) filters.
 

Is it at all possible they have done it in a similar way to a PST mod using internal erf a 1/3 way down the ota. Why have a front double stack with the expense when you could fit an internal ? I assume you get the same desired effect? Of the top of my head I'm sure lunt do a similar thing with their 80mm don't they??

[Stu]

11 minutes ago, spaceboy said:

Is it at all possible they have done it in a similar way to a PST mod using internal erf a 1/3 way down the ota. Why have a front double stack with the expense when you could fit an internal ? I assume you get the same desired effect? Of the top of my head I'm sure lunt do a similar thing with their 80mm don't they??

I think it's the external filter which is 60mm so will reduce the effective aperture.

[spaceboy]

Sorry just read Shanes post again with my eyes open this time  . So it's NOT 70mm at all then!!!

[Stu]

2 minutes ago, spaceboy said:

Sorry just read Shanes post again with my eyes open this time  . So it's NOT 70mm at all then!!!

For the DS, no!

[MarsG76]

I'm curious exactly how much real world difference would be visible on the sun when comparing to the SolarMax II.

Would it be worth upgrading?

[timwetherell]

I had the impression that many of these were actually just crown glass singlets. I think my old 60mm Coronado might be. From what I recall reading the destructions years ago, the rationale is that less glass is less scatter and since they only pass about half a nanometre of spectrum anyway, chromatic aberration isn't an issue. This is all based on my dim and foggy recollections though, so it may be somewhat apocryphal  The Coronado eyepieces are definitely achromatic though - quite good GP plossls actually!

[Merlin66]

Coronado solar scopes always had doublet objectives - claimed to be optomised for Ha.

the single objective lens was introduced by Lunt.

 

[Peter Drew]

7 hours ago, Stu said:

That's a bit off!

Yes, 10mm off  My reading of the advertising is that it is a 70mm aperture short focus achromat with an internal small etalon. To the front of the objective is a 60mm external type etalon which double stacks the internal one albeit operating as a 60mm overall Ha system. The price reflects the high cost of a 60mm etalon and a BF15.  There is a distinct difference between external and internal etalons, the former has to be (usually!) a full aperture to suit that of the objective and designed to accept parallel light, the latter configured to accept converging light, not directly interchangeable.  

[Merlin66]

peter et al,

Based on the blurb I've seen, it's a 70mm achromat, no internal etalon, fitted with either a single or double 60mm external tilt etalon.

 

[Moonshane]

That sort of sleight of hand won't go down well with customers. 

[Highburymark]

Presume Meade has seen how many Lunt 60s are sold with 50mm double stack etalons. I'm saving to trade up to a LS60 with a 60mm double stack unit - trouble is I'm going to be 95 before I can afford it.

[Stu]

10 minutes ago, Merlin66 said:

peter et al,

Based on the blurb I've seen, it's a 70mm achromat, no internal etalon, fitted with either a single or double 60mm external tilt etalon.

 

So even single stacked it is 60mm? That's very dodgy advertising then!

[Merlin66]

Yes, that seems to be the case......

[Peter Drew]

14 minutes ago, Merlin66 said:

peter et al,

Based on the blurb I've seen, it's a 70mm achromat, no internal etalon, fitted with either a single or double 60mm external tilt etalon.

 

You could well be right Ken, just shows that the advertising script could be even more misleading?. Reading it again from your perspective perhaps it would have said "stacked" instead of "stack" if there was an internal etalon as supplied. If you are correct, it's even less of a deal!.  

[Stu]

4 minutes ago, Merlin66 said:

Yes, that seems to be the case......

I've just read the spec on their website. I think that is a very poor piece of marketing. It is clearly a 60m Ha scope which they are trying to make seem more attractive. I suspect few people would use it as a standard refractor with filters removed so the 70mm is irrelevant.

[garryblueboy]

I agree very miss leading