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parallaxerr

Which WL Frac?

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OK, my trigger finger's been itching for quite some time now for a WL solar setup. It will be based around a 1.25" Lunt Wedge and Baader Solar Continuum filter. I don't want to use my Equinox 120 for this, I'd rather something smaller (shorter), lighter and cheaper.

It will sit on my HEQ5 to start, however, if solar grabs me then maybe the SW AZ GTi solar jobby will get ordered. So for £150 for an OTA I'm considering an ST102 on offer at FLO or an Opticstar AR80S 80/600 achro.

Which would you go for? I see the pro's & cons as follows:

ST102 - more aperture but shorter FL + less mag with my EPs.

AR80S - Longer FL so more mag, dual-speed crayford focuser, nicer all-metal construction.

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I've used my Lunt Wedge with my ED refractors (including the ED120) and briefly recently when I had an ST80 achro. The ST80 worked fine with the wedge but the better optics in the ED scopes provided crisper, contrastier and more detailed images of the solar features, the Tak FC100DL especially so (though I'd not suggest a TAK FC100 just for that use !).

To me, the message is that white light solar deserves good optics just as much as nighttime viewing does :smiley:

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If you can increase the budget a little bit the Bresser AR-102xs/460 makes a great WL scope. Very compact with a great focuser and good optics.

 

 

 

6D529654-3863-4028-A0E4-98428E539D03.jpeg

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Personally I would use your 120mm, it won't do out any harm and will give you great results.

I often see comments that any old scope will do for solar,  but as John says,  if you want the best results it is worth using a well corrected scope and by that I mean one with low spherical aberration as much as anything. 

I would consider something like the 102mm f11 clones which can be sourced quite reasonably on the used market, or how about a TAL 100R which you could pick up on budget, example here

http://www.astrobuysell.com/uk/propview.php?view=138552

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I'm with Stu. I use my 120mm Equinox as my sole white light scope and it's excellent in every respect.

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I've always thought that wedges work best with

longer FL scopes , I use a Baader 2" with a cheap as 

chips bresser 127 L , so yes 120 and longer if poss would

get my vote.

 

 

Brian 

 

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Several interesting comments chaps.

Reasons for me not wanting to use the Equinox are twofold.

Firslty I was worried about heat, what with the tube being black, moreso externally than any internal off-axis issues. Also, I've had black anodised motorcycle parts fade badly to a pale green coulour and don't want my prized scope going the same way. @Moonshane, I assume you have seen no fading of the anodizing?

@Stu, always fancied a 102 F11 but it kind of busts my requirements being longer than the Equinox, the TAL is interesting though and Peters recommendation bodes well, only issue is collection from afar.

@johninderby, I can find little in the way of reviews on this scope. Mainly comments are based around not expecting much from F4.5 ED optics at the relatively cheap pricepoint. You seem to rate it OK though?

12 hours ago, John said:

To me, the message is that white light solar deserves good optics just as much as nighttime viewing does :smiley:

I've no doubt that is the case John. I suppose I'm trying to prevent the hobby from sending me bankrupt!

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@parallaxerr

Just be aware that the 1.25” Lunt Wedge you mention in your original post isn’t recommended for refractors over 4”. 

If you do follow the recommendations to use the 120, please note the advice about Wedge size. Clearly if the Wedge hasn’t yet been bought your options are wide open. But if it’s “in the kit bag” already your 120 probably isn’t an option...

Edited by Stargazer McCabe

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16 minutes ago, Stargazer McCabe said:

@parallaxerr

Just be aware that the 1.25” Lunt Wedge you mention in your original post isn’t recommended for refractors over 4”. 

If you do follow the recommendations to use the 120, please note the advice about Wedge size. Clearly if the Wedge hasn’t yet been bought your options are wide open. But if it’s “in the kit bag” already your 120 probably isn’t an option...

This is my exact reasoning for considering a smaller frac. The 2" wedges are very expensive and whilst the total cost of a scope up to 100mm, plus a 1.25" wedge may come close, it negates my other concerns about using the Equinox.

Edited by parallaxerr
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5 minutes ago, Stargazer McCabe said:

@parallaxerr

Just be aware that the 1.25” Lunt Wedge you mention in your original post isn’t recommended for refractors over 4”. 

If you do follow the recommendations to use the 120, please note the advice about Wedge size. Clearly if the Wedge hasn’t yet been bought your options are wide open. But if it’s “in the kit bag” already your 120 probably isn’t an option...

I've often used the 1.25" wedge with my ED120 and so have others here. I believe Peter Drew uses the same wedge with a larger aperture refractor again :icon_scratch:

Telescope House say this:

" The Lunt 1.25" White Light Solar Herschel-Wedge is designed for use with refracting telescopes up to 150mm aperture with 1.25" focusers. This provides superior White Light views and images of the Solar surface, granulation and Sunspots. Complete system with installed ND3.0 Neutral Density filter. "

 

 

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7 minutes ago, Stargazer McCabe said:

@parallaxerr

Just be aware that the 1.25” Lunt Wedge you mention in your original post isn’t recommended for refractors over 4”. 

If you do follow the recommendations to use the 120, please note the advice about Wedge size. Clearly if the Wedge hasn’t yet been bought your options are wide open. But if it’s “in the kit bag” already your 120 probably isn’t an option...

I'm not sure that is totally correct, I have used the 1.25" in a 120mm scope with no issues and have heard that it is ok up to 150mm. I think in UK conditions it is unlikely to be a problem but obviously it's up to you to be comfortable with how you use it. A 100mm scope will show plenty of detail and should be lighter and shorter which meets your needs better.

Personally I would be a little wary of the very fast scopes. They tend to perform worse in terms of spherical aberration and will likely show less detail particularly at higher powers which is where I really enjoy white light solar. Picking out granulation cells at x200 is great fun :)

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5 minutes ago, John said:

I've often used the 1.25" wedge with my ED120 and so have others here. I believe Peter Drew uses the same wedge with a larger aperture refractor again :icon_scratch:

Telescope House say this:

" The Lunt 1.25" White Light Solar Herschel-Wedge is designed for use with refracting telescopes up to 150mm aperture with 1.25" focusers. This provides superior White Light views and images of the Solar surface, granulation and Sunspots. Complete system with installed ND3.0 Neutral Density filter. "

 

Yet FLO say:

The 1.25" model is suitable for use only with refractor telescopes up to 100mm aperture, the 2" model up to 150mm aperture. The full energy and heat of the sun will be inside the telescope so Lunt advise using only refractor telescopes with a Herschel Wedge.

I  have, however, read of many people using the 1.25" Lunt in 120mm scopes.

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2 minutes ago, parallaxerr said:

Yet FLO say:

The 1.25" model is suitable for use only with refractor telescopes up to 100mm aperture, the 2" model up to 150mm aperture. The full energy and heat of the sun will be inside the telescope so Lunt advise using only refractor telescopes with a Herschel Wedge.

I  have, however, read of many people using the 1.25" Lunt in 120mm scopes.

And indeed it's what Lunt mention on their website Jon...

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28 minutes ago, Stu said:

I'm not sure that is totally correct, I have used the 1.25" in a 120mm scope with no issues and have heard that it is ok up to 150mm. I think in UK conditions it is unlikely to be a problem but obviously it's up to you to be comfortable with how you use it. A 100mm scope will show plenty of detail and should be lighter and shorter which meets your needs better.

Personally I would be a little wary of the very fast scopes. They tend to perform worse in terms of spherical aberration and will likely show less detail particularly at higher powers which is where I really enjoy white light solar. Picking out granulation cells at x200 is great fun :)

I was only going by what FLO and Lunt say on their websites... So if they are inaccurate or overly cautious  I stand corrected...

Edited by Stargazer McCabe

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I do agree with Stu that using a well figured objective is what really counts. The reason I mention ED scopes is that I've found that they tend to have better figured objective lenses, rather than their CA correcting properties, in this context. A well corrected achromat such as the TAL or the various brandings of the 102mm F/11 achromats (eg: Altair Starwave) will also do well for this reason. Spherical Aberration (either under or over correction) is often found in chinese achromat objectives and more so in the faster ones. This will impact the crispness and contrast in the white light solar image as the magnification is increase just as it does when the scope is used at night.

The Vixen 80mm F/11 optical tubes are often around for low prices and would be another prime contender I would think. Vixen know how to figure a good objective lens ?

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23 minutes ago, Stargazer McCabe said:

I was only going by what FLO and Lunt say on their websites... So if they are inaccurate I stand corrected...

Well to be fair it says 'is best in 4" or less' rather than 'cannot be used in greater than 4" '

Most other sites says it's ok up to 150mm. I take a pragmatic view on these things, I always cover the scope when not actually observing and wouldn't necessarily leave it tracking the sun all day. The back plate has a warning that it can get hot, so my assumption is that it's ok if it does. Mine rarely did.

Sometimes this info can be confused and misleading, I accept that.

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11 minutes ago, John said:

I do agree with Stu that using a well figured objective is what really counts. The reason I mention ED scopes is that I've found that they tend to have better figured objective lenses, rather than their CA correcting properties, in this context. A well corrected achromat such as the TAL or the various brandings of the 102mm F/11 achromats (eg: Altair Starwave) will also do well for this reason. Spherical Aberration (either under or over correction) is often found in chinese achromat objectives and more so in the faster ones. This will impact the crispness and contrast in the while light solar image as the magnification is increase just as it does when the scope is used at night.

The Vixen 80mm F/11 optical tubes are often around for low prices and would be another prime contender I would think. Vixen know how to figure a good objective lens ?

There's a Vixen 80mm F11 on sale @ ENS for £150! http://ensoptical.co.uk/telescopes/vixen-80mf-refractor?sort=p.price&order=ASC

I dunno, I'm considering using the Equinox now, good optics and more resolution. Buying a 1.25" Lunt wedge and SC filter to use with it would be the cheapest option by far and I could add a Telegizmos solar observing cover to allay my fears. This option would also slip easily under the wife radar :)

You've given me plenty to think about chaps, I've got some decision making to do.

Edited by parallaxerr
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Just now, Stu said:

The back plate has a warning that it can get hot, so my assumption is that it's ok if it does. Mine rarely did.

Good info Stu, actual application data is more valuable than written recommendations.

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4 minutes ago, Stu said:

Well to be fair it says 'is best in 4" or less' rather than 'cannot be used in greater than 4" '

Most other sites says it's ok up to 150mm. I take a pragmatic view on these things, I always cover the scope when not actually observing and wouldn't necessarily leave it tracking the sun all day. The back plate has a warning that it can get hot, so my assumption is that it's ok if it does. Mine rarely did.

Sometimes this info can be confused and misleading, I accept that.

I hadn’t seen the up to 150 for the 1.25” advisory previously. So maybe I was being overly careful. If others have gone before without self immolation I shall give the Wedge a whirl in the 120 next time we see the sun...?

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6 minutes ago, Stu said:

Relevant thread here

 

Good find !

Shane posted in that thread "... Marcus Ludes who designed this wedge confirmed once that he uses a 1.25" wedge in his 10" apo...."

When I get a 10" apo, I'll give it a whirl ?

It is sensible to be cautious with solar observing though :thumbright:

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I would go for anything above f8, the less glass you have to use the better ie barlow ect. charl.

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1.25" Lunt wedge, Baader solar continuum filter and Baader polarising filter ordered :D

I'll give it all a go in the Equinox120 to start with, I can always pick up another scope later on if I'm not happy, but it sounds like it'll be OK and it would be daft to downgrade the view with lesser optics.

If @FLO are all over their dispatch game, I may even get some WL time in before the weekend ?

 

Edited by parallaxerr
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