Skywatcher Startravel 102/120 as a solar scope?

[lee g]

So I’m still toying with the idea of getting one of the skywatcher startravel scopes to accompany my 8”sct.

my question is would one of these give good views of the sun? If so what filter would work best and which scope would be best suited the 102 or the 120

thanks

[Cosmic Geoff]

I tried using my 102mm f5 Startravel as a solar scope during a transit of one of the inner planets a few years ago, to project the image.  It would not resolve it and I had to switch rapidly to projecting with my 127mm Mak in order to view this unique event.

Nowadays I use the Mak with a full-aperture Baader film filter.

I put a bit of spare film over the 2 inch hole in the 102mm scope's dustcap - very easy to do.  I will probably use this to try imaging the upcoming partial eclipse (wider field).

[Stu]

1 hour ago, lee g said:

So I’m still toying with the idea of getting one of the skywatcher startravel scopes to accompany my 8”sct.

my question is would one of these give good views of the sun? If so what filter would work best and which scope would be best suited the 102 or the 120

thanks

Personally I would go for something of longer focal length. The faster scopes tend to suffer from spherical aberration which can kill the fine detail visible on the sun. An f10 102mm achro for example would be worth looking at I think. Aperture does help show more with solar so a 120mm might be worth it depending on what mount you have and how portable you need it to be.

Filter wise, I would go for a 1.25” Herschel Wedge such as the Lunt. These give excellent results and are quite reasonably priced. Check that it comes with the essential ND3.0 filter and you will also need either a polarising or continuum filter to get the brightness to a comfortable level.

If wanting something cheaper, you could start with a sheet of ND5.0 Baader AstroSolar film and make your own filter housing for it from cardboard; it’s quite easy to do, following the instructions with the film and is the cheapest way into solar observing. Just make sure the filter is firmly attached and cannot blow off!

[AdeKing]

I started out with a ST102 as my first refractor and actually think it punches above its weight.

I've used it as a WL solar scope with a 1.25" Lunt Herschel Wedge and have enjoyed some excellent views.

@Stu is correct about short refractors and SA, though o have to confess that I've never really noticed it with my ST102 to though maybe I'm not observant enough as CA has never bothered me whilst using it either.

I've just looked up how to identify SA and will now have to test the ST102 to see how badly it suffers.

If you're looking for a cheap refractor to dip your toe in the WL solar waters and accept it's limitations then it's a fairly cheap way in, though as Stu says there are other better options out there.

Most of my solar viewing tends to be in short sessions and I mostly use an old William Optics ZS70 as it's really compact and it travels everywhere with me complete with a WL and nighttime setup in its little flight case.

However, if I'm viewing from home for longer sessions then I tend to set up my Altair 102 f/11 Achromat or my recently acquired TAL 100RS (f/10), both of which do give better views but without the portability and convenience of the ST102 or ZS70.

Hope this helps.

Ade

[Stu]

Thanks Ade. I do think the differences would show up at higher powers and with good or better seeing conditions. I’ve not used a 102 ST before, just an 80mm with solar film. For the price it gave good views, just not the level of high power detail achievable in other better corrected scopes with a wedge. They do vary sample to sample too, so some will be better than others. Like all these decisions, it’s a balance of convenience, price, performance and sheer personal preference.

[AdeKing]

14 minutes ago, Stu said:

Thanks Ade. I do think the differences would show up at higher powers and with good or better seeing conditions. I’ve not used a 102 ST before, just an 80mm with solar film. For the price it gave good views, just not the level of high power detail achievable in other better corrected scopes with a wedge. They do vary sample to sample too, so some will be better than others. Like all these decisions, it’s a balance of convenience, price, performance and sheer personal preference.

I tend to be a low power observer Stu as even with my best scopes I find that whilst I can pick up granulation easily at low power that as soon as I get over about 100x I struggle to pick it up.

Maybe that is a sign of SA so now I know how to look for it I'll test all the scopes out to see if they suffer from it, though that might be an expensive mistake 😳.

[Stu]

1 hour ago, AdeKing said:

I tend to be a low power observer Stu as even with my best scopes I find that whilst I can pick up granulation easily at low power that as soon as I get over about 100x I struggle to pick it up.

Maybe that is a sign of SA so now I know how to look for it I'll test all the scopes out to see if they suffer from it, though that might be an expensive mistake 😳.

That’s interesting. I think at low power you are looking at what might be called ‘macro granulation’ ie the overall impression of the granulation and its variation in density across the solar surface.

At higher powers with good seeing you should see the individual granulation cells (which are around 1 to 2 arc seconds across), these stand out very clearly in my scope when conditions are right. I use up to x200, and it tends to get more vivid at the higher powers. Binoviewing definitely helps with this too I think, and my impression is that the Coolwedge shows it better than the Lunt type wedges.

I do think there is benefit in optimising each element, scope, wedge, barlow/GPC, binoviewers and eyepieces.  I often see people describing white light as a bit boring, but with the right setup it is anything but, even when there is little activity around.

Your Altair f11 in particular should be pretty good I should think, they seem to be well corrected scopes. I’ve found TALs to be a bit variable, the one I’ve got now is pretty decent but others have been less good.

[Barry Fitz-Gerald]

I use a Startravel 120 with a Baader Solar Film filter (DIY) and a Baader Solar Continuum Filter, the views are very good, faculae, sunspots and granulation all sharply defined with good contrast. I have not used high powers preferring to see the complete disc in one FOV. 

[Stu]

33 minutes ago, Barry Fitz-Gerald said:

I use a Startravel 120 with a Baader Solar Film filter (DIY) and a Baader Solar Continuum Filter, the views are very good, faculae, sunspots and granulation all sharply defined with good contrast. I have not used high powers preferring to see the complete disc in one FOV. 

Sounds good Barry. The only thing I would say is that you will not properly be seeing the granulation  low powers, just the overall mottling of the surface and variations in density over the disk.

By using a setup that works at high powers you can really see much more detail in the active regions and also the granulation gets much more like tiny open cells. I say this not as any form of criticism, I’m just quite passionate about WL solar and want to encourage people to get the most out of the views.

[Neil H]

Hi I use my bresser 127/1200 with a Lacerta wedge and continuum filter and the views are great I would love to try a Lunt wedge to see what it better I also use my 8 inch Orion optics Newtonian with a Kendrick full aperture filter and that also works well , just love solar viewing 

[Stu]

2 minutes ago, Neil H said:

Hi I use my bresser 127/1200 with a Lacerta wedge and continuum filter and the views are great I would love to try a Lunt wedge to see what it better I also use my 8 inch Orion optics Newtonian with a Kendrick full aperture filter and that also works well , just love solar viewing 

The Lacerta Wedge seems to have quite a good reputation so I doubt the Lunt would be any better. I haven’t used a Lacerta so don’t know myself.

How do the views compare between the Bresser and the Newt?

[Neil H]

The bresser is tight image around the Sun spots you can see the granular surface , the newt image is a little smaller it shows the Sun spots but harder to see granular surface , but I found it you use a phone to take a photo the newt works better , still working to get images from refractor using a phone or the ASL224MC

[Barry Fitz-Gerald]

1 hour ago, Stu said:

Sounds good Barry. The only thing I would say is that you will not properly be seeing the granulation  low powers, just the overall mottling of the surface and variations in density over the disk.

By using a setup that works at high powers you can really see much more detail in the active regions and also the granulation gets much more like tiny open cells. I say this not as any form of criticism, I’m just quite passionate about WL solar and want to encourage people to get the most out of the views.

That is probably very true - my solar viewing tends to be quite quick and not too detailed, so have never pushed the magnification up very high - but for a wide field view it works fine. I keep my higher power aspirations aimed at the moon.

[AdeKing]

4 hours ago, Stu said:

That’s interesting. I think at low power you are looking at what might be called ‘macro granulation’ ie the overall impression of the granulation and its variation in density across the solar surface.

I agree that it's definitely macro granulation that I'm seeing as the individual cells aren't visible, just an overall orange peel type texture.

4 hours ago, Stu said:

At higher powers with good seeing you should see the individual granulation cells (which are around 1 to 2 arc seconds across), these stand out very clearly in my scope when conditions are right. I use up to x200, and it tends to get more vivid at the higher powers. Binoviewing definitely helps with this too I think, and my impression is that the Coolwedge shows it better than the Lunt type wedges.

I think I've seen what you're describing once very briefly through the ED100 with binoviewers, but I've not seen it since.  I tend to use the Coolwedge when I'm using one of the 4" Fracs or the ED120 and I agree that it does offer a subtle but noticeable improvement over the Lunt.

It sounds like I need to put a bit more effort in and set a bit more time aside rather than grabbing short sessions.

5 hours ago, Stu said:

I often see people describing white light as a bit boring, but with the right setup it is anything but, even when there is little activity around.

Your Altair f11 in particular should be pretty good I should think, they seem to be well corrected scopes. I’ve found TALs to be a bit variable, the one I’ve got now is pretty decent but others have been less good.

I actually really enjoy White Light, the fine detail visible in the penumbra and umbra is amazing.

Thanks for the info on the f/11 it's a lovely scope and now it's in a soft carry case rather than a heavy bulky flight case it's seeing more action so I'll make sure that I get it out in the sunlight a bit more often.

The solar views through the TAL have been pretty good so far so I'm hoping that it's a good one.

[John]

I'm not a regular solar observer but when I do some white light observing with my Lunt HW I've noticed that the views of the solar surface are very sharp with my Tak 100 so I agree with Stu that having good optical quality throughout, pays dividends.

[lee g]

23 hours ago, Barry Fitz-Gerald said:

I use a Startravel 120 with a Baader Solar Film filter (DIY) and a Baader Solar Continuum Filter, the views are very good, faculae, sunspots and granulation all sharply defined with good contrast. I have not used high powers preferring to see the complete disc in one FOV. 

So I’ve ordered a skywatcher st 120 and plan to get a solar film filter as well as a solar continuum filter. Would it be better to use 1.25 or 2” ep so I know what size filter to get.

[Stu]

21 hours ago, AdeKing said:

It sounds like I need to put a bit more effort in and set a bit more time aside rather than grabbing short sessions.

I think it is worth it Ade.

Focus is also critical to pick up the maximum detail, that’s why I like a nice dual speed focuser on my scope to properly nail it.

Your eye can also play tricks on you by not quite focusing properly on the granulation. A few times I’ve been looking at a blank disk, no granulation visible at all, and then just panning the scope gave enough for my eye to pick up the focus point properly and the granulation snapped into clear view.

Seeing changes quite frequently too, so in the same way it is worth observing planets or the Moon for quite a while to catch the best moments, it is worth spending time at the eyepiece at different times of the day for solar.

[Stu]

50 minutes ago, lee g said:

So I’ve ordered a skywatcher st 120 and plan to get a solar film filter as well as a solar continuum filter. Would it be better to use 1.25 or 2” ep so I know what size filter to get.

Which eyepieces do you have? Solar observing tends to benefit from simple eyepiece designs like orthos or plossls. With only 600 mm focal length, there is no need for 2” eyepieces, a 11mm Plossl say will give around 1 degree of sky and x54. That will fit the full disk in (sun is about 0.5 degrees across) and give nice lowish power views. You could even go to a 15mm I guess which would give x40 and 1.25 degrees, depends what you are looking for. So, a 1.25” filter should be fine.

[lee g]

15 minutes ago, Stu said:

Which eyepieces do you have? Solar observing tends to benefit from simple eyepiece designs like orthos or plossls. With only 600 mm focal length, there is no need for 2” eyepieces, a 11mm Plossl say will give around 1 degree of sky and x54. That will fit the full disk in (sun is about 0.5 degrees across) and give nice lowish power views. You could even go to a 15mm I guess which would give x40 and 1.25 degrees, depends what you are looking for. So, a 1.25” filter should be fine.

I have a diagonal which is either 1.25” or 2” and my ep’s are the explore scientific 82°some are 2” some are 1.25 so I was wondering which size solar continuum filter I would need 

[Stu]

7 minutes ago, lee g said:

I have a diagonal which is either 1.25” or 2” and my ep’s are the explore scientific 82°some are 2” some are 1.25 so I was wondering which size solar continuum filter I would need 

That’s just what I tried to answer for you Lee. There is no need to use the 2” eyepieces as the sun will just appear to small in them. Anything from 17mm and shorter will likely be 1.25”, and from my previous post, something anywhere  from 15mm down towards 10mm will give nice full disk views, even lower with 82 degree eyepieces.  I repeat though that complex eyepiece design are not always best for solar viewing, simple plossls can often give better results.

So, I would personally save some cash and buy the 1.25” Continuum filter.

[lee g]

3 minutes ago, Stu said:

That’s just what I tried to answer for you Lee. There is no need to use the 2” eyepieces as the sun will just appear to small in them. Anything from 17mm and shorter will likely be 1.25”, and from my previous post, something anywhere  from 15mm down towards 10mm will give nice full disk views, even lower with 82 degree eyepieces.  I repeat though that complex eyepiece design are not always best for solar viewing, simple plossls can often give better results.

So, I would personally save some cash and buy the 1.25” Continuum filter.

That’s what I was hoping you would suggest mainly due to the price difference between the 1.25 and 2” filters.

 Thanks for sharing your knowledge 

[ScouseSpaceCadet]

The Skymax 102 proved worthy today.

A fantastic view, beautifully framed through an Altair UFF 24mm.

 

My very first time solar observing. With a pink neck and shins to prove it! 😄

I found hand held smart phone photography a touch tricky... The pic doesn't do the view justice tbh

Edited June 5, 2021 by ScouseSpaceCadet