Lunt 40mm solar scope vs Lunt 60mm solar scope ?

[Altair8389]

https://luntsolarsystems.com/shop/solar-telescopes/40mm-telescopes/lunt-40mm-dedicated-hydrogen-alpha-solar-telescope/

 

I have a 70mm refractor and currently using a Quark chromosphere filter. I am getting reasonable views but working out how to switch to a straight through optics arrangement (as advised by Martin Wise, Wise Imaging).

I have problems with Newton's rings, and despite tilt adapter, have problems removing the NRs. I have had a break from solar as the weather is - too wet/windy/cloudy/damp/too hot and have added work to do despite the pandemic.

 

I really want to get full disk images, but wonder if I can get the Lunt 40mm dedicated solar h-alpha scope or a Lunt 60mm. Which one would give me a good full disc image. I know you need a match camera to get a full disk. Can you get a full disk easily without having to do mosaics ? I find mosaics difficult, although I have not given up. I saw Michael Wilkinson's images using more than 80 frames to get a single full disk. I don't know if I can use 300 GB for each full disk, as that would mean over 10 Terabytes in less than a year ?

 

Anyway, any advice would help. I don't really want to spend 8000 pounds just to get a full disk. Can the 40mm Lunt do this easily and would the images be of much poorer quality compared to a better scope ?

 

Thanks.

Magnus

 

[Altair8389]

I see, my question is too simple or the answer is not easy at all. I think I know the answer anyway. Thanks for looking.

[Highburymark]

I’m not an imager (at least not yet) but having admired the work of others for many years, I don’t think you’d have any problems getting full discs with any of the smaller Lunts. If it’s affordable, having a Quark for high power imaging and an LS60 for full discs would be the perfect combination 

[bilbo]

Hi Magnus

They're all pretty much designed for full disc viewing and imaging, I had an LS35, Great little scope and now have the LS60. Both will do full disc. Just Make sure the blocking filter is the B600 (6mm).  You'll gain nothing from buying one with a larger filter aside from a being able to get more "black" on a larger sensor.

I use mine on an evolution mount, Align on the Sun, barely have to touch it.

Steve

Found a pic from last year on LS60, pretty blank sun, but its using the sensors full resolution. 1280 x 1024, 6.78mm x 5.4mmm.

 

Edited January 27, 2021 by bilbo
add image

[Altair8389]

15 hours ago, Highburymark said:

I’m not an imager (at least not yet) but having admired the work of others for many years, I don’t think you’d have any problems getting full discs with any of the smaller Lunts. If it’s affordable, having a Quark for high power imaging and an LS60 for full discs would be the perfect combination 

Thanks Highburymark,

You confirm my ideas are correct, thank you.

I will start saving even more for the Lunt LS60 with the B600 blocking filter. I will also optimise my Quark setup, still a lot to work on, including image train, camera and processing and acquistiion. Thanks.

Magnus

[Altair8389]

15 hours ago, bilbo said:

Hi Magnus

They're all pretty much designed for full disc viewing and imaging, I had an LS35, Great little scope and now have the LS60. Both will do full disc. Just Make sure the blocking filter is the B600 (6mm).  You'll gain nothing from buying one with a larger filter aside from a being able to get more "black" on a larger sensor.

I use mine on an evolution mount, Align on the Sun, barely have to touch it.

Steve

Found a pic from last year on LS60, pretty blank sun, but its using the sensors full resolution. 1280 x 1024, 6.78mm x 5.4mmm.

 

Hi Steve, that's a good image of the sun,  I am really keen on the Lunt LS60.  Which camera did you use for this, and was there problem with Newton's rings interference in the imaging process ? Many thanks.

 

Magnus

[Nigella Bryant]

I have a Lunt 60 DS it's a fantastic scope but with a b1200. I believe imaging is more difficult with the b600 but fine for visual. Image taken with my setup using Zwo ASI 178mmm. False colour added in PS CS2

[bilbo]

1 hour ago, Nigella Bryant said:

I have a Lunt 60 DS it's a fantastic scope but with a b1200. I believe imaging is more difficult with the b600 but fine for visual. Image taken with my setup using Zwo ASI 178mmm. False colour added in PS CS2

That's just a dealer spin to get you to fork out (a lot) more cash, Lunt are a little more honest, on this occasion they say "it'll give you a little more wiggle room"

I've used the scope on all sorts of mounts. As long as you have a reasonably decent one and take a little care to make sure you level the tripod, It should remain in the frame with little intervention.  I've had it stay put for hours on an evolution alt az mount to such an extent that I can actually "shrink" the sensor area down using the ROI.  In reality 10 sec's is enough to dump down 500 images.

Not really into imaging but I usually spend a little time with the camera when I start to get too hot. The sensor used on the mono pic was an e2v560, (Machine vision camera with gigabit interface).  This throws out around 100MBytes, (not bits) per second at full tilt, e2v570 is the same physical size but has smaller pixels giving a resolution of 1600 x 1200. Pretty happy with both. I then just throw the resulting tiffs or AVI at autostakkert or registax (no idea what i'm doing), just select the files and keep pressing nextor go or whatever. That's as far as I go.

have fun

Steve

PS, Nice image Nigella

 

Edited January 29, 2021 by bilbo

[SimM]

3 hours ago, bilbo said:

That's just a dealer spin to get you to fork out (a lot) more cash, Lunt are a little more honest, on this occasion they say "it'll give you a little more wiggle room"

I've used the scope on all sorts of mounts. As long as you have a reasonably decent one and take a little care to make sure you level the tripod, It should remain in the frame with little intervention. 

Is the blocking filter operating like an ordinary 1.25" filter that you might put next to a ZWO sensor (except it blocks and is smaller e.g. B600 is 6mm and B1200 is 12mm diameter)? Is it after the diagonal on the EP side?

Tracking an object accurately for a reasonable time isn't so hard with an equatorial mount, even when only roughly aligned as would be the case in the daytime (from trying a solar wedge for WL).

So, to use the example image from above, the sun is 4.2mm and the sensor is 4.9mm x 7mm. A blocking filter that is not close to the camera sensor and that is only 6mm seems a bit borderline e.g. won't it vignette the camera sensor if it isn't sufficiently close to the camera sensor and that's why they recommend a bigger version for imaging.

Or is the path of the light from the objective, through a positive and negative lens that causes it to pass "parallel" through the Etalon and also the blocking filter e.g. vignetting of a cone of light e.g. an f/4 or f/7 refractor, no longer applies?

Since the target is only ever fixed then there is no reason to accommodate two or three suns. By the same reasoning there would be little point having a zoom e.g. the 7.5mm - 21mm that will show about 1.25x - 3x sun diameters for visual use?

So apart from zooming out to find and centre the sun, you would always want the 7.5mm end of the zoom? OR is (likely) it more comfortable to use a lower power EP than need not completely fill the FOV?

Except, I notice that it's often recommended to use a 10mm or 12mm EP with the 60 Lunt scopes? I'm not a fan of zoom EP but I can see the wow factor of zooming in with ease for this "special case" target.

I ask because the cost and benefit increases of having a bigger blocking filter are good to know and because I was considering using a fixed EP rather than the zoom e.g. a 10mm or 12mm as recommended with an existing 17mm or 21mm for the find/centreing exercise. With the smaller blocking filter there would be nothing additional to look at with a longer EP or with a small sensor to see?

Simon

[SimM]

5 hours ago, Nigella Bryant said:

I have a Lunt 60 DS it's a fantastic scope but with a b1200. I believe imaging is more difficult with the b600 but fine for visual. Image taken with my setup using Zwo ASI 178mmm. False colour added in PS CS2

Lovely image. Do you "tweak" every image with moving sliders on a curves dialog or do you have some kind of preset that you use?

Is the colour around the sun achieved with the same "tweak" or is it different on the outside?

It must be different because the starting point is shades of mono and all are in the inner part too?

For a "natural look" would you be aiming to not have the outside totally black e.g. grey or something else shows up the prominences? 

[Nigella Bryant]

6 minutes ago, SimM said:

Lovely image. Do you "tweak" every image with moving sliders on a curves dialog or do you have some kind of preset that you use?

Is the colour around the sun achieved with the same "tweak" or is it different on the outside?

It must be different because the starting point is shades of mono and all are in the inner part too?

For a "natural look" would you be aiming to not have the outside totally black e.g. grey or something else shows up the prominences? 

The false colour is achieved by changing first the mono bit image to RGB and using colour RGB to then apply to gain a reasonable associated colour. All the image is changed by applying the different amounts of RGB. The outer colour will always be darker because it's darker in the original image. If you go to black you loose the contrast of the prominences. It's a fine balance to keep the surface details with that of the prominences. As this screen shot from today only in mono as I've not processed all the data yet.

[SimM]

2 minutes ago, Nigella Bryant said:

The false colour is achieved by changing first the mono bit image to RGB and using colour RGB to then apply to gain a reasonable associated colour. All the image is changed by applying the different amounts of RGB. The outer colour will always be darker because it's darker in the original image. If you go to black you loose the contrast of the prominences. It's a fine balance to keep the surface details with that of the prominences. As this screen shot from today only in mono as I've not processed all the data yet.

I have started using Affinity and I couldn't understand why changing colours had no effect - until I switched to a colour space! It was the same first time a tried to use a toaster - so much more fun when plugged in - LOL.

I did find the prominences look good against mid grey background but the reddish background makes a "powerful" statement in your coloured image.

Simon

[SimM]

17 minutes ago, Nigella Bryant said:

The false colour is achieved by changing first the mono bit image to RGB and using colour RGB to then apply to gain a reasonable associated colour. All the image is changed by applying the different amounts of RGB. The outer colour will always be darker because it's darker in the original image. If you go to black you loose the contrast of the prominences. It's a fine balance to keep the surface details with that of the prominences. As this screen shot from today only in mono as I've not processed all the data yet.

This is the result of stacking a video of images?

What you see with an EP doesn't compare to it? OR does your eye only capture the good moments (or probably averages it and sees it as worse?).

 

[Nigella Bryant]

11 hours ago, SimM said:

This is the result of stacking a video of images?

What you see with an EP doesn't compare to it? OR does your eye only capture the good moments (or probably averages it and sees it as worse?).

 

No it's just a screen shot of one frame that I've just tweaked in Photoshop. Not had time to process the 1000 frames yet. In the eyepiece it's a little less pronounced from my experience but I've 62 year old eyes, lol. 

[bilbo]

18 hours ago, SimM said:

So, to use the example image from above, the sun is 4.2mm and the sensor is 4.9mm x 7mm. A blocking filter that is not close to the camera sensor and that is only 6mm seems a bit borderline e.g. won't it vignette the camera sensor if it isn't sufficiently close to the camera sensor and that's why they recommend a bigger version for imaging.

Hi Simon

Lots of good points, The layout is objective, collimating lens, etalon, refocusing lens. Blocking filter is on camera side of diagonal. Attached a cutaway. 

You have triggered an OOPs in my head though,  The blocking filter that came with this had an issue, (long story and long fix which I need to write up). While it was away I had two other B600's one slightly enlarged. The bug in my head now is did I use the slightly enlarged one while I checked out the rest of the scope.  The mono image posted was part of the blocking filter tests I submitted to lunt so I'm 100% confident that was the stock one. I also observed an absolute mega prom coming way, way off the sun during the break in lockdown, sadly no camera as I was at the caravan and didn't notice any cutting off to suggest vignetting, but I could have had the sun off center. Now I need to double check the obs against a cam.

Thanks a million, You've give me something to do.

Pic below is the lunt cutaway, but they've been tinkering about a lot swapping in cheaper components.

Steve

[SimM]

On 30/01/2021 at 18:20, bilbo said:

Hi Simon

Lots of good points, The layout is objective, collimating lens, etalon, refocusing lens. Blocking filter is on camera side of diagonal. Attached a cutaway. 

Thanks a million, You've give me something to do.

Pic below is the lunt cutaway, but they've been tinkering about a lot swapping in cheaper components.

Steve

Thanks Steve for the cutaway diagram.

See the mods to the LSMT60.

They use the same red front-mounted 60mm clear etalon as the outgoing LS60THa.

The scope is 420mm f/7 with ED doublet FPL-51 replacing the single objective and not coloured.

As a normal scope it's 420mm f/6 (uses full 70mm objective).

It's anyone's guess if they improved (or cost reduced) the scope. Claim is < 0.65A or < 0.45A.

So, at least there is one front mounted-etalon in DS configuration (a good thing?).

Simon

[bilbo]

It does look interesting,  but a bit gimmicky for me.  still not convinced about pressure tuning long term reliability. You can get spare '0' rings for the tuner but what about the sealed chamber containing the etalon. If the seal in there gives up, the scopes duff.  (Why I bought a tilt tuned LS60)

If I had the cash spare, I'd go for an etalon & filter kit which can be fited onto any scope. options are then endless.

I loved my little LS35, The LS60 was a dissapointment when I got it , but that turned out to be down to the fact that lunt swapped out the 1mm AR coated IR Cut Glass for a 3mm uncoated type resulting in a big light loss. I've corrected that now so hopefully this year I'll be able to enjoy some long awaited activity.

I'll let you know how it goes

All the very best

Steve

 

[SimM]

23 hours ago, bilbo said:

It does look interesting,  but a bit gimmicky for me.  still not convinced about pressure tuning long term reliability.

It is certainly not a reason to change what you know works - "if it ain't broke - don't change it".

Sort of "chicken and egg" as well, as there are not many users to get opinions about it, to get interested in it.

The "gimmickry" is OK, but I can see that many astronomers will probably be already starting with some existing equipment, anyway.

Simon

[Merlin]

It’s a problem when trying to compare different Ha ‘scopes for the reason that the quality of the etalon can vary from one ‘scope to another. I’ve heard that only about 10% of PST etalons are REALLY good. It could be the same for other makes.

[Peter Drew]

Of the many PST etalons that I have used, all were good enough, quite good and a couple were exceptional.  One of the latter couple was stolen along with the modded  6" refractor and its full aperture ERF, the other is in my 6" replacement.       🙂

[Nigella Bryant]

20 minutes ago, Peter Drew said:

Of the many PST etalons that I have used, all were good enough, quite good and a couple were exceptional.  One of the latter couple was stolen along with the modded  6" refractor and its full aperture ERF, the other is in my 6" replacement.       🙂

Sorry to hear about the theft. I guess they were never recovered. 

[Peter Drew]

1 minute ago, Nigella Bryant said:

Sorry to hear about the theft. I guess they were never recovered. 

Some years ago now Nigella, life still goes on though.     🙂

[Altair8389]

Thanks everyone, especially Nigella and Bilbo. So I have digested your advice and I have discovered:

Bilbo advises LS60 or LS35 can image full solar discs. Recommends B600 filter (B1200 not needed).

Nigella Bryant says; Lunt 60DS with a B1200 filter, ZWO ASI178mm. Fantastic image of the sun using this combination.

 

So I will have some more research into the Lunt60DS B1200 or B600, but still much too expensive at this stage. Maybe I could buy a small LS35 or LS40 and then practice my imaging on that. Then sell the scope when I am ready for a larger LS60DS scope.

 

Thank you all.

Magnus

[Solar B]

Yes as the LS35 & 40 have front mounted etalons they would make great intros to

HA viewing as for the LS60 well they're great dumbbells and about as heavy 😉

Brian 

[michael.h.f.wilkinson]

On 27/12/2020 at 14:41, Altair8389 said:

https://luntsolarsystems.com/shop/solar-telescopes/40mm-telescopes/lunt-40mm-dedicated-hydrogen-alpha-solar-telescope/

 

I have a 70mm refractor and currently using a Quark chromosphere filter. I am getting reasonable views but working out how to switch to a straight through optics arrangement (as advised by Martin Wise, Wise Imaging).

I have problems with Newton's rings, and despite tilt adapter, have problems removing the NRs. I have had a break from solar as the weather is - too wet/windy/cloudy/damp/too hot and have added work to do despite the pandemic.

 

I really want to get full disk images, but wonder if I can get the Lunt 40mm dedicated solar h-alpha scope or a Lunt 60mm. Which one would give me a good full disc image. I know you need a match camera to get a full disk. Can you get a full disk easily without having to do mosaics ? I find mosaics difficult, although I have not given up. I saw Michael Wilkinson's images using more than 80 frames to get a single full disk. I don't know if I can use 300 GB for each full disk, as that would mean over 10 Terabytes in less than a year ?

 

Anyway, any advice would help. I don't really want to spend 8000 pounds just to get a full disk. Can the 40mm Lunt do this easily and would the images be of much poorer quality compared to a better scope ?

 

Thanks.

Magnus

 

I could get full-disk images with the little LS35 I had with the bigger sensors, (actually, the ASI178MM would do that easily, at a very good resolution) I made the mosaics with the LS35THa way back then because I was using a much smaller sensor (using a DMK21), so to get sufficient resolution, this was needed. An LS60 would be fine on modern, bigger sensors. Currently, if I barlowed an LS60 with a 1.5x Barlow I would get the whole disk on the sensor of an ASI183MM. The reason I do mosiacs with the 80mm is purely because that system is more Quark like,  has a narrower FOV and operates at F/27 or so, and requires larger pixels, so the ASI174MM is best.