lunt 50mm solar telescope

[Stu]

Hi Derek,

There is some useful information here at the Lunt website regarding blocking filters. The difference is in the aperture of the filter, and it affects the field of view possible but it also depends upon the focal length of the scope. The Lunt 50 is f7, making it 350mm focal length. Whilst the Lunt site does not detail the B400, the designation implies it is suitable for scopes up to 400mm focal length. This again implies that in visual use you should get the full field of view with the B400.

The reason for imaging needing a bigger filter is explained below.

http://luntsolarsystems.com/product/lunt-blocking-filters/

I would expect however that you would still get a larger FOV with the B600 so personally I may be tempted to go for this one.

On the double stack, I have no direct experience, but from what I have read on here they are more suitable for imaging than visual. I believe they darken the image a fair amount, including the proms whilst improving the contrast on the surface detail; this is easily compensated for in processing but less so in visual.

Personally on this one I would probably save the money and not go for the Double Stack. I am sure the views through the single stack will give you more than enough entertainment, and you can always add the DS later down the line if you desire.

Cheers,

Stu

[Stu]

Nice book Aything you can include Jabeo would be great. I'm torn between purchasing a Quark for the TV 76 or going for a more dedicated solar scope like the Lunt 50mm (Tal + Coronado mod is no man's land for me).

As a purely visual observer, it would be nice hear your views or see (sketch or posted image) the kind of detail you are able to tweak from the Lunt. You know, whether it Is a bit like Moon or White Light observing where you can clearly see detail, or more like galaxy hunting where you get hints of detail at the horizon of visibility etc. Being in Spain and living near a smallish town, I don't know anyone with a solar scope, so basically have no idea of what is possible visually.

As such, any input would be great and would be really appreciated

Hi Rob,

I won't interfere with your question here, but I will say that in either combination we are talking about 'moon/white light' observing rather than 'Galaxy hunting'.

The detail visible is lovely, and quite obvious. There are subtle features of course, but lovely proms, filaments, granulation etc etc are visible easily.

I will say that my desire for better Ha views was in part driven by the mind blowing white views I was getting through the TV85 vs Ha in my PST40, so aperture does help!

Cheers,

Stu

[michael.h.f.wilkinson]

Regarding the blocking filters: my LS35 came with a B400 (4mm diameter) which was OK for visual, and even got me some decent images. I could then get a second-hand B1200 for the price of a new B600, so pounced. It is definitely nicer, but I wonder how much difference it would give on a 350mm focal length instrument (the LS35 has 400mm focal length). For imaging, the B600 would give a bit more leeway. 

Regarding double stacking: Its aim is to decrease the transmission band by adding an extra etalon. As said before this darkens the image, and increases surface contrast.  I would not go for that option initially. Instead, you could consider getting a Quark later, and using that for both detail views in a larger refractor, and double stacking in the LS50. I myself am thinking of getting a quark, and using it for full disk in the ST80, and perhaps double stack in the little LS35 (or sell the latter).

Just my tuppence

[DRT]

Thanks guys, that's very helpful.

Now I just need to persuade Mrs T to buy me one :-)

[Moonshane]

hi Derek. My experience is slightly outside of your exact question but I can add this if it helps. Hope I am not too far off topic. I have only ever looked through a standard 40mm PST and then this converted to an effective aperture of 80mm and then 100mm as a PST mod with a TAL 100. The views through the PST were actually a lot better than I remembered through previous short views although in truth they were very brief and my first experiences so I was almost certainly not used to the process of how to observe in Ha. 

The PST comes with a 5mm blocking filter and has a 400mm focal length so whilst a 4mm (b400) filter would have been OK it is slightly bigger than needed in a PST for whole disk views. I use this happily in my 100mm PST mod although I have borrowed a 10mm (effectively a BF1000) blocking filter very kindly by Ian (Uplooker) and this provides really superb field compared with the 5mm - it is four times the area of course. Full disk is just possible with a 15mm plossl (67x) with the 10mm aperture. That said, I find my observing style is to look at the full disk only briefly and then increase magnification to seek out and observe in more detail some of the specific features of the day. To do this I use the sweet spot which may or may not exist with the other options, to scroll around the surface and limbs and this creates a rolling 'best picture'. Centralising features always creates the sharpest and most detailed images. I can get about a third of the disk in my view with the BF5. I may try drilling this out to 6mm as has been done by others to gain a little more but I am not sure if it's worth it.

I suspect that the features available are almost always seen with even a 35-40mm aperture Ha scope based on other people's reports but the finer detail does increase with aperture (resolution). I mainly observe at between 60-100x and this allows all detail to be seen.

In short whilst I would recommend the larger B600, the B400 would be more than adequate for visual I would think. There is no increase in the quality of the view with a larger BF. I don't have experience with double stacking but based on my experience with larger aperture, if I had a choice between a larger aperture single stack and a smaller aperture double stack I would choose the former every time for visual.

You'd be welcome to come over to me in Stockport if you fancy looking through a 100mm pst mod and I could easily convert back to standard PST mode at 40mm for you. That is, if the sun ever shows again!

[DRT]

Thanks, Shane.

I got some advice from Steve at FLO along the same lines and have decided to go for the 400 version.

The best news of all is the The Boss has said yes!!!        

[michael.h.f.wilkinson]

Thanks, Shane.

I got some advice from Steve at FLO along the same lines and have decided to go for the 400 version.

The best news of all is the The Boss has said yes!!!        

Great! Now all we need is some sunshine

[Merlin]

I have a LUNT LS50F front-aperture etalon that I've double-stacked to the PST. I wasn't sure if the two units were compatible, but they work very well.

There doesn't seem to be any diminuition in solar surface or proms brightness, although there must be some, as every piece of glass introduced into an optical train soaks up some of the light, if only by a miniscule amount.

[Pig]

I did spend quite a lot of time researching blocking filters before I bought my Lunt 60 and I concluded that the size of the blocking filter clearly is related to the focal length of the scope being used

I must admit prior to reading this I presumed the higher the number of blocking filter the better the view of the sun would be  The difference in price between them is pretty huge so I would have naturally expected a better view

[Moonshane]

I suppose if you consider the surface area it is cheaper the bigger you go.....

[trazor]

I have a LUNT LS50F front-aperture etalon that I've double-stacked to the PST. I wasn't sure if the two units were compatible, but they work very well.

There doesn't seem to be any diminuition in solar surface or proms brightness, although there must be some, as every piece of glass introduced into an optical train soaks up some of the light, if only by a miniscule amount.

I have to agree with Merlin here.

A second Etalon reduces only the bandpass, but does not  reduce the brightness by any appreciable amount.

I use my 60mm Lunt for visual only, and the views are stunning and take on a 3D appearance, significantly better than without the second etalon.

It always amazes me that various posters on this site, talk of the second etalon being unsuitable for visual.......    

[Stu]

I have to agree with Merlin here.

A second Etalon reduces only the bandpass, but does not reduce the brightness by any appreciable amount.

I use my 60mm Lunt for visual only, and the views are stunning and take on a 3D appearance, significantly better than without the second etalon.

It always amazes me that various posters on this site, talk of the second etalon being unsuitable for visual.......

Very interesting and useful info trazor.

My information comes indirectly from a number of posters on this forum who have said the double stacked PST is quite dim for visual; I've not tried it myself.

Perhaps the difference is the additional aperture you have with the 60 meaning brightness reduction is less/not noticeable vs a 40mm PST?

EDIT: I have just re read my original post, and I should have made clear in it that I was referring to double stacked PST's as they are what I have read about. My apologies for being unclear on this.

My advice to Derek still remains though, I think there is plenty of enjoyment to be had with the single stack Lunt 50 before a potential upgrade in future.

[trazor]

Very interesting and useful info trazor.

My information comes indirectly from a number of posters on this forum who have said the double stacked PST is quite dim for visual; I've not tried it myself.

Perhaps the difference is the additional aperture you have with the 60 meaning brightness reduction is less/not noticeable vs a 40mm PST?

EDIT: I have just re read my original post, and I should have made clear in it that I was referring to double stacked PST's as they are what I have read about. My apologies for being unclear on this.

My advice to Derek still remains though, I think there is plenty of enjoyment to be had with the single stack Lunt 50 before a potential upgrade in future.

Yes, perhaps I also should have referred to the fact that all my observations are with a 60mm Lunt only.

Significant dimming may well be the case with a double stacked PST, I would not know.

I used a single stack, for 18 months before adding the second etalon, now, I would not observe without it.

[michael.h.f.wilkinson]

I have a LUNT LS50F front-aperture etalon that I've double-stacked to the PST. I wasn't sure if the two units were compatible, but they work very well.

There doesn't seem to be any diminuition in solar surface or proms brightness, although there must be some, as every piece of glass introduced into an optical train soaks up some of the light, if only by a miniscule amount.

I find this a bit odd. If you reduce a bandpass from 0.7 to 0.5 A, you must be cutting light (even assuming ideal bandpass: some 30%), more realistically, the throughput could drop by as much as 50%. This is a figure I have heard from some imagers (can't quite remember where, but it makes sense). Note however, that the human visual system is much more sensitive to relative brightness differences in the field of view (in particular edges)  than to absolute changes in overall brightness. It is very hard to estimate these reliably. I would not be surprised if the brain interprets the dimmer, but more contrasty image as almost as bright as the single-stacked image.

[spaceboy]

I would have thought visually it would look darker also??

I know when I get moments of perfect seeing in white light the granulation POP and all that extra contrast in my eye's darkens the image. I know it isn't darker and if anything it is I assume its going to be lighter if anything but all that extra detail and contrast in place of an otherwise washed out surface takes my eye a while to compute.

As for reducing the bandpass is this not just decreasing the amount of red spill so your getting a truer red at the ep ??(sorry don't know the tech terms) Similar to filtering at night where you block all the spill from light pollution and an object you can't see or very little of with out a filter then you drop in an OIII filter and hey presto. I know different filters filter differently and two different OIII filters can bring out more or less detail. I'm aware that using a double stack is supposed to lower the detail on proms and this is why most dedicated solar scopes hit a happy medium of between 0.7 - 0.8 A so both proms and surface details can be seen. The lower the angstrom the more surface details and the higher the more prom details.

I will mention at this point I have absolutely no idea what I'm talking about so I hope something makes sence

[Qualia]

Hi Rob,

I won't interfere with your question here, but I will say that in either combination we are talking about 'moon/white light' observing rather than 'Galaxy hunting'.

The detail visible is lovely, and quite obvious. There are subtle features of course, but lovely proms, filaments, granulation etc etc are visible easily.

I will say that my desire for better Ha views was in part driven by the mind blowing white views I was getting through the TV85 vs Ha in my PST40, so aperture does help!

Cheers,

Stu

That's a cracking reply, Stu and thank you for taking the time to reply. I think it's the first time I've actually been able to create a possible picture in my head of what is going on without second guessing via photographers' images. You're right about those phenomenal views possible in white light with a wedge, so if something 'similar' could be tweaked from either a Lunt or Quark I'd be more than a happy man. The real problem now is to decide what to go for

[Moonshane]

I agree with Stu. The detail seen is really remarkable in my 100mm PST mod. I did a sketch here http://stargazerslounge.com/topic/232650-busy-ha-sun-281214/ and there was a lot more fine detail than I could ever hope to sketch.

[Moonshane]

ps given the scrawling above, you can tell I find Ha sketching a lot more challenging than white light!

[Davey-T]

ps given the scrawling above, you can tell I find Ha sketching a lot more challenging than white light!

Nothing wrong with that sketch, almost like being there

Dave

[nipper1967]

l wonder if the people at flo have any news of the availability of the double-stack unit.

[Merlin]

Just to mention that I've been using the AZ-3 mounting for several years, including in PST mode. It makes life much easier if we had a counterweight to the mounting: www.spacegazer.com/index.asp?pageid=9749 .