Wowza ...Solar

[NickH]

Just gota heads up from Michael in Ireland about this

Yahoo! Groups

Jeepers...

[Dangerous-Dave]

Price $15,999.00

Is that all?

[NickH]

Compare it to what a Maxscope 90 was up until a few weeks back

Interesting, I agree way too much, but 230mm, that's some scope

However, now the modding game gets more interesting in seeing Rogerio's 50mm LS with a 200mm Zeiss, if someone could put together a sub £3000 200mm refractor/mod kit...then we're cooking!

[Peter Drew]

My 220 mm refractor/PST mod cost me under £1000.

[Solar B]

We all know whos going to be getting one of these

I really think the Lunt boys are having a laugh.

The LS152 only uses a 60mm etalon ,the LS100 a 50mm.

Real costs and expertise go into making large unobstructed etalons,just ask Ken how hard it is to make an SF100.

There is no real substitute for etalon aperture.

Brian

[NickH]

Absolutely agree Brian...and this price is silly.. just very silly..

Rogerios images however do kind of kick the full aperture argument a bit.., but if the LS50 etalon can deliver that with a 200mm front objective..then

Peter...so how did you get a 220mm ERF for that cost?

[astroshot]

I wonder if I bought two and binoviewed with them....

All joking aside, large ERFs are normally expensive.

My 135mm DERF cost 750euro. That is a 1/10th wave glass.

However, if this was set down the tube a bit from the objective lens, a smaller ERF may be possible provided one doesn't go wild and place too much heat on a small ERF. As the better ERFs work on reflecting the energy away rather than absorbing it, the heat may get trapped between the ERF and the objective lend. Therefore, vent holes may be required on the OTA between the ERF and objective lens to let the heat out and reduce thermal currents in the OTA.

Michael.

[astroshot]

The PST etalon and blocking filter may be a bit small for this kind of project.

A 50mm etalon and B3400 blocking filter would be better.

More expensive solution obviously.

Michael.

[brianb]

if someone could put together a sub £3000 200mm refractor/mod kit...

1. How often is your seeing good enough to make the extra resolution of an instrument bigger than 150mm actually work on the Sun?

2. How much do you think a 200mm Zeiss refractor OTA tube (or one of similar quality)

costs?

3. How are you going to carry it?

4. What are you going to mount it on?

Practicality, practicality, practicality ...

BTW I must say that images I've seen taken with the LS152 have been pretty encouraging (Stephen Ramsden on CN).

When you're imaging at long focal length i.e. small field, the relative disadvantage of the small aperture etalon is reduced, and something tells me that a 200mm+ aperture instrument is wasted for the purpose of full disk imaging. Far more resolution than is required, and much clumsier than a smaller instrument which would do the job adequately. So there may well be mileage in the design ... but, if it's going to be restricted to those with permanently sited observatories, Paramount class mountings and reliable seeing conditions to match, the price tag really doesn't matter much. (If you need to check, you can't afford.)

[NickH]

1&2 fair points not often and a lot, but as is monochromatic, and after seeing Dodi's images with a c6R, the Zeiss isn't really the issue, point 1 is!

3,4 not an issue.. have obs, and bigger mount is planned.

Stephen's LS152 images, I have yet to see anything which really convinces me..sorry Alan Freidman's SM90's shots or Pete's SF70 shots yes..

Anyway at $16000 it's steep, and they are only making a few...I guess after they announced the 200mm reflector version and then didn't deliver, they had to do something

[NickH]

It's an interesting point on the seeing front. Looking again at Dodi's modded PST shots on the C6R from I guess sub optimal locations, they were superb (albeit at 150mm). Rogerio's ditto at 200mm with noticeably more detail, and I doubt he's on the top of a mountain in Chile for them...:-) (he's not as we know)

[astroshot]

I think the focal length will be more of an issue than aperture. I use a daystar filter in my TEC140 @ 4m focal length. Even in damp auld Ireland, one can get reasonably good seeing in the early morning before the Sun gets too high.

With the Lunt scope, it operates at only 1,610mm so I don't think the seeing will choke the aperture too much. Even if a 2x barlow was used, it's still manageable IMHO.

[Peter Drew]

Nick. I purchased a good s/h 145mm ERF for £110, a s/h 8.8 F12 achromat for £500 and a s/h PST for £350, I built the scope, mount and observatory myself, total cost under 5K. The scope is primarily for lunar and planetary visual obs but being a keen solar observer and PST mod enthusiast and having the bits it was worth a try. I'm still experimenting with the 8.8" set-up, I've only tried an 80mm ERF so far which was a bit near the focus heatwise, the 145 ERF could be placed nearer the objective. I plan to try out an ERF cooling system in the near future as the results at this aperture have exceeded all my previous results. The 5mm b/f of the PST does mean a resticted field but what is available is well worth looking at. If eventually successfull, a larger b/f will be a good investment.

[NickH]

Peter, very interesting. The ERF I guess is not the Baader. I tried a few other makes and options and they all fell over at high mag

Be interested to see the images from that

[Peter Drew]

Nick. The 145mm and 80mm ERF's that I currently use were reputedly Daystar although I would have liked to have seen Daystar engraved on them! They are both around 6mm thick and in good condition. I have a 3rd ERF 85mm diameter and around 3mm thick that I purchased at Kelling last year for £50. All 3 have given me much better results than the standard PST so I consider them good value. I take your point about performance at high power and I would really like the opportunity to compare them to the Baader equivalents. Visually I rarely use more than 100X particularly in view of the small B/F.

[NickH]

If they are Daystar then I really want to see what they deliver...as they are very good..

You did mention 220mm PST, what's the ERF for that?

[Peter Drew]

Nick. The ERF for the 220 was the 80mm (Daystar?) set around 60cm from the prime focus as a sub aperture unit, hence the heating problem still to be addressed. I'm planning to try the 145mm further up the lightpath to mitigate the heat but the weather has been so poor recently that I have diverted my attention to a high res 12" F8.5 Newt project.