LUNT LS60THA REVIEW BY STEPHEN RAMSDEN

LS60THa MANUFACTURERS INFORMATION

The LS60/Ha is a complete Solar Telescope. The refractor based system has a precision aligned singlet chromatical lens with a 60mm aperture. The front singlet lens reduce half the straylight of an achromat , fully eleminate the possibility for on axis coma, astigmatism, decentering aberrations and provides with the matched collimation lens set a full spherical corrected flat-field Solar-Telescope. The focal length is 500mm providing a ~4.5 mm image thru a 6mm blocking filter. Fine adjustment is achieved with a Crayford style focuser or feather touch focuser with 10:1 reduction standard. An internal etalon with tune adjustment allows for a <0.8 Angstrom bandpass.

Review of the LUNT LS60THA

(part one-cloudy skies-scroll down for part two)

By Stephen W. Ramsden Tuesday, July 22, 2008

First things first. I am an avid solar astronomer with about 2 years experience in Ha and decades experience with night time viewing. I own a Celestron CPC 9.25 and a Celestron CGE1400 system both set up for white light viewing through Thousand Oaks Type II glass filters and a Coronado 90mm SolarMax and a Coronado Double Stacked PST. I have no experience with other brands of Ha filters, just Coronado and now Lunt. I am not an expert astronomer nor am I paid reviewer. I am an average solar astronomer who is still looking for the right combination of camera and scope for solar narrowband imaging.

This is what the packaging looked like for the LS60THa:

The scope arrived by UPS ground in Atlanta in a single ply cardboard box with Styrofoam peanuts protecting it’s contents. Inside the box was a silver attaché style case of sturdy construction wrapped in 2 layers of taped bubble wrap. It was protected very well from jarring and dropping during shipping. I was very impressed with the case as it was

sturdy and had two beefy latches on the front. The handle was thick and rugged and seemed to be able to take a lot of stress.

The scope occupied about 30% of the case. I noticed that there were several predrilled holes in the case for eyepieces and plenty of room to make your own holes for other items such as a dovetail mount or sol-finder. The case was a big winner in my book, very rugged.

Inside the case where the following items:

1) Lunt 60mm single Ha scope

2) A Televue style mounting ring

3) A Warranty card

4) A key for the case.

The case did not contain any accessories. There were no instructions, no parts list, no catalogue of accessories, no eyepiece, no mounting hardware, no solar finder. There was no hardware other than the scope and a mounting ring.

The first thing I noticed was the excellent construction. The scope had a very attractive pearlescent finish with black trim. The lens cap screwed on to the inside of the objective lens cavity and was made of metal. It had a stylish cactus logo on it. The Crayford style focuser was meaty and had an excellent feel. There were no rough spots and seemed to go smoothly through it's entire range with either the coarse or fine adjustment knob. The eyepiece and blocking filter were held in with what brass compression rings.

The 1.25” B600 diagonal blocking filter had a long 2 inch insertion tube where it went into the focuser. The screw that adjusted the compression ring for the blocking filter was at the same angle and almost the same position as the focuser. If it were to be confused for the focuser by a first time user it might have a bad result however it was much smaller than the focuser and i did not confuse them.

There was a red plastic plug in the eyepiece holder

Looking through the objective lens, one saw a large etalon securely seated deep in the optical tube. The retaining ring for the objective lens unscrewed along with the lens cap the first time I tried it but I soon found how to remove the cap without dropping the objective lens.

The scope was heavier than the single PST and about the same weight as a double stacked PST. It was easy to handle and was not slippery.

It was not apparent how to mount it onto any standard mounting hardware other than a photo tripod since it had 3 threaded 1/4-20 holes on the underside in a straight line. Once I dug out a 2 inch ADM dovetail plate and some screws that would fit the holes, I put it onto a Vixen Alt/Azm mount, added an 18mm CEMAX eyepiece and headed outside.

Unfortunately there was a thin high layer of cirrus clouds over Atlanta with occasional breaks so it was not the best day to test any solar scope but I think I got a good feel as I compared it to the same conditions with my PST. The sun was bright enough to appear in the LS60THa but there were clouds. Please wait for the second installment of this review where I plan testing the scope under clear, sunny skies.

After focusing it for a while and playing with the etalon adjustment I was able to get a focused image. The tuning dial was black and located in a recess in the black area of the scope. It was not apparent where the etalon tuner was so it took a few seconds to find it. The etalon adjustment has much more range than the PST but it did not seem to make much difference through it's range, probably due to the haze and clouds. The only prominence seen was on the eastern edge. It was difficult to get any definition. I believe that the thin cloud layer was responsible for a majority of this. I waited for a break in the clouds and then tried again. Unfortunately, the breaks were of short duration.

The image was then much sharper during the breaks in the clouds but it seemed that there was way too much light getting in if you put the etalon into the position where the prominence was visible. There was a bright red glow around the disk like it needed another filter or something The disk itself was a solid reddish orange no matter how you adjusted the etalon.

The below is an unaltered exposure straight from the Canon 40D and a T-adaptor holding the 18mm CEMAX eyepiece. Photographically the glow was not as bad but visually, there was a lot of red glow around everything. Probably the clouds. It was very similar to having the PST etalon tuned all the way to the bright side. I moved the etalon tuner all the way each way and the disc never stopped glowing. The prominences where visible in an extremely small area of the tunable region. The Double stacked PST ,on the other hand under the same conditions gave a focused view with 2 filaments and one large prominence and one small prominence. The single etalon PST gave about the same image as the LS60THa. Of course you can see for yourself the thin layer of clouds between me and the sun so I cannot give an accurate rating of a cloudless view. I believe the glare was produced by the extra aperture of the 60mm Lunt with the small blocking filter. It was a little uncomfortable to look at. The image was slightly bigger in the LUNT but not more detailed or sharper. It seemed that if you focused one side of the sun, the other became blurry. This may have also been the clouds. As I said, I plan on testing it again without clouds.

My initial impressions of the scope are that it is better viewing than the standard PST and not as good as a double stacked PST. This cannot be measured under the cloudy conditions so I will wait until I get clear skies to be sure.

The retail price of $899 seems to be commensurate with it's relative performance. The PST comes with an instruction manual, eyepiece, Malta mount, mounting screws and a case for $659 plus a $100 manufacturers rebate. It also has a short pamphlet inside describing how it works and what the parts are. The PST case is much less sturdy but you can take the PST out of the case, set it up anywhere with included hardware and use it immediately.

I believe the sturdier construction and the far superior focuser of the LUNT LS60THa is worth the difference in price if you have to choose one or the other. I would not recommend it as an upgrade from the double stacked PST unless you buy the the double stacked version (which has not been reviewed yet).

If I were to have received this Lunt as my first Ha scope, I would have been disappointed that there were no instructions, no eyepiece and no screws to mount it to anything. The LS60THa did not have a solar finder like the one built into the PST. I used the old "watch the shadow on the pavement" technique to find the sun with the LUNT. That was a disappointment also.

The photographic quality was also a little better than a single PST but no where close to a double stacked PST.

I believe the strong points of this scope are the very tough construction, sturdy hard shell case and excellent focuser. The LUNT had a very nice dual speed focuser. This was the standard LUNT focuser, not the feather touch. I can only imagine how nice the feather touch version must be.

I believe the weak points are that it is a stripped down setup with absolutely no accessories. It also could benefit from a standard mounting ring and an included solar finder.

Hopefully the double stacked 60 and the larger LUNT scopes will be much better optically than this one.

I would like to add that Rikki and the staff at LUNT have been nothing short of extremely courteous and helpful on the phone or via email. That is worth a lot to me.

Stephen W. Ramsden

Atlanta, GA

DAY TWO UNDER SUNNY, CLEAR CONDITIONS, FINALLY!!!

Today the conditions were 8 out of ten. It was clear and sunny with a 3-5 kt variable wind on the surface. The humidity was 45%, the temp was 87.9 °F / 31 °C. Visibility 10 miles. No clouds with just a slight haze associated with downtown Atlanta in the summertime.

I started with the Solarmax 90 and the double stacked PST side by side on my CGE mount in order to get an idea of what was really there today. I saw around a dozen small prominences and 2 larger ones. There were 2 small filaments and one VERY large filament on the NW limb.

The below picture is a single frame from the Coronado SolarMax 90mm taken with the Canon 40D/CEMAX 18mm eyepiece projection with a brightness/contrast/tint adjustment in Corel Draw.

Then I got out the LUNT LS60THa. I attached it to the CGE mount with the GPS accessory and custom ADM knobs with a 4 inch ADM dovetail plate with a countersunk trough down the middle. I secured it with 2 1/4-20 screws that came with my PST originally. This plate was then attached to a ADM dual mount that Anthony Davoli made for my PST/Solarmax 90 setup. (I think that Anthony Davoli's work is awesome!) The scope was mounted and balanced and then I realigned to the sun. I also added a Televue Sol-Searcher ($35) onto the mounting ring of the LS60THa. It was easy to install and did not require adjustment. It certainly made the scope feel whole as I did not have to watch the pavement to find the sun. The police came by as usual. They seem to get real nervous when I set up my equipment.

I must say here that under these conditions the LUNT LS60THa outperformed the single PST. ("Crow" may be eaten later today).

The LUNT had a bright detailed view that was easy to look at. There was no apparent sweet spot. I moved the disc all around the eyepiece and it did not waver in detail or brightness.

The below image is a short exposure shot through the double stacked PST that I think illustrates the "sweet spot" that we are all used to dealing with. I believe that the sweet spot is exaggerated with the addition of a second etalon but it is still evident on the single PST.

This phenomenon was not evident through the LUNT LS60THa. The LS60THa was less detailed than the sweet spot on the double stacked PST but it was much more even detail through the entire image.

OK, so then I put the same 18mm CEMAX eyepiece into the LS60THa and the Coronado PST. I refined the views in each and focused and aligned them. I watched for several minutes trying to pick out the differences. Then I added the 2nd etalon to the PST and again compared the images. The results were right in line with yesterdays cloudy skies review.

The LS60THa had a roughly 20% larger image with more detail than the single stacked PST and less detail than the double stacked PST. Here are some single exposures from the Canon 40d/18mm CEMAX eyepiece of each scope:

LUNT LS60THa:

PST single etalon:

Double Stacked PST:

Then I watched it for a while longer and invited someone else who had never heard of a H alpha scope over for their opinion. Michael *****, a local EMT, happened by and I asked for his impressions. Michael was very thorough in his comparison. He looked.......

and looked, and looked, and looked

and then looked some more. He examined all of the setups for at least 15 minutes. Thank you Michael.!!

Michaels summation of the views was the same as mine and as the two other people who looked though all of them. The LUNT LS60THa had a superior view than the single PST but less detail and clarity than the double stacked PST. Michael also raved about how much easier the focuser and the general mechanical feel of the LUNT LS60THa was than the PST. I agree. The LUNT is far better designed and much easier to use than the PST. The tiny PST focuser knob is not very smooth and it does not have any way to do fine adjustments. The LUNT double speed focuser and focuser lock make it much easier to attain and keep a crisp focus. There was no issue today of the disk being unevenly focused as there was yesterday under thin clouds..

Once the LUNT was outfitted with the proper accessories and eyepiece it had a much better feel. My mentor tells me that almost every "real" refractor comes without any of the accessories I mentioned but still, I believe as a consumer that these things should be included, even if it raises the price a little. My friend says that anyone who would buy this scope would not want a "cheapy" eyepiece and sol finder but I disagree. I believe a complete setup even if it is cheap gives the buyer a better feeling upon purchase and will not incur additional expense for the buyer if he/she is a beginner.

I spent some more time with the scopes and decided that I liked the etalon adjustment better on the PST in either configuration. The LUNT etalon adjustment did not seem to make much difference with many turns when compared to the significant change shown by turning the PST etalon adjustment even slightly. I wondered if this had any effect on the apparent absence of a sweet spot with the LUNT.

Thank you for your time in reading this review and I hope you found it interesting.

I may be reached at ramsden@mindspring.com or you may visit my site www.solarastrophotography.com to see more of my amateur work.

Stephen W. Ramsden

24 July 2008