Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Lunt DSII Glow

solar
  • Please log in to reply
61 replies to this topic

#1 jerwin

jerwin

    Apollo

  • *****
  • topic starter
  • Posts: 1,007
  • Joined: 16 May 2012
  • Loc: Romeoville IL

Posted 12 September 2016 - 03:48 PM

I had something odd, yet somewhat amazing happen today and I wanted to pass it along and see if anyone else has similar results.

 

I have a LS100 with a DSII and B1800, and anyone knows the DSII gives a pink glow that is pretty frustrating.  I've tried different things, rotating the DSII 180 degrees, I tried tilting the DSII slightly, tilting pushed all the glow to one side, so I could do that to the side away from the prominances.  A few weeks ago I bought a little LS50 with B600.  Got it off ebay for a decent price, figured I'd play with it a bit, if I don't like it dump it before the 2017 eclipse and maybe make $100 on it.

 

Don't know why this configuration even occurred to me, but I took the B600, and put it in the LS100 and ALL of that pink glow is gone when viewing the full disk in the zoom ep at the 21mm mark.  It is slightly more difficult to line my eye up on the eyepiece, it seems to have a narrower zone, with blackouts if my eye is too much towards the edge.  When I went to zoom in on a prominence, I moved the disk so the side was in the middle of the EP and the pink haze returned, zooming in the view was fine, so I zoomed back out, and moved the sun a little more and realized the pink glow is the size and shape of the blocking filter.  So the pink glow is being hidden by the sun when viewing the full disk.

 

I think my buddy has a lunt with a B1200 that I might see if I can borrow it and figure out the sweet spot for visual, where the pink stays behind the disk, but I maybe get less blackouts.  

 

If any of you with DSII's have multiple lunts, or friends with lunts, you might try this out.  Where my thinking is at right now, I might buy a spare B600 or 1200 to use for outreach, and even for myself.  I'm thinking MAYBE the B1800 would still come in handy for imaging, so i probably don't want to trade it or sell it just yet.  

 

anyway, totally unexpected result that I just wanted to pass along and see if anyone else has similar results.  It's like it's a whole new scope having the prominences on a black background.

 

clear skies,

Jim


  • ghutton likes this

#2 jerwin

jerwin

    Apollo

  • *****
  • topic starter
  • Posts: 1,007
  • Joined: 16 May 2012
  • Loc: Romeoville IL

Posted 12 September 2016 - 04:02 PM

My binoviewers are basically useless in the b600, such a small opening, and it seems your eyes need to be lined up perfectly.  but the 1800 back in and binos were back to normal



#3 GUS.K

GUS.K

    Viking 1

  • -----
  • Posts: 671
  • Joined: 13 Aug 2014
  • Loc: Katoomba, NSW, Australia.

Posted 12 September 2016 - 04:59 PM

Hi Jim, I have the LS100 with the DSII and the B1800 as well and have the same issues. I also have an LS60 with a B1200 which I've tried with the DS LS100 and it doesn't make a difference. What I've noticed is that on a full disc, if I move my eye away from the EP (about an inch) the glow is not as noticeable, and I can get a black background around the disk. 

If I want to move the glow away from an interesting area, I just rotate the whole scope in the rings, or flip the whole scope 180 degrees in the mounts saddle to move the glow to the other side ( I have another dovetail mounted to the top of the rings. If I want to remove the ghost completely, I install a circular polarizer between the two etalons and have a perfectly black sky around the disk, the view is equal in quality to my LS60/60DS scope which has an ink black background.With binoviewers, I don't find the glow to be an issue.


Edited by GUS.K, 12 September 2016 - 05:13 PM.

  • Live_Steam_Mad and ghutton like this

#4 jerwin

jerwin

    Apollo

  • *****
  • topic starter
  • Posts: 1,007
  • Joined: 16 May 2012
  • Loc: Romeoville IL

Posted 12 September 2016 - 06:09 PM

If I want to remove the ghost completely, I install a circular polarizer between the two etalons and have a perfectly black sky around the disk,

Gus, Did you get this from lunt?



#5 GUS.K

GUS.K

    Viking 1

  • -----
  • Posts: 671
  • Joined: 13 Aug 2014
  • Loc: Katoomba, NSW, Australia.

Posted 12 September 2016 - 06:40 PM

HI Jim, no, it"s a photo  CP, and allows the use of high powers without image degradation.


  • Live_Steam_Mad and ghutton like this

#6 ybor

ybor

    Messenger

  • -----
  • Posts: 459
  • Joined: 07 Jan 2006

Posted 12 September 2016 - 09:08 PM

Does the Lunt 100 SS have the same  pink after glow or is it only obvious on the Lunt 100 DS ?

 

Thanks



#7 jerwin

jerwin

    Apollo

  • *****
  • topic starter
  • Posts: 1,007
  • Joined: 16 May 2012
  • Loc: Romeoville IL

Posted 12 September 2016 - 11:27 PM

no, the single stack doesn't have a noticeable glow.



#8 Kent10

Kent10

    Aurora

  • *****
  • Posts: 4,846
  • Joined: 08 May 2012

Posted 12 September 2016 - 11:39 PM

I have an external DS for my LS100 and there is no red glow.  It would be interesting for me to try the internal DS to compare.  I have the internal DS for my LS152 and it is of the newer type so there also isn't any red glow.  I had the internal DS for my LS80 and there was some glow because it was the older type.  It didn't bother me too much because I mainly looked at the surface with the DS and not the prominences but I can see how it would be annoying if you want to see the prominences.  Jim, do you still have the LS80?  How are you liking the 100 in comparison?



#9 ghutton

ghutton

    Lift Off

  • -----
  • Posts: 24
  • Joined: 13 Aug 2011

Posted 13 September 2016 - 11:39 AM

Gus, How exactly did you install the circular polarizer please. Is there room when you put the DS unit in the main OTA? Any pics would be most appreciated. Thanks. Graeme



#10 ybor

ybor

    Messenger

  • -----
  • Posts: 459
  • Joined: 07 Jan 2006

Posted 13 September 2016 - 03:31 PM

Please send pictures . I would also like to know how this is installed .

 

Thanks



#11 BYoesle

BYoesle

    Fly Me to the Moon

  • *****
  • Posts: 6,629
  • Joined: 12 Jun 2004
  • Loc: Washington USA

Posted 14 September 2016 - 02:23 AM

You would generally locate the CP between the two etalon units, with a slight amount of tilt.  The B+W Kaesemann filters are about the best of the ready-made photography purposed filters:

 

https://www.bhphotov..._kaesemann.html



#12 GUS.K

GUS.K

    Viking 1

  • -----
  • Posts: 671
  • Joined: 13 Aug 2014
  • Loc: Katoomba, NSW, Australia.

Posted 14 September 2016 - 05:32 AM

I purchased a rubber camera lens filter hood and installed it on the DSII unit minus the red anti glare screw on assembly. The hood fits perfectly around the anti glare filter threads. The filter opening is 52mm and I can use adaptors to install whatever size filter I want (40mm is about the smallest due to the DSII etalon size). I tried a few different filters and found one that produced excellent views. The reason I removed the Lunt red filter was to allow for a brighter image. In good seeing, I can up the magnification to 200x, and the detail is the same with or without the circular polarizer filter, but with the benefit of no glow. The image is obviously darker than with the Lunt AG filter, but the view of the full disc without the glow is great. Using the lens hood makes it easy to remove and revert back to the lunt filter. When binoviewing, the CPL filter makes the image a lot darker, so I BV without it, the glow is not as noticeable when binoviewing anyway.

 

Note: Removing the anti glare filter as supplied by Lunt on the DSII unit is not a modification that affects the safety of the scope as the primary etalon has an ERF installed on it already, and the second ERF is only used as an anti glare filter to reduce the ghosting.

 

 

Attached Thumbnails

  • LSDSII 3.jpg
  • LSDSII 2.jpg
  • LSDSII 1.jpg

Edited by GUS.K, 14 September 2016 - 05:41 AM.

  • BYoesle likes this

#13 jerwin

jerwin

    Apollo

  • *****
  • topic starter
  • Posts: 1,007
  • Joined: 16 May 2012
  • Loc: Romeoville IL

Posted 19 September 2016 - 12:47 PM

Based off Gus's pictures, and Bob's filter recommendation I went out and made a similar modification.

 

https://www.amazon.c...0?ie=UTF8&psc=1

B+W 40.5mm XS-Pro HTC Kaesemann Circular Polarizer with Multi-Resistant Nano Coating - $64.02

 

https://www.amazon.c...?ie=UTF8&psc=1 

Goja 40.5-52MM Step-Up Adapter Ring (40.5MM Lens to 52MM Accessory) - $7.48

 

https://www.amazon.c...3?ie=UTF8&psc=1

52MM Collapsible Rubber Lens Hood for Camera Lens with 52MM Filter Thread - $7.99

 

So all told it cost me $79.49.

 

There isn't a super tight fit between the DSII and the mod, so I added a piece of masking tape just so it doesn't come lose inside the OTA.

 

Clear skies all,

Jim

 

I've only had the scope out twice since building this and there was zero glow,  I didn't try removing it to see if there was any edge details I was missing because of the extra filter, I'll do that next time I have it out.  I do monthly solar outreach, so making it easier for people to see the edge detail I think it a win.  



#14 BYoesle

BYoesle

    Fly Me to the Moon

  • *****
  • Posts: 6,629
  • Joined: 12 Jun 2004
  • Loc: Washington USA

Posted 19 September 2016 - 02:51 PM

:waytogo: There should be no missing detail, other than the overall brightness may be diminished. The trade off with removing the "glow" is that you may actually have improved prominence visibility.



#15 jerwin

jerwin

    Apollo

  • *****
  • topic starter
  • Posts: 1,007
  • Joined: 16 May 2012
  • Loc: Romeoville IL

Posted 19 September 2016 - 04:46 PM

Good to know Bob.

 

It's a shame that Lunt doesn't just replace that 2nd erf in the DSII with a polarizer.  Charge an extra $100 on the price of the DSII, but if there is this much of an improvement, it's totally worth it in my opinion.  

 

Jim


  • torsinadoc likes this

#16 ybor

ybor

    Messenger

  • -----
  • Posts: 459
  • Joined: 07 Jan 2006

Posted 21 September 2016 - 08:03 PM

Check with Lunt . They have a new filter that you can put on the pressure tuned  double stack to reduce glow .

If anyone has tried this $160 filter , please provide your input .

 

Has anyone used the more expensive front double stack filter on the Lunt 100 ?

 

I've read that this more expensive filter has no light internal glow .

 

Thank you 



#17 Kent10

Kent10

    Aurora

  • *****
  • Posts: 4,846
  • Joined: 08 May 2012

Posted 21 September 2016 - 08:06 PM

Yes, I have the front DS for the LS100 and there is no glow.



#18 ybor

ybor

    Messenger

  • -----
  • Posts: 459
  • Joined: 07 Jan 2006

Posted 21 September 2016 - 08:12 PM

How are the views with the front loaded double stack ?

 

Did you compare it to the pressure tuned double stack ?

 

Was there noticeable visual difference ?

 

I am in the process of buying a double stack for my Lunt 100 and I am trying to figure which is the best way to go .

 

Thank you

 

 

Thank you



#19 Kent10

Kent10

    Aurora

  • *****
  • Posts: 4,846
  • Joined: 08 May 2012

Posted 21 September 2016 - 08:23 PM

I think the views are fine with the external DS but I don't have the internal DS in order to compare.  I have the internal DS for the 152 and they are also fine with no glow because I think the 152 DS has the glow reducing filter built in.  From what I have heard from others the external DS should be better than the internal.  There is a small central obstruction which is not in its favor but there is no glow.  I wish I had the internal to compare.



#20 George9

George9

    Surveyor 1

  • *****
  • Posts: 1,662
  • Joined: 11 Dec 2004

Posted 21 September 2016 - 09:40 PM

Jim or Gus, just curious why you picked a 40.5mm polarizer and a 40.5-to-52 step-up instead of just getting the 52mm version of the filter from the same company? The price difference is only about $10 and covered by the elimination of the step-up. I ask because I wonder if the 40.5mm vignettes the cone of light. My LS80 DSII has a 36mm front end to its DSII, and at f/7, that leaves only a little over an inch of clearance before a 40.5mm vignettes it.

 

Vignetting the cone between the primary and secondary is one way to reduce reflections because the reflections seem to be concentrated on the outside.

 

And a simple ND filter is also pretty effective because the reflections have to traverse 3 or more times, versus once for the primary.

 

Therefore, my question is, how much does the circular polarization actually add, as opposed to the simple attenuation of light plus possible vignetting?

 

I use the $160 HRG filter that Lunt sells in my LS80 DSII, and it is pretty effective. Not a total loss of reflections but substantial. The image is darker, however. It is 42mm, and I wonder if it doesn't vignette slightly, too.

 

I was under the impression that Lunt included the HRG filter as part of the LS100's DSII nowadays, but I am not sure.

 

George


  • GUS.K likes this

#21 GUS.K

GUS.K

    Viking 1

  • -----
  • Posts: 671
  • Joined: 13 Aug 2014
  • Loc: Katoomba, NSW, Australia.

Posted 22 September 2016 - 12:04 AM

Ybor, the front mounted LS100 filter, being a tilt model, you can move the ghost image out of the view so there will be no glare. With the DSII unit the two etalons are almost parallel and the reflections bounce back and fourth between them, and if you defocus in or out far enough you can actually see multiple out of focus solar discs.

 

George, I picked the 40.5mm as that matches the so called anti glare filter diameter, and with the lens hood in position, the CPL is almost in the exact original position that the Lunt filter occupies. The anti glare filter that came with my scope has a red ERF glass in it and looks identical to my Lunt 100mm ERF I bought for another project. In fact the view through both is identical, and knowing lunt sells 40mm ERF's, I'd say that's all it is. Viewing without this filter, the glare is only slightly more noticeable. With the CPL in place, the glow is completely eliminated, and the sky surrounding the disk is ink black. Features that were underneath the glow with the lunt filter looked washed out and didn't take magnification well, but with the CPL detail is visible equally well across the disk. I tried ND and linear polarizing filters, but the glow was still noticeable.

 

A member on solarchat tried the optional HRG filter on his LS100 scope and mentioned that it made the glare only slightly less noticeable, but was only able to eliminate it completely with a CPL.

 

My LS60/60F produces a great DS view with a black sky surrounding the disk, and with the CPL I now get the same with the DS LS100 scope.


  • George9 and Live_Steam_Mad like this

#22 George9

George9

    Surveyor 1

  • *****
  • Posts: 1,662
  • Joined: 11 Dec 2004

Posted 22 September 2016 - 07:13 AM

Thanks, Gus. I will give it a try.

 

My Lunt HRG filter is grey, not red, so they may have evolved. I got one of the first ones. While I don't have a complete elimination, the difference is large. Like 80%-90% reduction. Definitely wouldn't call it slight. Perhaps they started with a darker filter (mine) and evolved to a lighter one to keep the view brighter.

 

I may try the 52mm just to see if it works without vignetting (I can always stop it down). Unless I can find one that exactly fits my HRG cell, in which case I can avoid the lens hood.

 

George



#23 GUS.K

GUS.K

    Viking 1

  • -----
  • Posts: 671
  • Joined: 13 Aug 2014
  • Loc: Katoomba, NSW, Australia.

Posted 22 September 2016 - 08:12 AM

George, the CPL works great in mono viewing, but when binoviewing, the image in one side of my WO binoviewer is a lot darker than the other side, must have something to do with the phase coating. So I binoview without the CPL, as the glow is not as obvious.


  • George9 likes this

#24 ybor

ybor

    Messenger

  • -----
  • Posts: 459
  • Joined: 07 Jan 2006

Posted 22 September 2016 - 08:33 AM

Is the CPL filter the one listed earlier in the tread that is sold by B & H?

 

Does it tread at the same location as the new Lunt HRG filter? 

 

When putting on this filter do you have to remove anything from the Double stack unit  ?

 

 

Thanks

 

 

Thanks



#25 GUS.K

GUS.K

    Viking 1

  • -----
  • Posts: 671
  • Joined: 13 Aug 2014
  • Loc: Katoomba, NSW, Australia.

Posted 22 September 2016 - 08:57 AM

Hi Ybor, the circular polarizer is a standard camera CPL you can purchase at any camera store and using a rubber lens hood also a standard accessory at any camera store, you install it on the threads on the DSII unit once you remove the anti glare filter housing. The lens hood I have fits tightly over the threads, you have to stretch it slightly to get it on the threads. 




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics





Also tagged with one or more of these keywords: solar



Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics