99 replies to this topic

[ccwemyss]

Thanks to Bomber Bob I now have one of these. Of course it has rained since it arrived. Finally had a brief bit of sun today, so I tried it with the Pentax 85, using its 0.965 tailpiece, partly because it's always ready to grab and go, and partly because I don't have a solar filter for it. I went through the collection of eyepiece sun filters that I've removed from the loaner scopes and found a very nice one from an AO Mayflower, stamped JAPAN SUN, to use in place of an OD3/ND3 filter. 

 

Sadly, the Pentax's long focuser did its usual trick of refusing to bring anything to focus that isn't going through a Pentax diagonal. The Pentax diagonals all have 38mm barrels, so they go all the way into the focuser. The 0.965 tailpiece and the nose of the wedge lengthened the optical path by about 1/4" too much. I did get to see that even with the full 85mm aperture, the image is still not very bright. It gives a slightly greenish orange color. Then the clouds started to roll in again.

 

 I'll have to pull out a different classic to make this work.

 

Chip W. 

[kansas skies]

I purchased my Vixen P80L as a complete set, so everything included would have been original to the set circa 1985 (give or take a year or two). I was concerned when I first saw the sun filter, since it appears to be a rather taboo item (and rightly so if used without the wedge). From what I gather, the wedge cuts the incoming energy from the sun by 96% prior to reaching the filter, which apparently renders the filter to be safely used with the 80mm refractor by effectively reducing the incoming solar energy reaching the filter to that of a 16mm objective. When the wedge/filter combo is used with the 60mm F/5 Tasco, it still presents a comfortably bright image. The wedge/filter combo presents a slightly dimmer image in my 114 Unitron refractor when using the same 10mm eyepiece, but is still sufficiently bright.

 

I will admit that I spent many hours in my teens (mid-1970's) staring at sunspots through a fifteen to twenty year old 60mm Tasco refractor using only its included sun filter. I remember the image being sufficiently bright but not uncomfortable, and if my memory serves me, not unlike that of my current wedge/filter combo when used in the F/15 Unitron.

 

Which leads me to another concern in that it is possible the solar filter included with my Vixen P80L is designed to block less light than the solar filters included with telescopes which did not include a wedge. If this is the case, those filters would block more incoming light and present a rather dark image when paired with the solar wedge. The bigger concern would then be if this is the case, the filter supplied with the wedge might then pass dangerous levels of the suns rays if used without the wedge, especially if paired with an 80mm scope (which might be the case if the filter got separated from the wedge and someone decided to use it as such). Since the filter packaged with my Vixen scope is only labeled as "Sun", it likely would be impossible to tell the difference without actually measuring the filter density. Another concern would be that someone might try to use more aperture to counter the effects of a denser filter in an attempt to create a brighter image, which might possibly stress the filter beyond its limits.

 

Bill

Edited by kansas skies, 09 May 2025 - 10:11 AM.

[deSitter]

The classic SUN filter is much darker than an ND3/OD3 (ok David?), probably more like ND4, and probably too dark for a small refractor with a wedge. But it may work very well with a 4" refractor.

 

-drl

[Bomber Bob]

IME, there's observable difference between the dozens of bundled MOON & SUN filters that I've used over the years.  I gave away a bunch years ago, but I kept several of each.  When using the Carton .965" Wedge, I found the darkest one too dark for my sub-60mm refractors, but ideal for my FC-76.  The SUN bundled with the Carton wedge is lighter, and gives comfortable views with my TS-50 & PILOT 47mm; but, it's not dark enough for my TS-65 - it's dazzling!  At least it's easy to tell these 2 apart - Darkest is bright red.  Medium is engraved Carton.

[Werckmeister]

I agree, the sunfilters are of variable shades but are all too dark to be really nice in a 60 mm scope. But the moon filter I have that came with a Polarex scope is darker than usual moon filters. So I gave that a try. Turns out to be exactly right for the sun with a wedge and 60 mm scope. Same brightness and light-green colour as with the Vixen filter for sun wedge. Lucky me!

It is the type that is put on top of the eyepiece as a cap. In practice it works quite well. There is no risk of omitting the filter when switching eyepieces, as the glare is very apparent when  the filter is not present.

 

[Garyth64]

Yesterday, I did some solar observing.  I used a .965" Hershel wedge made by Swift.  I also used a nice old Swift 839, 60x810. (Thanks, Terra.)  I also used the "dangerous" Sun filter that came with the scope.  Yep, it's like the one that can crack when exposed to the concentrated sunlight from a lens.

I screwed the filter into eyepiece and started viewing the Sun.  No issues at all.

After a few minutes, I pulled the eyepiece and filter out of the wedge to see if it was getting hot.  It was barely warm if that.  I also stuck my finger into where the eyepiece would go, and I could not feel any heat. The light from the wedge is still very bright and would damage one's eye.

Now the Sun light going straight thru the wedge was very warm, and when I brought my had close to the image plane it did get very hot.  Too hot, but the image plane was outside the wedge.  (See the OP's hand with the Sun on it in #1.)

The intensity of heat is the greatest at the image plane.  About 1/2" either side, the out of focus Sun would be very warm, but would not burn anything.

So, IMO, that "dangerous" Sun filter that comes with many telescopes is dangerous and shouldn't be used at all. But if used with a Hershel wedge it will be fine.

 

 

Edited by Garyth64, 10 May 2025 - 11:03 AM.

[deSitter]

Yes the only question is if it is too dark.

 

You might just get away with looking directly into the wedge - it would be like a flash gun going off right in front of your eyes, but probably wouldn't do any damage (not going to test it). The real danger is that you have a regular diagonal installed and forget, thinking it is your wedge. My wedge looks exactly like one of my classic diagonals, because it has the same housing. I am thinking of painting the wedge red or white.

 

My setup is pretty easy to spot already - I have a 24.5mm -> 1.25" adapter, and the Plossl eyepiece has a stack of the ND3 filter followed by the polarizer. But I'm not taking any chances!

 

What a beautiful scope!

 

-drl

[Garyth64]

Yep, I had a 3" Tasco reflector back in the middle 60's.  The cap for the tube had a reduced aperture, that I believed was to be used with the Sun filter that the scope came with.  So when I took a look at the Sun with that setup, I got a great view of the Sun.  Then I heard a crack, and got a flash of light.  You know what happened.  I never used any Sun filter like that since, until yesterday with the wedge.  I will be using the wedge a lot on my 60mm scopes.  Otherwise, I will use my Baader homemade white light filters.

[ccwemyss]

Yes the only question is if it is too dark.

 

You might just get away with looking directly into the wedge - it would be like a flash gun going off right in front of your eyes, but probably wouldn't do any damage (not going to test it). The real danger is that you have a regular diagonal installed and forget, thinking it is your wedge. My wedge looks exactly like one of my classic diagonals, because it has the same housing. I am thinking of painting the wedge red or white.

 

My setup is pretty easy to spot already - I have a 24.5mm -> 1.25" adapter, and the Plossl eyepiece has a stack of the ND3 filter followed by the polarizer. But I'm not taking any chances!

 

What a beautiful scope!

 

-drl

The fact that it doesn’t burn your hand as you try to get aimed at the sun would be good sign. Shouldn’t the regular diagonal be the one with the warning color, if that’s the one you’re afraid of using? 

 

Rather than paint the wedge, you could put one of those laser warning/eye safety stickers on each side (as a reminder that there is going to be a really hot beam emerging from the back. 

 

Chip W. 

[Bomber Bob]

It's worth checking ZEN periodically for vintage Herschel Wedges.  I should've bought an ASTRO model:  It featured a lid / dust cover, and overall looked better-made than others.  (I need to see if I already have a plastic plug that'll fit the Carton.)  Should be easy to make one with a 3D Printer...

 

Most of the time, my 3" refractors have 1.25" adapters, and I'll use the Lunt Wedge.  But I like having a simple old-school Solar Scope ready to go -- another reason for keeping the Oddball PILOT 47...

[DouglasPaul]

It's worth checking ZEN periodically for vintage Herschel Wedges.  I should've bought an ASTRO model:  It featured a lid / dust cover, and overall looked better-made than others.  (I need to see if I already have a plastic plug that'll fit the Carton.)  Should be easy to make one with a 3D Printer...

 

Most of the time, my 3" refractors have 1.25" adapters, and I'll use the Lunt Wedge.  But I like having a simple old-school Solar Scope ready to go -- another reason for keeping the Oddball PILOT 47...

The Lunt is quite heavy in my opinion, I like the classic wedges better with the right filter. 

[Bomber Bob]

I've noticed that Carton bundled Wedges more often than other exporters -- and with their small AZ refractors, versus EQ kits.  

 

Seemed strange to me at first.  The 2 EQ kits (60 & 80mm) that I got back in 1970s had the projection screen instead -- AND that unsafe SUN Filter.

 

Makes sense to me now -- that's the way I use my wedges:  I'll put a 65 or smaller refractor on the KDS-AZ.  I don't need an EQ to track the Sun at 100x.  Keep it simple -- and light.

[SporadicGazer]

I put a .965 wedge with a Vixon sun glass for solar prism on a 60 mm and a Lunt 1.25 wedge with a Baader continuum filter on a 102mm refractor this morning and spent some time with both of them observing the spectacular sunspot we have today.

Honestly, I think I like the classic set up better. No green tint and very sharp.

 +1.  The Baader Continuum filter's tint is aesthetically gross!  (YMMV, I suppose someone might like baby-puke green views of the Sun! )

 

But it is not necessary with Lunt wedge, (though you might want a polarizer, or something, to control brightness for comfort without it.)  The reason to use it is that it can bring out more details by cutting down on the effect of the atmosphere on sharpness by selecting a single color.  (Minimizes "chromatic distortion"?  I struggle remembering big words. )

[deSitter]

 +1.  The Baader Continuum filter's tint is aesthetically gross!  (YMMV, I suppose someone might like baby-puke green views of the Sun! )

 

But it is not necessary with Lunt wedge, (though you might want a polarizer, or something, to control brightness for comfort without it.)  The reason to use it is that it can bring out more details by cutting down on the effect of the atmosphere on sharpness by selecting a single color.  (Minimizes "chromatic distortion"?  I struggle remembering big words. )

 

Solar full-aperture film, no matter how well made, is hardly an optical surface, and it's plastic, so it will scatter light. The only way to see the Sun accurately is with optical filters and light reduction.

 

The full aperture filters are good for whole-disk viewing during eclipses.

 

-drl

[DAVIDG]

 Here is a picture of part of my collection of  solar viewing wedges. I have two Optica B/C herschel wedges and the filters that came with with them which are a 1.0 ND, 0.1 ND and two polarizer filters. I also have a Baader OD 3 filter I use with them. The numbers on the ND filter look to represent % transmission vs F-stop or Optical density since the 0.1 is darker then the 1.0. 

   Herschel Wedges do give great views but they have the disadvantage that one needs to understand  how to use them correctly with the correct additional  filtering and to avoid the the dangerously bright and hot light coming out the back.

   Full aperture filter made from Baader film scatter very little light and have the advantage that they  filter the light before it enters the telescope. So very little heating of optical element take place which can be problem on certain designs and there is little heating  the inside of the telescope so less tube currents. 

   So it comes down to understanding how these systems work and how to use them correctly to get best solar views.

 

                    - Dave  

 

[kansas skies]

 +1.  The Baader Continuum filter's tint is aesthetically gross!  (YMMV, I suppose someone might like baby-puke green views of the Sun! )

 

But it is not necessary with Lunt wedge, (though you might want a polarizer, or something, to control brightness for comfort without it.)  The reason to use it is that it can bring out more details by cutting down on the effect of the atmosphere on sharpness by selecting a single color.  (Minimizes "chromatic distortion"?  I struggle remembering big words. )

For some reason, I really like the view of the sun through my Lunt wedge with the Baader Solar Continuum filter. The green color does seem strange at first, but I find it very easy to get used to. I also like to add a Baader IR Cut filter to the Solar Continuum filter to increase the contrast ever so slightly. That being said, I also really like the yellowish-white color produced by the older Vixen wedge/Sun filter combo.

 

Bill

[Terra Nova]

For some reason, I really like the view of the sun through my Lunt wedge with the Baader Solar Continuum filter. The green color does seem strange at first, but I find it very easy to get used to. I also like to add a Baader IR Cut filter to the Solar Continuum filter to increase the contrast ever so slightly. That being said, I also really like the yellowish-white color produced by the older Vixen wedge/Sun filter combo.

 

Bill

Yes, I agree, the Baader continuum filter is really nice with the Lunt wedge. It vastly improves contrast and brings out fine detail and subtle features. Another nice supplementary filter is the Baader yellow 495nm Long Pass filter. In conjunction with the Lunt wedge of course. It give you a nice yellow view. It has very high transmission of the Sodium D lines (D1 @  5895.92Å and D2 @ 5889.95Å). It has a bit higher overall transmission than the Continuum filter but you can stack it with a single Baader polarizing filter and vary the brightness by simply rotating the eyepiece. The Continuum filter by comparison has a narrow bandpass between 5350 and 5450 Angstroms.

[DouglasPaul]

Yes, I agree, the Baader continuum filter is really nice with the Lunt wedge. It vastly improves contrast and brings out fine detail and subtle features. Another nice supplementary filter is the Baader yellow 495nm Long Pass filter. In conjunction with the Lunt wedge of course. It give you a nice yellow view. It has very high transmission of the Sodium D lines (D1 @  5895.92Å and D2 @ 5889.95Å). It has a bit higher overall transmission than the Continuum filter but you can stack it with a single Baader polarizing filter and vary the brightness by simply rotating the eyepiece. The Continuum filter by comparison has a narrow bandpass between 5350 and 5450 Angstroms.

It seems the 1.25 variety is scarce, but they are available with some looking.

[Terra Nova]

It seems the 1.25 variety is scarce, but they are available with some looking.

I see they also cost a lot more than they used too. I’ve had mine over twelve years. The APM/Lunt is the best I’ve ever had. It’s also the safest!

[DAVIDG]

 One of the reason why  a narrow band filter improves the contrast is your most likely using it with a refractor and the filter is removing the chromatic aberration of the objective.  With a green filter, green is  also were almost all objectives are designed to have the least spherical aberration as well.

  So it has more to do with improving the optical quality of the image vs any particular wavelength in the solar spectrum were features are better seen with the typical band pass of these filters. 

 

              - Dave  

[Terra Nova]

 One of the reason why  a narrow band filter improves the contrast is your most likely using it with a refractor and the filter is removing the chromatic aberration of the objective.  With a green filter, green is  also were almost all objectives are designed to have the least spherical aberration as well.

  So it has more to do with improving the optical quality of the image vs any particular wavelength in the solar spectrum were features are better seen with the typical band pass of these filters. 

 

              - Dave  

 Very true. According to Baader Planetarium:

 

The Baader 7.5 nm Solar Continuum Filter, CWL 540nm

• A must for owners of achromatic refractors. This narrowband-filter cuts the spectral range where lens optics draw sharpest and contrastiest. The Baader Solar Continuum Filter lets you use the full power of your telescope.
• Enhances contrast and reduces the effect of atmospheric turbulence (in combination with white light solar filters)
• Enormous contrast gain in monochrome photography even on apochromatic systems
• Important note: The Solar Continuum Filter must be used ONLY with additional filtering (e.g. Baader Herschel prism or AstroSolar Safety Film)

https://www.baader-p...lter-540nm.html

[ccwemyss]

Had a little bit of sun yesterday, and tried the wedge with the Jaegers 110mm f4.65 PVC plumbing scope. It came to a nice sharp focus, just as clouds started to roll across. The 110mm aperture also gave a pleasantly bright image with the old sun filter.

 

The only issue with this combination is that the short fl needs a fairly short eyepiece to get to a good scale with the image, which reduces eye relief and FOV quite a bit. Hard to know if that will be a real problem, given that I had less than a minute to test it, and I was fighting with the mount being out of balance due to the light load. 

 

It also looks a bit silly, stepping down from a 2" focuser to a 0.965". But that just means it fits the whole theme of the scope. 

 

Chip W. 

[ccwemyss]

I remembered that the Pentax 100 came with a custom adapter from the Pentax threads to T2. I had put it away because I also have a 38mm to thin 1.25" tailpiece combo that has worked well on it. But if I put that on the Pentax 85 with the thin tailpiece, I think the wedge may come to focus. Of course, the forecast is for rain until Monday, so I can't try it for a while. But rummaging through the adapter collection was a good cloudy nights activity. 

 

I've also ordered a $10 OD3 camera filter, and am going to pick up a 1" diamond hole saw, to see if I can make a custom ND filter that will fit in place of the old sun filter.

 

Chip W. 

[ccwemyss]

Despite the forecast, we had an hour or so of mostly clear sky this evening, so I took the Pentax 85 out again, with the shorter adapter, and was able to bring the wedge to focus with a Celestron Vixen Kellner 40, Kellner 18, Ortho 9, and Ortho 7. The 40 was comfortably bright, while the 7 was getting a bit dim.  Took a couple of shaky cell phone pictures, one with the O9 and one of the full disk with the K18. 

 

  

 

As usual, the phone camera didn't capture the sharpness I could see, but at least it gives an idea of the brightness and color with the old AO sun filter. I'm really happy to at last have a way of using the Pentax for solar viewing! Thanks again Bomber Bob!

 

According to the manual, Pentax made a Herschel wedge for these scopes. But I've only ever seen one as part of a very complete Pentax 100 kit that was for sale. Highly unlikely that I'll ever find one, and the focuser design is also going to make it nearly impossible to adapt something modern. 

 

I do need to break the habit of grabbing the diagonal from the back to make small adjustments in pointing...

 

Chip W. 

[Bomber Bob]

YW!

 

Pentax made a Herschel wedge for these scopes.

 

I don't recall seeing one on ZEN.  Pentax star diagonals (with that 38mm thread) do pop up, so... there's Hope!