48 replies to this topic

[LunarFox]

I recently started a thread on comparing the transmission spectra of various nebula filters, and I thought I would do the same for some planetary filters. Most of these were scanned by me personally on a Shimadzu UV-Vis spectrometer, except for the Baader Neodymium and TeleVue Bandmate Planetary, which were emailed to me by Don Pensack (thank you). 

 

First up, I have a few of the more specialized planetary filters. They include the: Baader Neodymium, Orion Mars, TeleVue Bandmate Planetary, and a generic "Moon and SkyGlow" I picked up here on the forums. 

 

 

It was interesting to compare these filters. It seems that there are two "classes" of planetary filters. The first is a single notch design that cuts out the entire 530-600nm range, the Orion Mars and TeleVue Planetary fall into that class, and the second is a dual notch design that cuts out pretty much the same range but leaves the 540-570 yellow/orange wavelengths, which is where the Baader Neodymium and Generic Moon & SkyGlow fall into.

 

My biggest surprise was how similar the generic $15 Moon & SkyGlow is to the much more expensive Baader Neodymium. I've used this filters on Jupiter in the past and really liked it, so I was relieved to see it exhibit similar transmission to the Baader. It has no writing on the side, but it looks exactly like the Solomark Moon & Sky filters that are being sold on eBay.

[LunarFox]

Next up is a full set of Celestron Color filters, ones that are commonly found in beginner kits with eyepieces. Not much to say about these. I also got my hands on a single Meade 80A Blue and its scan is identical to that of the Celestron, which leads me to believe that all brands of color filters are the same. The point here is, don't spend your money on expensive Baader and Lumicon color filters, they're all likely the same as the cheaper brands.

 

 

One thing worth noting here is that the Moon filter is an Orion 13% Transmission, but as you can see it really only transmits around ~5% across the visible spectrum, so it's much darker than advertised. It's also not exactly a "neutral" density filter as it fluctuates across the visible range, but by only a couple percent. 

 

A much more neutral filter is the variable polarizing set from Orion. Not only does it provide tunability of transmission, but is very neutral and flat across most of the visible spectrum. 

 

Edited by LunarFox, 07 April 2016 - 06:20 PM.

[russell23]

Next up is a full set of Celestron Color filters, ones that are commonly found in beginner kits with eyepieces. Not much to say about these. I also got my hands on a single Meade 80A Blue and its scan is identical to that of the Celestron, which leads me to believe that all brands of color filters are the same. The point here is, don't spend your money on expensive Baader and Lumicon color filters, they're all likely the same as the cheaper brands.

 

 

 

A couple things to keep in mind:

 

The Wratten filter numbers correspond to specific defined transmission curves so it is not surprising that the Meade and Celestron would have matching curves.  I wouldn't be surprised to learn that they have the exact same source. 

 

There is more to the color filters than the transmission.  The quality of the optical glass and coatings of the filters can vary.  Some filters are more prone to introducing glare and reflections.  Others can negatively impact image quality.   The Baader and Lumicon filters are of very high optical quality.

 

The Baader color filters are not Wratten filters.   I've compared the #12 Wratten to the yellow Baader 495 Longpass filter and the 495 LP has different transmission characteristics.  There is a stronger color shift with the #12 and the Baader transmission curves show greater than 95% transmission from ~510nm-700nm.  The 470 Bandpass blue Baader filter has a unique transmission curve and the color is very different from any other blue filter I've used.

 

Dave

[faackanders2]

Planetary filters I have include:

TV Planetary

Televue Bandmate B

Denkmeier Planetary

Orion Mars - favorite for 

Numerous colored

 

Plus I really like Orion Skyglow as a planetary, especially on Jupiter.

[Scanning4Comets]

IMO, planets are best viewed Au naturale.....

 

Sometimes.....a ND filter helps. Color filters....meh!

Edited by Scanning4Comets, 08 April 2016 - 12:42 PM.

[LunarFox]

So far, I have found the Baader Neodymium clone (Moon & Skyglow) to be my favorite on Jupiter, with a variable polarizer set to ~30% transmission coming in very close second. The 80A blue is also quite nice, but it makes the gas giant just a tad bit too blue for me.

 

On that note, the Moon & Sky filter does give the planet a bit of a purplish/pink hue, but it's hardly noticeable. The Mars filter shown above, however, makes it look VERY pink! Definitely wouldn't recommend using the Mars one on Jupiter, we'll have to see how it performs on its intended target in a couple months..

 

For anyone interested, here is what the Generic Moon & Skyglow I am using looks like. There are no markings on the other side to indicate a manufacturer, but you can see how closely its transmission resembles that of a real Baader Neodymium. It's slightly lower transmission across the spectrum, but that's in a way a good thing when it comes to viewing planets.

 

 

 

I'm also going to post the Orion Mars and TeleVue Planetary on their own in this post, I realize the diagram in the first post is a little messy and it's too late for me to edit it now.

 

Edited by LunarFox, 18 April 2016 - 11:34 AM.

[David Gray]

I have seen a few planetary-filter threads on CN; and in the main I resisted commenting as I expect my defence would come across as my being a filter-obsessive.   In fact I have been contributing hundreds of planetary observations to such as the BAA Sections since the 1960s; and Venus aside, very few were made with filters. 

 

For me they are there as part of my observing ‘tools’ to be on hand for specific inquiry – and possibly little or not used for months.  After all having a hammer in my toolbox does not mean I need to be knocking nails in everyday – but glad of it when the need arises…….

 

I have a fair set as shown on the attached (the 2” Baader Neodymium not shown) – just this week the #29 added and not yet evaluated.  Some of these the province of larger aperture of course where filter work is much more productive and with numerous possibilities experimental-wise

 

A common dismissal I keep seeing on those posts is the somewhat anthropic statement of preferring to view planets in natural colours – well so do I, but define it differently!  When what passes through filters to our eyes is still natural not ‘painted on’……….

 

Then one poster speculating that using an orange filter, on Mars, an orange object, as pointless/ineffective; missing the point that darker albedo, less ‘red’ objects, will be rendered darker, more contrasty, relative to the deserts.

 

I can confirm impressions with the Baader Neo on Jupiter – even so as I spend a good deal of my observing trying to render non-filter hues planets are mostly observed that way – or non-anthropically:  in white or integrated light………!

 

Venus is a different situation – here I find filters come into their own.  Apart from the usual dark blues, I found years ago that stacking a #15 (light orange) with #58 (green) frequently brought out the delicate shadings very well.  Never liked the ‘sickly’ 80A but adding that to the other two often works to advantage.

 

Some links to posts where I more detail my experiences –Venus:

 

http://www.cloudynig...e-filter-views/

 

In particular see the notes on the attachments on posts #1 & #15.

 

Mercury:

 

“Initially I applied the W#22 (orange) filter which has proved very useful for Mercury when the chromatic effects of the atmosphere are still strong at lower altitudes…..”

 

http://www.cloudynig...eat-conditions/

 

With regard to stacking filters I would be very interested to see any test results that you might apply!

 

Those filters on the attachment labelled BAS (Bedford Astronomical Supplies – no longer trading) were from a firm formed by two of its founders who custom-built my 16.3” Dall-Kirkham in the mid 1970s.  Some of these filters differ from the regulars of these days: their #85 (Amber) sold as a planet-contrast filter – never entirely impressed me tho’, the star of these to me is the #22 (no not #21!).  The Parks were substitutes for out-of-stock Celestrons.

 

Dave.

 

[Starman1]

You're missing a #12, the filter I've found shows the most detail in Saturn's rings.

[LunarFox]

Dave,

 

Thank you for sharing your experience, I agree with much of what you said. While I'm mostly in the category of those who prefer to view the planets in their natural colors, I couldn't help but find the #56 Lt Green to be another good filter on Jupiter last night. It was strange to see the planet with a green hue, and I wanted to switch off the filter immediately due to the false coloration, but I couldn't deny that it helped bring out the bands with a different contrast than the other filters in my kit.

 

I guess it's all about what you're trying to see in the particular moment. Once you let go of the fact that the planet is the "wrong" color, you can see things you couldn't otherwise. That's pretty much the whole point of filters right?

[LunarFox]

With regard to stacking filters I would be very interested to see any test results that you might apply!

 

I would gladly perform tests on any combination of filters you may have in mind, but I unfortunately don't have a #15 that I could stack with the #58. However, if I were to hazard a guess, and that's all this is going to be, I would assume a Lt Orange would fall somewhere in between the Yellow and Orange as shown below. 

 

 

The #12 Yellow splits at 510nm and the #21 Orange at 570nm, so I placed the #15 Lt Orange directly in between at 540nm. The above is not real data from a #15 filter, I made it up for demonstration purposes! But if we assume that is the shape of the transmission curve for a #15 Lt Orange, if we were to stack it with a #58A Green what I think we would see is transmission from the area under both curves.

 

 

In essence, what you should get is an attenuated #15 Lt Orange. The #58 will present the #15 with its attenuated spectrum, and the #15 will only pass 540nm and beyond. The same should hold if you stack them the other way, order shouldn't matter.

 

Now I'm curious to see if this holds true, I'll bring my filters with me when I go in to lab later this afternoon to see how stacking actually affects transmission.

Edited by LunarFox, 17 April 2016 - 10:56 AM.

[David Gray]

You're missing a #12, the filter I've found shows the most detail in Saturn's rings.

I do not doubt it – #15 has done that often for me – but as I say prefer Saturn non-filtered; apart from some specific inquiry.  Some of which posted on CN in recent years   ; i.e. spokes, also the NPC hexagon effect etc. – enhanced with the #15 and #22 which also cope better with the increasingly lower altitude these recent apparitions.

 

Of course with Saturn currently at 13º altitude from here and even such as #12 not expected to often get me much.  Tho’ the ‘unlikely’ conditions, even there, sometimes surprise – vigilance being the watchword.   One good (non-filter) view so far since January.

 

As I said I had just acquired a #29, but I was also seeking the #12 and #11 – but currently out of stock – but no hurry.  That #11/#12 (and #29 especially) shortfall has been in mind for too many years………..

 

As for ring detail attached is a sample from many fine views over the years non-filter.  These when the planet was riding high here!  Back then with a Tele Vue 19mm Widefield – but the last 10 years with Meade 5000 20mm Plossls and binoviewer.

 

Dave.

 

[David Gray]

Dave,

 

Thank you for sharing your experience, I agree with much of what you said. While I'm mostly in the category of those who prefer to view the planets in their natural colors, I couldn't help but find the #56 Lt Green to be another good filter on Jupiter last night. It was strange to see the planet with a green hue, and I wanted to switch off the filter immediately due to the false coloration, but I couldn't deny that it helped bring out the bands with a different contrast than the other filters in my kit.

 

I guess it's all about what you're trying to see in the particular moment. Once you let go of the fact that the planet is the "wrong" color, you can see things you couldn't otherwise. That's pretty much the whole point of filters right?

Yes I think we need to have specific goals/questions; then applying whatever filters are to hand – stacking adds another dimension of inquiry - and random idle looking not excluded! 

 

Many thanks for the #15+#58 speculation – a step further than my mental visualizations looking at the curves in my 1961 Kodak book…………!

 

I do not think the stacking order matters but with Venus in daytime (sun well up) I have tended to put the one that darkens the sky most on the sky-side of the stack – my reasoning: why let that unwanted light half-way through the ‘door’ so to speak.  But I have to say I have neglected to do that on occasion and never noticed any difference…..!

 

Dave.

[LunarFox]

So I went ahead and took a few scans of stacked filters, and sure enough, you simply get merging of the passbands. It felt good to validate a hypothesis, that doesn't happen much in actual science

 

Here is a #12 Yellow + #58A Green. This is the closest I could come to what we talked about above since I don't have a #15 Lt Orange.

 

 

As you can see, you get pretty much the exact same curve as what I diagrammed earlier today. You simply integrate the two curves and that's your new transmission curve.

 

The same holds for a #12 Yellow + #80A Blue combo.

 

 

But you'll notice the tail transmission dropped some as well. This makes perfect sense though. The #12 transmits 90% in that range, and the #80A around 82%, so 0.9*0.82 = 0.74, which is exactly what the combined filters transmit.. 74%. This isn't as evident in the above combo because 90% of 10-20% is still pretty much 10-20%.

 

And lastly, I combined a #12 Yellow with a #21 Orange, and as you would expect, all you get is another #21 Orange, but with slightly lower transmission due to multiple 10% losses.

 

 

So if you're ever wondering what your new transmission profile is when stacking filters, just integrate the two curves and multiply your transmission losses. That'll be your new transmission curve

Edited by LunarFox, 18 April 2016 - 01:03 PM.

[David Gray]

Many thanks for your efforts on this……

 

I suspect that at least part of stacking is that it gets the image down below the glare-level to deliver those delicate contrasts more surely – as indeed with filtering in general.  Similarly with apodizing, but here, in my experiences, I very much feel there is the further benefit in line with apodizing theory.  Even so, either way it is a very good neutral filter – I do not trust glass ones for my colour-rendering pursuits.  Polarizers likewise – my Celestron set giving a distinctly bluish cast – maybe rivalling an 80A……

 

As I said before: a favourite is the BAS #22; which strangely I find much preferred to the Celestron #23A; maybe different manufacturers need to be factored in I feel.  Also the #15 (BAS) I find to be very versatile and often found useful.

 

There is a lot I could add here: but maybe later – and I’m starting to look like the filter-obsessive I said I wasn’t………. ....

 

My Appreciation,
Dave.

Edited by David Gray, 18 April 2016 - 09:20 AM.

[LunarFox]

A local club member recently gave me a Gosky Moon & Skyglow (eBay brand) to measure and compare against the Baader Neodymium. As with my other generic Moon & Skyglow filter, it has essentially the same transmission profile as the Baader Neo.

 

[faackanders2]

So far, I have found the Baader Neodymium clone (Moon & Skyglow) to be my favorite on Jupiter, with a variable polarizer set to ~30% transmission coming in very close second. The 80A blue is also quite nice, but it makes the gas giant just a tad bit too blue for me.

 

On that note, the Moon & Sky filter does give the planet a bit of a purplish/pink hue, but it's hardly noticeable. The Mars filter shown above, however, makes it look VERY pink! Definitely wouldn't recommend using the Mars one on Jupiter, we'll have to see how it performs on its intended target in a couple months..

 

For anyone interested, here is what the Generic Moon & Skyglow I am using looks like. There are no markings on the other side to indicate a manufacturer, but you can see how closely its transmission resembles that of a real Baader Neodymium. It's slightly lower transmission across the spectrum, but that's in a way a good thing when it comes to viewing planets.

 

Generic Moon & Sky.jpg

 

Moon & Sky.png

 

I'm also going to post the Orion Mars and TeleVue Planetary on their own in this post, I realize the diagram in the first post is a little messy and it's too late for me to edit it now.

 

Mars.png

so impressed by Moon & Skyglow plots and low price that I ordered both 2" (~$28) and 1.25" (<$8) Moon & Skyglow filters from two different companies on e-bay (soligor & vite).  And I already have orion skyglow filters which I like on Jupiter, and multiple DSOs, etc.

[faackanders2]

 

So far, I have found the Baader Neodymium clone (Moon & Skyglow) to be my favorite on Jupiter, with a variable polarizer set to ~30% transmission coming in very close second. The 80A blue is also quite nice, but it makes the gas giant just a tad bit too blue for me.

 

On that note, the Moon & Sky filter does give the planet a bit of a purplish/pink hue, but it's hardly noticeable. The Mars filter shown above, however, makes it look VERY pink! Definitely wouldn't recommend using the Mars one on Jupiter, we'll have to see how it performs on its intended target in a couple months..

 

For anyone interested, here is what the Generic Moon & Skyglow I am using looks like. There are no markings on the other side to indicate a manufacturer, but you can see how closely its transmission resembles that of a real Baader Neodymium. It's slightly lower transmission across the spectrum, but that's in a way a good thing when it comes to viewing planets.

 

Generic Moon & Sky.jpg

 

Moon & Sky.png

 

I'm also going to post the Orion Mars and TeleVue Planetary on their own in this post, I realize the diagram in the first post is a little messy and it's too late for me to edit it now.

 

Mars.png

so impressed by Moon & Skyglow plots and low price that I ordered both 2" (~$28) and 1.25" (<$8) Moon & Skyglow filters from two different companies on e-bay (soligor & vite).  And I already have orion skyglow filters which I like on Jupiter, and multiple DSOs, etc.

 

Both filters came in, but I haven't used them yet.  The 1.25" was added to my Orion 8 slot (planetary) 1.25" filter slide.

I don't really have an opening in my two 2" Astrocrumb filter slides, and may have to order another.

Visual inspection shows the filters to be very similar to Wratten light blue.

[BGazing]

A local club member recently gave me a Gosky Moon & Skyglow (eBay brand) to measure and compare against the Baader Neodymium. As with my other generic Moon & Skyglow filter, it has essentially the same transmission profile as the Baader Neo.

 

Gosky Moon & Sky.jpg

 

I have both filters (generic Skyglow and Neodymium) and, prior to seeing these transmission curves, they looked similar but at a different levels of brightness, and your diagram confirms my impression. Simply put, Baader executes the ups and downs closer to the extremes and puts out more light where it appears to be desired light.

I did not like Skyglow on Saturn, but Neodymium looked good on Saturn too (Jupiter goes without saying).

Edited by BGazing, 09 September 2016 - 10:55 AM.

[LunarFox]

I also find the Neodymium clone to be superb on Mars. Definitely not Saturn. 

 

Ive settled on the following filters for our Solar system neighbors:

 

Venus - variable polarizer 

Moon - variable polarizer

Mars - moon & skyglow (neodymium)

Jupiter - moon & skyglow (neodymium)

Saturn - none, sometimes #12 yellow (Celestron brand, Orion one is too yellow)

[BGazing]

I also find the Neodymium clone to be superb on Mars. Definitely not Saturn. 

 

Ive settled on the following filters for our Solar system neighbors:

 

Venus - variable polarizer 

Moon - variable polarizer

Mars - moon & skyglow (neodymium)

Jupiter - moon & skyglow (neodymium)

Saturn - none, sometimes #12 yellow (Celestron brand, Orion one is too yellow)

did you happen to measure what the fwhm is for the neodymium?

[LunarFox]

As Don pointed out, the Neo doesn't really have a FWHM since its a multi-notch type filter. I have a spectrum of the Baader Neo at the beginning of this thread.

[faackanders2]

IMO, planets are best viewed Au naturale.....

 

Sometimes.....a ND filter helps. Color filters....meh!

Au gold is nice

[faackanders2]

 

 

So far, I have found the Baader Neodymium clone (Moon & Skyglow) to be my favorite on Jupiter, with a variable polarizer set to ~30% transmission coming in very close second. The 80A blue is also quite nice, but it makes the gas giant just a tad bit too blue for me.

 

On that note, the Moon & Sky filter does give the planet a bit of a purplish/pink hue, but it's hardly noticeable. The Mars filter shown above, however, makes it look VERY pink! Definitely wouldn't recommend using the Mars one on Jupiter, we'll have to see how it performs on its intended target in a couple months..

 

For anyone interested, here is what the Generic Moon & Skyglow I am using looks like. There are no markings on the other side to indicate a manufacturer, but you can see how closely its transmission resembles that of a real Baader Neodymium. It's slightly lower transmission across the spectrum, but that's in a way a good thing when it comes to viewing planets.

 

Generic Moon & Sky.jpg

 

Moon & Sky.png

 

I'm also going to post the Orion Mars and TeleVue Planetary on their own in this post, I realize the diagram in the first post is a little messy and it's too late for me to edit it now.

 

Mars.png

so impressed by Moon & Skyglow plots and low price that I ordered both 2" (~$28) and 1.25" (<$8) Moon & Skyglow filters from two different companies on e-bay (soligor & vite).  And I already have orion skyglow filters which I like on Jupiter, and multiple DSOs, etc.

 

Both filters came in, but I haven't used them yet.  The 1.25" was added to my Orion 8 slot (planetary) 1.25" filter slide.

I don't really have an opening in my two 2" Astrocrumb filter slides, and may have to order another.

Visual inspection shows the filters to be very similar to Wratten light blue.

 

I have used the 1.25" mOON & sKYGLOW AND IT IS COMPARABLE TO the orion lt blue filter in the Orion MaRS 3 FILTER SET.

 

I haven't used the 2" version yet, since my 2" Astrocumb filter slides are filled up.

Edited by faackanders2, 18 September 2016 - 07:33 PM.

[ftwskies]

It's interesting that nobody has mentioned so far that the one big difference in the Baader spectra is the cut to the violet down at the 400nm range...

[LunarFox]

While certainly noticeable on a graph, I doubt that difference is significant in the eyepiece. We're talking about a matter of 30% lower transmission (on average) across 20nm at an extreme of the visible spectrum where the sensitivity of our eye is pretty poor to begin with. I would be surprised if that contributed to any performance difference, especially when viewing a bright object like a planet.