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Magenta & Salmon Filters for Mars: Latest News

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#1 Sarkikos

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Posted 12 April 2011 - 11:01 AM

Experienced Mars observers know that #30 Magenta and #85 Salmon filters are probably the best filters available to bring out contrast and detail on Mars. The Salmon filter brings out the maria. Magenta seems to be about the best general filter for Mars. (My personal favorite setup is Magenta stacked with a Baader Moon & Sky Glow.) Unfortunately, most vendors either don't seem to know about the Magenta and Salmon filters, or if they do know, they still don't provide them for amateur astronomers.

Ideally, we would want the Magenta and Salmon filters in 2" and standard 1.25" sizes. The 2" size is good to screw onto the end of 2"-1.25" adapters, or they can go on wide-field 2" eyepieces for nondriven Mars observation on a Dob. The 1.25" filters can screw directly onto 1.25" eyepieces. But the main reason I want to find these two Mars filters in 1.25" format is so I can insert them in my filter wheel. That way I can switch immediately among them and other filters to bring out different types of surface features on Mars. It just makes good sense. :ubetcha:

I'll tell you what I know about the current availability of the Magenta and Salmon filters. The closest you can get to standard 1.25" filters in these colors are the ones from Vernonscope. But they have a Vernonscope threading which is not compatible with the vast majority of eyepieces or other accessories. They are compatible with Brandon eyepieces. Period.

If you want to use Vernonscope 1.25" filters on other eyepieces, you must purchase adapter rings. If you want to screw them into a filter wheel, forgetaboutit. It won't work, even with the adapter rings. A Vernonscope filter combined with an adapter ring produces a stack that is too tall to fit into a filter wheel, at least into my Orion Filter Wheel.

On the other hand, the Vernonscope 2" filters do have standard threading. They will screw very smoothly onto 2" eyepieces and 2"-1.25" adapters. No problem. Also, the Vernonscope #30 Magenta 2" filters are a very good deal at only $30 each, plus $5 shipping. Compare that to at least $67 + shipping elsewhere. True, you can buy #85 Salmon 2" (48mm) filters on ebay or from various vendors all day long for just a few dollars each. But Vernonscope is definitely the best source of the 2" Magenta.

Be careful, though, to look under Birding Accessories at the Vernonscope website. That's where you'll find the 2" filters. The 1.25" filters are under Astronomical Accessories. Go figure. :scratchhead:

Mike

#2 Sarkikos

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Posted 12 April 2011 - 11:14 AM

I'm still searching for a source of 1.25" Magenta and Salmon filters with standard threading. I've nearly resigned myself to the idea that they do not exist anywhere in the known universe. You either rig one up yourself or do without. Unfortunately, I don't have the equipment or skills necessary to cut a larger Magenta or Salmon filter down to 1.25" size and fit it into a filter ring. Ain't gonna happen'.

Mike

#3 Sarkikos

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Posted 12 April 2011 - 11:30 AM

Now I'm investigating the possibility of Magenta and Salmon filters slightly smaller than 1.25" that could be fitted into 1.25" filter rings. Even if I needed to rig up some kind of washer or O-ring to wedge the smaller filter into the ring so it wouldn't fall out, it would be worth it. Vignetting should not be a concern, since Mars observation is usually done at high magnification with eyepieces that have relatively narrow field stops.

Maybe a 30mm filter would do the trick? Something to think about. Has anyone tried fitting 30mm filters into 1.25" filter rings?

Mike

#4 Sarkikos

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Posted 12 April 2011 - 11:37 AM

Here is a 30mm #85 filter. The description is "Orange," but 85 is the correct Wratten number for Salmon.

Series V 5 30mm Drop-In Filter KODAK TYPE A #85 ORANGE

Mike

#5 David Knisely

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Posted 12 April 2011 - 02:47 PM

Actually, over the years, I have found that a Wratten #23a filter (or its equivalent) helps the dark albedo features the best on Mars. Also, the 82a light blue filter is good for bringing out the white clouds and polar caps, although for me, I use the Lumicon Deep-sky filter for that, as it is a passable blue filter. Clear skies to you.

#6 Sarkikos

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Posted 12 April 2011 - 04:20 PM

Hi David,

I've tried all those filters for Mars. The 82a Light Blue does bring out the clouds and caps. The 23a Red and 21 Orange work well on the maria, and for bigger aperture you can try deeper reds. But for me, 30 Magenta showed the maria better, and was not bad for the clouds and caps. The Lumicon Deep Sky was a good overall contrast filter when I tried it on Mars. IME the Baader Moon & Sky Glow is even better. IMO & IME, nothing beats Magenta stacked with M&SG as a general Mars filter.

I tried the other filters over and over, but I kept going back to the Magenta + M&SG. That doesn't mean I won't try them all over again, as well as any other possiblities, during next opposition. Using an apodizing mask and binoviewer this next time might make a difference in which filters work for me.

But if I have limited time, and I want to sketch Mars, I go straight to the Magenta + M&SG.

Clear Skies,
Mike

#7 Rick Woods

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Posted 12 April 2011 - 04:52 PM

Red #25 was my standard for a long time. The #30 filter does such a good job because magenta is a blend of red and blue, and so the filter has the benefits of both. I agree, magenta is the go-to filter for me, but many other filters are good too. If you can find a Sirius Optics Mars Filter (company now defunct), those are also exceptionally good, virtually a toss-up with the magenta (but much more delicate).

#8 Sarkikos

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Posted 12 April 2011 - 07:54 PM

I have several 1.25" filter housings/rings/cells that I purchased from Surplus Shed. Using my digital caliper, I determined that in order for a filter to fit into the ring without falling out, the filter's diameter must be between 27.5mm and 26mm.

However, the size given for photographic filters is the diameter of the male threads, not the diameter of the actual glass filter that fits in the filter ring. The caliper reading for the male threads seems to be 28mm.

If I can find Magenta (Wratten 30 or CC30) and Salmon (Wratten 85) filters in 28mm threading format, I should be able to use them as 1.25" filters on my eyepieces and in my filter wheel ... if there are photographic filters available in this size, at the pitch I need, and in these colors. So far the search doesn't look very promising.

Mike

#9 Rick Woods

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Posted 12 April 2011 - 08:20 PM

Maybe we could talk Don Y. into coming out with a proprietary filter wheel!

#10 Sarkikos

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Posted 12 April 2011 - 08:45 PM

No, that's NOT the option I'm looking for! I already have two filter wheels with standard 1.25" threading. One is for DSO filters, the other for the planet I'm observing most at the time. A third filter wheel would not be prudent ... or frugal. :crazy:

Besides, do we really want to encourage Don to create even more astronomical accessories with NON-standard threading? I don't think so. :foreheadslap: I wish someone would talk him into making Brandons and 1.25" filters with STANDARD threading.

:grin:
Mike

#11 Sarkikos

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Posted 12 April 2011 - 10:13 PM

Here is a possible 28mm Salmon filter. It is described as having a light salmon color. I don't see the VLT listed. The 80 Salmon filter has an 80% VLT. Elsewhere the KR 1.5 is called a Skylight 1A filter.

Heliopan 28 mm Skylight KR1.5 Glass Filter

#12 Sarkikos

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Posted 13 April 2011 - 07:44 AM

I can't find the VLT for KR 1.5 aka Skylight 1A filters. I know that Skylight 1A is often used as a bug/dust shield in the visual backs of SCTs, so I would assume it's pretty transparent. They probably are not a very close substitute for the 85 Salmon filter. But if I can get one for a few bucks in 28mm or 48mm format, I might give it a try.

Mike

#13 Sarkikos

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Posted 13 April 2011 - 09:02 AM

Going back through my spreadsheet list of filters, I notice that I had picked up a 1.25" 85B Orange / Warming filter. My notes say it is slightly warmer than the 85 Salmon, converts tungsten film to daylight (whatever that means), and the VLT is somewhere between 50 and 67, compared to 80 VLT for the 85 Salmon. There is also an 85C filter, which I don't have. It is supposed to be cooler with tungsten film in daylight than 85 or 85B (again, I'm not sure of the exact significance of this). All three filters are 2/3 stop.

85B Filter

(Yes, I know this link is for a 62mm filter, too big for amateur astronomy. But I reference it for the information it contains about 85, 85B and 85C filters. Also, counterintuitively, the 85B filter is called a "Blue Filter," though the filter itself has an orange or amber hue. Apparently, photography might be an even weirder hobby than astronomy.)

I haven't had a chance to try the 85B Orange to observe Mars. I will definitely slip that filter into my filter wheel come next opposition. 85B Orange will probably be a good substitute for 85 Salmon, and might even be better.

Mike

#14 proud uncle

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Posted 13 April 2011 - 04:50 PM

On the other hand, the Vernonscope 2" filters do have standard threading. They will screw very smoothly onto 2" eyepieces and 2"-1.25" adapters. No problem. Also, the Vernonscope #30 Magenta 2" filters are a very good deal at only $30 each, plus $5 shipping. Compare that to at least $67 + shipping elsewhere. True, you can buy #85 filters on ebay or from various vendors all day long for just a few dollars each. But Vernonscope is definitely the best source of the 2" Magenta.


Thanks for the update, Mike. This is good information to know.

#15 Sarkikos

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Posted 13 April 2011 - 05:12 PM

No problem, Kenneth. I mentioned this is in the "Mars 2012" thread, too. It's good to know that Mars enthusiasts can get standard-thread 2" Magenta and Salmon filters from Vernonscope.

Now if we can only find a source for them in standard-thread 1.25" format.

Mike

#16 azure1961p

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Posted 13 April 2011 - 07:02 PM

Magenta is a color that straddles both the red and blue part of the spectrum so its logical that it would a good all around filter for a fairly yellow subject - Ive never used one personally. A good question is wether or not one filter that seems to do it all is better than filters more aligned with one specific hue. Neat thought kinda. My fav is w23a on maria and w58 on poles and clouds.

Pete

#17 Sarkikos

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Posted 13 April 2011 - 09:42 PM

Pete,

I've tried many filters on Mars. I've loaded my filter wheel with various selections of filters that are supposed to be beneficial for different types of features on Mars. All the usual suspects are interesting, and do seem to make it a bit easier to discern the features that they are purported to emphasize. But, as I said, I keep going back to Magenta, and especially Magenta stacked with M&SG, for the best image of Mars - the image that, overall, shows me the most contrast and detail.

But I would rather have Magenta and Salmon loaded into my filter wheel with perhaps an 82a and a 58, to cover all - or most - of the possibilities. I'd probably leave one slot empty. But I'd have an M&SG at the neck of my binoviewer or my filter wheel, so it would be stacked with each of the other filters as I turn the wheel. The empty slot would default to showing the M&SG alone, of course.

This is why I want 30 Magenta and 85 Salmon in the true, standard-thread 1.25" format. It just makes good sense, IMO & IME. YMMV.

Mike

#18 Rick Woods

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Posted 14 April 2011 - 12:24 AM

Now if we can only find a source for them in standard-thread 1.25" format.

That's what Vernonscope sells! Remember, the others are "foreign".

#19 Sarkikos

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Posted 14 April 2011 - 09:00 AM

Rick,

"Standard-thread" is what most 1.25" accessories have, and what most amateur astronomers use. Vernonscope threading is not standard. Vernonscope is a US company, so technically their proprietary threading is "domestic," not "foreign," but I don't care about that. "Foreign" vs "domestic" is not the point. "Standard" vs "nonstandard" is my concern and one of the main points of this thread.

I want threading that will work with the equipment I use. I'm not going to use only Vernonscope equipment so that it will be compatible with Vernonscope threading. There is a big wide universe of astronomical equipment beyond Vernonscope. I have a couple Brandon eyepieces and a couple Vernonscope filters, but except for them, I am well ensconced in the non-Vernonscope world.

I will never say that Vernonscope threading is a good thing. It is definitely a negative feature of their product. I can work around the narrow field of view and short eye relief of Brandons. But I can't fit their filters into my filter wheel. That prevents me from doing what I want to do at the telescope. It's not a good thing.

Mike

#20 Sarkikos

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Posted 14 April 2011 - 09:30 AM

Here is a possible way to fit Vernonscope filters into a filter wheel. I might be able to find a step-up ring that can be wide enough to hold the Vernonscope filter, be short enough so it would fit into the filter wheel, and be able to screw into a slot in the wheel. I would have to remove the filter from the Vernonscope filter housing and place it in the step-up ring, maybe using some kind of washer (black foam core? rubber washer?) to hold it snug in the ring.

A potential problem could be that the step-up ring might be too wide to fit into the wheel with the other filters. Also, $34.95 is a steep price to pay for an experiment. (I had heard that B+W products were expensive. Yep.) Maybe I can find one used for a few bucks.

Mike


B+W Step-Up Ring (Lens to Filter) 28mm - 30.5mm

#21 Sarkikos

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Posted 14 April 2011 - 09:41 AM

Here is another step-up ring. It is cheaper ($6.95) but wider.

General Brand 28mm-37mm Step-Up Ring (Lens to Filter)

#22 Sarkikos

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Posted 14 April 2011 - 09:45 AM

This one is slightly narrower, still pretty cheap ($10.99), but it is shiny. Shiny is not good for astronomy, unless it's one of the mirrors.

Cokin 28-36mm Step-Up Ring (Lens to Filter)

#23 Sarkikos

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Posted 14 April 2011 - 09:51 AM

The next thing I need to do is remove a 1.25" Vernonscope filter from its housing and measure the filter's actual diameter. Then I could look for a step-up ring that will be as narrow as possible to fit in the filter wheel between the other filters without being too narrow for the Vernonscope filter.

Mike

#24 Sarkikos

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Posted 14 April 2011 - 09:56 AM

Here you go ($1.99 + $2.00 shipping):

28mm>30mm 28-30 Step Up Filter Ring Stepping Adapter

#25 Sarkikos

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Posted 14 April 2011 - 11:24 AM

Here is a #85 30mm drop-in filter that might fit in a 28-30 step-up filter ring. The ad calls this an "Orange," but I'm pretty sure it's what we've been calling "Salmon," because the Wratten number is 85. But I think the "TYPE A" designation means that it is an "85A" rather than an "85." $9.95 + $3.41 shipping.

Series V 5 30mm Drop-In Filter KODAK TYPE A #85 ORANGE


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