Baader contrast booster

[Nicola Fletcher]

I’ve been listening to the Real Astronomy Podcast (which is brilliant), and they have mentioned several times how much they love the Baader contrast booster. They said it improves the views of the planets and they use it more than any of their other filters. Has anyone used one? What do you think - is it worth buying?

[vlaiv]

I have one and I think it is worth having if you have achromatic refractor.

There are several threads here on SGL where people discuss ways to reduce chromatic aberration and Contrast booster is often mentioned as one of the best solutions (next to aperture mask).

[Nicola Fletcher]

14 minutes ago, vlaiv said:

I have one and I think it is worth having if you have achromatic refractor.

There are several threads here on SGL where people discuss ways to reduce chromatic aberration and Contrast booster is often mentioned as one of the best solutions (next to aperture mask).

Thanks - I probably should have just searched the forum for contrast booster - I included Baader in the search and didn’t get any hits. 
My refractors are all apochromats so I don’t know if this would offer any benefits. 

[Franklin]

Baader Contrast Booster is a minus violet filter and a neodymium filter rolled into one. It is, as @vlaiv says, effective at reducing the CA in achromatic refractors but with a slight dimming and yellowish cast side effect. Beyond this it has been found to be a useful filter for planetary contrast enhancement, not just in achromats but apochromats and reflectors. I have used one in observation of the moon and planets and it definitely has a positive effect, much more than traditional colour filters. Baader Semi-Apo filter is similar but it's effect is weaker.

[Ratlet]

I can't comment on the Baader contrast filter, but:

I view with a 130pds 5" Newtonian reflector and use a "baargain contrast booster".  It's a cheap yellow and 'moon and skyglow' filters used at the same time.  literally the cheapest filters I could find on eBay with threads on both sides of the glass.

The difference it made to the contrast was, to me, astounding on Jupiter and Mars.  I struggled previously to see much beyond a washed out image (it was like someone had put a picture of the planet over a torch and I was looking at that), but using the filter showed much more detail and on a night of really good seeing it was like looking at a tiny photo.

I'm a big proponent of it lol.  It costs like £12 and was a bit of a game changer for me.  Your milage may vary.

 

Edited August 3, 2023 by Ratlet

[bosun21]

I found the contrast booster beneficial for the planets. It definitely brings out more contrast. I actually prefer unfiltered views so sold it on. I don’t like the slight yellowish tint it portrays. Some people don’t seem to really notice it but unfortunately I’m not one of those.

[Nicola Fletcher]

1 hour ago, Ratlet said:

I view with a 130pds 5" Newtonian reflector and use a "baargain contrast booster".

Certainly sounds like one of these might be good to try! Baargain before Baader 😂

[Franklin]

4 minutes ago, Nicola Fletcher said:

Certainly sounds like one of these might be good to try! Baargain before Baader 😂

Quick question. You have an ultra high contrast, high end super-duper Takahashi dream scope, so why the contrast booster query? 

[Nicola Fletcher]

10 minutes ago, Franklin said:

Quick question. You have an ultra high contrast, high end super-duper Takahashi dream scope, so why the contrast booster query? 

Just that I’ve been binge listening to the Real Astronomy podcast and I think they mentioned it in two episodes today. I felt like the only kid in the room who hadn’t heard of it and I got curious.
 

I have Celestron coloured filters and I really don’t like them. I’ve had some fantastic unfiltered views of the planets through my FC76 and my Starwave 102mm. I’m sure the 100mm Tak will be excellent too but I just wondered if this was some super duper game changing accessory. I had FOMO!!

(Fear of missing out)

Edited August 3, 2023 by Nicola Fletcher

[Ratlet]

57 minutes ago, Nicola Fletcher said:

Just that I’ve been binge listening to the Real Astronomy podcast and I think they mentioned it in two episodes today. I felt like the only kid in the room who hadn’t heard of it and I got curious.
 

I have Celestron coloured filters and I really don’t like them. I’ve had some fantastic unfiltered views of the planets through my FC76 and my Starwave 102mm. I’m sure the 100mm Tak will be excellent too but I just wondered if this was some super duper game changing accessory. I had FOMO!!

(Fear of missing out)

Do you mean the Actual Astronomy podcast?  I absolutely know what you mean if you're talking about those guys.  They're brilliant and got me fired up for visual astronomy in a big way.  It's not so much what they say about observing, but how they say it.

If you're happy with the views you're getting them it might not provide that much of a benefit.  I was very much not happy with my planetary experience.  The baargain contrast booster made a big difference for me, but from reading other reports it brought me up to a level that made me able to relate with what everyone else was seeing.  I think if you have a good view (I couldn't easily see banding on Jupiter, it was too bright) it might only provide an incremental improvement.

It does provide a strong yellow cast, but I really don't mind it as it always makes me think of the gas planet images from the early 90s.

@Louis D I think put me on it.  He does a lot of really interesting testing with filters.

[Louis D]

The other most commonly mentioned filter for planets is a variable polarizer to cut the glare.  Actually I would recommend two linear polarizers for your setup.  One would go on the front of your diagonal and the other on the bottom of your eyepiece.  Just rotate the eyepiece to vary the amount of dimming to the best level.

I don't know if you've tried binoviewing, but I've found it really takes visible detail on planets up many notches.  In particular, Mars at opposition goes from an overwhelmingly bright orange orb (haven't tried the above crossed polarizers on it yet) to loads of details in a BV.  Same goes for the full moon.

I'd recommend a #56 green filter or cheap Chinese green filter on Venus or on any planet low in the sky.  It really cuts through the red/blue color separation/scintillation due to the atmosphere.

[Roy Challen]

5 hours ago, Franklin said:

Quick question. You have an ultra high contrast, high end super-duper Takahashi dream scope, so why the contrast booster query? 

I have owned a Baader CB and the Semi Apo filters but not at the same time. I preferred the SA in my long achro. I also tried it with my FS60-CB - it made no noticeable difference.

The contrast booster did help with a short achro I owned at time albeit with a yellow cast.

I also tried a Baader Solar continuum filter in the baby Tak while viewing Venus. It sharpened up the image a fair bit, but with a very strong green cast. As @Louis D says, a less aggressive green filter would be better.

Edited August 4, 2023 by Roy Challen

[Nicola Fletcher]

7 hours ago, Ratlet said:

Do you mean the Actual Astronomy podcast? 

Gosh yes, the Actual Astronomy podcast. Apologies to Chris and Shane if they ever read this! I absolutely love listening to them and their enthusiasm is getting me thorough the cloudy spell. 

4 hours ago, Louis D said:

I don't know if you've tried binoviewing

Not yet, but I’d love to. It’s definitely on the list. The Baader Maxbright would be my choice but I’ll have to let the Astro funds build up again - or ask Santa!

Thank you for the recommendation of the linear polarisers- I’ll give those a try. The green filter for low planets sounds good too and I might already have one. I do find Mars very challenging although I never thought I got out on a night of great seeing during the last opposition. To me, it was an over-bright disk mostly. 

[chiltonstar]

Simple ND filters work well with my 180 Mak for Mars and Jupiter, showing a lot more detail which would otherwise be bleached out by the brightness of the planetary disks, particularly at low mag.

Chris

[Stu]

I’ve not tried a Contrast Booster for a long time, but have a Neodymium filter. I have found that at moderate magnifications this does give a perceived contrast boost, but at very high powers:smaller exit pupils I saw more detail without the filter. In general I’ve found them more beneficial on Jupiter and Mars but didn’t gain anything on Saturn for some reason.

[Mr Spock]

I have a Baader contrast booster. I can't say I'm all that impressed with it. I also have a neodymium. I may try these on my recently refurbished120mm achro to see if they help. 

The only filters I've found useful this year on Venus is the variable polariser and a selection of blue filters. I find a combination of the two removes the glare and reveals subtle cloud detail.

[badhex]

I have a rebuilt short FL 6" quasi-petzval (Bresser AR-152S) which I'm hoping to revive when the weather behaves. Although I've never had chance to use it properly (storage for 8 years) I'm aware that it will likely show CA despite the additional rear lens design. I've always wondered if something like the Baader Contrast Booster will help. 

Some time ago I came across a visual rundown (I assume it was a post here) of all the various contrast boosters, fringe killers etc, with photos of the end image. If I can find it, or anyone else remembers seeing it, I'll post here. 

[badhex]

Okay, I couldn't find the original post, which seems to have been on CN, but I found a reference to it on SGL. Not sure if I read it here or CN but regardless, the interesting bit is the photo comparison shown below:

 

[Franklin]

baader-contrast-filters_US-ATT_review_0414.pdf (firstlightoptics.com)

[cajen2]

I have the Baader CB, bought when my main scope was an 8" dob, obviously not for CA but because I'd heard it was good on planets, particularly Jupiter and Mars. It turned out to make a difference, if only a subtle one: slightly more detail was there.

I'm looking forward to trying it on Jupiter through my Starfield 102ED (all I need is a night of clear skies!). Again, not to reduce CA as I've never detected any through the SF, but to see if it has the same subtle improvement.

[Don Pensack]

After years of using all kinds of planetary filters, I was advised to try the Baader Contrast Booster on Mars.  It was sharper and revealed more surface details than any colored filter or planetary filter.  It was magic.

I tried it on Jupiter and Saturn but found the yellowish tint a bit too intense (though it worked to bring out details).

Upon recommendation, I tried the Neodymium oxide filter without the minus violet, the Baader Moon & Sky Glow filter, on Jupiter and it was amazing, and it brought out tons of details not seen with any other filter.

Saturn, I think, benefits from a #8 light yellow to bring out details in the rings (though we're quickly losing ring detail as we head toward the edge-on rings in 2025), though my best views have always been without a filter.

So I think a pair of the Baader filters are useful for Jupiter and Mars,  but on Saturn, especially now that it is getting dimmer with the rings closing, using a filter for enhanced details is becoming dubious.

[Nicola Fletcher]

If it helps with the views of Mars, I’d certainly be interested in trying it. The photos of the effects of the various filters on daytime objects are really useful - thanks @badhex and @Franklin. I’m not dissatisfied with the views through my refractors by any means- equally I’ve never really got into using filters so this is really helpful!

[badhex]

21 hours ago, Franklin said:

baader-contrast-filters_US-ATT_review_0414.pdf (firstlightoptics.com)

Cheers @Franklin I think I may have also seen this. Great review and technical breakdown—although I personally find the car headlight photos a bit of an odd choice since it's quite hard to see the edges of anything, which is often where CA shows up. 

The other picture from CN is also in daylight, so not necessarily the best representation, but it has edges and background sky to give an idea of colour. 

Oh BTW @Nicola Fletcher — I think Chris is @Drkneb on SGL, I'm sure I've seen Shane floating about too but not sure of his username. 

 

 

Edited August 5, 2023 by badhex

[Louis D]

If you want information overload, take a look at this spectrograph of multiple violet reduction filters:

I have the Hirsch 12A and find it just about the best compromise of the purely yellow violet-cut filters.  There's still a tiny bit of violet fringe, but it is hardly noticeable.  There is also very little yellow cast introduced.  It also doesn't cut into the Hβ line much, so it could be left on with nebula within bright open clusters.  The problem is, it isn't made anymore.  The closest modern equivalent are some of the generic yellow filters coming out of China (which I have).  The problem with them is that they tend to scatter more light than the older US, Japan, and newer Taiwanese filters like Meade, Hirsch, and GSO.

The modern #8 Light Yellows are similar to the Meade #8 above (which I also have).  It cuts a little bit of the far violet, but not enough to be effective.  On the plus side, there's little to no yellow cast.

The older, true Wratten #8 (Yellow K2) is very similar to the modern Baader 495 Longpass.  However, the yellow cast is strong.  It's not as strong as the modern GSO #12 Yellow, but still strong.  I tried the GSO #12 first of all my yellow filters, and find it the least usable because it cuts all blue and some green, which is massive overkill.  The Yellow K2/#8 filters are still available as new old stock 48mm (2") filters on ebay for under $20 if you want to try one.  It cuts into the Hβ line, so not appropriate for those nebula that strongly emit it.

The Baader Contrast Booster and Semi APO filters simply add a Neodymium glass base that cuts some of the yellow and yellow-orange part of the spectrum to compensate for the loss of violet.  The CB is basically a #8/K2 Yellow or 495 Longpass combined with the Neodymium glass.  The SA is somewhere between the Meade #8 and Hirsch #12A in cutting violet as you can see from the graph, and then adds the Neodymium glass.  In my experience, the SA gets rid of enough of the violet fringe without adding a nasty yellow cast.  My poor man's CB still shows some yellow cast and no violet fringe at all.  The Baader filters add violet cutting coatings to the Neodymium glass to get higher transmission.  However, this doesn't really matter all that much on the bright objects that display violet fringing the most.

There's no violet-cut benefit to the Neodymium's suppression of teal-blue to green wavelengths just above 500nm.  However, when combined with the yellow/yellow-orange cut, the Neodymium filters increase contrast by separating blue from green from red with bandgaps.  Eyeglasses for the color blind work in a similar manner to cut notches between the colors they can't separate with their retinas.

Here's some of my yellow filters run through my spectroscope.  It also includes some Rosco yellows and my attempt to photograph an artificial star through my ST80 with some of these filters.

[Don Pensack]

Given the results from the Fringe killer, this scope didn't have the most severe CA I've seen in doublet refractors.

But looking at the bottom edge of the coupler on the right, only the contrast booster eliminated the violet.

Of course the Moon & Sky Glow filter did not eliminate any violet--it has no violet filtration at all.

It tends to create a "cold" image of Jupiter as well, which is one of the reasons it enhances the banding, like a #82 light blue, only without the red filtration of the blue filter.