Baader's newest addition for Achromat owners. The Semi-APO works like it's name implies - delivering an amazingly neutral view, while cutting most of the annoying and contrast-robbing violet fringe that plagues all achromats. The Semi-APO filter combines a stronger Fringe Killer coating formula with the Moon & Skyglow Neodymium substrate. The result is similar performance to the Fringe Killer + Moon&Skyglow combination, but with a slightly stronger violet cut - and at an even greater $$ value.
The Semi-APO filter benefits from all the host of world-class Baader filter attributes. The Semi-APO filter is truly the world's most advanced 'minus-violet' type filter in every regard. It's high efficiency and neutral coloration make it practically disappear in use - while making most of the violet fringe disappear! The effects on sharpness, contrast, and aesthetics are remarkable, even with small refractors. The RGB enhancement of the Neodymium substrate actually boosts color contrasts, particularly for Jupiter and Mars.
As a side benefit, the Semi-APO filter has also proven to be the best Mars filter we've used - with ALL Telescopes, including large Dobsonians, SCTs, and Apochromats. The unique properties that result from the combination of the Fringe Killer's blue wavelength attenuation (attenuation - not total elimination), plus the selective Neodymium RGB passbands, result in a significant contrast enhancement of Martian features. The image retains its natural coloration and brightness, and the optically polished surfaces maintain every bit of the image sharpness, unlike other manufacturer's filters.
The high quality of Baader Planetarium filters permits their use well ahead of the focal plane with no image degradation (ie, for cameras or binoviewers). The inclusion of Baader's renowned UV/IR Cut coatings on the Semi-APO eliminate UV and IR wavelengths to make it ideal for high-resolution imaging with Webcams, DSLR, and CCD cameras (see details of Baader's UV/IR Cut filter for more detail on these coatings). The high transmission and fringe reduction work great for both planetary and deep sky imaging.
Jan 22, 2019
Excellent product - It works as advertisedPros: Cons: Comments:
Read the "Semi APO" claims and bought one expecting to quickly return it for non-performance.
Tried it in my Bresser AR 127L / 1200 attached to the 2" diagonal, focused on the moon, very bright stars and in daytime on a Birch tree down the street.
After many sightings with and without, It really works! Even on white tree bark in direct afternoon sunlight, no purple haze around the edges!!!
Additionally, the filter does disappear, with no detectable bluish tint or reduction in brightness.
Reduces the need for an expensive field flattener (which cuts magnification) and you would still need a filter anyways.
Amazing! A Keeper!
This review was provided courtesy of AgenaAstro.comMar 27, 2015
It's okPros: Cons: Comments:
I have a Celestron 102slt refractor. It has some CA but not too bad. I bought this semi-APO filter based on my own research which seemed to suggest that this filter would make CA almost nonexistent. Well, that's not true. It does help but I wouldn't say I was blown away by the difference with and without it. Perhaps my telescope is better than I think or perhaps others who have this filter are overly enthusiastic about its performance. With the filter in place there is still a halo around the moon and some brighter stars and planets. What I do like about it is that it also increases contrast a little. But for me this was only useful for the moon where it's so bright that it's painful to look at. Then having a little light reduction and an increase in contrast is nice. There is a yellowy-green color tinge to this filter but I do not find it objectionable and quickly forget it's there. Overall I do not plan on using it much. For anything other than the moon I will not use the filter and will live with the CA because I would rather have all the light I can get than have even a little light (and slight halo) reduction. If I could do it again I would not buy it. But, I am satisfied enough with it and will not return it either.
This review was provided courtesy of AgenaAstro.comMar 22, 2013
Perfect for achromatsPros:
Great For Imaging,Quality LensesCons:
None That I Can DetermineComments:
Purchased this to use on a Borg achromat that had blue/violet halos around brighter stars when imaging with a Dslr.
This filter performs as described, taming the halos, and as a bonus, improves contrast as well.
Have imaged with an almost full moon and over streetlights, thanks to the built in LP coatings also.
It has become a permanent addition to the achro imaging setup and I recommend it without reservation.
This review was provided courtesy of AgenaAstro.comDec 13, 2012
The Very First Filter You Should Get!!!Pros:
Strong Construction,Quality Lenses,Accurate,Easy to UseCons: Comments:
This filter combines the Moon & Skyglow with the Fringe Killer filters, I used this on my 12" F/5 dobsonian scope looking at Jupiter and it looks awesome!!! something Baader hasn't advertised about it, seems to work best on lunar & planetary targets not as much difference on stars or galaxies.
In short spend the extra money on this single filter instead of two filters. An absolute MUST have for dobsonian or reflector telescopes!!!
This review was provided courtesy of AgenaAstro.comApr 29, 2012
Play it again, Sam.Pros:
Quality Lenses,Strong Construction,Doesn't dim the view much,Easy to Use,LightweightCons:
A little priceyComments:
This is the second Baader Semi-Apo filter I have purchased. That should tell you something. I got the second to have two for my eyepiece bino-pairs that go with my APM 100mm 45 degree binoculars. They don't completely remove the false color on bright objects, but, they substantially reduce them without messing with the view and as a bonus improve the contrast.
This review was provided courtesy of AgenaAstro.comDec 19, 2010
Baader Semi-APO FilterPros:
Quality Lenses,Compact,Strong Construction,AccurateCons: Comments:
The 10 inch f-12 doublet refractor at our facility shows noticeable improvements with the filter in place, working to restrict chromatic aberrations at low to medium powers and above. The filter's secret is a coating of Niobium, a rare earth metal that is has been used for such things as controlling glare for the night vision on rear view mirrors on automobiles.
Visually is great on the moon helping to suppress false colors on the limb. It also enhances reds, say in the belts of Jupiter and improving overall contrast and brightness of this planet in the field of view. It maybe one of the best Mars filters ever. For imaging with the Baader Semi APO filter and your instrument try to be critical of proper exposure, as some of the latitude and flexibility will be removed from the image as the filter works to selectively adjust the wavelengths of light that reach the eyepiece. For Lunar & Planetary work you'll need to increase your exposure perhaps as much as two stops, and therefore may not be as well suited for small refractors, due to a certain amount of dimming of the image. Again, I have had good results for Jupiter, by reducing false color at the planets edge while enhancing belt structure keeping in mind such brightness concerns are negligible for larger instruments. The results were interesting - using minimal software some of the final images certainly look more like they may have been taken with an early apochromatic telescope rather than a classic refractor! Understand the filter is not however; a cure all. In our large short focus telescope it will certainly not help to remove the fringes encircling brilliant Venus but may do a wonderful job with a better color corrected or longer focal length instrument. Over all I'm impressed. It is one of the best investments for the money to improve the performance of your medium sized and up standard or semi APO refractor!
Al Paslow - Director Mingo Creek Observatory
This review was provided courtesy of AgenaAstro.comApr 2, 2010
Very well worth the expense!Pros:
Strong Construction,Quality Lenses,Accurate,CompactCons: Comments:
I was hesitant to purchase this because of the price but have found it well worthy of the expense.
Last month I used my 5" refractor on M42 and resolved the trapezium at a relatively low power. I then inserted the filter and the difference was nothing less than amazing! The star cluster was better resolved and even the nebulosity was extended! This is a fine addition for any achromatic refractor. It is soooo nice to be free of the CA...
This review was provided courtesy of AgenaAstro.comSort by