Baader CA filter comparison

[jgs001]

Over the course of the past couple of months, I've added a couple of CA filters to my collection and now have the following Baader filters.

Fringe Killer (FK), Contrast Booster (CB) and Semi Apo (SA). I thought it would be good to compare them side be side (well one after the other) on my little f5 achro scope. I used the moon as the obvious test subject, and compared both visually and with the 450d at prime focus. Ok, so Visually.

CB - This worked very well and reduced the intensity of the moon nicely, however, the view had a very obvious yellow tint

FK - This also worked very well, didn't have a lot of effect on the intensity and had less of a yellow tint

SA - This worked very well also, but, and this is the most useful difference, the image seen was by far and away the most natural and balanced in terms of colouring.

Here's the images. I manually set the white balaned to Daylight to force the camera to not adjust the captured image automatically.

CB

FK

SA

On the basis of this test, the SA filter is now going to be living in my scope. I hope that's helpful to some of you.

[GazOC]

That SA looks amazing, you can still see the 'shadow' of the CA but the Moon looks very natural. I have a Fringe Killer but I find the yellow colour more objectionable than the CA so I don't use it much.

[Neon]

Nice comparison jgs001. Was the test carried out on your little Konus? If so, you're getting semi APO performance at great value for money.

I've got a semi APO scope and I use a 2" William Optics VR-1 filter to get a better image. I've taken it out on a couple of occasions, but it practically lives in my 80mm Sentinel. The image is slightly yellow with it in, but you only notice that when it's removed from the 'scope. The filter certainly reduces halo effects to almost zero, even at relatively high magnification.

[jgs001]

Thanks guys. Neon, yep, the test was carried out on my little Konus. The Owl cluster I posted was also shot through the Konus with the SA filter in place. The only editing on those images (should have said) was a bit of sharpen in raw processing and turning the right way up.

[MjrTom]

Wow John that's quite a difference in the colour cast. I shall have to pick up one of those Semi Apo filters sharpish!

Thanks for taking the time to perform this side by side review

[A McEwan]

I've found the SA filter to be most impressive in my 6" f8 achro. I've read that the VR-1 is very highly sought after and very hard to find. A stacked FK + Moon&skyglow has the same effect with slightly higher transmission values, but is costly to do so, specially in 2" format.

For me, the next step up would be a Chromocorr/Raycorr - and that's a big step up in price too!

Ant

[David Smith]

Thank you for this jgs001, very helpful indeed. I have been considering one of these filters for my 80mm achro scope for a while now and would probably have gone for a Fringe Killer based on price. Think I will save a bit longer and go for the semi-apo instead.

[Starlight 1]

Jgs thank for the link . and I can see SA is the one to go for.

[JamesM]

many thanks John for taking the time to do the test. More important to get a review based on real experience than reading the 'promises' on the outside of the box.

Many thanks

James

[nightfisher]

Good review, just wonder how the s/a would work on tals and vixens that tend to have a yellowish colour

[sologuitarist61]

Thanks for that John, I have toying with getting the Baader semi apo but wasn't sure that it was worth the money, but your test has helped to make my decision, so thak you for that.

[oldfruit]

Having read your comparison i bought the 2 inch Semi Apo filter and must say i am really pleased with it. I am using it in an Evostar 150 and i fing it does reduce the colour considerably.