baader semi apo or fringe killer

[daine042 (Daine)]

Just wondering if anyone out there has used either of these filters?I need to reduce the CA in my 6" f5 refractor and really don't want to waste money on something that will do a poor job at it.

[glend (Glen)]

I have a Semi-APO that I used with my two AR102s and it worked ok in the f9 version but not so well in the f6 shorty. I sold those scopes and now have just my 127mm iStar f12 and it really isn't needed at that 1500mm focal length but i use it just for planets. There is a good CA chart kicking around on IIS somewhere.

[cometcatcher (Kevin)]

This chart?

I have the Semi-Apo filter. It definitely helped reduce the CA for planet viewing with my 100mm F8 achro refractor and 120mm F5. But it also reduced the light considerably. I use it a lot for photography because the Semi Apo also has LP filtering. For deep sky viewing I don't use it / don't need it.

[glend (Glen)]

That's the one!

[dannat (Daniel)]

you could just try a light yellow #8, reduces a fair bit of violet

[Renato1 (Renato)]

I use mine on a 100m f/5 achromat. It certainly improves things at high power, and turns the moon and planets yellow (not that pleasant) - though the image isn't as good as in my real APO refractor.

However, do you remember years ago they used to sell Ambervision, Ambershades and BluBlocker sunglasses everywhere, and eventually they were all in the $2 shops? The first two were the best, and Blu Blocker just behind them. They were better than any of my yellow or yellow-green filters, and, nearly on par with the semi-Apo filter. One could either wear the sunglasses when there was long enough eye relief, of cut pieces off the lens and stick them inside or over the eyepiece with Blu-Tack.

Regards,
Renato

[Marios (Marios)]

I read the Semi APO filter is color balanced but dims the view given it has some LP properties in the spectrum. My question to the Photography users can the yellow be WB out or edited easily in post processing without color degradation??

[cometcatcher (Kevin)]

Originally Posted by Marios

I read the Semi APO filter is color balanced but dims the view given it has some LP properties in the spectrum. My question to the Photography users can the yellow be WB out or edited easily in post processing without color degradation??

I'm a little confused. Are you referring the the Semi-Apo filter or a plain yellow filter for photography?

The Semi-Apo filter is colour balanced for photography. There is very little noticeable colour shift. I like it because of this.

A plain yellow filter for photography, depending on how deep the filter is (light yellow to deep yellow), a light yellow can be balanced back to "normal" but the deeper ones retain some colour shift. For reference the GSO yellow is deeper than a Hoya K2.

I sometimes use a yellow or yellow / green filter on an achro refractor to subdue the blue fringe.

[Marios (Marios)]

Hi Comet

My question was in refrence to the Baader Fringe killer for Day time photography use . I am geting a bit of CA in my daytime photography and is effecting the over all sharpness. I was hoping a member who has photograpahed with the Baader Fringe killer might be able to comment on the ease of post processing the Yellow cast.

I am shying away from the semi apo due to the fact it seems to cut out more of the spectrum, which probably in not ideal for my day time requirement.

Originally Posted by cometcatcher

I'm a little confused. Are you referring the the Semi-Apo filter or a plain yellow filter for photography?

The Semi-Apo filter is colour balanced for photography. There is very little noticeable colour shift. I like it because of this.

A plain yellow filter for photography, depending on how deep the filter is (light yellow to deep yellow), a light yellow can be balanced back to "normal" but the deeper ones retain some colour shift. For reference the GSO yellow is deeper than a Hoya K2.

I sometimes use a yellow or yellow / green filter on an achro refractor to subdue the blue fringe.

[cometcatcher (Kevin)]

That's a very gentle filter. I would be surprised if it colour shifted beyond getting it back. I don't have one, but it's on my "to get" list lol.

[Marios (Marios)]

Pricey bloody things for 1.25 inch, aaaahhh I hear the sucking sound coming from my wallet again...

[cometcatcher (Kevin)]

With the 2" being worse. Probably why I've put it off for so long. It's worth half a telescope.

[Marios (Marios)]

The flip side of the 1.25 it can be threaded onto the auto guider camera to make stars a little tighter for PHD.

[AG Hybrid (Adrian)]

Well I have both. Honestly. I don't use either these days. I don't point my AR102 at planets and mag 2 and brighter stars. I know that's not particularly helpful. But... if I had to give some advice. I would say, get the Semi Apo and use it on bright stuff. Moon, Planets etc. Then take it out for everything else.

Then again your 6" f5 will give a much brighter image then my 4" f6.5. Your 6" probably gathers enough light to negate the dimming effect of the semi apo filter. Alternatively, if you don't want to sacrifice any brightness at all and don't mind a yellow tinge on white objects. I.E moon, planets and bright stars get the fringe killer.

Option 3. Sell the 6" refractor and get this. Posted its $843 US. Sure you lose some aperture but you gain a seriously sharp image with no visible false color. It comes with a ton of extra's and you wont need any filters.

[Timbo82]

I have used the Semi-Apo on a 6 inch f8 Achro. I have tested it on bright stars and the moon. It reduces violet flare on first mag stars but where it excels is the moon - it eliminated false colour without to much yellow cast and I got really contrasty, pleasing views of lunar landscape. You should give it a whirl.

[daine042 (Daine)]

I am now thinking of selling and getting the 8" imaging newt on eq5 combo from andrews but thanks for the advice

[Marios (Marios)]

Originally Posted by daine042

I am now thinking of selling and getting the 8" imaging newt on eq5 combo from andrews but thanks for the advice

Just beware for visual 8" is fine on that mount you would be pushing the upper limits for AP.