What Filter Do/Would You Use With A 150mm F8 Achomatic On Jupiter?

[refractordude]

Hello There

A few days ago I observed Jupiter comparing a yellow #8 filter against a four inch aperture mask. At the time it looked like the mask did a better job with color. This evening I noticed the filter showed more resolution and there was no great change in color. The atmosphere was much better than the last time out allowing 200 mag. Perhaps the sky conditions made the difference. There was observed swirls around the Great Red Spot only visible with the filter. I also compared contrast and resolution with and with out the barlow at 120 mag. I will not be using barlows any more. I am happy with the #8 yellow on Jupiter but curious what others use. Thanks to you all.

Clear Skies

[AstralTraveller]

I use a Baader FringeKiller with the frac., which kills most of the blue fringe and gives a yellow tint. It makes the scope usable for lunar and planetary viewing. It's perhaps not as necessary for DSOs but I put it at the front of the diagonal and so tends to stay there.

[Saturnine]

I'll 2nd what Dave said but will add the Baader Semi APO filter as being very good at suppressing the violet fringe on the moon and planets, possibly better than the Fringe Killer filter . Use mine on an 150mm F6.5 achro and it does a good job, again not necessary for DSOs'.

[skysurfer]

I have a Baader Semi APO filter and use it with a small 80mm f/6.5 tabletop and a 4mm TMB Planetary eyepiece. Color fringe free images.
On my 110 ED I don't use this filter, not needed.

[refractordude]

Hello There

Has anyone ever used a #8 yellow and how does it compare to those Baader filters?

[Saturnine]

The Baader filters are a step above the coloured filter and the Semi APO doesn't impart any noticeable colour change to the view.

[Don Pensack]

I would try the Baader Contrast Booster.
Read this review:
https://www.cloudynights.com/articles/cat/articles/using-filters-for-lunarplanetary-observation-r3261?st=50
and look at his #1 choice for Mars, Jupiter, and Saturn.

[refractordude]

Hello There

Thanks for all the replies. Using the four inch mask allows me to get high magnifications. Sometimes I can go high as 300 mag. Without the mask objects breakdown a little after 100 mag. Which filter will allow me to up the mag with full aperture? I once tried a #12 yellow but it did not work. By the way I have a six inch aperture F8 DOB. However, I do not like the diffraction spike on Jupiter and Mars. Also with the DOB I can not change the angle of the focuser to stop Crater Illusion when viewing the Moon.

Thanks to you all

[Don Pensack]

You need to step down the aperture to increase the f/ratio to reduce chromatic aberration. Seeing always has a certain degree of scintillation, but reducing the aperture also makes that scintillation smaller than the resolution of the scope.

If diffraction spikes bother you, continue to use a refractor, though you might like a Maksutov-Cassegrain, which doesn't have diffraction spikes or chromatic aberration.

Great seeing will allow you to increase the magnification. Great collimation will as well. And, the third "C": cooling of the optics.
Cooling:
Your scope will get better image quality at high power after cooling the optics to the ambient temperature. Some time outside will improve the images, especialy with a 6" lens.

Collimation:
The use of high quality collimation tools is essential for higher power use. If you ever want to use 300x in a scope, good collimation is critical. Collimation tolerances are loose at low power, but very tight at high powers.
Fortunately, refractors are usually collimated, though it is something you should check.

Conditions:
High powers demand good seeing. You can control seeing to a small degree:
--observe objects when more than 30° above the horizon, and, preferably, 45° or more.
--don't observe objects directly above a roof, as roofs leak heat all night long and that causes turbulence in the air.
--try to avoid setting up the scope on asphalt or concrete, as they lose heat all night long under the scope. Instead, choose dirt or grass.
--don't set up anywhere near a bonfire or barbecue at night due to the heat rising from them.
--if you can, set up in the middle of a valley, not at its edges. Air rises and falls at the edges, but the air in the center of a valley is more stable.
--observe at high powers 2-3 days after the passage of a front, not immediately after. Slow air movement, even stagnant air, leads to more stable seeing and the ability to use high powers.
--observe after midnight. Quite often the morning hours have the calmest skies.

I am not sure what you mean by "crater illusion". If you mean that craters appear as domes and vice versa, this goes away with time and familiarity of viewing the Moon. More moon viewing will help.

If by that you mean the appearance of floaters: dots, amoebas, bacilli, lines, and squiggles against the moon when viewing, know this: it is a universal human problem, and the older we get, the more of those are in our vision.
They seem to appear more at small exit pupils, like when the focal length of the eyepiece equals the f/ratio of the scope or shorter (8mm and shorter in your scope). By the time you get to an eyepiece whose focal length is 1/2 the f/ratio of your scope (~4mm), virtually everyone sees these "floaters in the eye". They are small concentrations of opaque material in the vitreous humor of the eye. The cure is to use a lower power or to ignore them, though ignoring them is hard to do when they settle in the center.

But, your original question was about a filter, and, sadly, there is no filter that will improve seeing (turbulence). Some have said that by cutting off the violet and blue they see less light scatter in the eyepiece, but that is not the same as improving seeing.
What is true is that the more you observe, the more likely you will be observing when the seeing is great and high powers can be used. Seeing varies from night to night and even hour by hour.

maybe this will help:
6" scope at
low power--22-60x usable every night it's clear.
medium power--60-120x Usable most nights.
high power--120-180x Usable fairly often, but not every night.
ultra high power--180-300x. Not frequently usable.

The Seeing scale:
https://www.damianpeach.com/pickering.htm

[refractordude]

Hello Don Pensack

Thanks for the reply.

[doug mc]

Here is a picture of three filters . As you can see the fringe killer has the least yellowing effect but does a decent job of cutting the unwanted fringing. It certainly sharpens the contrast on the moon and Jupiter. I owned a Synta 150mm f/8 achromat some years ago.

[refractordude]

Hello doug mc


Thanks for the reply.