Telescope Reviews: Planetary Eyepiece Comparison

Hi Jason,

Great comments and I agree. Here's a piece of another review that covers this issue, which I've pasted here. BTW, I use B+W filters now. I have a cream tone which is a coffee tint and an 82A. Now I can use a TakLE's for example and add the coffee hue.

WARM VS. COLD

This is one of the main issues I addressed some years back in a planetary eyepiece review because I noticed that it was constantly being overlooked by even some of the most experienced observers in the world and it was a topic that was not tapped into yet, or at least as far as I know. I also believe that the topic needs some scientific study but from a visual standpoint, I’ll express what takes place. There are some cases where either the glass or possibly the coatings will influence the images seen in a telescope or an eyepiece. I have come to find that most purists have a bias for cold images.

Warm is simply a term used to describe an optic that has a slight coffee tone or yellowness, while cold represents a bright, white or crystal clear image that is completely neautral. We can think of cold as favoring the blue while warm favors the yellow. For most deep sky targets, I prefer an optic that produces cold images, with the exception of viewing Jupiter in particular and sometimes Saturn but it also depends on the magnifications used, particularly with the rings.

If you take an 82 wratten light blue filter and view Jupiter, you’ll notice that Jupiter’s equatorials belts will become darker and therefore you may interpret that as having more contrast. But, there’s a negative trade off that must be considered. The trade off comes at the cost of losing some of the color fidelity the planet has to offer because Jupiter’s belts now take on a more monochrome appearance. This is one of the reasons why I actually don’t like images to be cold while viewing Jupiter. I still use Televue plossls as a planetary eyepiece for Jupiter because they are slightly warm. They are the only eyepieces in production that have a warmer tint to them while the Clave of Paris are the warmest I’ve ever seen. Telescopes behave in the same manner.

Some observers misunderstand how filters behave because they just expect them to make features pop into view. In order for a filter to work, the feature under scrutiny needs to be visible to some reasonable degree first before the filter can accentuate it. I personally can’t stand filters because most of them are so much darker than they need to be and many of them ghost too much, probably because they need good coatings. With filters being as dark as they are, they take away the natural color and beauty planets have to offer. There are some cases where highly experienced visual observers like Carlos Hernandez or Sol Robbins benefit from them and that makes perfect sense because they're more interested in documenting a specific feature and filters can sometimes help in this case.

I sometimes use a very special 48mm warming filter and a #82 light blue filter for planets made by B+W optics of Germany. They are the only brand of filters I use. Other than that, I don’t use color filters at all. I often use the warming filter on Jupiter and don't always have to be as concerned whether or not the eyepiece produces the warmth I want. Every observer is different, so it just depends on what you like.

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