Filter for viewing the moon.

[nates_mom]

It has been suggested to me that you can damage your eyes by viewing the moon through a telescope without a filter because of it's brightness. Is there any truth to that? I just bought my son his first telescope for his 5th birthday!

 

[adzel_3000]

Although the Moon is certainly not as bright as the sun, extended views can be downright painful!!<br /><br />I would recommend a neutral density filter (usually sold as a Moon Filter). It cuts down on the light and depending on the filter can allow you to see some details a little better.<br /><br />Depending on the model you bought for your budding astronomner, the telescope maker probably carries them (or it may be in the telescope box as an accessory).<br /><br />Clear Skies!<br /><br />--A3K

 

[tfwthom]

Yes and no.<br /><br />It's not like when you view the Sun, the Moon doesn't have UV light so it's doesn't burn your eyes. <br /><br />The Moon is just bright with reflected light so it gets uncomfortable to view without a filter.<br /><br />Personally I like the Variable Polarizing Filter made by Meade or Celestron because you can adjust how much light to filter. <br /><br />http://www.buytelescopes.com/product.asp?t=48&pid=224&m=2<br /><br />http://www.buytelescopes.com/product.asp?t=48&pid=574&m=1 <div class="Discussion_UserSignature"> <font size="1" color="#3366ff">www.siriuslookers.org</font> </div>

 

[thalion]

I don't think you can actually injure your eyes viewing the Moon with any telescope an amateur is likely to have, for two reasons:<br /><br />1.) The Moon is so much dimmer than the Sun that it would require a very large telescope to really do damage.<br /><br />2.) As a general rule, the larger a telescope is, the longer the focal length and the higher the minimum magnification is. This doesn't sound that important, but keep in mind that doubling magnification reduces light intensity per unit area to a fourth of its previous value. Therefore, the Moon looks brighest at low magnification, and dimmer with higher magnification. <br /><br />That said, looking at the Moon through a large telescope can be quite uncomfortable, so a filter will make viewing much more pleasant. It will also enable more details to be seen, since it will prevent features from being washed out by glare.<br /><br />For the record, according to my Orion catalog, good filters for viewing the Moon are neutral density filters, polarizing filters, and yellow or yellow-green filters. All of them thread into the eyepieces you're using. I can personally vouch for the utility of a yellow-green filter for Moon watching; sometimes, it can make the disk seem almost 3-D. <img src="/images/icons/smile.gif" />

 

[heyscottie]

Congratulations on buying a telescope for your son! May we ask what telescope you purchased? It would help us better determine what, if any, filter would be useful for moon viewing.<br /><br />Scott

 

[nates_mom]

We purchased an ETX-70AT. I'm hoping that it will be powerful enough to view Jupiter and Saturn relatively clearly. Viewing nebulae would be spectacular. My son is only just turning 5 and we don't know how long this obsession with space will last. <br /><br />I've read some other threads on this site and have been kind of intimidated to try the GO TO feature.

 

[tfwthom]

grrrrrrr....people talking power...grrrrrr<br /><br />The primary function of a telescope is to gather light, power is only a byproduct. The more light you can gather the more power you can use.<br /><br />Rule of thumb is 50x for every inch of aperture.<br /><br />You will have no problem with seeing the Moon, Jupiter, or Saturn. Might be small but you'll see them.<br /><br />The go-to will be great once you get used to it. I have scopes with and without go-to, with DSC and without. Play with it in the daytime to get used to it. <div class="Discussion_UserSignature"> <font size="1" color="#3366ff">www.siriuslookers.org</font> </div>

 

[heyscottie]

With a 70 mm aperture, you should be able to view even a full moon without any discomfort. However, you'll find that a nice neutral density filter like the ones others recommended in this thread will bring out more contrast and more features, especially when the moon is near full.<br /><br />Scott

 

[heyscottie]

Incidentally, I agree with crazyeddie....

 

[nates_mom]

Where were you people a month ago when I was researching this? <img src="/images/icons/smile.gif" /><br /><br />We know NOTHING about finding objects in the night sky. We purchased this model in hopes that once it was oriented to our location we could learn about different objects.<br /><br />I've seen calculators that tell you what's visible based on time and location, but I still don't know how to relate that to what's in the dome shaped sky above.<br /><br />We live near the Cernan Space Center and (weather permitting) we hope to attend a monthly skywatch this weekend. Short of that, what other resources can simplify this for me so I don't have to rely on complicated GO TO technology?

 

[heyscottie]

A book I always recommend for beginners trying to learn the night sky is "The Monthly Sky Guide" by Wil Tirion and Ian Ridpath. It has a chart for each month, with details about interesting targets in the sky for that period of time. They also come out with a new one every couple of years that give details about meteor showers and visible planets over a few years' span.<br /><br />Don't worry too much about your telescope. If you already have it, and can't (or really don't want to) return it, why then keep it and use it! It will still give you good views of the moon. You should even be able to see moons of Jupiter and rings of Saturn, and split a couple of wider double stars, like Alberio or Alcor/Mizar. It will also give decent views of the Pleiades, Beehive, the double cluster, the Andromeda Galaxy, and many other objects that are considered binocular targets and don't need high magnification.<br /><br />Don't believe that you can push this scope to a higher magnification than about 150x or so. Anything above that region will be very dim and will suffer greatly from diffraction.<br /><br />If you can and want to return your scope, do as crazyeddie suggested. Get yourself a 4.5" Netwon reflector like an Orion XT4.5 or a Celestron Firstscope 114. These are still beginner's scopes, but they will show you an awful lot more -- you should really not run out of things to see with one of them for a very long time. My only scope is still a Celestron Firstscope 114, which I've had for about 8 years now, and I still haven't run out of things to see with it. (Not that I don't want a bigger scope now -- I do -- but 8 years is a pretty good run.)<br /><br />Scottie