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plastic lid on scope

darc

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darc

darc

Posted
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Sorry if this is a really stupid question and you may laugh but I can take it on the plastic cover lid there is a smaller lid why is do you take of the whole lid for better viewing or the little lid I am a complete novice so if this is a really stupid question don't be to hard in your replies :)

Geoff

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Hightower

Hightower

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You are going to want to take the whole of the plastic cap off. Remember the point of a telescope is about gathering as much light as possible - so using the small hole on the cap will make your telescope greatly under perform.

I'm not sure why they put that smaller cap on the big cap, but a lot of members have used it to turn it into a home made solar filter, because with viewing the sun there is such a thing as 'too much aperture', so using the small cap bit for that gives better viewing.

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RikM

RikM

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The small cap in the lid is used to reduce the amount of light going into the scope, to reduce the brightness from very bright objects like the moon. It also increases the f/ratio of the scope which might or might not improve the contrast. Cheaper than buying a moon filter if you find the moon too bright!

The downside is that reducing the aperture also reduces the resolution. So you might have more contrast but the image is less sharp.

I have used the centre hole on my 80mm refractor to make a solar filter (as Hightower suggests), but I don't use the small holes in the lids of my Newtonians at all. If the moon or Venus is too bright, I either use a neutral density filter or normally just increase the magnification as this dims the view quite a bit naturally.

Bonus point if you can work out what the other little 'not a hole in the cap' is for :)

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darc

darc

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Cheers I thought that would be the case but being a newby I have a lot to learn I have been trying to find somebody in my area who would not mind coming over to give me some pointers but so far had no luck.

Geoff

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knobby

knobby

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The small cap in the lid is used to reduce the amount of light going into the scope, to reduce the brightness from very bright objects like the moon. It also increases the f/ratio of the scope which might or might not improve the contrast. Cheaper than buying a moon filter if you find the moon too bright!

The downside is that reducing the aperture also reduces the resolution. So you might have more contrast but the image is less sharp.

I have used the centre hole on my 80mm refractor to make a solar filter (as Hightower suggests), but I don't use the small holes in the lids of my Newtonians at all. If the moon or Venus is too bright, I either use a neutral density filter or normally just increase the magnification as this dims the view quite a bit naturally.

Bonus point if you can work out what the other little 'not a hole in the cap' is for :)

To put the other cap on so you don't lose it!

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Whizzy

Whizzy

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I'm new to this as well and i was afraid to ask anyone. I assumed it was to cut out light but thanks for highlighting this problem. Stargazinglounge is proving to be essential to me, i just wish i knew how to post things myself. I need advice too. Fingers crossed for clear skies.

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patomlin76

patomlin76

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I use mine specifically for lunar viewing, reducing the glare. I've tried iron the planets such as mars, didn't work for me. As mentioned earlier just increasing magnification worked much better to dun the image...

Sent from my iPhone using Tapatalk

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roymattblack

roymattblack

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[quote

I'm not sure why they put that smaller cap on the big cap, but a lot of members have used it to turn it into a home made solar filter, because with viewing the sun there is such a thing as 'too much aperture', so using the small cap bit for that gives better viewing.

DON'T use it to look at the Sun!!!!

You still need a solar filter unless you're fed up having eyeballs that work!

Roy

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gillipies

gillipies

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So glad I saw this thread... I've been using my scope for the past 3 months with just the little cap being taken off. I had begun to question the aperture size but just thought "nah, don't be stupid, the whole top doesn't come off".

But low and behold my 'stupid' suspicions have been proved right. I feel such a complete idiot for not realising this earlier! Might actually get further with viewing DSOs now!

Thanks folks, and to the OP for posing the question in the first place!

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