- #1
sravet
- 3
- 0
I am helping my son design and build a refractor telescope for a science fair project (8th grade). He has read some on lens types and focal lengths. We also read that Galileo's most powerful telescope was 33x, and was able to view Saturn's rings and Jupiter's planets. We want to be able to do at least that with purchased lenses and a home made tube. Our first step will be to mount the lenses with clay on a yardstick so we can easily measure lens position.
I'm hoping to get there with something like United Scientific lenses which run $5 to $15. We aren't looking for professional grade results but we don't want to be disappointed either. Depending on cost we may get several lenses so we can experiment and note what works best. So I have some basic questions, and am looking for some rules of thumb:
1) glass or acrylic? After a quick search it looks like plastic is surprisingly more expensive than glass. What's the difference?
2) Lots of suggestions for achromatic lenses. Given that this is a science fair project are single elements lenses suitable?
3) focal lengths. We can get there (Galileo 33x) with something like 300mm/10mm, or 900/30, or lots of other values. It's my understanding that there is less distortion with longer focal lengths, but they require longer tubes. Are there any general guide lines on focal lengths? longer generally better?
4) Anything else I may not have thought to ask?
thanks in advance for any help or suggestions.
--steve
I'm hoping to get there with something like United Scientific lenses which run $5 to $15. We aren't looking for professional grade results but we don't want to be disappointed either. Depending on cost we may get several lenses so we can experiment and note what works best. So I have some basic questions, and am looking for some rules of thumb:
1) glass or acrylic? After a quick search it looks like plastic is surprisingly more expensive than glass. What's the difference?
2) Lots of suggestions for achromatic lenses. Given that this is a science fair project are single elements lenses suitable?
3) focal lengths. We can get there (Galileo 33x) with something like 300mm/10mm, or 900/30, or lots of other values. It's my understanding that there is less distortion with longer focal lengths, but they require longer tubes. Are there any general guide lines on focal lengths? longer generally better?
4) Anything else I may not have thought to ask?
thanks in advance for any help or suggestions.
--steve