- Posts: 521
- Thank you received: 0
Maximum useful magnification
- jhoare
- Topic Author
- Offline
- Red Giant
-
17 years 8 months ago #39551
by jhoare
John
Better that old people should die of talk than to have young people die in war.
Maximum useful magnification was created by jhoare
Here's a thought.
People frequently quote the rule of thumb that the maximum useful magnification (safe bet value) is 50 times the objective diameter. But they often don't add "(in inches)". What if a total newbie takes it literally? 200(mm) x 50 = 10,000x :!:
Except for a few of ranges of high end Dobs sold in North America every telescope objective measurement I see advertised uses millimetres.
Twice the objective diameter (measured in millimetres, as they usually are) will give a close enough result to the original rule of thumb to be of the same value. So why bother doing the metric to Imperial conversion?
8"x50=400x.
203.2x2=406.4x
Go metric. Use the 2
People frequently quote the rule of thumb that the maximum useful magnification (safe bet value) is 50 times the objective diameter. But they often don't add "(in inches)". What if a total newbie takes it literally? 200(mm) x 50 = 10,000x :!:
Except for a few of ranges of high end Dobs sold in North America every telescope objective measurement I see advertised uses millimetres.
Twice the objective diameter (measured in millimetres, as they usually are) will give a close enough result to the original rule of thumb to be of the same value. So why bother doing the metric to Imperial conversion?
8"x50=400x.
203.2x2=406.4x
Go metric. Use the 2
John
Better that old people should die of talk than to have young people die in war.
Please Log in or Create an account to join the conversation.
- pmgisme
- Offline
- Red Giant
-
- fguihen
- Offline
- Main Sequence
-
- Seanie_Morris
- Offline
- Administrator
-
17 years 8 months ago #39568
by Seanie_Morris
He's taking the mick! Just click the 'Ignore User' button beside his name!
Midlands Astronomy Club.
Radio Presenter (Midlands 103), Space Enthusiast, Astronomy Outreach Co-ordinator.
Former IFAS Chairperson and Secretary.
Replied by Seanie_Morris on topic Re: Maximum useful magnification
I use Angstroms myself.
Thats why I was able to watch Cassini orbiting Saturn last night.
Peter.
can you see cassini?? what scope do you use?
He's taking the mick! Just click the 'Ignore User' button beside his name!
Midlands Astronomy Club.
Radio Presenter (Midlands 103), Space Enthusiast, Astronomy Outreach Co-ordinator.
Former IFAS Chairperson and Secretary.
Please Log in or Create an account to join the conversation.
Time to create page: 0.095 seconds
  