Where do you keep your scope?

[DanDare]

I also keep mine in the garage, less cool-down time that way. I think the truss tube I'm working on will also have to stay in the garage or perhaps I'll stick it in the summerhouse when its done. Its 6 foot long so won't bother keeping it the house.

Roy

[Jack]

I keep my equipment in the spare room snugly packed in their appropriate coverings and away from any heating panels or direct sunlight.

Best regards.

Jack.

[vlebo]

I keep all my stuff in the garage which is connected to the house via the utility room. Even though they are both pretty large scopes I still consider them grab n go as I can be outside viewing through either one in less than 10 mins and seeing as they are in an uninsulated garage they are always at near outside temp.

[saturn5]

In the garden summerhouse,no need to cool down scopes,just take them out and plonk them on the pier,ready to go in minutes.

[Vlad]

Any scope, especially Newtonians, should be kept as cool as possible. Tube currents ruin the view for up to two hours, so keep it where it is cool.

The eye sees anything as blurred that is greater than 2 arc minutes in diameter. An F/5 Newtonian has a field of view of 2.6mm diameter that is "sharp"; beyond this, the image is blurred.

An F/8 Newtonian has a "sharp" field of view that is 11.6 mm diameter, more than four times larger!

An F/10 Newtonian has a sharp field of view 22 mm diameter!!

Moral? greater F ratios are always better performers than low F ratios. The F/5's maybe convenient, but the F/8's outperform them every time.

[dark knight]

Vlad, many people use faster scopes for imaging, the faster focal ratio means shorter exposures are required, important if your alignment isn't spot on. There is no one perfect design, they all have shortcomings.

[Vlad]

All your statements are true, Can't argue with any of them. However, my article was not to propose against any one of them for any reason, but to simply point out the mathematical physics of optics. Using a camera does not relieve any of those facts. I did intend to infer that for visual use the F8 gives a sharp image over a wider field. Photographically, the actual difference in exposure times would be small, but the resulting photograph would be sharp over that field.

[Ben Ritchie]

An f/8 Newtonian is great, but not very practical in larger apertures - a 12" f/8 is huge, either needing a beefy mount or, if dob-mounted, a ladder. An 8" f/8 is fun though, I agree.

Tube currents ruin the view for up to two hours, so keep it where it is cool.

The eye sees anything as blurred that is greater than 2 arc minutes in diameter

Did you mean arcminutes? Venus at its largest is just over an arcminute across, Jupiter is 0.5-0.75 arcminutes. If you meant arcseconds, you must also remember that we're heavily seeing-limited in this country so sharpness may be rather academic on many nights.

[Vlad]

Arc minutes. This is not to say that anything greater is blurred beyond usefulness, but it does say it is not as sharp. I personally have seen Sinus meridiani probably at around 0.35 arcsec, when the planet subtended an angle of ten arcsecs, in a six inch Schmidt Cass. Cassini's division is at best around 0.6 arcseconds with the rings fullly open, and these are seen in a 75 mm aperture scope. ( re. Julius L Benton) As for the seeing in this country, my 55 years using scopes has taught me that you are absolutely right there!

My original statement about the field diameters of sharpness is slowly fading into an entirely different discussion.

Phil

[Vlad]

Very Sorry!!!!

Field diameters are given in millimetres! Not arcminutes, but an actual measurement of a diameter of the sharp field at the focal plane.

Phil