Minimum Aperture Rule

[Stu]

Well here's a confession. Never seen M1 in over ten years of observing. Maybe I'll fix that this weekend at PSP

Stu

[Beulah]

Well here's a confession. Never seen M1 in over ten years of observing. Maybe I'll fix that this weekend at PSP

Stu

Too much choice, that's why.

[RikM]

I have only just made it out once or twice with my 6".

[MjrTom]

Well here's a confession. Never seen M1 in over ten years of observing. Maybe I'll fix that this weekend at PSP

Stu

Its one I have always struggled to see as well with my kit

[Moonshane]

I think these sort of comments are really referring to the difference between 'detecting' and 'seeing detail'. as others have said, you can detect many objects naked eye and with small apertures. some objects look best with a wide field/small aperture/low magnification. others you really need aperture or high magnification.

yes, for visual you often need more than one scope!

[bish]

Quite right. M31, M42, M45, M44, the double cluster, some clusters in Auriga etc can be seen with the naked eye. I've seen loads with my 50mm bins, but would still wouldn't mind a 40" scope at my disposal.

[JamesM]

Sabana, it very much depends on what you mean by, "....just be as successful with a 3". There is a difference in seeing an object and therefore recognising what it is, than actually being able to secure enough resolution through increased aperture to be able to look and examine detail within the object. I agree with Ben that a 'trained' eye is often overlooked and it does take a little observational experience to be able to tease out that extra detail. In a discussion such as this, it also depends on what kind of object you are observing. Stars can't be resolved so aperture here is of less importance as is probably viewing the moon given that there will be plenty of light to secure a fair amount of detail and where focal length for refractors will be more important in its ability to contain problems associated with chromatic aberration. That leaves deep sky objects such as galaxies and nebula where the laws of physics that are played out through aperture do make a real difference, and I am sure a lot of us have had the opportunity to witness its effects. On these targets I do subscribe to the view (no pun intended) that 8" provides really good views and 12" and beyond allows you to go deeper. That is not to say that you can't see these objects in anything smaller but that something larger my afford you the opportunity to look at it for longer. I would add, that as a refractor person, the lack of any central obstruction does assist in an increase in sharpness that helps bend the above rule on aperture and resolution just a little bit.

James

James

[umadog]

"I think these sort of comments are really referring to the difference between 'detecting' and 'seeing detail'"

+1 Exactly.

[MjrTom]

Quite right. M31, M42, M45, M44, the double cluster, some clusters in Auriga etc can be seen with the naked eye. I've seen loads with my 50mm bins, but would still wouldn't mind a 40" scope at my disposal.

Sorry I should have added that I was referring to under suburban sky of my back garden.

The extra two magnitudes of light grasp that the small bins offers allow me to pick these objects out.

From a dark site it's a completely different matter