aperture fever for visual observation

[ETX Astro]

How much of an improvement is there for visual observation if you doubled the light gathering capability of a scope, is it just detectable or much better or blow your mind

[GrahamL]

hi

Do you mean double the aperture you have now ?. as I believe doing that would gather more than double the light .

[ETX Astro]

No, doubling the aperture gives you 4 times the light gathering capability of a scope approximately
90mm to 127mm gives you 2 times the light gathering capability of a scope approximately

[wavelandscott]

There is a mathmatical formula that will give you the answer...doubling the size will get you much more than double the light.

On the Obsession telescope website they do some comparisons froma visual perspective...might give you a better idea of the differences.

[ETX Astro]

I could not find it on Obsession telescope website

[marki]

http://www.obsessiontelescopes.com/m13/index.html

Cheers Mark

[GrahamL]

I jumped from a 10" to 12" scope and had a little time to compare the two before the 10 " got moved on , the modest jump in aperture was
definately noticable at the eyepiece , I remember well looking at
ngc 2070 over two nights and noteing much more detail in the 12".This did surprise me a bit as reading some of the info online you get the impression the differance is quite small .My change was souly about makeing my own scope so the dollar outlay wasn't figured into it . I think this is were you'd have a good look at what you get back imo .. is that improvement worth shelling out cash at least the same as you have already spent?..Looking at both of factors these I'd go with more aperture
everytime unless portability is a major concern.

cheers graham

[wavelandscott]

Thanks, that is the one I was thinking of...

[Starkler]

If your ETX is a 125, then a 150mm scope will show a noticeable improvement, and a 300mm scope will 'blow your mind' ;)

My first view through an 18incher changed my perspective forever on what I expected a scope to deliver for me.
Aperture fever can be very expensive, but moving from an etx to say, a 10 or 12inch dob could satiate that and leave you with money in your pocket considering the premium you are paying for tracking and portability with an etx.

[Kevnool]

Remember also that the image scale gets larger as well, Oh yes aperture fever is a fantastic feeling....cheers Kev.

[Quark]

Bigger is always better, the only proviso's I would put on that are;

1) A reasonable understanding of collimation.
2) A decent set of collimation tools at hand.

If you have 1) & 2) then you will achieve 3)

3) = Observing Bliss.

Regards
Trevor

[ETX Astro]

At the moment I have an ETX90EC and I was looking at getting some accessories or selling it and getting an used ETX125EC I still don't know which way to go but leaning towards ETX125PC

[Rodstar]

Aperture definitely rules, just wander around an observing field and take in the views through various scope sizes. The differences quickly become apparent.

In one sense, it is all relative...I am sure my 20 inch scope pales next to a 30 inch. Simple fact though is the larger the aperture the deeper you can go. More aperture can multiple many times the range of objects which become observable, a bit like jumping on a plane and discovering other countries exist.

[AstroJunk]

It's a really tough call. I owned an etx 125 and it was a nice scope, but ultimately let down by the rigidity of the mount. I think the etx 90 is a better scope for that reason. Trouble is that you want more light - don't we all, and that means a number of other factors come in to play - the main one being budget, rapidly followed by portability.

Rather than give suggestions, I am going to recommend that you come along to the IYA event at the Sir Thomas Brisbane Planetarium on the 4th of April and meet a truck load of local Astro club members and all of their scopes.

Don't talk to me though, I have a bad habit of talking people into selling their house/car/loved one to buy something BIG from the SDM stable!

[White Rabbit]

I started out with a ETX125PE and I now have an 8"newt on an HEQ5pro mount (I also have a 12" light bridge). I should have went that route in the first place. For start, I paid less for my 8" and mount than I did for ETX125, and I bought all of them brand new.

My advise would be to get as far away from the ETX series as your pocket will allow. The optics are really good but the mechanics are a disgrace.

With the ETX I can see the tarantula nebula as a very fairt wispy cloud, I and have to use averted vision to make any detail out, but on the 8 I can stare right at it and make out the arms and lots more detail. With the orion neb you can see more of the dust and gas extending out of the nebula, through the 12" it's mind blowing. I'd love to see the orion through an 18/24" scope. The difference is very noticable. If you double the aparture of the ETX90 that would take you to an 8", and you'll be as happy as pig in #@$%.

Think big,

Sandy

[Screwdriverone]

Here is a comparison for you, (taken with the SAME camera and the SAME barlow) but the first is with the 5 inch SW135 and the second with the 12" SW collapsible dob. (also the amount of frames stacked is different)

I know aperture is more than double the size, but you get the idea.

Cheers

Chris

[Quark]

Not sure whether the jump from 90mm to 127mm qualifies as Aperture Fever, possibly a very slight increase in temperature but definetly not in the Fever range;)

Regards
Trevor

[Roger Davis]

Once you've looked through a 27" ... hmmm ... back to the 13.25".
Think of it as surface area a = pi*r^2 you can allow for the secondary size as well.
After the ETX90 go to an 8", it's worth it.

[Robh]

A magnitude 8 star is about 2.5 times as bright as a magnitude 9 star, a magnitude 9 star is about 2.5 times as bright as a magnitude 10 star etc.
So if your telescope aperture increases in area by 2.5 you will see a magnitude fainter. The following list compares aperture size and the estimated limiting magnitude in an outer-urban area affected by skyglow.
2.4 inch, Vmag 10
4 inch, Vmag 11
6 inch, Vmag 12
10 inch, Vmag 13
16 inch, Vmag 14
In each case the aperture size has increased in area by roughly 2.5.

[Satchmo]

I think focal length is a more important factor for me, in deciding how big I want to go.. As a casual observer, I find that 2 meters ( 80 inch ) focal length is about as long as I like before my favorite objects are getting too big or not framed with some sky around as I'd like.There is also the issue of how many steps you are comfortable to have to climb up and down.

Again 80" seems much less tiresome than even 100", often a single step onto a crate all thats needed near the zenith. Not long ago this meant 18" F4.5 scope being the most common available that fulfill my desires at Star Parties.

Expect to see more 24" F3.5 and even f3.3 scopes around as demand and optician skills increase and people opt to retain wider fields and keep their feet on the ground for as much of the sky as possible.

Mark

[GrampianStars]

& 4
Really DARK Sky ;)

[tnott]

I have an ETX 125 and it is great for the moon, planets, double stars, and the brightest DSOs. The earlier tripods with the aluminium legs were flimsy but the ones with the steel tube legs are very solid. Yes, it has plastic gears (the main cog and worm drive are metal) but so do the big SCTs!

Sometimes they have problems (eg. grease on the clutch plates) that are easy to fix if you look on the net. With a focal length of 1900 mm the field of view is a little narrow for wide field viewing (got some binos?).

If you are into Deep Sky observing then I would recommend 8 inches plus (my 10 inch truss dob takes up less room in the car than the ETX in it's case plus tripod). But, the difference in going from the ETX 90 would be noticeable. I noticed a substanial difference on all objects in going from a 16" to a 22" scope recently, which is about double the light collection.