Meade ACF v GSO R/C

mick pinner · #1 13-09-2009, 09:09 PM

simple question l hope. without going into deep technical detail that l and probably a lot of others would not understand or care about, can l ask, for astrophotography is one scope necessarily better than the other?
l know someone may bring up mirror shift in the ACF but it doesn't matter, fit a crayford, l'm not interested what accessories they have or don't have l'm only concerned with their pure designs and capabilities as imaging devices with DSLR's. thanks.

renormalised (Carl) · #2 13-09-2009, 10:30 PM

The Meades will have much flatter FoV's due to the optics employed in their design. They'll also have crisper views as they don't have the amount of central obstruction as the GSO RC's. They should also have almost the same (if not better) on and off axis stars as the RC's due to the ACF optics. To reach and/or exceed the quality of optics in the Meade telescopes you would have to buy a RC considerably better than the GSO's. That's not to say the GSO's haven't good optics...from what I can gather they do, but I can tell you from experience that the ACF optics are very, very good. If you can take images through similar sized Meade and GSO scopes and compare them, you will have a good idea of where they can be compared. Actually, I would like to own both scopes myself ( I already own an 8" ACF). Both will take excellent images using DSLR's and/or dedicated CCD cameras.

mick pinner · #3 13-09-2009, 10:33 PM

thanks Carl, very concise.

renormalised (Carl) · #4 13-09-2009, 10:39 PM

I know they're considerably more expensive than the Meades, but the new Celestron EdgeHD scopes look like they have optics of similar quality and capabilities as the Meade scopes. It would interesting to compare an 8 or 10" scope of both makes side by side to see how they measure up to one another.

dpastern (Dave Pastern) · #5 13-09-2009, 10:56 PM

From what I've read, the Meade ACFs have some field curvature and coma at edges. The Celestron EdgeHDs are better in both respects. That could be marketing hype, I'm not cluely enough to be really an expert judge.

Dave

mick pinner · #6 13-09-2009, 11:09 PM

l wouldn't buy a Celestron due to their price structure.
sticking to the original question, l'm really asking is their anything the R/C has in it's ability to give good images that the ACF hasn't?

renormalised (Carl) · #7 13-09-2009, 11:19 PM

Quote:

Originally Posted by dpastern

From what I've read, the Meade ACFs have some field curvature and coma at edges. The Celestron EdgeHDs are better in both respects. That could be marketing hype, I'm not cluely enough to be really an expert judge.

Dave

I haven't noticed any coma in my ACF at all, actually. There is some field curvature but it's not noticeable unless you take piccies covering the max possible FoV. I haven't experienced the new Celestron scopes to make a comparison.

renormalised (Carl) · #8 13-09-2009, 11:20 PM

Quote:

Originally Posted by mick pinner

l wouldn't buy a Celestron due to their price structure.
sticking to the original question, l'm really asking is their anything the R/C has in it's ability to give good images that the ACF hasn't?

In plain language....no.

rat156 · #9 14-09-2009, 09:28 AM

Hi Mick,

Actually there are two main differences. Firstly the Meades are available in sizes over 8", the GSO RC aren't yet available in sizes above 8". The 10" is due out soon (but has been delayed). I wouldn't expect a 12" version for a while. The GSO RC's are f/8 rather than f/10, which is either good or bad depending on what you're looking at. Judging from my (very limited) experience with the GSO (and the raging debate over the f-ratio myth) I'm not sure that either is going to be better than the other. I've not go real experience with the ACF scopes, but I do have an RCX, which I believe have similar optics.

The Meade has a corrector plate which some say is not good for a variety of reasons. The GSO has an average focuser, but no mirror flop. The GSO is cheaper.

Hope some of this helps.

Cheers
Stuart

mick pinner · #10 14-09-2009, 09:58 AM

thanks Stuart but these are all physical differences which seem to become a talking point for some people but l am more interested in pure imaging ability, as l said before mirror flop can be fixed with a crayford and the f/ratio is only a mount consideration anyway not really a scope issue.

dannat (Daniel) · #11 14-09-2009, 10:15 AM

cool down will be quicker with the gso won't it

rat156 · #12 14-09-2009, 10:45 AM

Quote:

Originally Posted by mick pinner

thanks Stuart but these are all physical differences which seem to become a talking point for some people but l am more interested in pure imaging ability, as l said before mirror flop can be fixed with a crayford and the f/ratio is only a mount consideration anyway not really a scope issue.

F-ratio is also a FOV issue for imaging. The GSO's don't have a dedicated focal reducer to increase the FOV. There are several that work with the Meade. The focuser really needs upgrading on the GSO for heavy loads, and that detracts from it as an imaging scope. The ACFs should be better planetary scopes due to the smaller central obstruction (debatable). All these little things that require attention nightly are the things that will annoy you and detract from the imaging pleasure.

Cheers
Stuart

mick pinner · #13 14-09-2009, 10:52 AM

you just wait a little longer with the ACF Daniel.
but FOV is also a mechanical issue Stuart, the end result is what l'm after (images) l don't care what it takes to get there. it boils down to all things being equal, if both have good focusers, same temp blah blah, would one be any better than the other.

rat156 · #14 14-09-2009, 11:20 AM

Quote:

Originally Posted by mick pinner

you just wait a little longer with the ACF Daniel.
but FOV is also a mechanical issue Stuart, the end result is what l'm after (images) l don't care what it takes to get there. it boils down to all things being equal, if both have good focusers, same temp blah blah, would one be any better than the other.

Really depends on what you mean as better and what you're taking photos of? Will one take noticeably better images? Depends much more on the skill of the photographer and the mount. Seeing also plays a huge part as to the quality of the photograph. Quality is measured here by sharpness and lack of artifacts.

So in answer to your question neither is better than the other, so other factors would have to decide between the two.

Take my recent decision as an example.

I've finally decided that the RCX, even though it's a great scope, is let down by the fork mount. So when a G11 came up here I bought it. Now I have to decide if I want to defork the RCX (not easy) or sell it and buy two scopes, the GSO 8" and a planetary scope (12" or better ACF/LX200 OTA (I too won't buy a Celestron because of the pricing)). So I decided that one would be better for deepsky one for planetary.

Cheers
Stuart

mick pinner · #15 14-09-2009, 12:28 PM

thanks Stuart.

Benny L (Ben) · #16 14-09-2009, 01:12 PM

I'm very happy with my 14" LX200R (The pre-legal dispute predecessor to the ACF's) with a STL-11K on the back the field is very flat except right at the edge of the sensor, in the corners.. There is a mirror flop issue but i have locked the mirror and put the shipping screw back in and that has solved it along with a motorized focuser

gregbradley · #17 14-09-2009, 01:44 PM

I thought there were quality control issues with the GSO like faulty
focusers, some reflections troubles. Perhaps these have been rectified.
Also I was told bu Bintel the Chinese company that makes them asked them how do you collimate an RC? Whhhaaatttt??!!

There are no known issues with the Meade that I have heard of.

There is a free Wodaski CCD calculator which is a handy tool when making up ones mind about scopes.

It will show what the same image will look like with different scope/cameras (image scale ie size of the object being imaged in different scope/camera combos).

That way you can decide yes that is the type of image scale I want to achieve and also match your camera/pixel size to the optics that best match your seeing.

But the short answer would be for a DSLR say, the F8 will give slightly wider field images than the F10 Meade.

As far as a reducer goes there is a good chance an AP 67 reducer will fit the GSO and work as it was common on RCOS scopes.

Anotehr aspect to consider are the little bits and pieces that make a scope good to work with or not. Cooldown time, mirror flop, strength of focuser, baffling, flocking of the interior, sharpness of the optics,weight, length of tube, dew prevention, cleanliness of the optics (RCs can get a bit dirty), ease of collimation, ability to hold collimation, quality control of the manufacturer, lead time for delivery, after sales service.

To some degree it comes down to confidence in the manufacturers ability to produce a quality product. Meade I think have an excellent reputation for OTAs. GSO is new kid on the block and there have been some problems although some have fixed them and some have gotten into trouble fixing them. Still an RC for such a low price with a carbon fibre tube is a lot of scope.

I'd personally go for the ACF.

As far as Celestron go, so far its all talk and no images or results proven to back up the hype and with the silly pricing - well, they are not even trying are they? And during an economic downturn - somebody wants to lose money.

If you want help deciding look at Fred's awesome ACF 12 inch images of which one made NASA picture of the day. I doubt very much there'll be a NASA picture of the day from a GSO any time soon.

Greg.

renormalised (Carl) · #18 14-09-2009, 05:06 PM

I've been a little disturbed at the recent optical and build quality of the GSO's of late. It seems there's been quite a few scopes come out here that aren't worth even worrying about. Yet I've seen examples of how good they can be. It seems to be a luck of the draw as to whether you get a good or bad one. On that basis, I would steer clear of them.