centroid
20-09-2008, 02:27 AM
I had been looking to ugrade my Skywatcher ED80 (600mm FL and f/7.5), with something a little 'faster', and a wider field of view (FOV).
The William Optics Megrez 88 (f/5.6), seemed to meet these requirements very nicely.
Fortunately, I was loaned one to try, and to cut a long story short, although the scope beautifully built and finished, being a'doublet' it showed an unacceptable level of chromatic aberation (CA) (colour fringing) in my images. So I had to look elsewhere.
It seemed that the only real way of eliminating this, was to look at 'triplet' refractors. However. 'triplet' is usually another word for high cost :(, and I really didn't want to spend TMB sort of money.
I found a review on the Cloudy Nights forum, on the Meade Series 5000 triplet APO, and this read very well indeed. After a bit more research, I decide to 'bite the bullet', and buy one. At £449 (around $Au 990), it seemed very reasonably priced for 'triplet', but not having had the opportunity to 'test drive' one, I have to admit to being a little apprehensive.
So, here is a mini review of my assessment:
The Meade Series 5000 80mm APO, is a three element (triplet) with a focal length of 480mm, and at f/6, is quite 'fast'.
Opening the packaging, revealed a very nice aluminium 'flight case', a 'nice touch'.
Inside, the scope was very securely enclosed in a custom cut foam rubber surround, that would clearly offer a great deal of protection during any rough handling of the case, e.g. airport baggage handlers.:(
The overall finish of the scope was far better than I was expecting really, given the price, and the fact it had triplet optics. The finish quality is very much superior to my Skywatcher ED80, but perhaps not quite as good as the William Optics Megrez 88.
Unlike the Megrez, the Meade only has a single speed Crayford style focuser. However, I really don't see this as an issue, as I've never found focusing the ED80 to be anything other than easy.
While similar to the ED80's focuser, the Meade does seem to be of a higher quality, and is both smooth and positive in its action, with no backlash or lateral movement. It was able to take the weight of my SXVF-H9C camera, without the drawtube 'creeping out', with the friction adjustment set, where the foucuser still moved smoothly, and easily when adjusted.
The dew shield retracts, sliding smoothly back over the OTA, thus reducing the overall length of the scope to just 380mm (ED80 fixed at 580mm).
A very pleasing point, is that the 'L' bracket for tripod mounting, is held on with single 'hex-head' bolt, which means that the bracket can be removed from the OTA, when mounting the scope in 'guide rings', as I intend to do.
The 'L' bracket is attached to a rotating ring, which enable the scope to be rotated through 360 degrees. There is a thumbscrew, which allows the ring to be locked in psoition.
Another real plus point, where the Meade scores over both the ED80 and the Megrez, is that the drawtube extends by some 120mm, compared to 80mm on the Megrez and 75mm on the ED80.
This should enable focus to be achieved without the need of an extension tube. For those who perhaps don't follow this, many refractors are primarily designed for visual observing, where a star diagonal would be used for comfortable viewing. For imaging, the diagonal is not generally used, and as a result, with the diagonal not there, the length of the focuser is effectively reduced, and there isn't then enough back-travel available to compensate.
Oh yes, another bonus point, is that the Meade comes supplied with the Meade Series 5000 2" diagonal. This is one that I know, as my 12" LX200R also came with one, and I've been quite impressed with it.
Although far from ideal, with an almost full Moon around, last night I was presented with a clear sky, and was keen give this scope 'its 'first light'.
As soon as the sky was dark enough, it was a race to get some DSO test imaging done, before the Moon appeared above the Eastern horizon.
It was evident that the Moon's appearance wasn't far off, from the sky glow on the eastern horizon, but at least the Moon itself wasn't visible.
I attached an eyepiece and pointed the scope at Altair, and was pleased to see that at focus, or either side of it, there wasn't any evidence of colour fringing at all.
Having read the review on the Meade 127 APO in the latest issue of Sky at Night magazine, where the reviewer commented that the Spherical Aberation performance of the Meade, wasn't was quite as good as that of Skywatcher Eqinox 120, I looked specifically at this parameter, but could not see any evidence of this at all in the 80mm variant.
At focus the stars were 'pin sharp', and the contrast very good indeed. A good start!!
Knowing that very soon, the Moon was going the be a problem for DSO imaging, I didn't dwell too long on the visual assessment.
A quick look to see what was available, best placed, and not requiring lengthy exposures, as the sky wasn't really dark enough.
So, I chose M27 to be the 'first light' object, for the new scope.
I wanted to try the scope at its natural focal length (480mm) and f ratio (f/6), so the SXVF-H9C was attached directly to the draw-tube, with just an IR blocking filter in place, as this is how the camera is always used.
I used the Lodestar and the 12" LX200R (at f/7), to guide the Meade APO, and captured 17x180 sec subs of M27.
Given the rapidly rising Moon, and the resulting sky, the end result is quite pleasing, and is attached below.
By now, the Moon was well clear of the horizon, and M31 'sitting' not that far above it. However, as I had used M31, and it's surrounding stars, in my assessment of the William Optics Megrez 88, I wanted to compare the Meade APO result with it.
I was a bit concerned at what the result would be like, as the the sky in that area, was now bathed in moonlight. However, as can be seen the the result below, the end result was better than expected. Clearly, a lot of the fine detail has been lost in the 'sky glow', but the object of the excercise was achieved, showing nice clean, colour fringing free stars.
Finally, before 'calling it a night', I put an eyepiece back in the Meade APO, and pointed in at the Moon, thinking if there are any chromatic aberation issues, then this would most certainly show them. To my relief and pleasure, the image was crisp and clear, without a trace of colour fringing. Needless to say, I went off to bed, a very 'happy bunny'.:)
If I had to make a negative comment on the Meade APO, then it would be that while very 'posh', the dew cap screws into the dew-shield, and is not as quick and easy to 'whip' on and off, as with the 'push fit' design.
I would also point out, that while being quite a small compact scope, it is quite heavy, due to the extra glass of the 'triplet' optics.
So, for price (£449), an 80mm triplet that performs this well, represents good value for money in 'my book', and I'm very happy to have it in my observatory.
I now have now achieved what I set out to do. Which was, to obtain a scope the would provide a bigger FOV, and be a bit 'faster' than my SW ED80, while retaining the colour fringing free results of the ED80.:)
Attached are the two test images, one of M27 and the other M31.
This is my first 'real post' on this forum, as a new member, so I hope it is as expected, and of interest to at least some.
Dave
The William Optics Megrez 88 (f/5.6), seemed to meet these requirements very nicely.
Fortunately, I was loaned one to try, and to cut a long story short, although the scope beautifully built and finished, being a'doublet' it showed an unacceptable level of chromatic aberation (CA) (colour fringing) in my images. So I had to look elsewhere.
It seemed that the only real way of eliminating this, was to look at 'triplet' refractors. However. 'triplet' is usually another word for high cost :(, and I really didn't want to spend TMB sort of money.
I found a review on the Cloudy Nights forum, on the Meade Series 5000 triplet APO, and this read very well indeed. After a bit more research, I decide to 'bite the bullet', and buy one. At £449 (around $Au 990), it seemed very reasonably priced for 'triplet', but not having had the opportunity to 'test drive' one, I have to admit to being a little apprehensive.
So, here is a mini review of my assessment:
The Meade Series 5000 80mm APO, is a three element (triplet) with a focal length of 480mm, and at f/6, is quite 'fast'.
Opening the packaging, revealed a very nice aluminium 'flight case', a 'nice touch'.
Inside, the scope was very securely enclosed in a custom cut foam rubber surround, that would clearly offer a great deal of protection during any rough handling of the case, e.g. airport baggage handlers.:(
The overall finish of the scope was far better than I was expecting really, given the price, and the fact it had triplet optics. The finish quality is very much superior to my Skywatcher ED80, but perhaps not quite as good as the William Optics Megrez 88.
Unlike the Megrez, the Meade only has a single speed Crayford style focuser. However, I really don't see this as an issue, as I've never found focusing the ED80 to be anything other than easy.
While similar to the ED80's focuser, the Meade does seem to be of a higher quality, and is both smooth and positive in its action, with no backlash or lateral movement. It was able to take the weight of my SXVF-H9C camera, without the drawtube 'creeping out', with the friction adjustment set, where the foucuser still moved smoothly, and easily when adjusted.
The dew shield retracts, sliding smoothly back over the OTA, thus reducing the overall length of the scope to just 380mm (ED80 fixed at 580mm).
A very pleasing point, is that the 'L' bracket for tripod mounting, is held on with single 'hex-head' bolt, which means that the bracket can be removed from the OTA, when mounting the scope in 'guide rings', as I intend to do.
The 'L' bracket is attached to a rotating ring, which enable the scope to be rotated through 360 degrees. There is a thumbscrew, which allows the ring to be locked in psoition.
Another real plus point, where the Meade scores over both the ED80 and the Megrez, is that the drawtube extends by some 120mm, compared to 80mm on the Megrez and 75mm on the ED80.
This should enable focus to be achieved without the need of an extension tube. For those who perhaps don't follow this, many refractors are primarily designed for visual observing, where a star diagonal would be used for comfortable viewing. For imaging, the diagonal is not generally used, and as a result, with the diagonal not there, the length of the focuser is effectively reduced, and there isn't then enough back-travel available to compensate.
Oh yes, another bonus point, is that the Meade comes supplied with the Meade Series 5000 2" diagonal. This is one that I know, as my 12" LX200R also came with one, and I've been quite impressed with it.
Although far from ideal, with an almost full Moon around, last night I was presented with a clear sky, and was keen give this scope 'its 'first light'.
As soon as the sky was dark enough, it was a race to get some DSO test imaging done, before the Moon appeared above the Eastern horizon.
It was evident that the Moon's appearance wasn't far off, from the sky glow on the eastern horizon, but at least the Moon itself wasn't visible.
I attached an eyepiece and pointed the scope at Altair, and was pleased to see that at focus, or either side of it, there wasn't any evidence of colour fringing at all.
Having read the review on the Meade 127 APO in the latest issue of Sky at Night magazine, where the reviewer commented that the Spherical Aberation performance of the Meade, wasn't was quite as good as that of Skywatcher Eqinox 120, I looked specifically at this parameter, but could not see any evidence of this at all in the 80mm variant.
At focus the stars were 'pin sharp', and the contrast very good indeed. A good start!!
Knowing that very soon, the Moon was going the be a problem for DSO imaging, I didn't dwell too long on the visual assessment.
A quick look to see what was available, best placed, and not requiring lengthy exposures, as the sky wasn't really dark enough.
So, I chose M27 to be the 'first light' object, for the new scope.
I wanted to try the scope at its natural focal length (480mm) and f ratio (f/6), so the SXVF-H9C was attached directly to the draw-tube, with just an IR blocking filter in place, as this is how the camera is always used.
I used the Lodestar and the 12" LX200R (at f/7), to guide the Meade APO, and captured 17x180 sec subs of M27.
Given the rapidly rising Moon, and the resulting sky, the end result is quite pleasing, and is attached below.
By now, the Moon was well clear of the horizon, and M31 'sitting' not that far above it. However, as I had used M31, and it's surrounding stars, in my assessment of the William Optics Megrez 88, I wanted to compare the Meade APO result with it.
I was a bit concerned at what the result would be like, as the the sky in that area, was now bathed in moonlight. However, as can be seen the the result below, the end result was better than expected. Clearly, a lot of the fine detail has been lost in the 'sky glow', but the object of the excercise was achieved, showing nice clean, colour fringing free stars.
Finally, before 'calling it a night', I put an eyepiece back in the Meade APO, and pointed in at the Moon, thinking if there are any chromatic aberation issues, then this would most certainly show them. To my relief and pleasure, the image was crisp and clear, without a trace of colour fringing. Needless to say, I went off to bed, a very 'happy bunny'.:)
If I had to make a negative comment on the Meade APO, then it would be that while very 'posh', the dew cap screws into the dew-shield, and is not as quick and easy to 'whip' on and off, as with the 'push fit' design.
I would also point out, that while being quite a small compact scope, it is quite heavy, due to the extra glass of the 'triplet' optics.
So, for price (£449), an 80mm triplet that performs this well, represents good value for money in 'my book', and I'm very happy to have it in my observatory.
I now have now achieved what I set out to do. Which was, to obtain a scope the would provide a bigger FOV, and be a bit 'faster' than my SW ED80, while retaining the colour fringing free results of the ED80.:)
Attached are the two test images, one of M27 and the other M31.
This is my first 'real post' on this forum, as a new member, so I hope it is as expected, and of interest to at least some.
Dave