Hi all, I plan to invest in a compact astrograph to gain a wider FOV. At the moment I'm using a William Optics FLT98 with it's dedicated field flattener, the AFR-IV which gives me F5.
It'a a lot of weight hanging off the focuser with my SBIG 8300 attached & whilst I'm relatively pleased with the results I like the idea of a flatfield Petsval refractor design without the complication of spacers etc. & less flexure.
These are the two I'm interested in:
I'm aware Casstony has the 61EDPH which seems very capable, (feel free to comment Tony ). I must admit I'm drawn towards the Sky Rover though with it's slight aperture advantage.
A flat field & good colour correction are important to me. Any thoughts?. Thank in advance.
Tony
The Skyrover f/5 and the Sharpstar 61edph and WO Redcat 51 all seem like decent imaging scopes. Perhaps choose based on focal length? The Redcat gets you more differentiation from your current scope.
The Skyrover f/5 and the Sharpstar 61edph and WO Redcat 51 all seem like decent imaging scopes. Perhaps choose based on focal length? The Redcat gets you more differentiation from your current scope.
It certainly does Tony, it has the widest FOV by a good margin. It was on the short list with the other two but I was a bit worried oversampling might be an issue with the KAF8300 chip in my cam.
I'm not sure how big of a problem this is but the FLT98@F5 is already pushing the boundary apparently according to the "Nyquist theorum".
The image of M31 I posted recently was done using my Z70 & .8 FR giving it a focal length of 344mm which is almost identical to the Sky Rover specs.
& to be honest I'd be happy enough with that image scale/Fov with a better corrected Fov & colour. The smaller stars were looking a bit 'blocky" in that image even though it was binned @50%.
I guess that's why I'm leaning towards the Sky Rover, it's not too far removed from what I know is doable with my camera but I can't find much in the way of reviews.
I believe it's a newer improved version of the model that was farmed out to Meade & William Optics as the 70mm Quad Astrograph & Star 71 V2 variant.
Your input has been valuable though Tony, I'm sorry for the long winded reply but it was helpful to get this reasoning out of my head & on to paper as such.
I'm going a bit trying to make a decision on this.
Cheers,
Tony
It would be an easier decision if you buy another telescope and another camera
I'm with Tony
Sounds like you're looking for other options
When it comes to resolution, it might be worth considering a little more focal length and a larger sensor. Full frame DSLRs/mirrorless cameras are relatively inexpensive today compared to just a few years ago.
That way, you can tune both your FOV and resolution as desired...
It would be an easier decision if you buy another telescope and another camera
Quote:
Originally Posted by Camelopardalis
I'm with Tony
Sounds like you're looking for other options
When it comes to resolution, it might be worth considering a little more focal length and a larger sensor. Full frame DSLRs/mirrorless cameras are relatively inexpensive today compared to just a few years ago.
That way, you can tune both your FOV and resolution as desired...
You're both absolutely correct, my first thought was just to buy a full frame DSLR/mirrorless camera which would give me the FOV without the expense of a new scope, I'm just a bit nervous about going in that direction as I'm only just getting proficient with the CCD.
I was afraid it might be step backwards with no cooling. I'd have to say I'm impressed by the results achieved with DSLR's though & I haven't ruled that out. I'm interested in your views on that too.
Thanks for the input.
Tony
Petsval designs seem to be a great imaging design.
70mm is still a reasonable aperture for the price. 61mm is getting pretty small. F4.5 at 61mm versus F5 at 70mm should be faster with the larger aperture.
Petsval designs seem to be a great imaging design.
70mm is still a reasonable aperture for the price. 61mm is getting pretty small. F4.5 at 61mm versus F5 at 70mm should be faster with the larger aperture.
Greg.
Thanks Greg, this my thinking as well.
Cheers,
Tony
I ended up ordering this scope through AliExpress on 11/11/19 with some reservations. United Optics could not supply at the time & the AliExpress seller was offering an attractive discount. The whole experience was a disaster I'm sorry to say. The seller failed to state there was a two month wait for the item & marked it as dispatched regardless, then cancelled the shipping a fortnight later without notifying me. It was AliExpress admin who drew my attention to this (to their credit). Eventually I got a response from the seller after numerous attempts stating rather bluntly "you must wait for supply" & I certainly did. I finally received the scope on 1/1/20, yes, new years day. Initial inspection of the scope revealed a number of dust particles 'suspended' inside the tube, some quite large along with a hazy look on the inside of the rear element with numerous sleeks apparent. Not what you want to see in a new telescope. I decided to reserve my judgement until I'd tested it under the stars. The first week of January was mostly clear with good seeing at my locale, (in fact it's been crap ever since) so I was able put it through its paces. The results? Dreadful I'm afraid, significant Coma was present across the whole field of view. So, decision made , it had to be returned which was a great pity as I had high hopes for this little scope. The fit & finish was impressive but it was clearly a bad sample which has been the case for many of its re-branded brethren. As I understand it these scopes which are made by United Optics are re-branded & sold as William Optics Star 71, TS Optics Quad 71 both of which are a tweaked variant which puts the aperture at 71mm instead of 70mm, the Tecnosky 70AG & the Meade series 6000 Astrograph 70, the Meade variant seems to have been least affected by optical issues but at almost twice the price of the Sky Rover it's easy to see why I went with the native branding. So it seems as though it's a bit of a lottery with these little quads as far as quality control is concerned, which is sad because good samples of these scopes produce excellent results. The other major player in Chinese optics is Sharp Star & it seems they have the edge in QC. I ended up having to lodge a dispute through AliExpress to secure a refund due to the total lack of communication & customer service by the particular seller. My dispute was upheld by AliExpress I'm pleased to say & I'm due to see the money in my account any day now (four & a half Mths after the purchase). So in view of my experience, in future I would only buy an Instrument with this type of "extreme" optics (F5 or faster) from a retail specialist who bench tests each unit prior to sale. Thankfully there is now such a retailer in Sydney, Adriano Massatani at TESTAR , & I will be placing an order with him for the Sharp Star 76 EDPH. I hope this rather long winded follow up was worth the read. & some pics just to prove it all happened.
Clear skies,
Tony