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Looking for advice (refractor-wise)

ZWO ASI183MC Equipment Refractors Buying Advice
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Which one of these two (2) refractors would you recommend for a newbie like me and why?
Single choice poll 4 votes
75% (3 votes)
25% (1 vote)
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Miska Saarikko avatar
Miska Saarikko avatar
Hi guys!

Since my budget is limited and I don't want to waste more money than necessary on this hobby at the current state I'm asking for your response and recommendations. I wish I could spend more money on a refractor, but because I need to get a new OSC with a bigger sensor and a filter I can't just throw money on everything I see.

Wondering if either of these telescopes would work with ASI183MC-C Pro or should I consider some other telescopes instead in the same price range.

I'm aware that I would need a reducer/flattener for either or of these two and I have count them in into the budget already.

Filter-wise I'm thinking about getting the Antlia Triband RGB Ultra 2", since this one works with both OSC and mono.

TIA!
Mark Germani avatar
Mark Germani avatar
Hi Miska!

For clarification, have you settled on the ASI183MC Pro for certain? I have heard only good things about the ASI533MC Pro, and it doesn't have amp-glow. It does have a square sensor, though, which some find off-putting. The 183 at 560-600mm would be appropriate, pixel-scale wise, assuming you had really good seeing, and excellent guiding (what mount will you be using?) Also, it is my understanding that a small pixel size is less sensitive to light, and at f/7-7.5 you could use the sensitivity. Full disclosure: I don't own either of these cameras, but I have researched them both and settled on the ASI533MC. The ASI2600MC offers the more traditional rectangular sensor, but is much more expensive.

In terms of the telescopes, I'll let other folks who have experience with those particular models weigh-in, but looking at your gallery I see that your Andromeda (nice!) uses 90-second exposures with your f/4.9 Redcat. Just doing some quick math, but to get the same amount of light from an f/7.5 OTA you'd need 210s exposures (assuming the ASI183MC had the same sensitivity as your Nikon) and with really small pixels your guiding and focus would need to be pretty good.

If you're willing to sacrifice a bit of reach, I've seen really great results with the Askar FRA400, which has the flattener built-in, saving you a bit of money. It looks like it's about the same price as the Sky-Watcher, maybe less if you consider you wouldn't need to purchase a flattener. Aperture is 72mm instead of the 80mm you are looking at in the models you're considering, and focal length is 400mm instead of 560-600mm, so I can understand why it might not be as attractive an option, but it might be more forgiving of guiding and generous with photons. The FRA400 has an optional reducer which brings the focal ratio down to f/3.9 which is pretty fast and might work better with the ASI183 if that's still your camera of choice.

Anyway, I hope my response isn't too discouraging. I wish you the best of luck with your new setup!

CS,
Mark
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Mark Germani avatar
Mark Germani avatar
Oh, and Antlia says the Triband works well down to f/2 so it should be fine with the FRA400 with the reducer, if that's something you might consider. Filters like the Antlia require MUCH longer exposure lengths, so this too would require good tracking/guiding. Something to think about smile
Joe Linington avatar
Joe Linington avatar
The 183 seems purpose built for fast and wide scopes. It's tiny pixels are often smaller than the scopes can provide which isn't necessarily a bad thing but in my opinion not optimal. It also has a pretty small FOV pushing small scopes to the limit. In my opinion, the FRA400 is a closer match while still technically over sampling the scopes capability and a better scope over all (triplet) for just a bit more. As a bonus you can get the 0.7 reducer (later when money permits) and have a very fast f/3.9 scope at 280mm focal length. This big of a reducer turns it into 2 different scopes. A very flexible and good quality setup for the money. A scope like this will also pair well with a much larger sensor and last for many years to come.

Full disclosure, I shoot with the Sharpstar 76EDPH which is from the same company and short of Takahashi FSQ-106EDX landing in my lap, I'm never selling it. A fantastic scope. If the FRA400 was around when I got the 76 I likely would have gone that way.
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