Prism

I have an 8" SCT and recently got an ED 102mm refractor. I 100% agree with the comment above from vlaiv (focus on optimising your view first by viewing when the planets are high in the sky with nights of good seeing + checking your collimation , thermals etc.). I had many of the same issues with the refractor as with the SCT (the major benefit being quick cool down and being relatively lightweight), Mars even at its closest on Oct 6th was still pretty tiny even at 250x (which is what the refractor was maxing out at), with very little visible detail.

mikeDnight I managed to get both scopes on hand and will post a brief comparative review of them shortly (with a few photos). First impressions are that the triplet has slightly better control of CA but the doublet is brighter and has more contrast, likely owing to the superior glass! CA on the doublet is definitely visible even without imaging, but is relatively mild and drastically less than my achromat. Most surprisingly, while I was certainly expecting a difference in cool down time, the effect is even more pronounced than I expected with the doublet literally ready for use right out a warm room vs 30-40 minutes with the triplet.

Adam have you have a chance to compare them side-by-side? I'm aware of the additional cool down time of a triplet as well as the superiority of the Kunming focusers vs the ES, but I'm strictly interested in which has the better visuals. The ES having ED glass and being a triplet should be (at least slightly) better than a doublet, albeit one with better glass, no?

For a retailer to try and sell a return as new at full price would be very dishonest. Most are transparent and let customers know if a customer has returned something before selling it - they usually call these "open box" items and sell them at a discount (great way to get a scope at a good price).

As a business owner I can tell you with full certainty that ALL retailers get a certain % of their sales returned to them - that's the nature of the business of being a retailer, they specifically plan and budget for this kind of thing. In a situation like the present (where the stores are shut and we can't test equipment out in person), it is unfair to expect customers to pay ££££'s for this sort of equipment and not allow us to test stuff out. My wife and I recently bought a used car and the company allowed us to test drive it for 7 days with a full return policy! With exception of certain conditions (such as when an item is faulty), a customer really doesn't have an obligation to inform the retailer as to why they are returning the item (could be personal financial reasons). There should to be reasonable allowances for someone to open up a box and test the optics of a scope without damaging it for instance. Plenty of good retailers (we all know who they are) have 30 day back guarantees, and that is why they will always get the lions share of my business.

Hello friends, Back with a topic that never seems to never really get resolved! I am trying to gauge the better choice between the following FCD1 triplet and these similarly priced FPL53 doublets: a) Explorer Scientific ED 102mm F/7 FCD1 Triplet (currently retailing for around £900), vs b) Any of the Kunming ED 102 F/7 FPL53 Doublet variants (such as the Altair Starwave 102ED-R FPL53 or the TS-Optics Doublet SD Apo 102) (all also currently retailing for around £900) All other factors aside (such as price, cool down time, quality of the focuser, included accessories etc.), which has the superior optics for viewing and photo use – the ES FCD1 Triplet or the Kunming FPL53 Doublet? Has anyone here on SGL had the opportunity to directly A/B test them side-by-side? And if so, do you have any photographic evidence you could share? I’ve searched the forums as well as Astrobin, but have never found a satisfactory answer to this, and due to COVID (as well as the unfortunate lack of an adequate returns policy from many retailers), I am unable to test these out in the flesh. I’m a numbers guy, so looking for solid evidence or any data that can prove the superiority of one over the other. Any specialists in optics out there that care to chime in? The closest I’ve come to an answer is in this link that someone on the forums posted: https://www.telescope-optics.net/polychromatic_psf.htm The charts in this document seem to suggest the triplet is the better option, but I know there are a lot of variables including build quality / QC etc that come into play, hence why I am asking about these specific scopes as opposed to triplets and doublets in general. Some background: Like many, I’m in the market for an affordable (<£1,000) semi-APO refractor for some casual observing. I plan to use this primarily for visual use (save for the odd shot of the moon taken from my smartphone with a suitable adapter) – mostly lunar and planetary viewing to be specific, from my balcony in (light polluted) central London. I already have a larger, rather heavy SCT on an EQ mount gathering dust in the basement, and I’m looking to simply my rig by switching over to a relatively light 4-inch refractor on a solid AZ mount. This size was chosen for being small / easily manoeuvrable, allowing adequate magnification for my needs (I have achieved a crisp 250x on similar sized ED scopes with good seeing), as well as for having the maximum aperture that I can afford at this time (i.e. that the Mrs will allow). As far as the mount is concerned, I’ll be using it with the TS Optics AZ5 (Skytee 2 clone) on vibration pads, with upgraded ADM saddles and a heavy-duty Skywatcher 1.75” steel tripod (borrowed from my EQ mount), on which it will be mounted weight-balanced with the top slot for the Telrad. The scope will be used with my Nagler 3-6mm and Pentax 8-24mm zoom eyepieces. I should mention that I briefly owned a cheap Celestron refractor that I bought on impulse, wrongly believing that I could improve it by using a quality diagonal and eyepieces. Unfortunately, the CA was unbearable (the purple fringe was wide enough to severely compromise planetary viewing) and expensive eyepieces made no discernible improvement, forcing me to return it. Lesson learned: your rig is only as good as the weakest link in the optical chain. Apologies for the long post, but I’m trying to avoid the usual, “I haven’t tried them both, but they both seem like great scopes…” type responses. All the best, Al

Shaun_Astro I'm in the same boat, it's an unfortunate mix of high demand due to people being stuck at home and short supply due to factory shutdowns in China. Add to this the fact that most astro shops in the UK are closed / online only right now and it is making sourcing equipment a right pain in the posterior! I've been ordering equipment from a variety of sources over the past few months as I can't get it all in one place. Always call / email them first to check stock as their websites tend to have originated in the 18th century and so aren't frequently updated. I see quite a few people have good suggestions here and I can vouch for them all (Widescreen-centre has been good to deal with with good communication and fast shipping, albeit a bit pricier than some). Likewise I've had good experiences with 365-Astronomy (the owner Zoltan is very helpful), Teleskop-Service in Germany, Microglobe here in London and finally FLO (always a great experience, but perennially sold out of most of the things I want these days). Also been in frequent contact with Rother Valley and Harrison (they're quick to answer emails and helpful but their lack of an adequate returns policy keeps my business at bay from them). One thing I don't understand is why some of these retailers don't allow returns - I sent Harrison Telescopes an email today asking if I would be allowed to return a telescope if I didn't find it acceptable. They replied saying they couldn't operate that way as they would get too many returns. I'll just repeat what I said to them - that it's surprising in a world where one can test out a car for a week or even try out underwear for size and then return it, surely a retailer should be able to have some sort of mechanism to allow people to test out an item before committing to the purchase. Best of luck with your search. Al