Rick_It

In 102mm f11, nobody I think could spot the difference between and FPL51 and an FPL53 variant. In a 102mm f7 (where we have both the FPL51 and the FPL53 doublets) I think this difference is much larger.

The focuser cannot costs too much, as the same unit is included in the 300€ Evolux 62mm. The difference in price between the two is quite strange. The price of the 62mm ED makes sense: same price as the Evostar 72mm, with 10mm less aperture but a better focuser and retractable dew shield. It's the 82mm price which is strange. In principle, it could eventually be the case that the 82mm is using a better glass (like FPL53 instead of FPL51). But consumers cannot consider that, as SW refuses to disclose this key technical characteristic.

A thing to consider when buying second-hand is the higher probability of getting a lemon. Suppose you buy a new C8: you will be much more likely to resell it if it is a lemon (say 1/3 wave PV) than if it is a fine scope (say 1/6 wave PV). This is expecially true for mass produced scope with some variability in their quality. I'm not talking about a specific scope, I'm referring to the chances of getting a good scope. Of course, this is not an issue for Tak, Televue etc..

IMHO, this is the new ED glass from CDGM, the H-FK71. It is somewhat in between FPL51 and FPL53, but closer to FPL53. I've already seen SW using terms like new or improved ED glass, and this glass is actually new and improved from H-FK61 (the previous "ED" from CDGM). And, from a marketing perspective I can understand that they don't want to disclose this glass, as (i) it is slightly inferior to FPL53 (and FCD100), (ii) it's new-unproven and (iii) not from the traditional glassmakers (Ohara, Hoya, Schott).

The 62mm should have the same glass as the Evostar 72mm ED (323€ on FLO, 10mm more aperture but mechanically inferior).

Italian prices are out, and they are much better than the australian ones. https://www.telescopi-artesky.it/it/skywatcher/rifrattori-apocromatici-/4726-rifrattore-evolux-62ed-skywatcher.html https://www.telescopi-artesky.it/it/skywatcher/rifrattori-apocromatici-/3150-rifrattore-evolux-82ed-skywatcher.html Evolux 62mm: 304€ Evolux 82mm: 760€

You can derive the refractive index and the Abbe number of a glass, but this require dismantling the scope and testing the single lens using professional equipments.

IMHO, when characteristics are not fully declared, it is a safe assumption to assume for the minimum / cheapest specifications. In this case, as the scope is still advertised as ED, I assume HK61 (chinese copy, and slightly worse, of FPL51). Then, if someone tells me that CA is on par with the ED80 (FPL53), I will change my mind. But, if this is the case (and SW is using FPL55 or FC100), then this is really a crazy marketing strategy. If you are using a good glass, why don't you declare it?

For sure it is not FPL53. But what's important is if the glass is FPL53 "like" (FPL55, FC100) or if the glass is FPL51 "like" (FPL51, FC1, HK61). I think a direct comparison (star test at high magnification) of the Evostar 80mm ED with this new Evolux should reveal the truth. The Evolux has almost the same diameter but it is a bit faster than the Evostar. If they are using an inferior glass (FP51 equivalent), chromatic aberration should be noticeable higher than CA in the Evostar 80ED.

The funny thing is that this situation, called natural monopoly, is a standard example of market failure which calls for state regulations. But state regulations are anathema for US and UK policy makers. Sorry for the OT

It depends on the economy of scales of the monopolist 😀

Congrats FLO and Rowan, the mount is a very interesting product. The mount is heavy and quite expensive: I think you could explore the possibility of producing a smaller mount - call it Rowan 50. It should have a payload of about 8-12kg (with/without counterweights), a weight of about 3-4kg, no slo-mo controls (as a cost-saving measure) but still the encoders option (this is what really differentiate this class of mounts).

I had the scope and the diagonal. I confirm the diagonal can be aligned.

Watch out. Encoders seem to be mounted internally in the Rowan 100, but externally in the AZ8. Having the encoder internally mounted (like in the AYO mounts) is better.

Think out of the box https://www.teleskop-express.de/shop/product_info.php/info/p6880_Explore-Scientific-MN-152-f-4-8-Maksutov-Newtonian-Telescope-with-Field-Correction.html

With a stable tripod, the EQ3.2 is not a bad mount. Visual only and, I stress again, with a good tripod, it can really arrive up to 5Kg (I used on that a TAL100RS). I also remind that a very light tube like a C5 is very steady. I suggest you to try the SW 72ED with a reducer/flattner for AP, as you want something light but also with a short focal lenght and a fast f-stop. The 80mm is longer, heavier and slower: probably too much for the mount. Guided or unguided pictures? I don't expect the EQ3.2 to have a very precise tracking.

This is the achro version but with the same body as TS: https://www.omegon.eu/instruments/omegon-binoculars-argus-12x50/p,47247 You can probably choose between two bodies (rubber or leatherette) and two glass version (achro or ED). As the APM uses the FK61 (one of the cheapest ED glass available), it's difficult to downgrade the glass even more while keeping the "ED". Different coatings are available, probably.

Good idea!! Any CA introduced by the Barlow?

So small and light, I would go with a Celestron Hummingbird and a monopod or, if 1.25" eyepieces compatibility is not important, with an Opticron spotting scope (MM4 60mm ED, weight 750gr or MM4 77mm ED weight 1250gr).

https://www.teleskop-express.de/shop/product_info.php/info/p7218_TS-Optics-Optics-LE-10x50-wide-field-Porro-binoculars---multi-coated---rubber-armoured.html These one... Better with a tripod

Have you a photo-tripod? I just ordered this https://www.amazon.co.uk/koolehaoda-Professional-Monopod-Compact-Lightweight/dp/B01H0BKX9O/ref=sr_1_7 to be used with my Celestron Regal 65mm. You can purchase a small scope (spotting or astronomical, OTA only) and use an arca-swiss system, which is lighter&cheaper than the Vixen standard and it gives you a lot of choice on ali express and amazon. My set-up will be less than 3.5kg and fully airline cabin compatible. I will leave it permanently mounted at home, so almost no set-up time (just the 30s required to extend the tripod legs). Of course, my Regal is expensive, but there are a lot of achromatic cheaper spotting / small scopes out there. Think about that!

http://www.skywatcher.it/montatura-cq350-pro/ Payload: 35kg, belt transmission, plenty of USB ports. Seems a sort of center-balanced EQ7. http://www.skywatcher.it/motorizzazione-azeq-avant/

Something below £300 is a fair price for the tube. As for the mount, if you can the best solution is to build it by yourself. You can have someone cutting the wood for you, so you will have just to assemble it. You have to purchase the formica laminate and the teflon pads. Only if you want encoder compatibility, you need a blacksmith (hope the word is correct) to make the central pivot with an hole for the encoder's shaft. Else, whatever M8 bolt will suffice.

I have the OOUK VX8L. Second hand, for the OTA only, I paid a lower price than 500€. In any case, the OOUK has those advantage: - It's much more lighter (7-8kg) - It comes with a good dual speed focuser - Having the tube rings, you will have no problem in balancing even with heavier eyepieces, binoviewer. Do not underestimate this aspect, this is important. - A lot of focus available, can be used with the binoviewer (I think) and can be used with a reflex (I'm sure) - The mirror cell is really another planets w.r.t. the SW. It keeps collimation very very well - Commercial solid tube dobson mounts (GSO, Skywatcher) are horrible. They weight a lot, they have an undersized ALT movement and they use cheap bearing materials. Much better to build your own mount using teflon, formica, baltic birch and large disks for the ALT movement. Do not underestimate this, smooth movements are important when manually tracking a planet or a double star at 250x. You will also ends up with a lighter mount (mine weight about 7.5kg, but it can be made even lighter). Moreover, it's much easier to add encoders in your mount.

Yes, but a C8 is not a rich-field scope, so it's not universal. For example, you can't frame the Pleiades. With a 200/1200 you get up to 2.26° FOV.