GTom

Thank you, just realized myself and checked the "filter sizing tool" here: https://astronomy.tools/calculators/ccd_filter_size

The replacement of the focuser seems to open a huuge can of worms, as it is not a standard M90 but a cemented tube adapter piece narrows down the tube to 70mm (69.8 to be exact) dovetail/grubscrew connection. So far I haven't succeeded removing the tube adapter. Might be willing to cut it off, but that's definitely a longer breadth project.

Instead of a reducer, I'll look for a simple flattener, 1.0x should be easier on vignetting and albeit slowish, f7 is still OK for AP. Following the maths, front element of the flattener should offer 49mm aperture. Still narrow a bit for the extreme corners, but I can live with that.

Found one candidate here, a user with a full frame camera already gave a positive feedback:

 https://www.firstlightoptics.com/stellamira-telescopes/stellamira-2-field-flattener-with-m48-adapter.html

However, no idea what is the difference compared to this product, with an originally higher price tag (now sold @the same price):

I am looking for recommendations, if any 2" reducers could illuminate an APS-H (KAF-16200, diag: 35mm) FOV with a 105 f/7 APO without significant vignetting? Any flat samples with APS-h or larger cameras are most welcome.

The scope is as far as I remember an early but very decent fluorite triplet in a carbon tube. As I do not know the designer and the seller can't be contacted after 15+years, can't go the "choose the matching reducer" path, need a more universal solution.

Just repaired the 2" Crayford focuser, if possible I'd stay with it instead of shoveling out the price of a new 2.5" one including the troublesome removal of the narrow tube adapter.

Many thanks, I think it is screwed (hopefully) on the outside, will try to warm it with a hair drier this evening.

crazy idea in case it doesn't want to come off: the black adapter piece with the thumbscrews has an ID of approx 72mm. Will try to get someone with a lathe and produce a 72 OD adapter to whatever the focuser needs. My current focuser is long, a shorter SC focuser could work.

The Crayford on my 105mm f7 generic APO gave up terribly and needs a proper replacement. 2" would be straightforward but I want to upgrade to a 2.5" RAP in order to accommodate larger format reducers/cover a FF sensor.

Any idea how to replace the thread adapter that appears to be cemented on the tube? So far tried turning by hand, didn't budge at all. Last resort would be to cut it off and screw a new, larger adapter on.

Any first hand experience with this scope and the recommended planostar reducer?

Regarding price one should definitely look at the 2nd hand market. Weight and size indeed a question if backpacking is the goal. Cooldown: wait until you get your c14😅

33 minutes ago, Adam J said:

a tally the 102 is very close the F-ratio is the giveaway. The design needs about a F13 ratio to work at full aperture that's 100mm for the 102mm so hardly any difference. The 127 is the worst it's not even F12.

Deal, 118 vs 100 then. 18% more resolution and 40% more light grasp.

17 hours ago, Adam J said:

There is not as much difference as you might think as the 127mm does not have a 127mm clear aperture only 118mm. No idea how SW get away with that. Honestly the 102 cools faster and is more portable as it will go in hold luggage easier. The 118mm will outperform it just don't expect the margin you would get if it was a true 5 inch scope. 

If the 127mm "is only 118mm" then the 102 isn't "102" either. Even 40% (will be more in reality)  more light will give a visible difference.

The FL difference is marginal, APERTURE gives you resolution and light gathering. Indeed, that 5" Mak will be brilliant on planets, even Uranus is possible.

ADC's are not without fault, diminishing returns @higher altitudes could be negated by optical imperfections of the ADC unit and collimation difficulties. ADC will not improve seeing either.

Still, it may very well save the day for us in the UK (clouds allowing...) and other countries at similar latitudes, I am in the process of choosing one.

Any update on these two?

My planned imaging train: lx200 10", Powermate 2x, ADC, Filter wheel, Altair 174m camera.

Anyone?

Seems only zwo specifies surface quality and publishes a transmission curve.

Altair just joins the possible candidates

Just found an ADC on our sponsor's website with a very attractive price tag from StellaLyra. Anyone could comment on its quality and usefulness? I intend to use it with a Meade f10 SCT for both visual and photo.

Just found an ADC on our sponsor's website with a very attractive price tag from StellaLyra. Anyone could comment on its quality and usefulness? I intend to use it with a Meade f10 SCT for both visual and photo.

Summary:

K9 glass
Anti-reflection treatment with a reflection of less than 0.3% and a range from 350nm to 700nm
Inclination of the prisms 2.5°
Total length 106mm
Free aperture 27.2mm

Looks great! Have you used a reducer/corrector?

Industrial IPA is likely good, would get a cleaner water though 😄

I was wondering if distilled water could be cleaner-better than de-ionised. Automotive suppliers nearby only stock de-ionised as it is perfectly fine for all kind of motoring use. Distilled from amazon/ebay is a bit more expensive (won't break the bank though at £2/L) but might be better...

Never added detergents before, guessing a fragrance, etc. free type is needed for telescope cleaning.

I am in the process of cleaning my recently acquired LX200 SCT. As mold just started to set foot, I had to act quickly, had a rough cleaning with isopropanol de-ionised water 1:1 mix followed by pure isopropanol. This worked so far with camera sensors and less-dirty mirrors. This one seems to be dirtier than usual, quite a bit of sludge remained.

As already wasted about 1/2L of precious isopropanol, I wonder what could be a more economical cleaning solution? Also, any recommendations for the water part, where to get larger quantities of pure distilled water? Can I add some detergents to get rid of less soluble-more stubborn contaminants that prefer just changing pattern instead of leaving the corrector plate😄?

Took my 10" LX200 GPS apart last night (decent cleaning is still to do): no counterweight

2 hours ago, John said:

The meade newtonians and their 7 inch mak-cassegrain certainly have large metal weights behind the their primary mirrors.

Often an early modification of such scopes is to remove the counterweight. I understand that it is thought that the weight slows down the cool down process by adding mass close to the primary mirror.

 

Having a heavy camera it would be a great idea to remove any weight from the primary side. Will have a look on my copy, being a wee bit scared to disassemble the entire OTA though 😀

Right, just picked up a 10" lx200: it came with stock mirror lock

Mind you it is an Achromat, for that f8 is a bit fast. The f15 would be great for planetary.

No problem unless it's a 25x150 comet hunter that might be bigger and heavier than your maximum carry-on size. My trusted 10x50 often comes with me.

The best is to try finding a drawing on the dovetail candidates and check which one offers the hole spacing you got. Wirst case buy one with no/very few holes and drill at your convenience, Aluminum is easy to drill and you won't destroy anything.

I recently bought a 355mm one for my TS 90/600:

You'll need something in the 400mm+ range.

Tip: even if you don't plan to import ftom Germany (I didn't either), the TS Optics site is very good for measurements:

https://www.teleskop-express.de/shop/index.php/cat/c308_Dovetail-Bars.html