Northernlight

Hi, just my 2 cents. Rc collimation is often seen as being a nightmare, but with the right tools it's very simple. 1. Use a good quality laser to adjust tilt on focuser so laser dot appears centered in dot of seconday reflection. 2. Use a Tak collimation scope, to adjust secondary, and then fine tune primary 3. Repeat steps 1 & 2 and you're done........simples..

Hi All, Just have a quick question on focal reducer spacing. So i have an AP .667 reducer which has an optimum spacing of 85mm to give x.667 reduction If i reduce the spacing by 5mm down to 80mm, will this cause a greater reduction i.e < .667 (e.g 0.6) or will it go the other way and be > .667 (e.g 0.7) i use the abovr numbers purely for illustration puposes. Many thanks, Rich

Thanks olly, now i see what you mean, hence why i get decent narrowband images using my 102mm doublet.

Olly how do you mean ? i have a cheap 102mm doublet and it seems to perform quite well as per the image below.

Thanks Dave, Just curious how good or bad it performs for imaging and there aren't that many reviews out on the web. I did however come across an old thread on cloudy nights which got quite heated discussing this scope with an batch of them that were sent to the usa which were about 10 users reported serious issues with the lens assembly and subsequently has issues with the supplier. So not sure what to make of this scope.

Just wondered if anyone is imaging with the Apm 140 or 152mm ED doublet scopes as i would like to get some owners feedback and maybe some links to images captured with either of these scopes.

Just a shame skywatcher or someone else haven't made a sub <£2,000 deluxe version of MN190. I would happily pay double if they just did a version with an upgraded focuser & mirror cell to get rid of the terrible mirror slop, not to mention the paying attention to Quality control. Even at double the price it would still be worth it as it Just seems to have a nice balance of aperture and speed. I think the reality is that due to my budget being limited to £3,000 I'm looking at either a 140/150mm doublet refractor if i want simplicity and reliability.

Thank you Olly, that was a great explanation. So essentially the larger aperture F7 scope will give a brighter image due to larger aperture regardless of focal ratio ? So does the focal ratio just impact the object size/image scale ?

So in my simplified mind, you are saying that there wont be much difference in the amount of data collected between a 102mm refractor @ F5.6 vs a 152mm refractor at F7 if both are doing 600s subs

Hi Dave, I did try a MN190, got one new but it's build quality was exceptionally bad. In my case the biggest problem was that the secondary wasn't marked correctly. The center dot on the secondary was infact a U shape and was drawn on in pen by someone with a very shaky hand. I would love a MN190 if it wasn't a project in itself just to getit setup working right. Olly, I could be wrong here but i thought i saw a post somewhere where you mentioned a Meade F8 ACF tube. Have you got any experience of them ? In regards to using a refractor at F7, i agree it would be simpler but i dont live in the darkest of area's, so i dont want have to jump up to 15-20min subs to get some good data. I normally do my Lum & Narrow band @ 600s subs at F5.6ish, and i'm guessing i would need to jump to 900 or 1200s if i was imaging at F7.

Anyone ?

Hi all, Looking for some feedback on a new scope selection. The scope will be permanently mounted in obs on a EQ8, so weight shouldn't be too much of an issue. I realized that spending 1k on a scope for imaging at the 1m mark just isn't going to cut it, so upping my budget to 3k Would appreciate feedback on pro's and cons. The scope selection criteria is as follows : ● Scope to be used primarily for imaging with a Kaf8300 chip. If it can do visual as well its a bonus. ● Looking for something fast F4-F5 ● Focal length around 1000-1200mm Options i'm considering are : Altair 10" F4 Truss Imaging Newt 10" F4 or F4.7 Teleskop Express ONTC Newtonian 10" Meade ACF with a reducer APM 152 (1200mm) F7.9 Doublet with reducer Cheers, Rich.

I think olly was referring to the cheap silver coloured wrapping tape you can buy at card shops or in cheap discount stores usually around xmas time.

Hmm..... i think my wife has a box of xmas wrapping goodies. Think i need to go and have a mooch and see what i can find. In regards to my RC i have it pretty close using my Takahashi collimating scope, but because i'm using a reducer to get the speed up, i'm never going to get rid of the mild coma in the corners. If i stuck with F8 on the RC and used a flattener i'm sure i could get it perfect, but who wants to image at F8. sure i can crop out the corners, but i just bugs me as i know they they are there before cropping.

Olly i think you are dead right as i've seen posts of people drilling holes in the sides of the rear primary cell and addind nylon screws to get the primary centered exactly in the middle with respect to the ota and to help stop mirror flop, so you really do need to be an expert to get o good result. I just dont want to be in the same position as i am with my RC where I'm spending 90% of the time trying to tweak it and only 10% actually imaging. John good idea about the tape, never thought to try anything like that.