Going to mod my Skywatcher 130P

[geppetto]

Don't get me wrong, I love this 130P scope and I'm not saying

there is much wrong with it but I tend to use it a lot now for

astrophotography because it's light weight and fast with a decent aperture.

The problems I have with it is a lack of "in focus" which means it won't focus

a DSLR at prime focus and also it only just reaches focus with my modded Toucam.

Also, I never have liked the collimation adjustments on it so to kill two birds with one

stone, I'm going to replace the collimation bolts with longer ones to push the primary

forward a bit. This will get me a bit more "in focus".

Also, there are no springs on the collimation bolts, just some rubber "O" rings which

can make collimation a pain sometimes. These will be replaced with some compression springs.

I realise that by pushing the primary too far forward will result in the secondary missing some of

the light cone but that's open to experiment (suck it and see 8))

Pictures below show the two parts of the mirror cell and the collimation bolts with "O" rings and

the allan key bolts which lock up the cell after collimation.

Will report back after the mod to see if things have improved or not

[FLO]

Good idea 8)

[Kaptain Klevtsov]

Good luck Phil.

Any idea how much too small it will make the secondary?

Captain Chaos

[geppetto]

Any idea how much too small it will make the secondary

CC

Plan is to do the mod then to see how far forward the mirror needs to be

then I can run the figures through Newt.

That way it's non destructive and can be put back if needs be.

The only other way I can do it is to fit a low profile focuser but that would

be expensive.

Also having looked at it, I could trim 5mm off the present focuser body as well

as moving the mirror a bit less.

Sent off for some springs so all should be revealed soon

[Alan D]

Will follow this with interest Phil. I was only talking to Steve (Flo) yesterday about the same problem I had with my 200mm Newt. I ended up after talking to Orion Optics (supplier) who suggested taking my scope back to their factory and they took off about 15mm in the tube length (freebie of course) which enabled me to get prime focus with my 350d. Still using the crappy focuser so some issues having to rack out nearly all the way to get focus with eyepieces. As you say new focusser is very expensive. Not sure whether to stick with the Newt and splash out on a focusser or go the refractor route (80ED/100ED) hence my conversation with Steve yesterday (by the way sorry for driving you mad Steve with all my questions)

Alan

[geppetto]

Alan

It really is a common problem...

My Revelation 8" F6 won't reach DSLR focus and neither will

a 200mm F5 Celestron that I know about.

Re the other thing, if you can afford it, go for an ED100

you'll love it. Also you swap in focus problems for out focus problems

but with that it's easy to stick in an extension tube

[daz]

I've jut bought an adapter which replaces the screw in part of the 2" R+P focuser on my newt. I will get a picture soon, so you can see, and I'll dig out what he called it.

[geppetto]

Just realised that if using a longer screw there was a possibilty of the screw going through

the cell ring and pushing into the back of the mirror. :shock:

The origional screws are not long enough to do this.

Slight change of plan, I will use 5mm threaded rod Araldited into the cell's threaded holes

Collimation will then be adjusted by turning three wing nuts pulling the mirror cell against

the three springs.

Got these tough springs this morning from these good folk 8)

Will do the mod on Sunday as the 130P is going in use, pointing at the eclipse tomorrow

[Alan D]

Looking good

Alan

[daz]

The item is called a 2TUA and allows DSLR's to come to focus when using a MPCC.

I have one, so it's a question of trying it out!!

Good luck with your mod Phil

[geppetto]

That's interesting Daz 8)

Wonder if they do one for 1.25" focusers...

Will check it out

[geppetto]

Fitted the threaded rods, springs and wing nuts today.

Extra forward direction is now 18mm max and 10mm min.

Just have to borrow Richard's DSLR now to see if the 130 will

reach focus.

Irrespective of trying to gain extra "in focus", this mod has made

the scope 100% easier to collimate and I suspect it will stay put

for much longer.

The threaded rod is standard 5mm metric stuff...

Fingers crossed

[Kaptain Klevtsov]

Wot no grub screws? Are the springs enough to hold the mirror rigidly Phil?

Captain Chaos

[geppetto]

Are the springs enough to hold the mirror rigidly

They are CC, really tough little blighters made from 1.2mm wire 8)

Will be adding three lock screws though made from the same 5mm threaded rod

with a screwdriver slot cut in the ends (thank heavens for Dremels )

[dazza1639]

Nice mod it looks like its been really successful.

Will you tell us more about collimating the scope with the new setup perhaps post some piccies.

Darren

[geppetto]

Quick nip out last night to test the modded scope.

Toucam comes to focus with the draw tube 18mm further out than before

and I got a couple of shots of M42 core through thin high cloud.

Seems ok so have just got to try a DSLR next then I can set the final mirror

position

[Shibby]

How's this for a bump?

Wondering whether you got the DSLR to focus? Did you leave the focuser alone in the end? I have the same scope and also can't achieve prime focus (eyepiece projection is not proving successful)

[themos]

I had the same issue with my 4.5" f/8 reflector. I took a cutter to the tube and shaved off about an inch and a bit. Now the DSLR can reach focus but I need extension tubes for the eyepieces.

[teh_orph]

Holy thread bump batman!

I just performed this mod on my telescope...and it works!

I have a 130P and a Canon 1000D but could only get focus before with a Barlow. With an EQ2 mount the tracking isn't the best so the Barlow made it worse!

I've got 5mm threaded grub screws in the place of the original screws, roughly two inches long, with wing nuts on the end. The mirror is held in place with some strong springs. Collimation is now unbelievably easier, and the camera comes to focus too! I do need extension tubes for eyepieces though. I had to make no permanent modification to the OTA - everything is reversible. No cutting of anything

Pics and full details if anyone wants them.

[spaceboy]

Great stuff. I had an old Helios with the same O rings and found it was forever loosing collimation. I would have thought cutting the springs a little shorter would be better but if it's working why mess. Have you found all your EP's come to focus due to the extra 18mm of outward focus?

[teh_orph]

Tbh they don't, so I use a barlow with the glass elements removed as an extension tube. Since the camera's sensor is so far recessed into the housing it's hard to get both EPs and camera to focus without modifying the focuser. I have the springs and grubs screws set so there's about 0.5 mm spare back focus for the camera and the EPs are at the complete other end of the rack and pinion focuser!

I'm so pleased with the result though. The FOV is much better without the barlow and I get the same problems other people get now. I get coma in my images! I can also locate things in a flash! No more "what is that star?"

[Zendrix]

Hello!

I also have a sky-watcher 130mm and my budget for now doesn't allow me for other than a Canon 1100D. Considering that i will have this focus problem, i am thinking in modifying it as well.

Would you be so kind and point out exactly how it is made? i never disassembled a scope before and, although i'm confident in doing it, i need some guiding of what exactly is necessary here.

Thanks a lot in advance,

Rui

[madatter]

Thanks for this great tip, did my Skywatcher 130p yesterday, total cost about £20, cant even see the end off the street with all this rain but looking forward to trying it out soon

[pjac]

Thanks for this great tip, did my Skywatcher 130p yesterday, total cost about £20, cant even see the end off the street with all this rain but looking forward to trying it out soon

I'm guessing that includes almost £10 on the three SC229 springs from www.strutdirect.co.uk (£0.69 per spring, plus £6.95 postage - ouch).

Did you source the bolts and butterfly nuts online too? Links would be good - saves disappointment with buying something which doesn't fit.

Any tips on the whole process? I've seen this thread on removing the primary mirror which makes this seem quite a job.

Thanks!

[paraletic mirror]

yeah i just tried to get the springs im not paying 6.95 delivery for something that ways mere grams!!!!!!!!!!