9x50 Skywatcher finder and QHY5L-II camera, fittings!

[LouisJB]

Hi,

I have a Skywatcher 9x50 Right Angle finder scope and a QHY5L-II camera.

I'd like to know how to connect them together so focus is guaranteed and the fitting is stable.

Seems more tricky with the RA finder due to back focus. Should I swap it for a straight through finder of the same type?

Also, is the inner thread on the QHY5L-II (not with extender) a C mount?

What is the thread on the 9x50 right angle finder, some form or 2" but not a filter thread?

What does the straight through equivalent use?

Sorry for so many questions, bit lost on connectors and adapters, not sure what I need to make it work.

thanks, Louis

[baggywrinkle]

My SW RA finder only has focusing by adjusting the objective lens over a very narrow range. The eye piece is firmly fixed, not sure you can connect a camera to it.

[LouisJB]

Hi,

Ok thanks, on mine the eyepiece did come off, but it was tight. However, that's not where I was going to put the camera.

I took the diagonal off, the back of the tube is approx. 2" but with some thread that probably is not standard M48 filter.

The idea is to connect that via some adapters to the camera.

Using a cardboard tube I mocked up the distance and got it to focus. Due to removing the diagonal the camera needs to sit 40-50mm back from the back of the finder tube, which can be done with tubes etc, if only I could work out what threads/adapters are required. 

I could probably make something, but for the sake of some threads / adapters it would be nice to get the right thing.

Modern astronomy have a right angle finder c mount adapter, that might be just right (depending how long it is) but it's also nearly £40 which is a lot for a bit of metal with threads esp. if it's not the right thing. (I appreciate they get these made, so the price is ok, but for that price I'm not just going to get it and see, it's nearly the price of the finder!).

thanks for any help, really a bit stumped!

[baggywrinkle]

Some people are using the SW Travelscope OTA, it is cheap and it works...as you say £40 on a punt might be money down the drain.

What OTA do you have to mount this on?

I misread the email, taking off the diagonal make sense of the sizing.

[LouisJB]

Just a little 130P, on an HEQ5 Pro synscan. The idea was to get the solid mount and then guiding working then using DSLR get some say 5min exposures working, then final step upgrade the tube, maybe next year if I can get the 1st steps working... I'm a beginner, making mistakes as I go

I might just use this finder as a finder (seems nice) and get a new guider scope, as this is proving more tricky than I'd like and I'd rather not put money down the drain fabricating something out of expensive adapters, £40 is 1/2 the price of a finder with the right adapter on the back! Guess I could sell the SW finder if I don't use it.

[JamesF]

I have been guiding my 127 Mak using a QHY5L-II and Skywatcher finderscope.  Modern Astronomy sell a suitable adaptor to that screws into the back of the main tube of the straight through finder (that is the entire plastic eyepiece assembly is replaced) to take the QHY5L-II.  What they don't appear to sell is a similar converter for the RA finder.  I have the straight through one and it works for me.  The camera just slips inside, so I guess it must be a 1.25" female fitting on the back.

Measuring an RA finder and straight through that I happen to have here, I reckon the RA is about 40mm shorter which would tally with your own measurements.  It is entirely possible that with the straight through adaptor fitted and the extension pieces screwed in on the camera that it will still reach focus.  If not then a short 1.25" extension should fix that.

If you're desperate I have some thread gauges and can probably work out what the thread is on the back of the finder body, but I can't do that this evening.

James

[Sandancer10]

Hi Louis

Can I ask you about your 9x50 finder scope as I am thinking of getting one. I have a 6x30 standard finder that came with my SW 150PDS, but I am having a lottoo problems with alignment as I am also a beginner. If the subject star is slightly off I can't seem to get it into the FOV, as everything is upside down and the wrong way round. Does the right angle help much and is there much difference in the 50mm. I also found out that my Polar scope is out of whack so that doesn't help either.

Brenda

[JamesF]

Hi Louis

Can I ask you about your 9x50 finder scope as I am thinking of getting one. I have a 6x30 standard finder that came with my SW 150PDS, but I am having a lottoo problems with alignment as I am also a beginner. If the subject star is slightly off I can't seem to get it into the FOV, as everything is upside down and the wrong way round. Does the right angle help much and is there much difference in the 50mm. I also found out that my Polar scope is out of whack so that doesn't help either.

Brenda

I'll chuck in my 2p worth here too...

For me having an RA finder is more about comfort of viewing rather than image orientation.  I like having one on the dob because it means I don't have to crane my neck to see down the finder.  After using telescopes for a while I found that I could swap between finder and main scope, or newt and refractor, and within a few seconds I have things sorted so I'm thinking the right way regardless of the image orientation.  I'm fairly sure that whilst some other people are the same, not everyone finds it so.  If that's the case for you then you may find that a "correct image" finder really helps.

In my opinion the 50mm finder is a huge improvement over the 30mm in all respects, to the point where I've bought a few second hand and no longer use a 30mm on any of my scopes.

Sorting out your polar scope may make life easier, but I don't think it should really matter for visual use.  It's not that hard to do though, just a bit time-consuming.  Fortunately it's the sort of job you can do during the day and potentially even indoors.

James

[LouisJB]

Hi,

Modern astronomy sell an adapter for the 9x50 RA that they say is recommended for the QHY5L-II, it's the skywatcher RA to C mount adapter (QHY5L-II has a C mount thread on front if you don't add the filter extension tube.

So that's £40, or another idea is to spend double that and get a dedicated finder, like the BST starguider 50mm, which might be better, no money on adapters and I get to also Keep the RA finder which does seem quite nice.

As for questions on the finder itself, well I think the point of it is

a) as per James comments, much more convenient to use

image is up the right way etc so matches the sky, that can be helpful

c) 50mm over 30mm, I was surprised how bright and clear the image is from such a little finder objective

Even though I've not used it much, I think I'd recommend it as a finder. Previously I used the red dot finder, it's great but like a straight through finder sometimes you find yourself struggling to crouch into position to see through it.

As for guider scopes, is the BST starguider 50mm any good (optically as good as SW 9x50?) and it appears the QHY5 1.25" body will go straight into the holder, is that right?

thanks for the help.

[JamesF]

If you can fit something like an ST80 onto your rig I'd be more tempted to go that way for a guidescope I think.  If for reasons of space, weight, expense or convenience you can't then that limits your options a bit, but without those restrictions I think the larger scope is a better bet.

James

[LouisJB]

I could fit an ST80, although getting one seems more tricky, they seem harder to locate in the UK.

However, then I'm not sure about mounting, I'd need another dovetail bar, some way to connect the camera again etc... Not insurmountable but I'm not sure I'm there just yet.

My main idea is to upgrade to something like an 8" astrograph (maybe an RC or mak), and minimising weight on the HEQ5 for maximum tracking - i.e. best 'portable' setup for astro, as I don't have a permanent observatory.

If i were wanting a refractor (and I may well do sometime), then well, the 102 or the 120 look nice also.

It's tricky, but I also read a review that said switching from ST80 to 50mm wide-field (F5 ~170mm focal length) actually improved guiding. More stars and brighter (smaller objective but same speed and wider fov).

So I'm still not totally sure. If an ST80 came along second hand with bits for the right price I'd get one. For now keeping within a £100 budget all in I may get a 50mm guiderscope and see how I get on.

I do appreciate your idea though, if upgrading the reflector wasn't my main goal I'd be up for it. At the moment I don't want two average tubes and nothing 'great'!

[LouisJB]

Having a rethink on this as the ST80 looks nice for other things.

Do you think it will guide a small 130P initially or is it going to be too sensitive? Ultimately I'll get something like an 8" RC, but ideally something that can guide both would be what I would like to get.

Would the ST80 guide a 130P or will it be too much?

thanks, Louis