Skywatcher 130p and prime focus

[BrendanC]

Hi,

After much research and head-scratching, I'm starting to realise that basically, a Skywatcher 130P , DSLR camera and prime focus don't get along well together.

There are mods I could do (scary), new OTAs I could consider (pricey), new lenses I could buy (ditto, plus I want to use my scope, not buy new lenses).

So, I'm considering selling the DSLR, and trying a dedicated astro camera instead. I already have the Bresser Mikrokular which is a joy to use but pretty limited. I'm after better planetary and moon shots, and the possibility of at least starting to delve deeper into the brighter DSOs, nebulae and galaxies and suchlike. 

However, I don't want the same palaver I've had with the DSLR re achieving prime focus. I want something like the Bresser - pop it in the eyepiece holder, off you go. Looks to me like the best candidates are those with 224 and 290 sensors, from Bresser, Altair and ZWO.

Which brings me to my question: if I go for one of these, will I be able to achieve prime focus ie remove the Barlow, in goes the camera, get focus? If it's just not possible with a 130P then I'll accept it, maybe have a little cry to myself in the corner, and then just crack on with what I've got ie good observing, sort of ok imaging.

I'd just hate to take delivery, get all excited, remove the Barlow, pop it in, then realise that I just cannot get prime because it's not possible with my scope.

I'm not after specific recommendations for cameras, but I really would like owners of Skywatcher 130P scopes (not PDS, because that works, apparently, darn it) to tell me their experiences.

Thanks, Brendan

Edited November 20, 2019 by BrendanC

[alacant]

Hi

You're only about a cm from focus with your dslr, so simply put longer bolts (this was a 250p, so m5 bolts) to move your primary mirror up the tube. Keep the original springs and shim using nuts and/or washers. Here we went for a 3cm extension.

Cheaper than buying a new camera;)

HTH

 

[daemon]

Hi,

Maybe I am missing something but I can't see why you would have trouble with this. I have a Skywatcher 130PDS and have no trouble using it and obtaining focus with my Nikon D5300 DSLR.

Without checking in detail I would have thought the only difference between the 130P and 130PDS is the Dual Speed Focuser on the DS version, but I could be wrong.

My imaging train is simple - D5300 - 'T' ring - Coma Corrector - and then straight into the draw-tube of the scope. I can easily obtain focus, although admittedly I only really go for DSO's so not sure if that is your issue.

Perhaps a coma corrector or small extension tube could sort things out for you and give you some more back-focus.

I also have the ZWO ASI1600MM as my dedicated astro camera and I can also recommend that with the 130PDS.

Good luck!

daemon

 

 

 

 

[alacant]

4 minutes ago, daemon said:

only difference between the 130P and 130PDS is the Dual Speed Focuser

And, more importantly, the length of the tube;)

Cheers

[daemon]

Sorry. I'm an idiot!! I do of course have a 150 PDS (not a 130)!!! 

So therefore probably lies the problem.

Guess I read sooo many threads on the 130 that I easily confuse the two!

I'll shut up now.

😫

 

[BrendanC]

@alacant That's one of the mods I've come across before but it scares the bejeezus out of me. The photo is useful but do you have any more specific instructions? You say you use M5 bolts because you have a 250, so what manner of bolt would I need for a 130? Is there such a thing as an M3 bolt? I have no idea. I've found the other threads knocking about regarding modding Skywatcher 130Ps, but the photo links are broken. Also, how does this affect collimation? And how does this affect viewing - presumably you need a longer eyepiece holder to compensate?

@daemon Yup, the PDS is a cool scope and I wish I had one of them now! Apart from the focuser, the crucial difference is indeed the length of the tube, which makes prime focus a doddle. That's another avenue I'm considering, exchanging the 130P OTA for a PDS.

Thanks for the suggestions. The mod is definitely a contender and would enable me to keep all my gear, but I'm just, well, scared, you know, like that first time you climbed the gym rope at school?

Edited November 22, 2019 by BrendanC

[alacant]

1 hour ago, BrendanC said:

The mod is definitely a contender

Hi. As soon as you remove the mirror, it will be obvious what you need, what you need to do and which size bolts you need. It's easy, but you end up with a compromised telescope; see below.

Is there an astro club near you? Most reflector owners there would do the modification for you.

1 hour ago, BrendanC said:

Also, is it reversible,

Yes.

1 hour ago, BrendanC said:

presumably you need a longer eyepiece holder to compensate

Yes, it's a pain. And you lose light around the secondary mirror which after moving the primary mirror is now too small to intercept all the light.

In the end, if you want to do astrophotography, sell up, get the 130pds and have done with it!

Cheers

[BrendanC]

Ta. I might go the PDS route. Or, I might go the new eyepiece camera route, assuming I can get prime focus with one. Looks like I managed to choose almost precisely the exact combination of equipment that doesn't work.

Thanks for the advice, really appreciate it.

Edited November 22, 2019 by BrendanC

[BrendanC]

Hi again, so I've heard tell that the PDS isn't great for prime focus for dedicated astro cameras. This surprises me greatly.

Any comments on this? I was virtually about to buy a PDS but this concerns me. I'm confident from what I've found out that it'll work with the DSLR, but if I ever want to invest in an astro camera, I'll be wanting to achieve prime focus with that too.

[happy-kat]

Have a read of the dedicated imaging thread on the 130pds, it's a very long thread full of images.

[BrendanC]

Good point, and I'd already been through the thread at https://stargazerslounge.com/topic/210593-imaging-with-the-130pds/?tab=comments#comment-2247736. Stunning images. So that means there isn't a problem with dedicated astro cameras, right?

Edited November 23, 2019 by BrendanC

[alacant]

27 minutes ago, BrendanC said:

I've heard tell that the PDS isn't great

Hi. Where?

 

[BrendanC]

On 'another astro forum' which shall remain nameless! (I don't want to get involved in a bunfight!)

Gist is that someone tried to use a ZWO120 cam but couldn't get focus even with the focuser all the way out, had to use adapters to make up the extra few mm. I get that the camera is more for planetary use, and for that you probably would insert a Barlow anyway, but it just gave me the willies, that's all.

The 130PDS thread is truly amazing, and it's pretty much made up my mind. Now, if I could just get my local supplier actually to respond to the emails I've sent asking a couple of questions about it, I'd be sorted. Actually, I may as well copy them here in case anyone can help! These are they:

* Can the mount for the 130P handle the PDS (ie dovetail fitting and weight)?
* Is the PDS OTA good for observing too, as well as imaging?
* Does the Skywatcher auto focuser work with its focuser?
* Finally, what are the chances of being able to sell just the 130P OTA to make up towards the cost of the 130PDS? I've seen loads of ads for the PDS, none for the P.

I just want to make sure I'm not making another mistake. I'm doing this on a budget and can't afford mistakes.

Thanks again, all the responses on this forum have been terrifically useful.

[happy-kat]

You might need to clarify which mount you have as I can't recall it.

The 130pds with an eyepiece needs a two inch extension adaptor (which comes with it I think).

Members some fettle their 130pds to further improve it.

Edited November 23, 2019 by happy-kat

[alacant]

1 hour ago, BrendanC said:

fight!

I think the 130pds thread speaks for itself.

2 hours ago, BrendanC said:

the mount for the 130P handle the PDS

As @happy-katmentions, we don't know what mount you have, but if you want astro-photography and have a relatively easy time of it, have a look at this.

1 hour ago, BrendanC said:

I'm doing this on a budget

Astro-photography did you say? Someone has to be first!

But seriously... good luck and clear skies.

[BrendanC]

This is my full kit: https://www.tringastro.co.uk/sky-watcher-explorer-130p-synscan-az-goto-telescope-528-p.asp

Yes, I know, very basic, better for visual than for photography, etc etc etc

I'm fully aware that I'm not going to get the results as per the 130PDS thread, but I do want to take a next step towards that as an aspiration, and the PDS could just be what I need.

I just need to know if the mount will handle the PDS. I figure they're similar in weight (around 4kg - yes, I actually just weighed mine to check) so it should be fine weight-wise, just not sure of the dovetail and whether the auto-focuser, which I have, will work with it because I'd quite like to keep it.

Totally appreciate that a strong EQ mount is called for, but there's absolutely no way I'm going to spend £999 on one, not until/unless I'm very confident indeed that this is something I want to pursue. 

Edited November 23, 2019 by BrendanC

[alacant]

24 minutes ago, BrendanC said:

This is my full kit:

Hi. In that case, you also need to look at this thread.

HTH.

 

[BrendanC]

Nice shots! Still need to know if the mount for my kit will work with the PDS OTA however...

[happy-kat]

You could add the weight of your motor focuser with your DSLR body to the weight of the 130pds to get a feel for the total weight you are considering of your existing mount will handle it.

[BrendanC]

Which I think would be almost exactly the same weight as the current setup ie a 130P plus DSLR plus motor focusser, which is a shade over 4kg which my current mount can handle ok.

Still don't know definitely if the motor focusser will work with it though, as in physically connect to it given it's a different kind of focuser. I think it will, but don't know.

Still don't know definitely if the dovetail for the PDS will work with my mount. I think it will, but don't know. Apparently the PDS has a vixen dovetail fitting, but I don't know if that's the same as for the 130P.

Still don't know definitely if the viewing is compromised with the PDS compared to the P. I think it isn't, but don't know.

Still don't know what the chances would be of selling the 130P OTA on its own. At all.

So many unknowns! If I can confirm these questions then I'm getting a PDS. If not, then I'll probably be taking the other route ie ditch the DSLR and get an astrocam.

Edited November 23, 2019 by BrendanC

[happy-kat]

If it were me I'd take your telescope off and instead just mount the DSLR with the lens you have on your mount and start imaging with that. There is so much to learn and experiment with that a telescope is not mandatory to imaging plus for the Moon and planets it's generally video clips that are taken to process into a final image and the size of the target is often very small with a DSLR. You can use this resource to check out the target size if imaging or visual.Link here

[BrendanC]

Sorry, should have mentioned: I don't have a lens for the DSLR. I just bought the body thinking, foolishly, that I could achieve prime focus with the scope. Nice idea though, and it's kind of why I'd like to hang on to the DSLR ideally, because it does open other possibilities of much wider field images (also, it's a modded DSLR with the IR filter removed). In future I could get a nifty fifty or a 135 f2 for other imaging. But right now I need to decide on what the best way forward is, with a PDS or a new camera. To decide this, I just need to know the answer to my four questions above!

Edited November 23, 2019 by BrendanC

[BrendanC]

Sorry to bump this thread but I have a chance to get a cut-price 130PDS, but I really must know the answers to these questions first, if ANYONE out there can help:

* Can I put the 130PDS (ie dovetail fitting and weight) on the mount for this: https://www.tringastro.co.uk/sky-watcher-explorer-130p-synscan-az-goto-telescope-528-p.asp
* Is the PDS OTA good for observing too, as well as imaging?
* Does the Skywatcher auto focuser work with its focuser?

Anyone?

[Ronclarke]

I would say YES to all 3 questions.. 👍

[happy-kat]

I found this on searching around. Answers one of your questions. 

Link here