vocalis

11 hours ago, Zermelo said:

The folk who image DSOs on alt-az hang out here:

Thanks Zermelo, I couldn't find it! Interesting read

22 hours ago, Louis D said:

You'll need a field derotator for DSO photography with an alt-az goto mount.  Alternatively, you can stack lots of much shorter exposures.  I believe there's a thread on SGL covering this technique.

Another alternative is electronically assisted observing using night vision technology.

Thanks Louis D. I never heard of a field derotator before! It seems like adding an extra layer of complexity!

I have a Skywatcher 127 SynScan AZ GOTO telescope. I find it pretty good for planetary observation but disappointing for DSO.

I'm considering a Skywatcher  250PX Flex Tube SynScan GOTO Dobsonian. To start with just for observation but eventually for astrophotography.

Any advice from the forum please?

Consider one of the Netgear Orbi Mesh systems like the RBK50  or even their newer (but more expensive) WiFi 6 systems.

The RBK50 covers up to 5000 sq ft and I find it excellent to cover the whole of my garden, which is big.

You could place the satellite unit indoors closer to the area where you're going to place the telescope. It should cover 50 feet easily.

Thank you Neil H, wrvond, reezeh and Ricochet for your very helpful replies.

It all makes much more sense now! 

It was particularly helpful to learn why some EPs are more suited to slow scopes like mine and some to faster ones; thanks rezeeh and Ricochet for pointing that out!

I have a Skywatcher  127 SynScan AZ GOTO with a set of BST Starguiders eyepieces, 8mm, 12mm, 15mm and 18mm

I am basically new to astronomy although I bought the scope in 2015

I'm trying to educate myself as much as I can but at times things can get too technical

I often read about EPs or diagonals in reference to "slow" or "fast" scopes and it's not clear to me what that means and if my mak is fast or slow.

Thank you!

23 hours ago, Louis D said:

Just be aware that if they are the same as the WO and other brandings, there's a 22mm or so lip inside that will vignette widest field eyepieces.

I've got the same type, and can verify the unnecessary baffle.  Since I only use it with binoviewers of 22mm clear aperture, it doesn't matter much to me.

Perhaps @FLO can verify if the StellaMira version does not have it.

Thanks Louis D. Good to know!

23 hours ago, Tiny Clanger said:

I had read that the standard diagonal was not great, and when the 'scope arrived it did seem a bit flimsy, but it's my first ;scope which uses such a thing, so had nothing to compare it with. I decided a slightly better dielectric star diagonal would be a good eventual upgrade, and noted there are two identical models on FLO at identical prices , currently £69  https://www.firstlightoptics.com/diagonals.html

which look like better made items without being silly money . I'd added them to my wishlist when a chance at a second hand one came up on the buy/sell here so I went for it. It has a much nicer engineered feel to it, is sturdier, and has one screw and a collar arrangement to hold the eyepieces rather than the original's  screws which might scratch the eyepiece barrel.

Exactly as with the 25mm eyepieces I've not taken the time to actually compare the views between the two diagonals, the better one was simply obviously better ! If I'd bought it new from a dealer, I would have compared them as I'd be able to return it if I didn't think it worth the expense. Which, by the way, is somethng you can do with eyepieces , distance selling reg.s in the UK give you that option. For the BST 25mm it might be worth checking if Alan at Sky's the Limit has any in stock, he is a good chap and responds to emails . https://skys-the-limit-108154.square.site/shop/1-25-bst-starguider-ed/8

After coming in last night and typing my reply aboutthe eyepieces, I stayed up and went out again with my 150 heritage dob after the Moon set at 2am ... the 25mm BST is really not as nice in it , star shapes were distorted around the edges of the view,  I found the 15mm BST better to use.  The mak 127 is f11.8, the little dob f5, so the dob is showing up shortcomings which do not bother the longer focal ratio mak .

Oh dear, I may have to look around for a better ( for better ,read expensive) low mag EP specifically for the dob now !

Heather

Interesting Heather! Thank you once again for your time and good advice.

Raff 

23 hours ago, Tiny Clanger said:

But ... you are a penguin ! 🐧 The weather should be ideal for you 🙂

True! I must have forgotten....  🙂

Thank you very much Tiny Clanger. Your post is extremely helpful and gives me a very good idea of what to expect from the different EPs

I think I will go for a 25mm Starguider to complete the set I have already.

Will check the FLO page you mentioned: I didn't know about it.

As a matter of curiosity did you buy a better 1.25mm diagonal than the one supplied with the mak 127?

Like you I took the chance to get my scope out last night mainly to test the SynScan WiFi adapter I recently aquired. 

It was so freezing cold that I thought I might end up just like Jack Nicholson in The Shining!

Thank you everybody for your comments. Food for thought!

8 hours ago, Zermelo said:

The stock Skywatcher 25mm has a quoted 50° apparent field of view and 21.8mm of eye relief. It is giving you 0.83° true field of view in the Skymax.
It's a "modified achromat" design - not awful, not great either.  Your Skymax at F/11.8 will give it a good chance. I found some obvious pincushion distortion on my F/5.

You would certainly notice the difference with the BST (60° APOV, 16mm eye relief) which is well corrected for most aberrations. Some have reported a little edge distortion on faster scopes. It would give you a TFOV of 1°, which is about the best you can get unless you go for 2" format as described above.

Now that you have used the other BSTs, you should have a better idea on whether you think it's worth the spend for the difference in performance (and the wider view).

 

 

Thank you Zermelo. Any suggestions regarding the diagonal?

19 hours ago, Louis D said:

First, don't bother with a 2x Barlow given the f/12 focal ratio and 1500mm focal length.  The 8mm will provide just about the highest usable power with your scope.

The 25mm BST or a 32mm Plossl would work well for widest field.  The BST would be wider and would fit in well with the rest of the BSTs.

If want to go wider, you can put a SCT thread adapter on the rear thread, install a 2" visual back on it, and then use a 2" diagonal.  With a 2" diagonal, you can use wider 2" eyepieces.  There is some vignetting and some odd reflections of bright stars with them, but I've found it actually works very well.  Here's an image comparing the difference:

Thank you Louis D, good advice.  With the 2" diagonal I would need to change all my 1.25" eyepieces, right?

Hi everybody. 

I'm a newbie to astronomy having returned to it after a while.  

I bought  a used  Skywatcher 127 which came with the entry level 10mm and 25mm wide angle long eye relief lens.

I read that these are the ones that most definitely needed upgrading so I went for a used set of BST Starguiders eyepieces which were available for a good price and had seen recommended here.

I have a 8mm, 12mm, 15mm and 18mm

Would it be worthwhile to upgrade the 25mm eyepiece? If yes what would people suggest? A 32mm Plossl?

I read also that the diagonal could do with an upgrade and I should get a good 2x Barlow, as the one which came with the scope seems rather basic.

My budget is not unlimited but would like to do justice to the scope.

Thanks in advance!