Ships and Stars

I've had the Baader 36mm and now own the 31mm for f5 and f4 dobs. They do have a bit of blur around the edges in fast scopes. I'm happy with the 31mm for what I use it for, mainly a finder ep, but if you are looking for a really high quality EP in this range that doesn't break the bank, the hot one to get apparently is the APM 30mm UFF (ultra flat field) for 199euro or c. £175. The 30mm APM is tested down to f4 and suitable for fast scopes.

I've currently three APM eyepieces - the 9mm, 13mm and 20mm 100deg XWAs. I would rate them against TV Ethos, having owned the 13mm and the 21mm) and I absolutely love them.

I have not used the 30mm APM, but the reviews I've read are all glowingly positive about this eyepiece. When I go to sell the Baader, it will be replaced with the 30mm UFF.

https://www.astroshop.eu/eyepieces/apm-eyepiece-ultra-flat-field-30mm-70d-2-/p,60560 

35 minutes ago, miguel87 said:

Aaah my bad, I didnt think about geographic location. I'm gonna have to skip ahead on my clear outside and see when if my darkness stops down here at 51.6 degrees north!

Have a look online at the 'suncalc' website and equally 'mooncalc', both really handy. Best viewed on a pc or laptop. I use those two frequently.

3 minutes ago, miguel87 said:

Good to know. I always assumed that the black section on clear outside represented astronomical darkness.

Hi Miguel, it does, but it seems that perhaps an hour each side is still dark enough for a quick look through the scope. I'm near Aberdeen, so fairly far north. Last night we had 1.5hrs astro darkness, but after this moon phase, that will be gone until late August here! I'm still going to try over the summer, but only with the smaller dob and binoculars.

2 hours ago, scarp15 said:

My new dark sky location is close to Carter Bar on the Scottish border, a location where there had been past skirmishes / battles between English and Scotch farmers. An area also noted for the lawless Border Reivers. In our time though for encountering Osprey, so 'Dark Sky Osprey' I think. 

Dark Sky Osprey (DSO) love it! Sounds like a good location there on the border. Last night was end of astro darkness, but I did notice a week ago with the unihedron I was still getting largely the same reading an hour after astro darkness was supposed to end, so perhaps I'll be able to view a little over the summer. 

1 hour ago, Astrobits said:

There is a review of the Orion Premium Linear BinoViewer in the May issue of Sky and Telescope. An interesting item as it fits any telescope that works with a normal 1 1/4" eyepiece without extras of any kind ( just more eyepieces!) , even low profile focussers.

Nigel

Hi Nigel,

Omegon also sells these as the 'Pro Triton' and both are on the Astroshop EU website.  I looked at them last year and they were immediately very appealing, but the reviews are not very good, seems they had some real problems with the beam splitting mechanism and the inner aperture is quite small, 19mm I think.

I'd be interested to hear if anyone on SGL has them, and what they reckon? I looked for the review on S&T but couldn't find it. What did S&T make of them?

They certainly look nicely crafted but don't know anything about them. If you go for one, I'd see if you can get the 1/8pv 96% reflectivity supremax 'professional' mirror option listed on their website, a 413EUR option, that would set it apart from the mass-produced 14" dobs, otherwise it just seems a slightly expensive dob for that aperture. In the mass-produced world, the SW non-GOTO flextube is £675 cheaper and the 350p GOTO is £105 cheaper, though the light weight of the Taurus might make all the difference in being able to use it more and the high-end optics option is quite appealing. The build quality looks a step up form your average mass-produced scope. I'd definitely check reviews, but I'm intrigued myself. Let us know what you find out?

PS I see they make a 24" T600! Hmmmm...

I don't think there is really a specific type of scope for asteroids or comets, but if you have the ED80 for imaging and want something for visual, then aperture is your friend as Jonathan mentions. Some people like refractors, but far as I know, they don't go beyond 150mm aperture without spending an insane amount of money.

I've owned a number of dobsonians, and most will agree they give by far the most aperture for the money, are super easy to use, and you can view many of the fainter, more difficult DSOs like nebulae and galaxies as well as asteroids and comets. They will do planets as well, so a dobsonian is a good all-rounder except for astrophotography. A 10" dob (254mm aperture) is more or less the standard for deep sky. I have the 300p 12" (305mm) and 500p 20" (508mm) Skywatcher dobs and can't fault them for the price. The 12" SW flextube dob to me is very portable, some might say it's too big, but the 20" is also portable (for a 20" dob, though a workout!) and gives some mind-blowing views under dark skies.

You can't go far wrong with a 10" dob, especially for price, and if it's not your thing, then you can always get most of your money back out of it, but they are very popular for a good reason and will show you a lot of deep space objects, plus you can easily take it to a dark site if you drive and really let it show you what's up there. 

At 'the ranch' various sites say 20.65 to 20.70, but I've never seen it over 20.42 with the SQM-L and that's with all local business lights off which is highly unusual.

20.20 to 20.35 is as good as it gets, unless it's an exceptional night.

Beyond home, I have code names for my dark sky sites 🤣 (I know, I know...)

Dark Sky Charlie is c. 21.4 and is only about 20 minutes away, the difference from home is massive. Like doubling the aperture.

Dark Sky Bravo is c. 21.55 to 21.60+ about 35 minutes away, brilliant. Saw (or 'detected') the HH through the 12" dob there without much fuss.

Then there's 'Dark Sky Alpha', which I've only been able to measure once. It was 21.85, but I'm sure it would easily crack 21.90 on some of the nights I've been there.  It's dark enough there you can easily detect light on the horizon from an urban area 75 miles away.

Therefore home is a bit of a struggle compared to what's relatively close by, and once the businesses open back up (they were closed before the outbreak) then it's pretty much game over for visual from home. 

1 hour ago, mikeDnight said:

Believe me, after sneaking this one past the wife, fitting it to the mount wasn't nerve racking at all. Thankfully / hopefully / prayerfully she'll never notice the difference. 

My mantra is 'It's easier to beg forgiveness than ask permission' 👍

It's worked out well, I have so much stuff now cluttering everything up, I just say I sold something else which easily covered the cost of whatever just came through the door, and no one can tell for sure.

PS I am a guy with several of those mirror on the bottom scopes, they are great for really faint DSOs, but am looking at a refractor now for imaging. It won't be as nice as yours however. The Tak is a beauty.

20 hours ago, mert said:

Had a pleasant session last night under decent skies with light cloud. I have decided to remove the Argo and Servo and upgrade to the Nexus equivalent. I feel the more advanced option and no need for a large battery will make transportation easier.  The scope is a dream to move and is very smooth. I just need to get it up north to a more permanent location and away from the light polluted skies in Edinburgh. 

Glad to hear it's up and running, as they say.

Also good to hear it's going to live under dark skies! These larger aperture scopes are amazing under dark skies. I'm 20.20-20.45 at home, pretty meh most of the time, and the difference with taking the 20" to my 21.85 site is worlds apart. Like doubling aperture and the sky background is so much darker with more contrast.

Are you thinking about selling the Argo/Servo? I wonder if it would fit my 300p flextube. Was thinking about adding a Nexus system to that. 

Thanks all. I need to refine the alt/az bearing system, just a matter of finding the right size bearings and perhaps nylon shims etc online. It's relatively crude looking at the moment, but I kind of like the look. Want to add spacer sleeves so the binoculars are away from the forks more, but they don't rub as it is. Nothing comes in contact with the paint of course. 

I thought about adding counterweights, etc but will try to avoid that to keep it uncluttered and free of snags from walking around it at night. It actually doesn't need counterweights, it's that solid.

I'm sure it could easily hold any size refractor as well for a super duty alt/az mount.  I've been wanting a 'cheap' 152mm achromatic to try out any way. 

More to come! 👍

That's excellent, it's a victory anytime you can reduce light pollution.👍

10 hours ago, JonCarleton said:

Yep...that's him.  And yes, I flew fixed-wings for 40 years, but almost exclusively gyros now.  They really aren't Ultralights...by US standards, anyway, and the most popular machines are usually 2 place these days.  They are as safe as any aircraft and safer than some.  A lot of people died in the 1970s-1990s trying to self-train and modifying designs making them unstable.  That gave them a bad reputation.  Most of that has gone away over the past 20 years.

I flew a few times in a powered parachute a neighbour had (rotax motor) - it was interesting in a breeze! I liked it on a calm day. One of his flying friends who lived down the road from me - and who I knew through work (mechanic) - apparently decided to use nyloc nuts instead of wired aviation spec fasteners, and he took the plunge one day from a high altitude when a brace or something folded. I never got the full details. That would have been around 1996 or 1997 in Southern Indiana. 

I still harboured thoughts about flying, but looked at gyrocopters after that.

Good luck with your camera set-up. Let us know if you find a good solution to increasing FOV!

My plan was to attempt mirror grinding and figuring for a larger dob this summer - I suspect that would easily burn up a summer and astro darkness would return in no time!  

It might also kill any interest in astronomy...

I've changed tack slightly though. I'm sticking to making and improving some alt/az fork mounts and tripod configurations for my observation bins and perhaps a large refractor...

And reading about galaxies and nebulae. I've tons of reading material now.

An interesting link to that!

https://madmax.fandom.com/wiki/Gyrocopter

Gerry Goodwin!

Ah the avatar is quite small but it's Donald Sutherland in Kelly's Heroes, however it does look a lot like the gyroplane fellow from Mad Max, another one of my favourite films! I always wanted one of the big air-cooled Kawasakis after watching the original. And the police interceptor and the gyroplane after watching the second one The gyroplane pilot that's a friend of yours was in the right place/right time! Very cool. I'll have to watch that again. Out of curiosity I looked at gyroplanes years ago, they seem fairly safe in regards to other ultralight aircraft and lots of fun. I'd love to fly one along the coast here or up around the hills a bit. 

10 hours ago, JonCarleton said:

Hmmm.  Stiching might be a solution.  Interesting results you got there!

This was sort of an accident, I was trying to image three separate sets of small (tiny) galaxy clusters in Hercules centred around NGC 6173 and NGC 6160 and NGC 6145 (I think). Had I thought of this before hand, I would take 50 subs, slew over about 50-66% of the frame, repeat, and so on. If you keep everything the same, i.e. same sub exposures, ISO and developing settings, they should stitch together in ICE in a snap, takes my 11 year old desktop about 30 seconds to stitch them. I'll try this again with more thought next time 👍

10 hours ago, saac said:

This is our 16 inch Dob,  built as school telescope with a mirror gifted by Andrew S (forum member).  It's a bit heavier than perhaps it needs to be and at F5 it calls for a stepladder but the views are fantastic. It's a sight to behold when I have it in the classroom the kids are mesmerised by it. My long term aim is to try to get some spectra with it to maybe confirm the blue shift  of Andromeda as this would link in really well to our Higher physics curriculum. I don't know how practical that may be but your photographs with your 20 inch Dob have inspired me.  The lock down will give me some time to experiment. 

 

That's a beautiful looking dob! F5 is good, less coma and less fussy on expensive eyepieces and more forgiving on focus. There is a big jump in coma between f5 and f4 from my experience and focus at f4 has to be just spot on for sharp images. 

A stepladder only adds to the drama of the moment - the process of climbing up to have a look lets you know you are using a BIG telescope  

1 minute ago, vlaiv said:

Top right - NGC7331 (main) - Deer Lick group (with smaller surrounding galaxies)

Bottom left - Stephan's Quintet

Thanks Vlaiv, Stephan's Quintet is incredible...👍

9 minutes ago, saac said:

I love those images; never thought you would have managed that with a Dob, well done. Any plans to experiment with DIY equitorial tracking base, I think they can give 30 minutes worth of useful eq tracking.  That said your images are already impressive -  you have given me some food for thought with our 16 inch dob.  

Jim

Thanks Jim! I'd love to double the number of subs for each of these but the weather has gone quite cloudy for the duration. I think if I add darks flats etc they will be decent, and they are still quite high resolution images, even after a heavy crop. 

I looked at an EQ base, but I think at my/our latitude the whole thing would fall over! I'd have to pour some kind of concrete pier and bolt the base to it or something, but will revisit that idea again after the past few weeks. 

If you have a 16" with tracking or a EQ platform etc and a DSLR, I'd say give it a go. Focus is very important of course, and stability, etc etc. A little practice saw a lot of improvement in my images in a short span of time. 

Although I want an EQ mount an refractor/astro cam now, it's fun to see what a dob can do.

23 hours ago, ollypenrice said:

I'm perfectly happy shooting galaxies with a focal length of a metre. I don't think I would lose much if I came down to 800mm provided I used slightly smaller pixels. You can crop images so that they instantly appear at, or close to, full size when opened on a forum like this. These are at about a metre.

 

Olly those photos are spectacular! May I ask what galaxy this is above? I'm fascinated by the interacting galaxies in the lower left. My novice brain is drawing a blank. 

22 minutes ago, JonCarleton said:

I've had pretty good luck with my camera (SVBony 305) and the 10" Dob with respect to getting enough lights to stack and get reasonable images.  The big problem is FOV.  I also have an Olympus DSLR that I haven't tried yet, but I expect that the difference in FOV would be minimal without something else going on.

I do understand the differences with Alt/Az versus EQ mounts, and have found that I can get by reasonably well by using short exposures.  This, presumably, because I collect more light pressure per second with the large aperture.  The problem I am trying to solve is really FOV, although, I asked the question in a way that I hoped would bring to light some other surrounding issues.  It seems to have done so.

Thank you all for your input!!!!!

What if you did multiple panels and stitched them together to get a wider FOV? You'd have more detail as well presumably.

I just tried this the other night on some obscure galaxies in Hercules simply for a record shot, it's not a great image but kind of fun to mess with. I combined then using Microsoft Image Composite Editor.

One way to get more FOV so to speak without a focal reducer (never used one, but would be interested to know if it works).

Just a thought!? 👍

1 hour ago, ollypenrice said:

Your pictures really are very good for the equipment used. Hats off. I don't agree with your view of aperture/ light grasp. It is not a simple matter of how much light you grab, it is a matter of how much light per pixel you grab. There are informative discussions on the forum including this one: 

 

What matters is not the total light grasp of your scope but the amount of light per pixel it puts on your chip. 

Thanks for clearing that up Olly, I assumed more aperture would simply create a quicker image with less exposure time. I certainly will go with your opinion! That's good news actually, if I do take up imaging I won't be obsessed with aperture like I am in visual astronomy.

I've not read up much on astrophotography, other than a few basics, so lots to learn. I may buy Make Every Photon Count, lots of praise out there for that book.

Thanks also for sharing the article on small galaxies, that's just the sort of thing I was attempting last night. Hercules galaxy cluster, mixed results!

All the best and thanks for the information.

After spending almost two weeks imaging with a 20" SW dob with goto  it's hit and miss and you will be taking thousands of exposures and deleting a lot of them at times. With a 10" dob (still a fairly large scope) you'll need two to three times more exposures to capture the same amount of light and/or detail presumably. 

I'm using a full frame camera but the image circle only really covers about half the total sensor area. I shoot in 5:4 mode and crop heavily, maximum 8" subs at ISO 400 or 800. At least 75 really to get enough decent data for an image, and upwards of 200 is not uncommon, plus darks/bias and flats (which I've yet to do).

Sometimes the mount tracks nicely for short exposure photos, sometimes it's jerky and all my subs get deleted. Not designed for imaging as Olly says, but possible if you are determined. It's fine for visual, which of course a dob excels at. The only thing going for my setup is sheer aperture, I can get in 30 minutes integration what would take a refractor or small reflector 2-4 hours I'm guessing, but there can't be any wind and the mount has to perform near perfectly. Plus taking subs near zenith can be impossible. It's a fun experiment and if you have a go-to dobsonian and a DSLR laying around with a remote release or intervalometer or interval setting, go for it, but you'll have to be patient! Otherwise look at a proper imaging rig. Hope that helps.

PS still working on getting the colours right, so sticking with B&W. Images below are lights only, between ten and twenty minutes total integration I think, no darks, dark flats, bias or flats. 

FLO has these on sale if your budget can stretch. Also the larger 20x80 pros are on sale for £165. Also the Helios Stellar in that price range. The Helios are very well regarded, I've the 15x70 Apollos as well but you defintely want a monopod or tripod for those. 

https://www.firstlightoptics.com/observation-binoculars/celestron-skymaster-pro-15x70-binoculars.html

Also look at first light optics, the site sponsor. Their prices are hard to beat and a good selection.