raadoo

41 minutes ago, mikeDnight said:

DZ on APZ 

 

For a minute there I thought you had two identical setups next to each other 😅

No one has mentioned it, so I'll chip in another candidate: the Orion Optics OMC 140 https://www.orionoptics.co.uk/product/omc140dx/

I don't have personal experience with one, nor can I remember anyone who has, but it does fit the requirements, albeit at a much higher price than the aforementioned Bresser and Sky-Watcher alternatives.

23 minutes ago, doublevodka said:

They are a bit of a one-trick pony, but they do that trick very, very well! A member of my local astro club has a RASA 11 and the pictures are really something else

A 9.25 though, f/10 standard, f/2.2 hyperstar, 0.7 reducer for f/7, 2x barlow for f/20 on planets really can be a bit of a Swiss army knife, albeit an expensive one once you add all those accessories, but there are lots of them around so the used market is ok and well supported with accessories etc. so maybe a little easier overall than an exotic newt?

Food for thought, indeed.

Alternatively, I could reconsider the 8" f/4 and try and pair it with the minuscule pixels of my 183.

Definitely have to do some back-of-the-napkin math for this one.

4 minutes ago, doublevodka said:

2.8 to 3.5 seems to be quite exotic, had a quick search myself and no results in the size range so far, but I suspect they would be very expensive and niggly to collimate to say the least

An 8 inch Quattro would fit the length limit though - https://www.firstlightoptics.com/skywatcher-quattro-f4/skywatcher-quattro-f4-imaging-newtonian.html and there are dedicated coma correctors

Alternatively the StellarLyra - https://www.firstlightoptics.com/stellalyra-telescopes/stellalyra-8-f-4-m-lrn-newtonian-reflector-with-2-focuser.html (slightly cheaper on the coma corrector side too)

I know you ruled them out, but with a bit of digging on the used market, you may be able to get a hyperstar based setup in the same ballpark, they do occasionally come on the market

Even an 8 inch F/3.2 is £3,199 - https://www.firstlightoptics.com/sharpstar-telescopes/sharpstar-2032pnt-f3-2-paraboloid-newtonian-reflecting-astrograph-telescope.html, can't imagine what a 10 inch would be, an 8 inch RASA is cheaper for referrence - https://www.rothervalleyoptics.co.uk/celestron-8-rowe-ackermann-schmidt-astrograph-rasa-ota.html

There does seem to be a very steep increase in price when you move from f/4 to anything faster, when it comes to Newts. I'd expect them to be more expensive but for a wee bit faster aperture you seem to be paying out of every orifice.

Good shout about looking for a used hyperstar; maybe pairing it with a standard 9.25 to keep cost down.

RASAs are the fastest option by far - my only concern is that they're a bit of a one-trick-pony. You can always un-hyperstar an SCT and use it for planetary work. And you can always chuck a 1.5x Düring Barlow on a Newt. But a RASA is a RASA is a RASA.

29 minutes ago, Alkaid said:

I would also consider the mount / tripod when the feet are 'splayed', my EQ5 is well over 90cm across the floor when the legs are out so wouldn't fit....   What will you mount the scope on?

I'm using an RST-135, and having had a Mewlon-180c in full imaging garb on it with good results (measured at 80cm from front to camera), I'm quite confident in its ability to handle a similarly sized Newt.

I've googled long enough to confidently resort to your collective knowledge in helping me track down a bit of unicorn.

We all have some personal limitations when looking at OTAs and quite often they refer to size. In my case, I'm limited by my long, but narrow, balcony - specifically 90cm. This 90cm limit includes image train and possible dew shield.

As I'm looking to dip my toes into some short exposure DSO imaging, aperture and speed are my main priority for any OTA, so a fast Newt seems like the most cost effective way to get there*. The obvious go-to would be a 10" f/4 but a quick bit of math puts any Newt of that configuration at about 100cm long.

An 8" would fit, but I doubt that's enough aperture for the intended purpose. Anything over 10" would be too heavy for my mount and certainly longer than my 90cm limit.

To cut a long story short:

Does anyone know of a 10" Newt with a native f ratio of between 2.8 and 3.5?

*RASA / Hyperstar setups fit the bill but cost is beyond what I'd be comfortable with.

Thanks so much for taking the time to reply, Tim!

Thankfully, I won’t need to move the CAA’s position as, upon close examination, it turned out that there was a 30mm extension sandwiched between focuser tube and CAA. It came attached to the scope so I didn’t give it a second thought, believing it to be part of the focuser tube itself.

Having regained about 25-30mm of focus travel, I’m positively jubilating, not to mention grateful for your help!

9 hours ago, Which one is Polaris said:

I had this problem.

I moved the CAA to downstream of  the Reducer.  Now the Reducer is hard up to the backend of the focuser.

This released a lot of inward focus travel (the length of the CAA).  Also, the CAA is now used as a Spacer, and in my case was M63, so helps delay the necking down to M48,.  This improved vignetting.

 

Cheers

Brilliant solution and one that certainly makes sense!

My CAA is a measured 20mm thick so I'm slightly doubtful that moving it after the reducer will not overshoot the backfocus requirement.

What does your image train consist of, if I may? It'd be massively helpful. Thanks!

I believe I've landed in stump-land with a new imaging setup I'm putting together.

In a nutshell: dialling in proper backfocus for my reducer causes the focuser to lose inward travel.

In depth: I used the classic "look at the stars in the corners and add shims until they no longer radiate" and I'm very close to getting it perfect (<1mm). Trouble is, as I've increased the distance between sensor and reducer, the focuser (situated between scope and reducer) has had to move ever more inward to achieve focus. This to the point that I now have no more inward travel available and cannot achieve proper focus.

I'd massively appreciate any ideas, thoughts, opinions or guidance.

_

Image train is:

FS-60CB ⇢ CAA (TKA21200) ⇢ Reducer (TKA20580B) ⇢ Adapter to M48 ⇢ OAG ⇢ Filter Slider ⇢ Shims ⇢ Camera

It's been a while in the making, but here's my little 127 in full imaging garb - the odd imaging mak among so many visual setups in this thread.

I figured you lot will get a kick out of the sheer madness of this setup, so I've marked up what's what.

Before anyone jumps in, yes, I know I'm oversampled and I know that Maks aren't the best tool for imaging.

That being said, last night was the first clear night since end of October, so I've quickly started working on M81. The below is just 2h, but I'm aiming for somewhere north of 20h in the end.

It ain't perfect, but it's better than nothing!

On 15/12/2022 at 13:42, pipnina said:

The big problem with adapters like these is they consume a lot of backfocus. This one starts at 20+mm, which is as thick as my filter wheel! They could be suitable for some of the fancy refractor, or typical cassegraine correctors, but where most correctors ask for a 55mm~ spacing, you'd likely have to give up an important bit of kit to accomodate one of those. I think that adaptor also would rotate the camera as you perform an adjustment? I can't quite tell.

It's an option I've considered but they don't seem like they'd be helpful for anyone using a 55mm spaced corrector, unless they only need the camera and an OAG perhaps.

It also moves the camera so definitely affects focal position, I don't know how much moving the corrector only affects the focal plane position but it could cause less motion and allow easier "real time" view of the corner star shapes changing.

It seems someone at TS has been listening. They just released an adjustable corrector: https://www.teleskop-express.de/shop/product_info.php/info/p16155_TS-Optics-Full-Format-0-8x-Corrector-for-APO-Refractors---M92x1-Connection---ADJUSTABLE.html 

You could have a go using one of the variable adapters that you see from TS / Altair / Optec? They promise to allow you to fine tune the backspacing without taking things off the imaging train.

I have no personal experience with these adapters, but perhaps SGL members who do can chime in.

Right, guess I'll play the outlier, then.

By the looks of it, a lot of things in this astrophotography business are new to you, so I'd suggest swapping the Mini PC for an ASIAir Mini (hold that thought*) as a stepping stone while you get familiar with all the terminology, quirks and, overall, your setup. I believe the most important thing to actually driving you forward in imaging the night sky is, well, to actually produce an image or two. The sooner you can produce an image, the less likely you are to abandon the practice altogether. For all their faults, ZWO have actually put together a decently intuitive interface in the ASIAir. There's not much in it to trip you over, barring the social features they added in the latest firmware. It's a fairly straightforward path of Focus > PA > GoTo > Guide > Autorun that can get you looking at subs coming in within about 15-20min.

NINA is very powerful, supports a myriad of devices, can automate everything and their grandma, you can enhance it even further with plugins and it's open source, to boot! There's two things I'd argue that NINA does not do well: 1) have a progressive, easy to follow, beginner astronomer's guide and 2) an interface that most people, but especially newcomers, find intuitive and easy.1

* I'm specifically suggesting the Mini version of the ASIAir as it's the least expensive way to get the Air experience, at £228. Once you feel comfortable to use the Mini PC as the permanent brain of the whole operation, the ASIAir will, effectively, become either a backup or, more likely, a sparkly red paperweight. Or, if you end up like us lot, use it as an excuse to get another telescope.

1. I'm actually working on contributing to NINA trying to address these very two features; if everything goes well these two points may become soon-to-be-forgotten history.

For anyone else that may find themselves in a similar situation and the shoe sole trick doesn't work, you're probably slightly screwed.

I reached out to ZWO directly to ask about the adapter they use for their mini cameras. They didn't mention the thread on the cameras, but did try to sell me a replacement:

It is possible to purchase the black adapter separately.
It is $10, and the shipping cost is $30, so the total price is 40USD.

Needless to say, I wasn't too happy about the idea of paying $50 (that's including VAT and customs) for a tiny, simple, thread adapter.

I then reached out to the fine folks at TS, but they unfortunately don't stock any such adapters.

👟

On 26/10/2022 at 12:03, david_taurus83 said:

Have you tried the rubber sole technique?

Place the filter/adapter between a pair of shoes/trainers/sneakers with soft soles, press together and twist? 

Finally got around to trying some other methods and your shoe sole idea kept lingering in my head.

Turns out, this method works best when you use the heel side of the shoe.

Regardless, it worked! @david_taurus83, I cannot thank you enough for what seems like something I should have known already.

1 hour ago, 900SL said:

Well, I've done the usual all round the houses twice on this one. Which is a good thing, as I think I had aperture fever combined with a case of keeping up with the Jones's.

On reflection (or should that be refraction), and after carefully considering my set up, preferences and having a good look at telescopius framing, the scope that seems to make the most sense is a 90mm f6 TS CF APO 

This seems to be a good match to the 533MC and D5600, in terms of resolution and FOV.  

It also has the advantage that I can use my existing WO 6Aiii 0.8 flattener/reducer, or use a Barlow for lunar etc

It won't overload my SXD2 mount, should give me a reasonably portable set up, and guiding should be a breeze.

Its not a big step up from the GT71 but I'll probably sell that, as the TS 90 is a better match I think.

My primary interest is widefield nebula, the usual suspects. I've still got a long way to go with imaging and processing, so don't intend to go much deeper for quite a while.

That will leave me with a Samyang 135 wide field, a Redcat 51 wide field (both for portable travel use with a Fornax LT)  and a 90mm for getting in closer on the SXD2

I think you went about it the best way possible, by building an arsenal that [almost] doubles focal length with each step. Camera and sampling notwithstanding, this is likely the best way to grow into ever more magnification without hitting that proverbial learning curve too hard.

You've now got:

• 135mm (Samy)
• 250mm (Redcat)
• 540mm (TS)

Looking into my crystal ball, your next additions should be something like:

• 1000mm (8" f/5 Newt)
• 2032mm (8" SCT)
• 3910mm (14" SCT)

Looking forward to seeing if my predictions turn out. 😊

On 26/10/2022 at 13:08, knobby said:

Also try slightly warming the larger part.

Gave this one a go as well, using a low power heat gun. The threads must be bound really tightly cause there was no give.

On 26/10/2022 at 12:03, david_taurus83 said:

Have you tried the rubber sole technique?

Place the filter/adapter between a pair of shoes/trainers/sneakers with soft soles, press together and twist? 

Wasn't aware of that technique. I gave it a go, but sadly they didn't yield. 

8 hours ago, knobby said:

I can't be the only one that thought this was a thread about zwo mini cameras 😂

😂 I guess I could have titled this thread a bit better!

8 hours ago, david_taurus83 said:

Have you actually damaged it or you can't get the filter off so looking for a replacement?

No damage yet, though I have gone hulk on it, trying to pry the filter off.

So, yeah, filter won’t unthread; it’s definitely bound on there.

I’m looking to replace the 1.25” adapter so I can use other filters.

20 hours ago, Tomatobro said:

male M28. 5x0. 6 thread

Weird that the pitch of the thread is the only difference. Any idea where one can source one of these adapters from?

You know the little black thread adapter that ZWO have on all their guide cameras?

Well, apparently, if you leave a filter on there long enough it binds itself to the threads so much so that there's no way to unscrew the filter without destroying the whole thing. 🤷‍♂️

I'm thinking these shouldn't be too expensive to replace, but for the life of me I can't find any information on what the camera thread is! 🤦‍♂️

All I can see is that it's just slightly larger than 1.25" (M28.5 x 0.75).

Do any of you file folks know what this thread is called / what size it actually is? Even better if you can point me towards an adapter from this unknown thread to 1.25"!

Does anyone know anything about this ASI991MM? https://astronomy-imaging-camera.com/product/asi990mm-pro-asi991mm-pro-2 

Apparently, ZWO are entering the scientific, SWIR game?

Here's a step by step that will hopefully this will clear things up:

1. Split your stars and background into two images
2. Use Photoshop's File > Scripts > Load Files Into Stack script to load the two images
3. Once you hit OK in the script dialog you should have the two images loaded as individual layers
4. Make sure the image of the stars is the layer above the background
5. Change the stars layer blending mode to Screen

I've attached a few screenshots of what these look like.

@Alexgc here's my take on your M31.

I often find that it's easier to learn by deconstructing what others have done, so I've also attached the PSD file. It ended up quite large at 829MB, but I didn't want to cheat you out of pixel peeping at the full 24MP 😁

I tried to keep as much of the editing using only Photoshop's tools, so at least these will be tools you're familiar with.

The one thing that I used that's not native to Photoshop is StarXTerminator (similar to Starnet++) to break apart the stars from the galaxy. SXT comes as a Photoshop plugin for added convenience.

22-9-24 Andromeda.psd