Stuart1971

24 minutes ago, Adam J said:

Yeah but you can say that about anything second hand Vs new. 

You can get a used 294mm for cheaper than a new 533mm....etc etc. 

exactly my point, so a beginner can get  better bang for buck buying second hand…IMO…👍🏻

Hmm, I think £200 extra for a TEC cooler is a lot TBH, especially when you can get a good secondhand 533 for around £550 now, which is a much better choice for a beginner with £600 to spend…and the 533 sensor, is pretty much double the size of the 585..

No problems with any sag or tilt being introduced with the DSD version…???

2 minutes ago, teoria_del_big_bang said:

Hi Bryan,

Glad I could be of some assistance but looks like you sorted much of it yourself.

Whatever, I am just so glad you have got it all working and hopefully like myself will come to think it is one of the best things I did to upgrade my rig, so easy when used with NINA to get perfect alignment of images session after session on same target .

Steve

I had the Pegasus version, and had it fitted between the scope and the flattener on the esprit 100, as did not have room the other side of the flattener, due to have a tilt adjuster fitted there, Pegasus supply the correct adopters to fit in this space, but they were an extra £70, it also meant the focuser did not need to come out as far, as this took up some of the backspace which was a bonus too…but I just found I never used it so took it out and sold it…maybe I will regret at some point…

I have the DSD motorised flats panel and that is superb…👍🏻

21 minutes ago, AstroGS said:

@Adam J @Stuart1971 I thought so too. We changed the orientation of the filter to eliminate this possibility and the results were more or less the same. Another thought was that Pertzval design OTAs might be more susceptible to such effects - especially on OIII @ 2.8nm. But, since the SII & Ha Antlia filters are excellent, I consider the OIII to be defective and will be returned.

The Petzval design should actually be better, as the flattener built into the scope is much further away from the sensor, to make a reflection such as what you are seeing,  so any reflections from that glass, going back to the sensor will be spread too wide by the time it reaches the sensor, your reflections are from a source much closer to the sensor itself.

My guess would have been the filter anti reflective surface that should point toward the sky is actually pointing at the sensor…but you have tested this so I am at a loss

9 hours ago, Adam J said:

Interesting that you are getting microlensing from a ASI2600mm?? Anyone else ever had this? Are you sure your filter is the correct way around?

Adam

Yea, my thoughts too, I have only ever seen this from the ASI1600..🤔

Brilliant review and comparison, the Optolong L-Ultimate 3nm comes out really well, much reduced noise too as well as nice small tight stars…

Some Halo on the L-Extreme and a bit too on the Askar, but the Optolong is excellent…

What I would like to see is if the Optolong produced halos on longer exposures, or whether it would still be halo free, as comparing it to 6nm filters for the same exposure length does not seem totally fair…so for example, a 3 min exposure on the 6nm variants against 6 mins on the Optolong Ultimate…would be interesting…

‘Excellent post all the same…👍🏻

4 minutes ago, Skipper Billy said:

Nope - no reducer or flattener. This is a very heavy crop - maybe less than 10% of the whole image using the Blue filter - the Oiii is just the same.

Hmmm, yes they are pretty bad, and also more worrying is the halos are off centre too, which only  normally happens at the out edges of the image, would not expect this at all with a Tak106…

I used to get halos off centre like that with my Baby Q which turned out to be a really poor example, with bad collimation issues…

5 minutes ago, Skipper Billy said:

I wish I hadn't read that! I am having issues with my Baader Blue & Oiii filters and was considering a set of Antlia 2" filters as a fix!

Do you use a flattener or reducer in your imaging train..? If so one thing to try is to put the filters on the telescope side of that, and you may find the reflections will be diminished..👍🏻

This was just a slight crop and a little stretch using just my iPad, hope you dont mind, if you do I will happily delete….👍🏻

That’s a superb image, 👏🏻👏🏻 but I can’t help but feel it could be stretched more to reveal more dust around the nebulas, exquisite all the same…

2 hours ago, drivera said:

Hey,

I tried to quickly surmise my situation in the topic!

So in the UK it's been terrible weather for months and with limited time (can't image during the week) it was about 2 1/2 months since I have tried to image. I have a GT71 setup with a ZWO 533MC, on my GEM45 (don't get me started but won't be upgrading soon).

I went to image about 3 weeks ago on my first calendar cleared/clear skies and I suddenly couldn't get focus, even more, the stars were off and my mask couldn't pull any spikes. I always take my scope and gear all off, don't touch it, store it and return it for my next session. Something has gone wrong and maybe suddenly knocked (wife wants to blame a cleaner, and I want to blame the wife so we resulted in natural causes and force majure).  I'm doing first tests on it on my next clear night such as removing the flatenner to see if it is that or not. Otherwise, something has damaged the scope and it seems FLO are manic busy can't do any tests, and I will see if Rother Valley can do a check. It's also out of warranty.  

So...back to my main next question. I'm going to have to buy a new scope. I've loved the GT71 for widefield and it's beautiful but I would love to get into galaxies more. I have been trying but unsuccessfully identifying the right scope like a RC8/10 that would provide great images for galaxies, but under acceptable GEM45 weight (45lb/20kg).

I'll be imaging with my 533MC until in the next 4-6 months I'll step up to mono (not sure which camera).

What scope would you go for to image galaxies but can handle the weight on GEM45.

Thanks!
 

Send it to RVO, they have the kit now to do full Zygo tests, and re align if needed, I don’t   think FLO have any kit like that, and would need to send it out to someone for testing…I have mine done at RVO and they were excellent…👍🏻

55 minutes ago, ollypenrice said:

When I started processing the crop I had it in a vertical orientation and there was something slightly disconcerting about it. It made me feel distinctly uncomfortable and I think you've identified the reason why.  It was a relief to find that its orientation for us was horizontal. Once rotated, I no longer felt spooked by the darned thing...

I do think that Paul's RASA has performed out of its skin, finding so much detail in a tiny object for a 400mm widefield focal length - and in broadband.  This is my answer to doubters who don't like its numbers on paper. In no small measure its success, here, is down tho the volume of signal it found in 5.8 hours. In the real wold of imaging the relationship between signal and resolution is complex. They cannot, on targets like this, be considered as independent properties.

Olly

So how do you stand in the age old Mono V OSC discussion…as you certainly seem to have taken to the OSC on the RASA…? Do you not feel that you miss mono imaging, as I know it’s pretty hard with the RASA set up with not being able to use a filter wheel.

5 hours ago, ollypenrice said:

Paul captured and pre-processed this with an eye on using it to enhance our Orion-Monoceros mosaic, which I'll look into later.

Initially I found a very nice starfield and a very small nebula in the data:

However, looking at the nebula at full size, it proved surprisingly interesting so I did a close crop and a more intensive star reduction so as to present it like this:

RASA 8, ASI2600MC, NEQ6. 116x3 minute subs.

Edit: blended into our giant mosaic it looks like this, if you can find it! (Below the Monkey Head nebula.) https://ollypenrice.smugmug.com/Other/Emission-Nebulae/i-G8HJCM3/A

Olly

 

Olly, with these superb broadband images you regularly post, and are using a 2600 OSC camera, do you use any filters at all, ie, any light pollution suppression such as an L-Pro or similar…? Or are they totally unfiltered…?

4 minutes ago, ollypenrice said:

I have changed my view on the RASA, for sure.

When time is limited, my view is that the priority has to be signal. I've come to feel that that's the case when time isn't limited as well. Obviously the signal has to be of a certain quality but in a trade off between slightly better star shapes and four times as much signal, I'll take the signal.

Olly

Edit: I entirely agree about choosing gear which suits your habits and preferences. Same with software. We need to be happy and comfortable.

I agree, we can do something about the star shapes now with BXT, but there is no Xterminator tool “yet” that will add more signal….👍🏻

8 minutes ago, Peter Drew said:

I also think it is Newton rings, the mating surfaces have to be quite close to show them and it's possible that thermal equilibrium can make them more or less easy to see.  Try looking at the objective under a monochromatic source like a strip light, this makes the rings easier to see.  I would be more concerned if the rings were significantly off centre or distorted in shape.      🙂

Yea, at least it shows it well collimated….👍🏻

Looks just like a collimation concentric star test image…like the one I got on my Zygo test with my scope, that’s really odd….🤔🤔

1 hour ago, Icesheet said:

I don't have enough clear nights to justify the amount of scopes I have so I’m going to thin down, again! I currently have a number in the 250-400mm FL range and I plan to sell them and replace with one dedicated imaging scope to mate with an ASI2600MC
 

Currently, the main contenders are:

Tak FSQ-85 (1.72”/px) 450mm FL, option of 330mm at f3.9

Pro’s
• Proven performer to APS-C (assuming good sample), even better correction with new flattener

• Ease of use

• New reducer looks fantastic at f3.9 and relatively reasonably priced  

 

Con’s

• Frustrating having to deal with back focus on what’s supposed to be flat field Petzval  

• Risk of sample variation, expensive if collimation out  

• Focuser not good enough?

 

RASA8 (1.94”/ px) 400mm FL

Pro’s

• Blazing speed

• Resolve more detail with >aperture?

• Cheaper

 

Con’s

• Collimation

• Not easy to get good correction at edge of APSC?

• Limited to ASPC and will need new filters. 
 

According to MeteoBlue my local seeing is tends to be in the 1.5-2 arc sec range and I’m in Bortle 4 according to light pollution maps. Have no idea if this is the case but in either case the sampling of both scopes seems ok. 
 

More important to me is to make use of the limited clear skies I have. I  tend to not image one target over multiple nights so I want to collect as much as possible in one night! That of course favours the RASA but I need to balance that with ease of use. If there’s regular fiddling to be done I tend to give up and losing a night to issues is more of an issue than what’s gained from the extra photons on the sensor. 
 

I’ve become quite picky with star shapes and sharpness. I’ve been using a FRA400 recently which is easy to use and gives me round stars but images appear a bit soft for me. I’m curious to hear what people might think would produce the sharper cleaner image out of the RASA/ Tak? Baby Q seems tighter with spot size etc but is this offset by the extra aperture of the RASA? I realise a lot of the processing tools we have these days can negate much of the negatives of both setups but I would like the easiest data to work with to start with.  
 

Right now I’m leaning to the Tak but I would say that’s mainly because of my trepidation of dealing with collimation etc. Otherwise, I feel it’s a toss up. 
 

Will cross post this on another site so apologies if you read this twice and thanks for reading and even better if you offer an opinion!

Chris

I will give you my experience…

I owned a Tak FSQ85 and it was very poor indeed with modern small pixel cameras, even with 2 flatteners it was still pretty bad, and why should you pay a premium for a 4 element Petzval design scope with built in flattener, and then have to add a second flattener on the back, and have all the backspacing issues that you should have avoided with the Petzval design,  it’s a joke to be honest, and the extra flattener gives about a 15% increase in image quality,  at least they now supply the extra flattener in the box with it, as for using a reducer, well, I never even got that far.

If you get a poor example then you are stuck, as there is no option but for it to go back to Japan for adjustment, with approx an 18 month wait.

If you really trawl the internet this issue is very common and they are not all they are cracked up to be…

Fo me the Rasa all the way…..

I was the worst scope I ever owned, and I have had a few

if you want astigmatism in the outer 1/3rd of your images like this, then go for the Tak

4 minutes ago, Adam J said:

We spent time making sure our optics worked correctly...some of us still do as BXT cant generate detail out of thin air. 

No, but when you have spent an age of time trying to get that last bit of tilt out of your system, but still get a slight elongation in one corner, BXT can do wonders, and for some people who just can’t afford high end optics or mount, it’s  a godsend to get half decent images….

So it has its place in my book…

15 minutes ago, SamAndrew said:

First imaging light for my Askar 103. I threw caution to the wind and went for the 0.6 reducer.

Initial impression

1. There's minimal tilt straight out the box
2. Corner stars are reasonable considering I haven't adjusted spacing to account for my filters yet, looks promising given it's a refractor at F4. ASP-C sensor.
3. Median FWHM on that single sub is 1.84 * 1.88" = 3.46"
4. Mechanical quality and fit and finish is excellent.

I'll try and do a full review once I've got some complete images, but so far I'm happy.

First frame with a stretch, no calibration:

raw corners (looks like spacing adjustment needed to account for filters):

Corners once BXT applied (basically perfect, wouldn't expect anything less now ) :

Single frame, no calibration, BXT, Graxpert and a stretch:

That’s look pretty darn good, especially with a reducer, I bet it’s almost perfect with just the flattener…what did we all do before BXT,  I think that has revolutionised processing for many people…👍🏻

21 minutes ago, symmetal said:

If you opt for a 15mm m54 extension I'd be wary of the Baader ones as they have a short thread depth and I've found many male threads will reach the end of the available Baader female thread before they're fully mated. I've tend to use AliExpress for extensions and stainless steel spacer ring sets etc. as they are normally better made, with deep thread depths and knurled outers on the extensions, and are a lot cheaper. 🙂 They take Paypal too.

M54 15mm extension and spacer rings from a company I've used and that's also been recommended on here.

Alan

Yes +1 for Aliexpress,

i have had a boat load of stuff off there including all sorts or adapters, extensions and such like, that are just  not available here in the U.K., and as you said always well made too. 👍🏻

Excellent rendition 👏🏻👏🏻

2 hours ago, fwm891 said:

@symmetal thanks Alan, I’ve just got an Askar 120 APO and want to use my 2600 duo with it and that means using the 54mm mountings. That also means taking the 48mm fittings off the scope which adds 18mm to the 55mm back focal distance (73mm) now.
With my current extension tubes and filter holder I need to turn 1.4mm off the length of one extension tube that will then incorporate the extra back focus needed. 73.6mm.

  Camera bf 17.5mm + filter drawer 20mm + 21 + 16.5 extension tubes = 75 I need 73.6 = 1.4 mm.

I’ve ordered an extra 16.5mm extension tube £19 rather than pay £190 for the variable bf adjuster Askar are selling…

Instead of the 16.5mm extension tube could you not get a 15mm one to replace, then you are there…? 15mm tubes are available in M42, M48 and M54…

I think as you still use a CCD camera this may limit your options a bit, as most of the newer filters are CMOS optimised, i use Optolong with my QHY268m camera both LRGB and HSO, and find them very good, and also a very good price..the LRGB are only about £250 for the 2” version I believe, but no idea how they would fare with a CCD camera…

‘Just my twopeneth

Elephant Trunk Nebula in SHO, shot with my Optolong 6.5nm filters and processed fully in Pixinsight…which is still pretty new to me. Taken on the 9th of January 2024

Not a long integration so had to be careful with the stretching on this, just 3 hours of 5 min subs in total spread across the 3 filters. Although most of the detail came from the Ha data,  Using my Esprit 100 and my QHY268 mono camera, the image had been cropped for the original to show the trunk more.

Used dark structure tool in PI, and also tried the new GHS stretch tool, but ended up using the Histogram as I have always done, I have done this object before a couple of years ago with a different scope, but prefer this one as has better colour and dark structures, well in my opinion anyway…

Thanks for looking.