rnobleeddy

16 minutes ago, PeterCPC said:

I loaded them as png taken from single RAW image. I use a field corrector bought from FLO at the time of purchasing the scope. All the trailing stars seem to be elongated from the corner towards the middle. Do I need a flattener? If so any suggestions.

To add a suggestion - it's almost certainly worth using the dedicated flattener https://www.firstlightoptics.com/esprit-professional-refractors/skywatcher_flattener_esprit_100_20188.html

I guess for astrophotography, I'd consider the matching flattener a must buy for the Esprit series, unless you just want to image very small objects, or are happy to fix the curvature in processing.

11 minutes ago, PeterCPC said:

I loaded them as png taken from single RAW image. I don't use a flattener or reducer. All the trailing stars seem to be elongated from the corner towards the middle. Do I need a flattener? If so any suggestions.

It's a common OTA so I imagine others will know the answer for sure - but the Esprit series don't claim to offer a flat field, so yes, I'd imagine this will need the dedicated field flattener to get a flat frame across a 4/3" sensor.

Are you using a field flattener or reducer?

The full image appears to be low quality when I download it, so hard to see the corners, but worth checking how the pattern varies across each corner. Are they symmetric around the centre of the image, or all pointing in the same direction?

2 hours ago, Lee_P said:

If you're curious, I posted an Askar D1 / D2 image here, and an Optolong L-Ultimate / Asakr D2 image here.

Thanks - curiously, after I wrote that, I found your site, which was very helpful. I didn't realise you were here too

I'll check out the comparisons.

The images you produce are stunning - do you do anyting special to bring out the blue/O signal from your dual band filter data? 

EDIT - I guess the 24h of exposure is the key thing making O stand out! I was happy with collecting about 10h each on 2 targets this week - so must try harder!

I guess this debate never gets old. I've gone OSC to mono to OSC, which is probably an unusual path.

I'd agree that mono is the choice if you want to produce the very best images. But astrobin is full of OSC photos that are far better than my mono images. So there's obviously more to it.

The reason I've gone back to OSC now is that I want to make everything as easy as I can.

So I can use my 2 hours of OSC data that I collected before the clouds roll in, but I can't do much with the 1 hour of L and the 1 hour of R that I collected. Not having a filter wheel is one less thing to go wrong, so if I leave my kit out overnight, there's a better chance it completes what I asked for. Your narrowband filters may actually be parfocal, but mine didn't appear to be, so I can avoid hoping that the automated refocusing works when I'm not there.  It means a lot fewer flats, and easier workflows in DSS. Perhaps I'm the only one who finds their equipment never works perfectly?

My take is that the duo narrowband filters for OSC are a decent approximation of narrowband for some targets. But the best OSC duo narrowband images you see either have tonnes of data, or are processed with skill that is beyond mine. It's far easier to make pretty images with mono. For anything rich in S2 you have no great options (apart from the D1/D2 askar colour magic filters, but yet to see much from them).

So if I shot narrowband exclusively, I'd go mono. Right now the cost I pay for the simplicity of OSC + dual band filters is in image quality. But for broadband targets I'm not concerned I'm missing out. For example, I'm convinced that a modern CMOS OSC with high QE is well ahead of an older mono CCD with LRGB filters.

I'm no guiding expert, but I'd imagine the difference between binding and other causes of bad guiding is usually apparent from the PHD2 graph. On my mount, when I get binding in the DEC axis it looks very different to bad tracking due to cloud, wind etc.

5 hours ago, GalaxyGael said:

For very widefield (depending on sensor size) the FRA300 is nice and easy to use. Good color correction for imaging, flat field and wide (300 mm) at f/5.

Light and a well thought out long dovetail and handle/guide scope placement if you need it. I enjoyed using it for a few months and got a good sample. Off to the classifieds for a new camera.

I found adding an astrozap dew shield removed the need for heated options, improved spurious light cover too. the Askar focusers are solid, no sag.

My camera is APS-C sized and I'm currently using a 290mm scope for widefield imaging. So this would be the same, but wouldn't cause as much frustration in the corners. I'd probably opt for this over the 400, but I'll probably spend some time assessing what does/doesn't fit amongst the objects I enjoy imaging.

1 hour ago, CCD-Freak said:

The Sharpstar 15028HNT at 420mm and the 13028HNT at 364mm could be added to the list though you will still have to get the 55mm spacing set right.

 

Was entirely unaware that these existed! I guess the main advantage over a refractor is the fact they're so fast? How do you find collimation? I also imagine I would a new dual band filter, which adds extra £.

4 hours ago, Louis D said:

Are you referring to these offerings?

Altair 70 EDQ-R F5 Quad APO Astrograph

TS-Optics 70 mm f/5 Quadruplet Flatfield Apo with 3-Element FPL53 Objective

TS-Optics 61EDPH - 6-Element Flatfield Apo 61 mm Aperture F/4.5

TS-Optics 5-Element Flatfield Photo Apo Refractor - ED61PHD

4 hours ago, fwm891 said:

@rnobleeddyTake a look at the Altair astro refractors 

Thanks both - didn't realise there was so many to choose from!

I didn't realise that getting a larger camera would just lead to a greater battle to optimise flattener spacing/tilt! I'm very much hoping this weeks efforts can be cropped or fixed it post processing, as it's otherwise been a great week.

Which got me thinking - I've been trying to reduce the barrier to doing astrophotography, because I want to keep going, but don't have as much free time as I did during COVID. One obvious way to do that would be to use an OTA that doesn't need a flattener or reducer, especially as I share a camera/filters/spacers between >1 scope, and swapping the kit tends to lead to needing to reset spacing.

I'd like something in the range 300mm-400mm, so was wondering what people recommend?

So far, I've got:

Askar FRA300

Askar FRA400

Redcat 71

Is there anything else I should consider? Are there any unforeseen downsides to using this type of scope?

As it stands, the Redcat costs more and appears to need an adapter to fit a ZWO EAF, so I'd need to see a marked benefit in terms of image quality to choose the Redcat over one of the Askars.

I have an older EQ6 and it appeared to have some stiction visible in PHD2 graphs this week. I wondered the same thing, but then came to the conclusion that I'd expect the opposite effect - if the worm gear is too close, then surely colder metal contracts and it's less likely to bind?

I've used astroberry for a couple of years. You get the usual, occasional issues that are common with linux + open source software, but it's generally very good. Not as easy to use as ASAIR, but cheaper.

When people mention the tilt adaptor, is that referring to the three screw ring that attaches to the dovetail, that takes the back spacing to 23.5mm? That appeared to be the only option with my OSC version, but it's not immediately obvious to me how to use it.

Nice to see it in use! Looking forward to seeing the images it can produce.

I wouldn't bother. Old cameras are likely to be bulkier and heavier, slower to download, be less sensitive and could have driver issues, whilst a 2nd hand CMOS guide camera isn't much more than £100.

autostakkert hasn't had an update for 4.5 years and registax for over 10 years, yet both are commonly used for planetary, solar and lunar imaging. 

I don't imagine there's a great deal of improvement to be made algorithmically, but both could be much easier to use.

I use these too. They work well and seem like good value.

4 hours ago, Xsubmariner said:

You might want to check out the QHY268MC, currently £1599 at MA. No good though if you operate with an ASI Air which locks you to ZWO camera’s only.

 

Thanks - this is actually very competitive. I've had 2 QHY cameras so far and they've been great, and I don't think it's worth the extra just to use ASAIR.

13 minutes ago, ONIKKINEN said:

You can save an enormous pile of money by getting the Rising Cam branded IMX571 chipped OSC camera: https://www.aliexpress.com/item/4001359313736.html?spm=a2g0o.productlist.0.0.6f047164JGhOx6&algo_pvid=88c7fc7f-59b2-4b58-9bdc-a75b08237944&algo_exp_id=88c7fc7f-59b2-4b58-9bdc-a75b08237944-0

Performance is the same (actually a bit better with lower read noise) than the 2600MC. No Asiair with this camera, but with the price difference between the RisingCam and the ZWO 2600MC you could fit a mini-pc and still be left with pocket change in the end. This camera has many happy users around the world and the paying/shipping process is painless so no need to worry about it being an AliExpress thing. The manufacturer is ToupTek, which makes all Altair cameras for example, but just without the Altair price. You can expect a high quality product and not some knock-off cheap chinese copy.

If AliExpress is not your thing, you can find the same camera (with extra price) here: https://www.teleskop-express.de/shop/product_info.php/info/p14967_TS-Optics-Color-Astro-Camera-2600CP-Sony-IMX571-Sensor-D-28-3-mm.html

Or here: https://www.teleskop-express.de/shop/product_info.php/info/p13286_Omegon-Camera-veTEC-571-C-Color-cooled--Sensor-D-28-3-mm.html

Even if you already had an Asiair (not sure if the case) you would still be saving money with these compared to the 2600MC.

294 is a sensor to avoid in my opinion. Seen too many threads about calibration issues with that one.

I don't have an ASAIR right now. I've used astroberry, but my 4Gb Pi 4 appears unable to handle the 48MP unlocked mode of my mono 294 (I haven't got as far as flats yet 😂). 

It's very tempting. The only obvious downside is I assume warranty repairs are close to impossible? And I guess VAT + import duty is added to the price I see on ali express?

21 minutes ago, Elp said:

The 294 you'll be in for a world of pain regarding flats calibration due to the sensor. The 533 would be a good choice if you can work around the square sensor. The 183 is still an excellent performer. What scope?

Does this hold for the colour version too? I heard of those issues as I own the QHY mono version right now, but my understanding was there were actually different chips, and QHY fixed at least some of the issue with new firmware.

EDIT - to answer my own question, yes, this still appears to be an issue, albeit some people are happy, so presume it's a sensor lottery?

Decided to move back to OSC as I've found I have less time this year, and a hard drive full of incomplete LRGB or SHO data  I realise the downsides to this move, so rather than a debate on if it's a good idea, I just wanted to check to see if my camera choice seemed rational?

I've narrowed it down to a ZWO 2600MC or 294MC, and that choice basically comes down to how much I decide I can spend.

Thoughts are below - any challenges or recommendations?

------------------------------------------------------------------------------------------------------

My decision criteria:

- I'd ideally like at least a 4/3" sensor size. Otherwise bigger is better.

- I'm using ZWO as examples because I may choose the ASAIR route. but I could be convinced to use a different brand if there are advantages (in terms of cost, or chips that ZWO don't use)

- Budget TBC - I'm selling all my mono gear and having a clear out, but I imagine I'll have up to £2K, but spending less is better!

- I'll shoot colour (obviously) and narrowband via a filter

- I have a couple of OTAs and a camera lens that I use, which cover the focal length scale, so I think aiming for the smallest possible pixel size makes sense. I use startools and find the fractional binning works very well, to get back to the correct sampling rate.

- Happy to wait a few months if something is coming soon?

So far, I've decided it's a choice between these - with the 2600MC being the preference if I can afford it.

- 2600MC: The upside of the 2600MC is the APS-C sensor size. The downside is the cost (it'll be at least £2300 for the camera, in the sale, and a cheaper narrow band filer). 

- 294MC :  Upside is cost - on sale at £1035 - allows £ for a good narrowband filter.

I've therefore ruled out:

533MC : Close with the 294MC. Upside is cost and ability to use 1.25" filters. Downside is 1" square chip size. Not too worried about the aspect ratio, but if my maths is correct, a significantly smaller surface area. As it's my only camera, I think I'll take the chip size, so would go for the 294MC over the 533MC.

071MC : Released in 2018. Hard to find exact data on QE, but recent backlit chips appear to be big improvements.

183MC: Superseded by the 533MC

1600MC : Older. I had the MM equivalent and I'd rather avoid the microlensing.

I assume this will turn out be obvious, but on a refractor with a dew heater wrapped around the outside of the lens, where do people place their auto-focuser temperature probe? 

I guess I want to measure the lens cell temperature, but I guess if I place this in contact with the dew heater strap, it'll be pretty constant, whereas presumably the lens cell dissipates heat according to how cold it is? So maybe I just put it anywhere else?

Got a new PC and https://www.astronomie.be/registax/download.html isn't working for me. Doesn't look particularly supported, so wondering if anyone has a copy of the two 6.x installers (one is the core program, the other the  update).

Alternatively, I just use it for sharpening, so any other free (non PS) options to achieve similar results would be appreciated.

I got this kit to try to do the same, but haven't ever got around to setting it up.

The pi camera probably isn't ideal, but I don't think it'll be a massive limitation for shots of the moon.

My suggestions:

- if you're using the lens with the pi, don't - if it's possible to setup with the scope focusing directly on the camera, do so

- take videos and learn to stack images like you were using an astro camera

3 hours ago, SthBohemia said:

Highly subjective opinion. The SW mounts are 'adequate' (prone to rust), however, overpriced like most astro gear. Biggest criticism being the Synscan hand controller is not in the same league as Celestrons Nexstar.

The older Meades, when they were made within USA, are teriffic 'scopes. Got one decades ago. It still performs like a champion, would not exchange it for a NEW Meade!!

I don't dispute that a lot of astro gear seems overpriced - I usually say this when I spend £30 on a tiny metal adapter! But SW mounts are the value options in the current market. Performance is ahead of anything else at the same price point.

I'd also probably agree that the SW mounts are adequate -  at least in the past, as shipped, out of the box performance could vary a lot, and whilst I'm sure FLO will accept returns on bad examples, no one really wants to spend £1000+ on a piece of hardware then realise they need to take it apart to get the performance they see other people getting. 

But I definitely don't agree about rust! I've had an EQ6 in the garden, under a £30 cover, for the last 2 years and rust has not caused a single issue.  Not much has rusted other than the counterweights, and that's just cosmetic. 

Can't offer much advice on handsets, other than to say that I don't imagine many imagers rely on handsets these days? Mine was quickly sold to free up another £100 for gear!