Clarkey

59 minutes ago, ollypenrice said:

My flats last for months

You have just made me think (rare). I always used to retake flats when re-framing images. However, I now rotate the whole imaging train in most cases so I don't need too. Do'h. 🤪

Generally, if I have changed nothing in the imaging train, I would not take additional flats for consecutive nights. However, my set up is in an observatory so it does not get moved about much. If anything changes other than fine tuning the focus, I would repeat my flats. I would prefer to spend 10 minutes doing this than not having decent calibrations frames.

Definitely large RASA for me. Just need the speed as there seem to be so few imaging  opportunities these days.

Maybe I'll still be able to persuade the better half to retire abroad where clear skies are not a dream...

1 hour ago, iwols said:

Well just imaged the above with 5 min subs but when looking through my images all the lum channels were well over exposed so just used R,G,B channels,just wondered if i re took the lum channels would it add anything to my final image,an thoughts  thanks

I theory the luminance channel carries most of the image detail, so it should improve the image. However, in reality, by doing RGB only you are effectively producing something more akin to a OSC image. How much difference, particularly on bright targets like these, is another question. I think for very dim fuzzies the difference is likely to be more marked. As a rule my total luminance time is normally about the same as the RGB total time - so three times the length of each colour channel.

On 23/04/2023 at 00:34, WolfieGlos said:

This brings the resolution to 0.74"/p, still unrealistic for guiding it seems

Yes, but if you bin x2 it will give you 1.5"/px and make the whole system 'faster' and be within your guiding limitations.

Personally, I am yet to be convinced of the F4 newts (cheaper ones anyway). I had to add a new focuser and use an aplanatic coma corrector so the set up ended up costing around £1000. Not only that, but they need pretty constant fettling.

On 25/04/2023 at 12:48, Ouroboros said:

Several of my shots had two satellites crossing at the same time

I had some recent 2 minute subs with 11 satellite trails! Personally, I blame Mr Musk.

When was the first flat taken? I have had similar gradients which I could not fathom out with my Rising Cam IMX571. Although I never found out for definite, I think it was dew. Since getting a new heater strip for the camera and turning the internal dew heater to 'max' it has not been a problem. Your issue might be something completely different - but it is the best I can come up with.

On 22/04/2023 at 23:34, WolfieGlos said:

I still use the t-shirt! I read elsewhere a year ago or so now, it's something to do with how screens emit light and that maybe the t-shirt helps to diffuse it

I have used the screen on a tablet without diffusing and it is fine. The only reason I use a t-shirt is if the flats are too bright. My led flats panel has a sheet of perspex over it with about 5 sheets of paper behind that. Dims it and diffuses - so solves both problems.

As the owner of an RC8, 115mm refractor and an F4 newtonian I will give my opinion. (I did have a 130mm refractor, but it did not fit my very small observatory). I think they all have pro's and con's and ultimately it is down to your preferences.

RC8 - yes, it is a bit tricky to collimate, but once you have developed a method they are not too bad. Fortunately, my focuser and primary mirror are well aligned so collimation is not that difficult. I normally need to collimate it once per season. For the RC8 I don't need a flattener with the 1600mm pro, but the IMX571 is probably pushing it. In terms of imaging, I use the native FL and bin2 or bin3 which gives 1 - 1.5"/px. I was planning to sell it when I brought the new refractor - but I just can't let it go. I like it that much. Once binned it is relatively fast and gives great images. FWIW I use a ST80 for guiding as I always find OAG's a pain. Collimation can be done with a Cheshire and star test. I do have the worlds most expensive LED light, otherwise known as a REEGO - but you don't need it.

The refractor has only had limited use due to the rubbish weather. In terms of resolution, there is very little difference between it and the RC8 due to seeing. At 805mm native FL it gives around 1"/px which is better than my seeing can support unless very good. However, it is simple and bomb proof - no collimation issues and easy to set up. The negative is that it is relatively slow compared to the 8" scopes.

I have a 6" f4 newtonian and in terms of collimation it is by far the most work. It does take great images but does require the most maintenance.

If it was me - and I had the choice of one scope - it would probably be the RC8 with a CCD47 and a Baader Steeltrack focuser. However, I love the simplicity of the refractor (which is also a good visual scope) and the speed of F4

I'm going to add this picture as it is the only image I have managed this galaxy season due to the permacloud. I now have virtually no astro darkness to use so the imaging kit is back indoors for the summer.☹️

This is Dwarf galaxy NGC4395. It is relatively large for a dwarf galaxy, but has a very low surface brightness. Found in Canes Venatici and approximately 14 million light years distant - so closer than many of the Messier objects.

This was taken in LRGB using a 115mm triplet over three nights 18th - 20th. The seeing on the first night was excellent but unfortunately deteriorated to be pretty poor on the second and third nights. Total of 5 hours luminance and about 1.5 hours of RGB.

I think for an hour of imaging this is a good result. Star shapes look good and there is a fair bit of detail, especially for a small scope. I would question the need for 5 minute exposures, 2 or 3 is probably enough. More subs will help with the intergrated result.

Other than that, I would be pretty pleased. After the summer, your 72ed scope will be ideal for nebulae and some of the larger targets so I would stick with it for now. (My kit has now been packed up for the summer - not enough darkness now until the end of August).

On 18/04/2023 at 22:44, AstroGS said:

The rig for the night was:

• Stallamira ED90 Triplet + reducer/ flattener
• ASI 1600MM Pro + EFW + Antlia 3nm 36mm unmounted filters

 Each sub was 600 secs.

I would agree with everything that has been said. I have the same combination (with the reducer / flattener at F4.8) and I typically use 2 or 3 minute subs in Bortle 6.

Well worth watching this video by Robin Glover if you haven't already:

9 hours ago, Ryan_86 said:

However there's lots there, so not sure whether to adjust mechanically again or isnit a guiding setting

I would suggest that 3.7 seconds backlash is excessive for the guiding to deal with. You shouldn't be able to feel any play in either axis. There are plenty of guides on line regarding the worm gear tuning. Basically, keep tightening until it binds, then back it off slightly. With my HEQ5 and AZ-EQ6 I can get the backlash below 1 second. I don't know how old your mount is, or whether it has been serviced, but I would strongly recommend giving it an overhaul if you can. I have stripped down and rebuilt both of mine and they perform much better now.

I will certainly wait for a few reviews, but £460 for a plug and play portable imaging set up is pretty astounding. Ideal for a travel small set up.

5 hours ago, DavidLF_ said:

but it gives me an ascom driver error in NINA when trying to move the telescope.

What mount and driver are you using? Is the driver the latest version? I have used NINA platesolving without issue - but I use ASTAP.

I doubt if it is a windows issue if Windows is normally working fine. (Not to say it is impossible).

On 12/04/2023 at 13:02, CraigD1986 said:

Thanks for your responses. I'm not looking for a full on observatory, more of an enclosure so my scope can live outside full time and is all set up and ready to go when the clouds clear.

I've decided to attach a plumb line on each end of the scope to try and work out the circumference of the area I will need for rotation. Then move the mount in RA and Declination to see if I can figure out the maximum arc

The only thing I would say about this is that you need to be sure you will not change scope. I built my imaging observatory on the footprint of an old flower bed in the garden which was fine at the time. However, I then purchased my 'ideal' scope, a 130mm triplet refractor. Unfortunately, this was about 3cm too long even if I added lead weight to one end to move the balance point.🙁 I had to sell it a few weeks later. So... if you 'might' change scope I would suggest give yourself some wriggle room.

Alkaid is not far out of shot. Looks like it might be some stray light from that. Just looks green as it a OSC camera.

Personally, I would go for the cooled camera. It just makes everything easier and as temperatures increase there is a difference. If you are on a budget, consider second hand. There are plenty of second hand camera's for sale and although there is a small risk, it is probably worth it.

On 13/04/2023 at 19:21, Nrmh02 said:

I’ve just received my eq6 r pro and needing to get some kinda power supply to it. 
 

has anyone tried this and can give me an indication if it’s long lasting or not

or if anyone can recommend something better ?

I have one of these and for the mount alone it is absolutely fine. If you start adding other stuff such as dew heaters it does have limited capacity. To be honest you are paying for a lot of extra's that you probably won't ever use (torch / radio / USB / red light). You could just but a standard 17 AH lead acid battery for a fraction of the price and wire it up to connect the mount. However - for simplicity and convenience it is fine.

I haven't had my observatory long, but so far, no issues with my set up. I have a vent fan running 24/7 (small 7W shower extractor) which only gets switched off for imaging time. If it is a cold frosty night (most of them in Penrith during the winter), I put a dehumidifier in the observatory for a few hours when shutting up in the morning. This helps melt / absorb the frost.

I leave the two mini PC's on permanently to prevent them getting damp - but everything stays put. 

11 hours ago, WolfieGlos said:

and I'm wondering why....

You will get awful chromatic aberration with the ST150. Go for an ED doublet as a minimum for imaging if you are looking at the refractor route.

The RC6 is a good scope, but you will need a flattener and I'm not sure how large the imaging circle is for larger sensors. The RC8 is usable without a flattener, but is at the limit for an HEQ5, even with an OAG. Collimation is tricky - but with care is not too bad.

I have recently purchased a 115mm triplet (Altair Starwave) and am using it with the standard StellaMira field flattener and small guidescope. I have not used it much as the weather has not been kind this winter. However, the images I have managed have been very good. Maybe more than you want to spend - but a possible option. If you are budget limited, the newtonians are a good choice in terms of value for money. Personally, I would go for an F5 as the upgrades required for the cheaper F4's are not worth the cost.

11 hours ago, Rallemikken said:

I'm slowly accepting that focal lenght ain't king, done some testing myself lately. The one that started this topic had a HEQ5. Maybe an 8" f/5 or the shorter 8" f/4 (if wind is an issue) would be the better choice. Most bang for the bucks. Don't think a triplet was on the table. Costly. And I wouldn't go under 800mm for a dedicated galaxy rig, regardless. 800-1000mm would suit the slightly older Canon cameras like the 450D, 600D and 5D MkII. I see that 1200mm might be a little long for those.

All completely valid points. I was just trying to highlight to the OP that FL was not necessarily critical and in most cases, over about 800mm you will not gain resolution (but you might get improved speed).

On 01/04/2023 at 22:29, Rallemikken said:

The Sky-Watcher Explorer 150PDS (750mm) will be short for galaxies. I have a 200 PDS (1000mm) and I would like to have an additional 200-500mm

You do need to consider the quality of the seeing. I have a 115mm refractor and an RC8 with about 2x the focal length. In reality the quality of the image is similar with both, with the RC8 binned x2 to give around 1"/pixel. The RC8 just ends up faster due to the larger aperture at the same pixel scale.

The two images below are examples. The first is the RC8, the second the 115mm triplet. Ignoring the colours and processing, the detail is similar on both.

Startools has a synthetic diffraction spike option - but you would have to buy the software. However, there is a free trial so you could give it a go first to see what you think of the results.

I think that with the Skymax at F12 and the mount you are using, in particular without guiding, you are going to really struggle. The combination you have is OK for lunar and planetary imaging with a motor drive- but not really good for DSO's. It would appear that you do have the core of M81 in the image, but it is difficult to see much more. It is also very noisy.

Personally, given the limitations of your mount, I would suggest trying some widefield shots. Even at much shorter FL's you may still struggle. Unfortunately, in AP the mount is the critical part, and the EQ3-2 is probably not up to the task.