Clarkey

If you are on a budget I would make my own. I have an excessively large power supply with multiple 12v and USB power supplies fed from a 12v battery. It is excessive as it 110 Amp hour but it will run all my kit with dew heaters, mount, camera etc for a 12 hour session without issue - even when cold. (If really cold I have a small heat mat to warm the battery). I suspect it would do 2 nights but I have not tried it. I think you are right in saying your 7Ah power tank would struggle. At a guess the two heaters probably draw an amp or so, plus a similar amount for the mount guiding only. If you add another amp hour for the other stuff the unit you have will give you a couple of hours. You could just buy a small leisure battery 40 Ah or similar and make up the connections required. I think you could probably get the whole set up for about £60. The other option is a jump starter from Halfords or similar. As long as it is rated to give the power you need that would be OK. There are a number of Lithium versions that will work well but will cost more.

I would agree an HEQ5 should manage to track reasonably well at 400mm. I have use one at 1000mm for a couple of minutes and that was OK. As you are not using a field flattener (I assume) the stars round the edges will always be stretched. The central stars are not too bad and with perfect polar alignment I see no reason why you could not manage 1 minutes subs. Check the mount though, as my HEQ5 did have quite a bit of backlash from new which I had to adjust out. Also the worm gears were loose and needed tightening. Both of these made a lot of difference, along with the belt modification.

I think 50 minutes under a full moon with the camera you have is always going to be difficult. Using 'proper' astro gear I rarely image anything under 4 hours unless it is very bright just to keep the SNR higher. Extending the imaging time will really help. The is a recent post about integration time which would give you an idea.

Testing increasing integration times (OSC, Bortle 8) - Getting Started With Imaging - Stargazers Lounge

If you could give a little more detail regarding your rig it would help. Are you using a EQ or AZ mount for example? Do you dither at all? What is your processing? Looking at the image I suspect you have had to really stretch the data to get anything which is why the noise is so bad.

A second had modified DSLR can be picked up relatively cheaply and this really would improve your results. A second hand Canon 600D or similar can be picked up for around £200 or less.

Just to add to the above. I have joined 2 of the USB dew heaters together to cover a larger scope - just plugged in both to 2 separate sockets.

8 minutes ago, old_eyes said:

haven’t figured out how to control it without creating noise yet.

Unfortunately I am not a PI user (yet) so I cannot advise on that. I think with a bit of colour balance you should have a great image.

Really nice detail and colour.

Maybe a bit green?

That's a great image. Not sure why, but it is probably my favourite from the last few months. Maybe I am missing gas clouds during galaxy season!

Excellent.

The report CraigT82 has included is a very thorough examination of each filter. FWIW I recently went for the contrast booster for my achro. It certainly removes the blue fringing but at the expense of slightly reduced brightness and everything has a yellow colour to it. I am only using it for visual and to be honest, unless looking at very bright objects I go without. If you are thinking of imaging it is probably the best option as the yellow tint can be removed in processing.

Not sure what the recommended grease is, but I would go for the lighter one. It's not like the is much load on the focused that needs a heavy grease.

I assumed the stuck grub screw was the one on the first photo - part of the focus knob. If it the screw in the 8th photo you should be able to get a pair of pliers on it to screw it all the way in until it falls out.

Just thinking about it, you could just leave the existing grub screw and put a new one in to replace it. Simple to do.

For the grub screw it should be possible to drill it our and re-tap the hole. It may need a size bigger but that should not be a major issue. If there is a local garage or engineering firm I'm sure they could do it for you. You can also buy stud removal tools but I do not know how small they go.

5 minutes ago, powerlord said:

1600 wise - there's one on ebay that might go cheapish is all

I wouldn't rule out a 1600 second hand if you can get a good deal. Yes, the 294 is better but the 1600 will still give excellent results. In a year or two the 294 with be 'old tech' too.

8 hours ago, The Lazy Astronomer said:

take a pass on the 1600 (it's "old tech" now).

I would agree with this. I got a 1600 last year and although there is nothing wrong with it, the performance of the 294 is definitely better - in particular the higher QE.

Sounds like you have the gear for a lightweight set up and widefield with the 72 ED and the AZ GTi. The 200P would be quite capable of imaging galaxies whether with a DSLR or Astro camera. I think your real shortcoming is with the mount. The EQ5 is going to struggle with anything larger than the 72. An HEQ5 is a reasonable mount but with the 200P or something similar it would be at its limit. Any wind or balance issues would make it tricky. If I was in you position the mount is the first thing I would look at - probably a NEQ6 or similar size. This can be used with all your existing kit and will really help with the guiding and longer FL scopes. (I use an AZ-EQ6 with a 1600mm RC and it is fine, typically I get around 0.3 RMS). Moving on with mono / NB can always be an option later - but I think you can get some really good images with the DSLR first.

32 minutes ago, Buzzard75 said:

However, when I check the same image in Pixinsight, I find I have holes in my stars meaning my focus is off. I don't trust Bahtinov's any more. I will use them to get close and then run an AF routine. It seems to perform better.

I have found that the AF routine and the mask give different focus points, but it has always been very close and not enough to see donuts when processing. I would hope if you get a good Bahtinov specifically for your scope it would give you accurate results. (Mine is a cardboard special!)

Stu1smartcookie? 🤔 Maybe a change of forum name is needed!

Yes, we have all done 'silly'.

1. 3/4's of a nights imaging in Blue as I put the wrong filter in the imaging plan.

2. Unable to work out why none of the kit was working. Power off! LED's all lit from the USB supply....

3. Mount broken. No, mount not connected....

The list goes on.😂

8 minutes ago, fwm891 said:

The other issue is subject brightness, if your FoV has few faint stars tthen an AF unit will be the better option otherwise your moving to a nearby brighter star each time you change a filter.

Very good point I forgot to mention. This can be a right pain when using a mask. Having said that, you can pre-focus with the mask then run the AF routine to check the focus has not changed. Interestingly, when I use a Bahtinov mask and the AF routine there is always a slight difference. Not sure why. It would not be noticeable visually so not an issue really a problem.

I have an auto-focuser and I would always focus at the start of a session and on changing filters using offsets (so not applicable with a DSLR). I do have the set up set to re-focus at 10% deviation of FWHM, but it very rarely needs to re-focus during a session. This is even with a FL of 1600mm. At very long FL and detailed imaging you might need to make changes during the session as the effect of temperature is likely to be exaggerated. The main cause for needing refocus would be large changes in temperature altering the optical train. In Cumbria it is always cold so this is not an issue🤣. I think at the FL of the ST80 I would be surprised if you really need to re-focus, but you could possibly get a marginal benefit. I generally do not need to refocus my ED80 - in fact I don't think I ever have. Change of target would not make any difference - infinity focus is always the same.

You could save even more money and make your own Bahtinov mask. I made my 'temporary' one six months ago and I have not felt the need to buy a new one. Eventually I will probably leave it outside and the dew will get at it as it is made from cardboard. But for now I'll save my £30 for some other expensive bit of astro kit!

8 hours ago, Longy717 said:

Not sure I'm keen on buying a 2nd hand one

Most sellers are pretty trustworthy on ABS and if you pick-up or use paypal you will have some protection. Most astro gear is well looked after so second hand is often a good option. I think you will find most people on this forum have bought gear on the used market as it is more cost effective. Also, a lot of astro buff's change gear regularly.

For that sort of budget I would seriously consider second hand. On Astro Buy and Sell there is a celestron 130 EQ with motor drive for 150 pounds which includes everything you would need to get started. I'd say this was a better bet. If you wait you may get a similar sized dobsonian.

On 19/04/2021 at 11:41, JemC said:

Has anyone used this one ,
Astro Essentials 0.75x Reducer for StellaLyra / GSO Ritchey Chretien OTA

The only thing to be aware of with this reducer is the imaging circle is quite small. I returned mine and replaced it with the TS version.

I think that is a great result with and ST80.

I have the Stella Lyra version and I have been really pleased with it. It is a lot of scope for the money. For the current galaxy season it has been my standard imaging scope. Some people have suggested the focuser is not too good but I have not had any problems. The only negative is that the focuser has no screw in camera connection - but this has not been too detrimental in my opinion.

I know the usual concern with RC's is the collimation. Fortunately mine arrived pretty well collimated so I have not had to adjust yet and it seems to hold the collimation well. (I have ordered a collimator so I will have time over the summer to get it 'perfect' for next season). The collimation is out slightly - or there might be some tilt in the image train, but until I start to improve the collimation it is not too clear. Generally I image with a reducer at around F6 as this about right for my camera in terms of pixel resolution. I have used binned at full FL and the quality was good.

Overall I have been happy with it and I feel it was a worthwhile addition. My only question is whether I should have considered an F4 photon bucket instead! But I think the size and weight is probably better for me as I need to set my kit up every time. Definitely a keeper for me.

On 09/04/2021 at 23:01, Avocette said:

So far I have found the StarTools Wipe module less effective than the APP tool for light pollution and gradient removal. APP’s tool requires much manual intervention. For this image I carefully drew 80 or so pixel boxes of various sizes in places where my eyes thought there was no specific stars, galaxies or nebulosity. I agree that once you’ve done something of that nature StarTools can no longer track the noise for definitive removal, but for this kind of image I think it didn’t do a bad job! If Ivo reads this and disagrees, I’ll stand corrected!

A bit late to this discussion, but I think providing you save the image as a standard background corrected tiff file, the data remains 'unstretched'. Yes it has been modified, but no more than using flats or bias frames. I use the APP background correction before working in Startools or other software for exactly this reason. (Depending on the image this could be each channel individually or the combined RGB).