Rustang

1 hour ago, david_taurus83 said:

If your looking at the 100mm refractor range, if it was me, I'd upgrade the mount. You don't want to spend all that cash on a shiny new scope only to find its too much for you current mount. Or at least belt mod your HEQ5 and stick around the 70/80mm range like the WO you mention above. The GT81 with a 1.0 flattener will keep you at your current focal length. A bit cheaper but with the same FPL53 glass and same rack and pinion focuser is the Altair Astro range of scopes. Pretty much the same as the TS versions. I've had 3 from Altair now. Lovely scopes.

Cheers for the info and advice, in and around 100mm but it will probably end up being somewhere between 80-90mm. I probably should upgrade the mount to future proof myself  but that would then take a big chunk out of the budget for the scope, filters etc. I'am considering modifying my mount though.

2 hours ago, ollypenrice said:

One simple trick is to use a spirit level. Set your counterweight bar to horizontal using a normal one. Then, if using a DSLR, hold it against the bottom of the camera and set that to horizontal as well (or vertical if in portrait mode.) If using a dedicated astro camera you can use double sided tape to stick a mini spirit level to the back of the camera. To find horizontal just take a sub of a few seconds while slewing slowly in RA. The star trails show the present camera angle. Adjust till the trails are perfectly horizontal and then stick on the mini spirit level. That will let you get a repeatable orientation very quickly.

This is a minefield! The really important aspect of light grasp is not how much light the scope grasps but how much light each pixel grasps. Unfortunately there is no ready made popular unit to describe this. It is determined by sampling rate in arcseconds of sky per pixel, and also by aperture. Sampling rate is determined by focal length and pixel size. Aperture, of course, is decided by the size of the objective. Depending on the specifics, a move from 80mm to 100mm might increase or decrease the amount of light arriving on each pixel.

I think the sanest way to look at telescopes is to start with the focal length because that will decide the framing of your picture. Short FL means wide field, long FL means tight framing of small objects. A move from 80mm to 100mm will, in all probability, bring a small increase in FL.  Do you want that? It probably won't be enough to give great results on small galaxies and planetaries but it may be enough to crop a larger object which you don't want to crop!

Once you have chosen your focal length, consider the aperture. Provided you don't compare F ratios of different focal lengths, F ratio and aperture are effectively synonymous as they are in the camera lens world. At your chosen FL a fast F ratio is to be preferred.

Rather than agonize over the small print of a scope's spec I would look for its results on here, on Astrobin and on other sites to see what you think of them.

£1800 would put you within bargaining range for a Takahashi FSQ106N. This is the old, fluorite version of the FSQ which I use myself and generally prefer over the latest one because it holds focus better during cooldown. It has a 530mm FL, can cover a full frame chip and operates at a speedy F5. A bit heavy for the HEQ5 though.

I'd also consider a TeleVue TV85 with dedicated flattener-reducer. Very well made and seriously under-rated for AP, so prices are attractive.  Check out Frans Kroon who has one of these in his arsenal: http://www.franskroon.nl/ngc2237.htm  You will not have any mechanical issues with one of these.

Olly

Thanks for all the advice and tips. You mentioned sample rate which I forgot to mention myself. I have very limited knowledge on this and have only done the calculations for my current set up but don't really understand it. Obviously this is a factor I would need to consider as i don't wont to shoot myself in the foot that way. As you probably know I have the QHY-9 mono CCD camera that I'm not necessarily looking to change just yet either so I would like the new scope to be compatible with that but what I don't wont to happen is if I look to change the camera later down the line I don't then wont to change scopes again! it the most basic of ways (if possible) what are the factors I need to consider then in regards to matching that camera , i.e focal length, aperture etc?  Sample rates and compatibility is honestly something I haven't got my head round properly yet while fumbling my way through this hobby. I do like my focal length, a little more room wouldn't matter but not tighter! If I had endless money I would get a range so I could capture galaxies and planets better but for now I'm happy with Neb's! Apeture wise, I'm not necessarily aperture hunting it more about the scope being a good upgrade in general.

So I currently have my SW80 ED DS PRO which is awaiting a test run with a new (second hand - Thanks Steve!) focuser to see if it will sort the upset alignment after its cat incident! Its been a great scope but after I sell my wedding photography gear at the end of September I'm going to be looking at equipment upgrades and first in line is the scope and I've already started on the NB filters, 3.5nm Ha here I come!!  . I've known about the TS PhotoLine scopes for a while. I like the idea of the 90mm which I have already turned down before because I wasnt ready at that time and ended up upgrading my camera which was the better idea (Thanks Adam!  ) The 90mm Photoline has a 600mm FL so with the same reducer I would get the same filed of view/FL, the 80mm Photoline is 480mm so would be the same field of view/FL with just a flattener! Why the 80mm though if i already have an 80mm!? I guess to keep things the same but with a better focuser-would it be worth it!?, is it a better quality scope!? I'm also considering a couple of the Williams Optics range, the FLT 91 - more light gathering, similar FL, great focuser and the 81 GT at 478mm FL again is pretty much the same as I currently have with the 85x reducer. I have also considered the SW Esprit 100 but it might just be to much weight for my mount which I'm not necessarily looking to upgrade because of funds! There's also the SharpStar 94 EDPH and the StellaMira 85mm ED2 Triplet 

So I would like to know what other options are out there but first what do I wont!? 

-Something that's going to be worth the up grade and be with me long term, I might buy other smaller widefield scopes for something different but this will stay as my main scope so i would like it to be future proof.

-Similar Focal length because I like what I have currently which is 480mm with the reducer 600mm without.

-A better focuser, i.e stronger and if it has a rotator then even better as I'm finding it a pain to keep the composition the same on targets when I have to keep removing the scope but I am looking to change that!

-Light enough still to keep my SW HEQ-5 PRO running. My mount is old and the guide graph is up and down but the RMS error has always been great so if it aint broke......! I might look to get it professional tuned/belt modified to help it out a little instead of moving up to a HEQ-6 Pro

-More light gathering would be nice, would going up to a 91mm from 80mm be much different? 100mm or there about's would be better I guess?

- I like the idea of having a handle on top, more practical because I have to keep taking it off the mount after each session but i think I would still look to have my guide scope directly on top so that might rule that out.

Budget for the scope, I would prefer a good second hand option to keep more funds back for other upgrades but possibly around £1500-£1800 if new, not sure yet so I',m looking at options first.

28 minutes ago, tooth_dr said:

I'm going to have a look for some older flats that I would have taken with the camera and ED80 but 0.85x reducer, and compare them to yours.  I used the QHY9 with 1.25" filters down to F4.7 so I'm surprised there are issues at F6.

Thanks Adam, appreciate that, I'm sure we will get to the bottom of it 👍

14 minutes ago, The Lazy Astronomer said:

Assuming your filters have a clear aperture of 26mm, then they could be up to 27.5mm from the sensor without causing issues (in theory). Is it possible your sensor is slightly offset such that it doesn't sit in the centre of the filter? Or maybe your filter's clear apertures are <26mm (my ZWO ones are ~24mm, my Astronomik ones are ~27mm, so they do differ).

Mine are Baader filters, the filter wheel is attached directly to the camera so I cant bring the filters any closer unfortunatley. It would be a real shame if it was the filters and not the reducer/scope because I am considering a scope upgrade, something like the SW Esprit 100, WO FLT 91, SharpStar 94EDPH f/5.5 Triplet or something along those lines so bigger aperture with similar FL. I wasnt really considering a camera/filter change just yet so it could mean I would have to live with the vignetting.

I believe mine are these so this info could be correct https://www.rothervalleyoptics.co.uk/baader-h-alpha-7nm-ccd-narrowband-filters.html

"Special Filter Cell: Baader's special filter cell design offers unique features that enhance their reliability and usability. Though difficult to produce, the ultra-thin filter cell results in the maximum possible clear aperture, in order to minimize vignetting (1.25" Filter clear aperture is 27mm, 2" Filter aperture is 45mm). The special threading has been designed to fit a wide variety of eyepieces and accessories (there is significant variation between the 1.25" filter threading used by eyepiece and accessory manufacturers). The front 'crown' of the filter incorporates milled notches which make handling and threading the filter a more secure operation in the dark."

10 minutes ago, The Lazy Astronomer said:

In terms of equipment compatibility, there are 2 points to consider: the sampling rate and the scopes imaging circle size.

Your current sampling rate is 2.3"/px, which is probably about right for typical sky conditions.

I tried to look up the imaging circle of your scope but couldn't seem find it, however you sensor diagonal is 22.5mm, so l would be surprised if the scope was not able to fully illuminate the sensor. There does seem to be some hard vignetting though - what size filters do you use, and how far from the sensor are they?

they are 1.25 filters in a filter wheel straight onto the camera then i have the 0.8x reducer, i think there is a spacer between the reducer and filter wheel

19 minutes ago, teoria_del_big_bang said:

I do not have a permanent setup either - on my wish list as it has been last few years. But I do keep all my imaging train, including FW and camera set up permantly. I have a sturdy handle on top of the rig and take the whole rig off that is sat on the dovetail and store it in a cupboard.
I am a bit of a fussy sod so I still take flats after each session, with a flat field panel really does not take long, for each filter I have used after each session. There has been a few instances this did not happen for what ever reasons but so long as the camera and image train has not moved I can pretty safely use the last set of flats. Yes a few more bits of dust may have settled or moved but generally it is better to use the last flats than not use any I have found.

Steve

I'm hoping as time goes on I can get a little more permanent, I'm considering some upgrades in a couple of months so will see how it all goes but I'm thankful and grateful for what I can currently achieve. 

6 minutes ago, teoria_del_big_bang said:

Pass, I think that is my worry same as my setup but I am not sure.
Also even if that is the case then so long as you are aware of them and they get cropped from final image then does it matter ?

Again, these are questions I am also asking myself. and my lack of knowledge is not helping me. 
I think that because this larger chip size on my new camera is fairly new and I did not see this before it just worried me, but then again I do worry about a lot of things hat I probably shouldn't 🙂 

 

And yes to me at least the rest of the flats look as I would expect but you can see the issue that if the camera rotates, even slightly, all those dark spots where dust is on your optics will be in a different place and so the flats will not remove them from the final image and also will add some lighter spots that correspond to the dark spots.

Steve

I'm still very much learning a lot of things so in the same boat as you and that's well into my 3rd year of doing this. The dark corners have been a bit of an issue especially with details and nebulosity that I would like to keep in the corners but it is what it is. In regards to compatability, i.e camera sensor size to scope apature/fl what would it need to be to gain the correct compatibility if that makes sense? Bigger apature? Smaller focal length!? 

4 minutes ago, teoria_del_big_bang said:

I thought is was essential to take flats just after, or just before every session and that the camera rotation with respect to the optics must not move.
I have heard of people not taking them for every filter, which is not ideal, but not using flats taken with a possible different camera rotation.

Steve

Your probably right but what a complete pain in the back side that would be, I really could do with a more permanent setup but there's no chance of that yet. As i say I always take the camera off and rotate each session to find the best orientation for each target.

8 minutes ago, teoria_del_big_bang said:

Take this with a pinch of salt as I am in no way expert but to me generally if I auto stretch the flats they look just as I expect with the exception of the black areas on the corners.

If it were vignetting I would expect these corners not to have such a defined circular edge but to gradually merge from grey to darker grey to blackish, If that make sense.
On the RH side the corners are a bit like that but on the left there is a very defined hard edge where it goes almost black from light grey as if the  sensor is too big for the optical disc.

I know I may be talking rubbish here as this is my very naive way I see it.
And one reason I have taken great interest in this thread is that since going to the bigger sensor on the QHY268M mine are very similar, just with far more crap and dust bunnies than yours and I have had the same concerns as you.
Not all my filters show the same though some look worse than others. Here is my  Red filter, okay the edge is not so defined but it soon goes from light grey to black.

 

But this is the LUM, a lot of dust bunnies or dirt but much more what I would expect.

I know this is not a real test as you have to be careful when auto stretching as you need to see how much it has been stretched and all these images will have different amounts so difficult to directly compare them.

I probably have not helped whatsoever here because of my lack of knowledge and understanding, so sorry if this just confuses things more, but I asked very similar questions sometime ago to whether my flats looks correct and never really got a definitive answer so still worry I am not doing things right, or something in my optics is not quite right.

Steve

So if i do understand you correctly, it could be that my scope and camera are not quite compatible then and that's whats causing the dark corners? but my flats in general seem ok?

2 minutes ago, tooth_dr said:

@Rustang that histogram looks ok. The scale is 1-34k not 0-65k.

You could try 25000 for your ADU, see if that helps. 

Thanks Adam, by scale do you mean what the histogram is showing as i think that was mentioned before, possibly by yourself? I tend to easily forget these things! if so is there a way of changing the scale in APT to show the full range of the histogram!?

21 minutes ago, newbie alert said:

First of all flats aren't temperature related, so no need to cool your camera down to its imaging temp...and yes I'd agree that the histogram is too far to the right.. I'd suggest a third of your camera range for flats

I'd also suggest you take flats for each time you remove or rotate the camera and for each filter

what i dont get then is i used APT's flats assistant to gain the correct ADU so the corresponding exposure is whats determining the histogram so if I try and move the histogram, wont the ADU then be wrong!? There's no way I'm taking new flats every time I remove the camera, its just to practical because it comes off after every session.

14 hours ago, teoria_del_big_bang said:

I am no expert and although my flats seem to help my final results I am always doubting they are totally correct so taking interested in this thread.

Can you put one of your flats, and the corresponding master flat for the same filter so I can have a look ?

Steve

Flat files as promised!

F_HA_2021-02-28_14-24-52_Bin1x1_4.8125s__-20C.fit MasterFlat_ISO0.tif

36 minutes ago, teoria_del_big_bang said:

I am no expert and although my flats seem to help my final results I am always doubting they are totally correct so taking interested in this thread.

Can you put one of your flats, and the corresponding master flat for the same filter so I can have a look ?

Steve

Sure, il do so tomorrow sometime. 

48 minutes ago, Budgie1 said:

You may be able to get away with it if you leave the camera attached to the flattener & filter-wheel. The Flats are helping to remove the likes of dust motes and other stuff on the front of the sensor, on the lens of the flattener and on the filters. Dust etc on the lens of the scope is less of an issue, unless it's quite large, because of the distance. 

I have to break down after each session as well, but I can keep the camera attached to the scope. But I still take a new set of Flats & Dark-Flats if I change anything, like a filter (I don't have a filter-wheel so I have to take the camera off to change them at the moment) or from reducer/flattener to just the flattener.

Flat's & Dark-Flats don't take that long to do so I generally do them the next day and just cool the camera down to the same temp as the previous night. I don't go mad and normally only take 15-20 of each.  

You say they dont take long to do! thats if you can get them right lol 😉 APT has a great Flats assistant which does help make them quicker to do, i just need to work out why it didnt work for me when I took them the first time!

20 minutes ago, Budgie1 said:

Firstly, Masters - When DSS does the stacking for you with any calibration frames it creates a Master Flat, Master Dark, Master Bias or Master Dark-Flat. You can re-use these Master files if you restack the image or you stack another image with the same settings, focus and rotation (you didn't move anything or remove the camera from the scope  ). 

All you do is select the one Master file for that calibration set instead of all the darks/flat..... you selected before. So, for instance, say you took 50 Flats and added them to a stack in DSS. DSS will produce a Master Flat from those. Now, say you want to stack a second image using the same calibration frames, this time you don't need to add those 50 Flats to DSS, you just add the one Master Flat. DSS knows it's a Master file and it takes less time for DSS to process the stack because it's not building the Master for each calibration set.  

This works well for Darks because you can build a library of Master Darks for all the exposure, gain and temperature settings you use and then simply re-use the Master that matches the subs you're stacking. For my ASI294MC Pro I tend to stick with the same cooling temp (-10°C) and gain of 120. So I then used those settings and I have a Master Dark for exposures of 45s, 60s, 90s, 120s, 180s, 240s, 300s & 360s.  I built this library when I got the camera and used the same Masters from February through to June. This season I want to go to -15°, gain 120 and offset 20, so I'll have to build a new library. 

Flats - I used to use a blank MS Word document on the screen of my PC and a white T-shirt over the end of the scope to take the flats with my DSLR and it worked well. 

With the ASI294MC it didn't work very well at all and now I just point the end of the scope at a cloudy sky (during the day) with about 5 layers of white T-shirt over the scope and take flats that are still about 25000 ADU but are 2-3 seconds long. For my camera this does work and gives a nice flat image. It's a bit of a faff to get it right but I get there in the end. 

I guess what I'm trying to say is; try different options for taking the Flats, other light sources, exposure times and more paper/t-shirts!  

I was lucky, in a way, that the ASI294MC is renowned for being a bit of mare when it comes to flats, so searching for advice was quite easy. But have a search round for what others have done to get their QHY9 Flats.

I hope that sort of helps.  

Thanks for your advice/tips Martin, I will wait until my scope is sorted then look to re take the flats and go from there. Sadly I have to remove my camera from the scope after each session because i don't have anywhere for a permanent set up, so if I rotate the camera even slightly in the focus tube of my scope, even though the flattener, filterwheel and filters etc are all in the same position, I would need to re take flats for every single roation/ position of the camera? That would be a nightmare!

6 minutes ago, StevieDvd said:

How far are you from Stevenage. I'm not an expert in this but can probably help with some of the basics.

To start with see the link below.

That looks a little like your problem, if it's the focuser on yours that's the issue we can try one of my spares (both from an Evostar DS80) - if that fixes it then you can order a new focuser or I can let you have one of mine cheap (£25 for the used one or £45 for the 'as new' one). Or we may be able to fix yours, having good ones to compare with,

Will have a read up on checking the collimation on refractors as it's been a while since I've checked mine, though have never had to change them. I've got some collimation tools left-over from having an SCT which may help.

This would be done in my garage as the missus is a bit wary due to covid and people in the, and we can both wear masks if you prefer.

And to be clear there won't be any costs involved I'm not looking to start a repair service or anything like that.  I'd be happy enough if you left with a zero cost solution.

If you'd rather get professional help or have a go yourself I won't be offended 🙂

Steve

 

That's incredibly kind of you, I'm only in Hemel Hempstead so not far from you so that would be amazing. I'm just not experienced at all in this kind of thing so another pair of more experienced eyes on it would be really helpful so thank you.

Well this isant going so well. I really appreciate your 'do it yourself' advice which I've got nothing to lose in trying so will at some point take a look. I really would prefer however to have had this looked at professionally because if I was to sell it on I would won't piece of mind that the new owner would have it fully functional. It's in searching for a professional that sadly isant seeming an option. SCT telescopes can't even be bothered to reply!!!! ES Reid is to busy! And ENS in Birmingham (and this is the second time I've been told this could be the case) recon that the cell could now be out of collimation so your looking at £170 plus vat for a full strip down and service so by the time it's got to Birmingham and back to be sorted its probably not worth spending that kind on money!. So note to self, don't brake your telescope, or allow your cat to! 😒

6 hours ago, The Lazy Astronomer said:

Yes DSS does all the background work for you (the main reason I like it - although it's far from the best stacker, it's much less faff than other software).

I doubt there's anything going wrong during the stacking process; due to it's automation, there's really very little you can do wrong in DSS. This leads me to believe it's the flats (or flat darks) themselves which aren't quite right - how do you take them? What does the histogram look like?

I had an issue with NB flats a month or so ago and the solution l found was to temperature match all subs, so I now take all lights and calibration frames at -10C. Seems to be working so far 🤞

I've been using an LED  drawing light panel as the light source with sheets of paper to dim it down. The camera was set to - 20 so the same temperature for everything. The hisgram to me in APT never seemed right, to far to the right (bright) but if I remember rightly I asked about this before and it was something to do with the hisgram not being able to show everything correctly! I think flats are the bane of many peoples lives in this game and when your barely scrapping by with all the technical aspects of this hobby it's frustrating when you follow step by step advice and for some reason it still doesn't work and that's where it leaves me with not alot of chance of figuring it out myself. 

You can see below an example of the histogram, it's reach the correct ADU but seems to far right to me. You can also see the vignetting in having to deal with. 

8 minutes ago, The Lazy Astronomer said:

Do you take flat darks as well?

The full image calibration process should be (flat - flat dark)/(light - dark)

Yes I use flats, dark flats and darks. When you say full image calibration process, I just select each in DSS then stack it all together with the lights like I've always done!? 

So its only really come to my attention today that I have been wrongly assuming in regards to my flats. I thought because my set up shows significant vignetting that when the flats are taken with each filter, they will have vignetting and so it wont be removed!! I just assumed it was down to my equipment being un compatible or something!. So anyway Olly has confirmed today that flats are supposed to get rid of vignetting so I'm here to work out whats gone wrong.

Equipment- QHY9 CCD mono, baader NB filters, SW 80 ED DS PRO with Altair 0.8 flattener/reducer., LED light panel and paper!

 I followed the advice Adam kindly told me in regards to taking flats, aim for somewhere between 27000 and 30000 ADU. I used the APT flats assistant to help me do this and got all of the filters into that range. I used my usual LED light panel as a light source with layers of paper over the top.

So I'm guessing for some reason the flats I took were never right as the vignetting has been in all of my stacked tiffs  making most images a right pain to process but Ive been getting by. I always just select approx 30 of each calibration set (flats, darkflats, and darks) each time i load my lights into DSS sas, i dont understand the master file side of things when it comes to calibration frames so I just load a quantity each time so could I / there be something going wrong in DSS?

I'm concerned this is going to get very technical and I'm afraid I probably wont understand your help/answers so go real easy on me!

P.S Olly recommended I download some free software to check the ADU range of my flats so if you know of any!?

Ive been using this one for a while and seems to be doing a good enough job for making flats!

Portable LED A4 Light Box Adjustable 3-Levels Brightness Light Pad Drawing Tracing Light Box Stencil Tattoo Animation Diamond Painting Light Pad with USB Power Cable for Kids Adults : Amazon.co.uk: Home & Kitchen

31 minutes ago, geordie85 said:

Just seen this on ABS and thought of this thread.

https://www.astrobuysell.com/uk/propview.php?view=176342

Cheers, i will look into this 👍

Thanks for all the comments guys, when I get a sec and if I can I will try and take a look at everything I can and see if I can sort anything 👍

7 hours ago, Roy Foreman said:

I feel your pain. I have dropped and damaged three telescopes over the years. One was a fatality with cracked corrector plate. A six inch refractor went out of collimation, as did an eight inch newtonian. In all cases I had put the scope on a bench or chair thinking it was secure. Sadly not.

My cat loves to join me in the observatory at night, and once he did get locked in over night, but fortunately no telescope damage occurred. 

Sorry to hear of you tragedy,  and the fact that you are not alone is probably of no help.

I know I'm certainly not alone, things like this happen to others all of the time, we all dread the day its us but you just role with the punches. I've lost expensive mobile phones and sunglasses to the jaws of our dogs, dented my current car two weeks into owning it, it's life I guess but always worries me when buying something nice! It seems I'm not aloud to keep it nice! 🙄