Simon Pepper

Hi all 

I have asked a similar question over on another forum and still not getting it. Let’s say you shoot over two months so two different sessions dust moats have obviously moved. How can you add data to the 1st stack? You surely need to run new stack new calibration etc so you are now left with two master lights how are those combined? I use PI. Thanks 

As above need more info also that’s Starlink not meteors 👍

22 minutes ago, vlaiv said:

You can use x3 barlow to get in closer - but there is simply no point in doing so. Amount of detail available is limited by aperture of the scope and above formula for F/ratio versus pixel size takes that into account. Detail depends on aperture and focal length with pixel size determines how zoomed in you are - F/ratio is ratio of focal length and aperture - so everything is taken into account.

With stronger barlow - you would get more zoomed in image - but without detail - same effect as like imaging with x2 barlow and then resizing image in software. When you enlarge image in software - image is larger but no additional detail exists in the image.

On the other hand - using stronger barlow causes issues with signal to noise ratio because light is spread over more pixels and each pixel gets less light because of that (there is only so much light that is gathered by any scope). This means lower signal and in turn lower SNR.

With planetary imaging SNR is important because it lets you sharpen image without making it too noisy.

Using x3 barlow would therefore - make larger and more noisy image without additional detail and is not advisable.

Ok perfect thank you again 2x it is! 

2 hours ago, vlaiv said:

You will probably need barlow with that scope.

With barlows magnification factor depends on distance between it and sensor. Increase the distance - increases magnification and decrease in distance - decreases magnification.

For that reason it is good to have "barlow element" - barlow which you can screw off the barlow body and use it on its own - so you can dial in needed magnification with extensions.

You'll need x2 barlow with your scope and ASI1600.

Optimum F/ratio is determined by pixel size and wavelength you will image at. For full spectrum (like RGB images) - we usually use 500nm wavelength as reference (rather than mid spectrum of 550nm or short end of visible spectrum at 400nm).

F/ratio = pixel_size * 2 / wavelength

For full spectrum and ASI1600 that would be F/ratio = 3.8µm * 2 / 0.5µm (500nm) = F/15.2 = F/15 or x2 barlow used with F/7.5 scope

As far as ROI (region of interest) is concerned - it serves dual purpose.

With planetary imaging, you want as high FPS as possible. First you want short exposure to freeze the seeing and that means exposure of 5ms or so (that alone gives you room for 200fps as exposure = 1s / fps), then you want USB connection to be able to transfer all that data - which is why you should use USB 3.0 connection. You want fast drive (like SSD) to be able to record all of that data.

In the end - if you transfer whole image instead just some part of it - you'll be transferring much more data then you might need, so it is better to use just central part of sensor.

Most planets fit well inside 640x480 ROI - with exception of Jupiter if you plan to image whole Jovian system with moons - then you'll need larger ROI.

The Moon is often larger than sensor and we need to utilize mosaic approach here if we want whole disk instead of shooting just certain feature. We still use ROI here as telescopes have diffraction limited performance only in center of the field. Further out, depending on design of telescope, aberrations start to increase - like coma in newtonian telescope or astigmatism in certain designs. Field curvature is present in APO triplets (for that reason flatteners are used for large sensors).

Although I'm not sure how large is aberration free field of your scope, I'd recommend using only central <10mm - and that would mean keeping ROI up to ~1900x1600 and not more for Lunar - even if that means more tiles for mosaic.

Do have a look around the youtube for planetary / lucky imaging tutorials to see how the capture is performed, and later, more important, how stacking and processing is performed.

 

Thanks Vlaiv really informative and helpful as usual one last question would stick with the 2x Barlow or go with a 3x to get in closer? Thanks 

2 hours ago, Phillyo said:

I bought the adapter that converts the SY from a canon mount into a screw on mount, then an updated filter drawer plus spacers so that everything screws together nice and tight. I found that using the usual canon connection there was a bit of sag any my star shapes at the corners weren't great. I also use step down rings on the front of the lens to bring it down to 36mm, so around F3.6 I think? Helps to tighten everything up plus it means the filters work better and you reduce the band shift issue caused by fast optics.

 

Thank you! Yes, I love the top one. I might try and add some RGB data just to see what it does but we'll see.

Thanks all.

Have you got the link to the screw on one please? Thank you 

Hi all,

Was looking for some pointers really after pointing my scope at the moon the other day for the first time in two years and seeing how majestic it was I feel I have failed to look around our solar system (I mainly go after DSOs), so I feel the time has come or at least to prepare now so I am ready. I have neglected our neighbours for too long. What I don't have is a planetary camera and a 2500fl scope with some serious aperture, however I am hoping the latter is optional lol. What I do have is 952mm ES 127 and a couple of ZWO pro cameras which I hope will do or I can buy a planetary, but I am sure with a Barlow I maybe in as my fl is lacking (hoping)?

• Can anyone recommend a good Barlow if so should I be looking for 2x 3x what's the cons here I assume like with a reducer where the F stop is quickened with a Barlow its slowed? Is this a massive issue if shooting in video?
• I have noticed when shooting a video via my 1600mm I have the option of formats. 360p up to 1080p and everything in between. Each option the picture scale size changes more zoom at lower format I assume this is pixel scale related? Is there an ideal resolution to shoot planetary? 

Thanks

Awesome your stars are on point! Something I just can’t get with my SY 135! Can you provide the gear you used to attach the camera I think the connection I have is letting it down. Great capture!

My submission here is M42 it was shot over two nights 04/12/21 RGB 45x60s for each channel and then 09/01/22 I added 145x60s Ha. In processing I realised the Ha was overpowering the RGB and realised I should have done LRGB here. In the end I blended 50% Ha and 50% R and mapped that to R and I think it came out ok. It’s the first time properly trying this and I found it was the hardest image I have had to process as above it took at least four attempts before I was happy probably caused by my rookie mistake. A lot of submissions on this one and some really awesome images good luck to all and the judges! 
 

R 45x60s, B 45x60s, G 45x60s Ha 120x60s

1600mm pro, WO RedCat

editing image as original was a screen shot another rookie mistake.

Welcome back and great shot! The kids thing is difficult two small ones here as well but as soon as they in bed if it’s clear I am out! Only the Mrs is not too happy about that I tell her she married into me but also astrophotography… it’s a package deal!!!

I have a HEQ5 pro and it doesn’t click when tracking at sidereal never has. It does make a light grinding noise when go to though but that is normal always has made that noise. I hope you fix it but wanted to note clicking is not right. Thanks 

I am glad I am not the only one noticing this. I have noted about 12 hours of clear skies in the whole of December. I am actually going to put together a calendar starting next year to show clear, partial and cloud to see how painful it is here in the UK for getting clear nights. Will be interesting to see and tally up the whole of 2022! Let’s hope January is an improvement! 

3 minutes ago, Uranium235 said:

Have you tried it on another camera? If its consistent, then you know its the lens. You can still shift it on (for daylight phtography) to MPB for a decent-ish sum.

I havent tried stopping down the lens yet, it might help with the vignetting. But like the first two I had, I want it running wide open as much as poss.

Hi Rob,

No I have not actually I have a DSLR and another dedicated camera so good shout will give that a go. Stopping it down didn't work for me at least to F5.6 I think I went to... Ill try the other camera

Thanks

7 hours ago, Uranium235 said:

Well... its been a LONG time coming... but I've finally gotten round to testing the new 135 (yes, this is my 4th!).

And, unlike the third (which was a bit of a lemon), this one is a keeper. No stopping down on this, I want warp factor 10 please!

 

Just 3x10min to test. But the corners look acceptable, gawd... cant be any worse than the last one...lol.

No calibration... just a test stack to see whats what, looks like I got the spacing kinda right with the mark just landing on the "L"  (close enough).

Mine has a shocking corner it’s so annoying I considered getting another one in the Black Friday sale as new on Amazon is £329! 

Awesome image I particularly like the HOO version!

Welcome to SGL and thanks for posting lots of friendly folks on here they have helped me on my journey in AP. I am a couple years in now but still learning every day there so much to see out there and learn whether its in the field, equipment or processing, but I love it and I am sure you will too. You have gone with a great starter kit as well cant go wrong with the SY135 I have one myself and love it. I also started with a star tracker and Canon 800D as well watch out for that rabbit hole I am sure you have heard of! Good luck in your AP journey

I have had this issue so many times es on my HEQ5 Pro but a simple power off an on works ever time. One time it did this I noted the power cable to the mount was not clicked enough even though it showed a red light could have been coincidence though. 
 

After PA I also go home using the app then sync to mount then select target. If it lobby’s still the floor power everything off check all power cables and try again it should work. It’s a known bug glad to see they addressed it on the plus lol! 

#facepalm! Well that’s that then! Really need to remember to check the moon I should have known really 3 weeks of shocking weather and a clear night was always going to be a full moon!

I finally have a clear night tonight and Orion is positioned perfectly just need some opinions please. HaRGB or LRGB I am not sure what I should be doing or if one is better than the other? Also is the RGB subs more important than the L or Ha? What kind of ratio should I be aiming for?
 

Can you tell I am new to mono….

Thanks

Hi,

Oh I see I used DSS but I never saw the comet option. Let me run it again now using that option to see how it comes out. 

Thank you

Hi all

Tried to bag 67p last night and thought it was going well till the stack and stretch! Any ideas what's caused the nucleus to do this?

This was 30x60s with a UV/IR Baadar filter. Since adding that to my OTA I have had nothing but issues!

Thanks

I don’t have this camera but I follow a lot of people that do and they have all had it. As Russell states this pretty much an inevitable with this camera but as he shows an east fix. ZWO I feel could do a bit better though the generic response is not good enough in my opinion and I am a ZWO fan boy!

First light tonight with ES127ED thanks to some members here was able to get the OTA together. Unbelievably it’s clear and moonless so I thought I would go OSC (didn’t want to introduce more complications) and picked NGC891 well I centred on NGC906 to get some of the smaller galaxies in the FOV counted about 20 so far! Just a simple stretch on one 300s sub. 

Thanks both I managed to brave it tonight before the rain came. I had to add one of the  ES spacer to the focus draw tube to get in the region I also used the Hotech flattener ordered from @FLO which turned up the next day really love those guys and that slot into the eyepiece holder and managed to do a quick test. 
 

I nearly lost the scope into the mount when balancing I thought I would do RA first and the top heavyness of the glass swung the Dec towards the tripod somehow the clutch was just tight enough and I managed to grab the Losmandy plate one lesson learned there! After that near disaster all went well. Guiding was at 1 total rms which is about normal for my heq5. 
 

I literally managed 30s on NGC891 and it started to spit it’s pretty bad as just a screen shot not the actual file. There is a little elongation in the corners so I think I just need to play with the flattener a little but overall success.

Can always count on the community here. Thank you! 

@KP82 ok this is awesome info so that’s sort of what I had but I actually had the 55mm spacing going into the eyepiece shown below. So basically if I use without a flattener this config I remove the zwo spacers and use the camera nosepiece. But adding a flattener (turns up tomorrow) that goes into the eyepiece compression and then I add the zwo spacers. Just one other question if I may is there an adapter from the ES extensions to the flattener that’s threaded? I have not used compression rings before can they be trusted? Thanks 

14 hours ago, mxcoppell said:

Folks,

First post here at Star Gazer's Lounge. 

Recently I started to build my ultra-wide-field rig based on Samyang 135/2. Finally, the pieces come together. And I noticed something unexpected.

The following are some photos of my setup. The payload at camera mount side includes QHY294m, CFW3s-us, CTU M48 and a custom-made CAA. 

If I push the tail of the camera downwards, I can see there is a very small play (flexure) between the imaging payload and the lens. It's not the M48 plate used to replace the bayonet - initially I suspected that and retightened all 3 screws. When I release the pressure from the camera, the tiny play "bounces" back. 

There is a picture with a YELLOW arrow to show where the flexure happens. 

Does anybody experience similar thing, or I got a bad copy?

Thanks in advance! 

-Min from Coppell, Texas

 

Nice setup here a lot of people have had issues with this lens if you scroll back through the thread with stars that are elongated in one corner. However as we know this lens does perform incredibly in picking up those photons. I tend to ensure when shooting I check which side my bad corner is and position the DSO out the way so I can crop the bad stuff! There are some others that have upgraded to better connections to stop flex which I have not tried and it looks like you have this adapter already? This makes me wonder if it is actually flex? Last thing you could try is some additional rings around the camera in order to reduce the stress and flex if that turns out to be the case? 
 

and welcome to SGL!