The Lazy Astronomer
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Posts posted by The Lazy Astronomer
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14 minutes ago, Neko said:
looks great! would be interesting to see the whole image too!
I've bought it also for gudiescope and hoped for wide field AP but my qhy8L has 20mm backfocus so for now will wait to get
the flattener...until I can get another camera with shorter backfocus haha
Thanks. I bought a licence for StarTools earlier this week, so will probably have a go at reprocessing this weekend.
You might be alright with 20mm - I use mono+filters the filter takes up a couple of mm of the threads so the camera doesn't fully mate with the flattener and it seems pretty good across most of the frame. The stars streak a bit near the edges so I have to crop 15%ish off, but still a decent usable area.
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So, I've got a potential couple of clear nights coming up over the next few days, but one of them is under a 78% illuminated moon. I use a mono camera with broadband filters (no narrowband yet - they're on the wishlist!), and my question is this:
Is there a preferable colour channel to shoot when the moon is so bright (R, G or B), or would they all be equally negatively impacted?
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All dedicated astro cameras need to be connected to a computer of some sorts.
It doesn't need to be a particularly powerful computer though, so if you have an old laptop lying around that would probably work - I use an almost 8 year old laptop that I've repurposed as a dedicated scope-side PC.
Also, if you have an old laptop running Windows 7 or 8, Microsoft allows you to upgrade to Windows 10 for free*
*I can confirm this to be true for Windows 8, it should work for Windows 7 as well, but I can't personally confirm that.
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I tried to think about this, but my thought processes were only capable of going as far as "something, something... pixel scale... something... seeing conditions" 😃
This seems like the sort of question @vlaiv will answer comprehesively.
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3 hours ago, Skinnypuppy71 said:
I just remembered also, I did do a three star alignment as opposed to the usual two star. I think maybe this could be why my tracking was better.
I don't think the stsr alignment process has any bearing on the tracking accuracy, just makes the initial goto slew more accurate.
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9 hours ago, Simon Pepper said:
Hi all,
This content is really helpful and I have been following, however I also have a question around flatteners / reducers. I currently have the RedCat which I have been using for Nebula and wide field imaging, but I want to go a little deeper perhaps things like M33 and M101, Hercules etc and checking astronomy tools FOV I think I want something around the 500mm focal length (which is still forgiving for a beginner) I will pair this with either my DSLR or buy a ZWO 294 MC Pro. I am keen to stay with William Optics as the build quality and image quality is great, so I am leaning towards William Optics GT-81 IV (478mm) or William Optics Zenithstar 81 APO (559mm) there is quite a difference in price here and I assume this is down to the F ratio being far superior on the GT. My question is do these two scopes need / require a flatter to obtain a flat field across the image? I don't really want to be adding a reducer as that will increase the FOV, price and bring down the focal length which I want to avoid as I already have a wide field Redcat it seems silly spending loads of pennies if I am only going from 250mm to maybe 350 / 400m once a flattener is introduced on the above. Any recommendations on this or other scopes would be appreciated. Checking the OP specs I believe they are using William Optics Zenithstar 73 II APO 2019 which is another scope to for me to consider.
Thanks
The GT81 is a triplet, the zenithstar is a doublet, so that accounts for the price difference (triplets are expensive).
I think, for larger sensors, basically every scope needs a flattener if it doesn't already create a flat field by design. Not sure if there is a non-reducing flattener either of those options you've listed above, but I'm sure someone will chime in with an answer to that.
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I've been using it as an imaging scope for a little while now. I haven't actually tried guiding it yet - I've found l can get 2 - 3 min subs out of it as long as polar alignment is half decent.
To take full advantage of the wide FOV, you will need the flattener though, and this gives you backfocus of 17.5mm, which should be perfect for your 533
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19 hours ago, valleyman said:
Just the Reds and Greens to do then.😏
19 hours ago, Mr Thingy said:It's going to be a stunning picture once you add 10 hours each of R & G, plus 20 hours of luminance 😂
Ha, yeah this has now turned into a much bigger project than anticipated. Hopefully will turn out really nice in the end 😁
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19 hours ago, Les Ewan said:
The closest thing to your experience that happened to me is during the Leonid fireballs in 1999(film camera) I discovered later in the darkroom all my shots were hopelessly out of focus.😩
Oh man, that must have been pretty disappointing. I'm sure I'll be making that mistake myself soon!
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Managed to get a couple of sessions in this week, totalling about 10 - 11 hours of luminance data on a couple of targets I'm working on at the minute.
Was a little disappointed with the level of detail in the shots coming out, but nevertheless continued, figuring it would be much better after stacking and processing.
Only today, whilst taking some flats, do I discover I've accidentally shot it all through the blue filter! 😣
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4 hours ago, knobby said:
I still don't get it ... We can't buy any astro gear because it's out of stock everywhere ... Yet it's still cloudy 😂
This is obviously because backordered items still count towards % cloud cover 🙃
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I was searching around for things to image next last night, and settled on the flaming star and tadpole nebulae.
No idea how difficult a target they are, they're mag 6 and 7.5 respectively, so not too dim.
Pretty high in the southern sky (if you have views south) from around 7pm - 1am according to Stellarium.
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Yep, well we were forewarned!
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Expect disappointment and frustration for a least the first couple of nights.
Oh, and set up and use plate solving software from day one!
1 hour ago, ollypenrice said:Mine may be a minority opinion but I hold it none the less, and spend a lot of time with beginners. Buy a good mount and autoguide from day one. Keep to a short focal length and, if you possibly can, miss out the DSLR stage and go straight to a cooled CMOS camera.
Olly
Did three of those, so at least I'm doing something right 🙃
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Would you be able to upload the unprocessed stacked image? I'd happily have a go at processing it, and I'm sure a few others would too.
Disclaimer: I'm by no stretch of the imagination an expert with GIMP, but have played around with it quite a lot over the last few months for astro image processing.
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2 minutes ago, Neila1975 said:
Thanks - What is APT?
Astrophotography tool - it's a software for setting up and controlling imaging sessions. See also: N.I.N.A
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Don't know too much about DSLR imaging, but l do know general histogram advice is to get the peak 1/4 to 1/3 off the left hand side, so you're there or there abouts.
I see a lot of advice from people saying to use iso800 to keep the noise down and increase exposure until you reach the desired level on the histogram, but I've also seen some really nice images at iso1600, so maybe that's not so important. Total integration time is key though!
Looking forward to the finished image, I really like widefield shots of Orion!
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Yeah unfortunately, astrophotography is not cheap. The general advice is the most important thing is the mount and this is where you should put most of your money. For a proper mount, you're looking at £700+, less if you can find one used.
A lot of deep sky objects are BIG, so you don't need a large telescope to image them. This is why l say stick to lenses, preferably widefield ones. You could then get away with using your current equipment for a while. Then, if you haven't thrown all your gear off a bridge due to the insane number of frustrations encountered in this hobby, you can look at upgrading equipment.
If you really wanted to use the mak, it would be well suited for the moon and planets (although you'll have to wait a few more months for Jupiter and Saturn to come back around).
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Do yourself a favour and just use your camera lens. Long focal length maks are not recommended for DSOs.
Alternatively, l recently saw a thread from a guy who was trying imaging using eyepiece projection with a mak and DSLR, maybe search for that and see how he got on?
P.s. Welcome! ☺
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On 31/01/2021 at 09:24, Jonny_H said:
Agreed using solely for a guide scope is probably considered as overkill but as Vineyard mentioned i will also use it as an independent scope also.
I now need to do some serious thinking 🙂
I can highly recommend it as an imaging scope in its own right and the possibility of duel purpose use was exactly why I bought it (in fact it's outside right now taking widefield shots of M81, M82, and a couple of their other very small, very faint friends).
The only complaint about it is that it suffers from some bloating in the blue and luminance channel* - managed to correct that with the Astronomik L3 filter and am now very pleased with the results.
*I use a mono camera, so I think it was caused by my filters passing unfocused UV, not sure if it would be an issue with a colour camera.
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On 01/02/2021 at 22:12, vlaiv said:
That is actually quite decent set of settings - except for planetary exposure time.
So for point 1 and 2 (lunar and planetary) - set exposure time sort enough so that you can freeze the seeing. Don't pay attention to histogram what so ever.
I often record with histogram being as low as 20-25%.
Point of the so called lucky imaging is to use very short exposures - most of the time around 5-6ms and on lunar often shorter than that because moon is bright enough. This is because atmosphere is in constant motion and if you use longer exposure - seeing will not be frozen on a frame but will rather move during exposure and this will create additional motion blur that you don't want.
Hi vlaiv, it's interesting you say this, as when I first started with planetary imaging last year, I followed the advice of The London Astronomer, who recommends lower gains and target histogram of between 40 - 70%, depending on target and filter used.
I was pretty happy with what l was getting so never really tried playing with different settings - will have to have to do some testing when the planets come back later in the year.
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Input your details here: https://astronomy.tools/calculators/ccd_filter_size
Remember that the clear aperture for 1.25" filters is less than than 1.25" (measure your filters).
I had a play around with some numbers, and you could probably get away with around 60-70mm filter to sensor distance (at a fairly typical focal ratio of f6).
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Sorry, second post.
I've just realised your scope is a long focal length mak. This would not generally be recommended for deep sky imaging.
Your stated budget for a dedicated astro camera will also limit you to small sensors, which will make your FOV very small (again, not generally recommended for deep sky imaging).
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1 hour ago, Erskine1980 said:
Thankyou for this - being limited to 20sec or so exposures presumably would mean better off with a tracking mount for the D3300 instead of a CMOS then?
If you are looking to do long exposure photography, then you would need to ensure you were using an equatorial type mount regardless of whether using a telescope or camera lenses.
What you have currently is an alt-az mount, so you would be limited in terms of maximum exposure time.
That being said, however, it is possible to obtain very pleasing images with alt-az. Check out this thread for some examples:
First Proper Deep Sky Image (M42)
in Imaging - Deep Sky
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I attach the filter as described in the first post here:
I've looked at the manual, but not really read it. I've been playing around with some images, but do need to read the manual properly to understand what all the options and sliders actually do!