Phillyo

I would think so yes. The only way to find out is to run some tests for your sky. You could always try using the sensor analysis inside Sharpcap software? It'll cost you £10 for the year but it's fantastic and will tell you what exposure lengths to use for optimal results.

Guiding is absolutely worth doing, as pointed out above you can dither which is always great. The l-extreme is a dual narrowband filter for Ha and Oiii which will work well with your DSLR (although your Ha will be limited due to the IR block inside a DSLR) but only on emission type objects, not galaxies or reflection type objects. 5min should be plenty and you can always up the ISO a little bit if needs be.

What DSLR are you using and why do you think going for the 'longest exposures you can' is a good thing? Not a dig, but a genuine question. The reason I ask is because your camera uses a CMOS sensor, not a CCD sensor. Once you have exposed long enough to get above the noise floor, the limiting factor for sub length is likely to be your light pollution levels. I would assume that Bristol LP isn't amazing so exposing for longer won't get you any more detail, just more light pollution. I would much rather shoot 100 x 2min subs than 2 x 100min subs. The longer subs also means more data lost due to aeroplanes, satellites, wind movement, bad guiding etc. If you take 2 subs at 100min and one of them is rubbish, you've lost 100min of data. If you take 100 subs at 2min and even 10 of them are rubbish, you've only lost 20min of data. Plus, with a lot of subs stacked together you can use an average combination method to remove satellite trails anyway. Try not to get into the mind set that longer is always better. More data is always better sure but not always longer, not unless you're imaging from a bortle 1 zone of course

Hmmm not really. A shade just directs the light in the 'wanted' direction rather than up or outwards thereby wasting light/energy for no reason. Also adds to sky glow and light pollution. I don't think taking them all down is really the same as putting a shade on them do you?

Signed. Shades should always be included, it makes no sense not to really.

Interesting comparison and I agree that the second one looks better than the first, there are always exceptions to the rule. That being said, if someone just snaps 50 darks at the end of the nights imaging and uses them as darks I don't think it'll make much of a positive effect during calibration. Throwing it in the fridge is a good idea, or a freezer to get even colder but how many amateurs go to that trouble and is it well documented that that's a good thing to do? There's also the option of using in camera noise reduction whilst imaging which can work well. The camera captures a dark frame and subtracts it from the light raw frame directly after each image is taken. That can work well if you're imaging when it is fairly cold outside, if it's warm then it won't make much difference. Hot pixel removal and bias removal is very important for DSLRs. It would be interesting to see your comparison above done with just dark frames and not bias to see what difference dark frames alone make to a DSLR image? Thanks for the comparison. Very interesting to see.

Patience, as they say, is a virtue! 🤣

Absolutely stunning. Can't wait to see the final full version!

What camera are you using that needs 15min subs for broadband data?

I use the ASIAir Pro for imaging and the platesolving is a blessing! So easy to use.

Some lovely images there. It always surprises me that people go for more than one target per session. To me, 4 in one night is just crazy! I understand sometimes due to objects blocking the way or LP in a certain direction you need to switch half way through the night, but I always only image 1 target per night as I want to try and get a good 6-10 hours of data on a target if not more before I process it to get the best out of it? Just my thoughts.

Here's my rendition. Lovely data again but I would echo what others have already suggested, flats would make a huge difference to clean things up.

I'll go take a look Alan!

Stick with the individual R G and B curves to try and get them even-ish. Don't worry too much if they're a little out as long as the background has a general 25, 25, 25 to 35, 35, 35 reading or as close as possible. It's tricky doing it manually. I use Pixinsight so it's much easier.

Curves are accurate so they should be lined up, however if you use the info button you should be able to hover around various points in the image and it'll give you an RGB value. Try to get the RGB at somewhere around 25, 25, 25 to 35, 35, 35 or as close as you can. That'll neutralise the colour cast in the image.

I don't think your flats are working correctly. They should be removing the dust from the image and it looks like they aren't. Can you explain how you're collecting the flats and the bias frames? Also, I wouldn't bother taking dark frames with a DSLR. They're only really useful for a set point controlled cooled astro camera; they can add more noise than remove it from none cooled cameras. Phil

As it's raining AGAIN here this evening, I had a little play with your data Alan. I think you just need a bit more integration time and if you can some Ha data to slot in and you'll have a fantastic image!

So nice! Loving the detail in those dust lanes.

Both lovely images. Tough one really, I guess if you had hundreds of clear nights and you wanted perfection then the APO might be the one to go with for more resolved images. However, if you only get a couple of hours here and there and you still want to make lovely images the RASA can collect that data in ~ 1/3 the time and get an image that is about 95% as good? Living in the UK, I know which I would choose based purely on the above images alone!

No real criticism from me, a great image. The only advice I could really give would be to try processing without using dark frames. Darks without a cooled camera can add noise rather than subtract it due to the variance in temperature of each frame.

Yes I drilled a couple of extra holes to attach it to that dual mounting dovetail. Mostly because I ordered the wrong one by mistake!

That is the 533 that you see attached there and it works perfectly. The lens has a very high resolution so sampling at 5.74 is perfectly fine. I have a number of images up in the DSO area of the site if you want to have a look. Pricing is tricky to find on that website, however if you click on the images, then click on "Do you need one?" it'll take you to this page for the prices of the various different parts. You can choose from a number of options to suit your needs http://www.astrokraken.fr/bracket-system-for-samyang-rokinon-135-f-2-telephoto-lens-a183920490 Phil

I went with this guy http://www.astrokraken.fr/samyang-135mm-f-2-c30078976 I have the 3 ring version with 3 holders, 2 for the lens and 1 for the camera plus the micro focuser which is amazing for nailing focus! Image of set up below.

I found mine on ebay for £290 which was a steal. Perfect condition too, hardly used and beautiful clean optics!

This is awesome. I love seeing starless images, for me it really helps to bring out the structure of the nebula. Great processing, well done!