Mark1489

Hi Adam! I really like your Orion Nebula, it looks very natural! I’ve noticed in your sub screenshot that it’s an 8 bit image, I’m not familiar with your camera but try shooting at 12 or 14bit if possible! That should capture greater detail per sub 😃

Definitely going to do a test next time and take some exposures just changing the iso and nothing else, while equalising all the exposures in processing! Yes very interesting read! The only reason I bumped the iso higher was to gain clear separation from the left, I image under 21.2 or 21.7 skies mostly so there’s some light pollution but not a lot. My next target is the Orion Nebula so a perfect example to test the extended dynamic range of a lower iso 😊

Hi, After a lot of reading I think I understand the iso invariance of some cameras, that being using a lower iso and boosting the exposure in post processing will not increase the image noise, and a greater dynamic range is produced (please correct me if I’m wrong). How do I apply this in a practical sense? I have a Nikon D5300 and the data points towards ISO 200 as the sweet spot. Now obviously if I expose for my usual sub frame length (1 minute) my histogram is going to be up against the left, I guess what I’m trying to ask is how do I know if I’m clipping data at this point? I’ve always used the histogram clear of the left edge technique to properly expose my images, but it seems this wouldn’t work if I’m using a lower ISO. Anyone have any ideas how I should go ahead with this? Thanks Mark

I’ve found that the focus is extremely critical, tiny movements have changed the elongated stars in my corners/switched the bad corners. To be honest I crop most of it out but I’m lazy!

Hi Dave Thanks, makes sense! I use the camera histogram yes, are you saying that I could possibly use a lower iso without clipping data? Would there be any way of getting a RAW histogram showing somehow out in the field? I’ve read the sweet spot for the D5300 is ISO 200 or 400 which is obviously a fair bit lower than what I’m using. Mark

Hi all, My local imaging site is SQM 21.2 Bortle 4, with my gear I can get 60 sec exposures reliably, I use ISO 1600 to get my histogram just clear of the left side. My dilemma is that I want to travel to a nearby site which is SQM 21.8 Bortle 2 but with my gear I think I’ll need to use ISO 3200 to get separation from the left. How much is the reduction in dynamic range going to effect my images? Does lower dynamic range reduce the amount of faint detail I’m going to be able to capture? I use a Nikon D5300.

00:24:43, 26/8/19, 60 seconds

Hi everyone, I wasn't sure where to post this, mods feel free to move if its in the wrong place! Was looking through my subs of Andromeda and came across this.....is it a meteor? Or something else? Pretty new to imaging so not sure what it is! Mark

Cheers, I’ve been using a 3D printed bahtinov mask for the Samyang that I bought online which does help things, though I tend to get elongation of stars in one corner if the focus is slightly out, suppose it’s what you get with fast optics! I’ve been trying to experiment focusing in different areas instead of the image centre but I think I need to be able to fine tune! A manual micro focuser would do me fine, I like to keep things simple haha! You’re right, BY Eos/Nikon is great! Very kind of you to say, thank you! I am very pleased! Looking forward to seeing more of your images, they’re inspiring me! Mark

Thank you! 😀 I’m using a Star Adventurer, Unguided. Still need to pin down the focus better, may have to invest in a micro focuser!

First go at Andromeda! Nikon D5300, ISO 1600, 53 x 60 secs @f2.8

Hi David First off, great images! I’m using a Samyang 135mm camera lens. I’d love to spend on a mono setup with a refractor - maybe one day. The lens has a hood but I still get stray light entering on one side. Really annoying since when I moved in the developer had not connected the lights and I had dark skies on my patio! I’m 40 minutes away from bortle 3/2 skies so I may just bite the bullet and put up with the drive!

Hello all, I’m considering buying a LP filter so I can image from my garden. The main problem is I have a streetlight directly behind me, just wondering if a LP filter would be effective at this short distance from the streetlight, especially with the glare etc. I believe it’s a sodium type not LED, any recommendations for a clip in filter for the D5300? I know it’s not ideal but I don’t have the time to drive to dark skies as often as I’d like, so just experimenting to see if it’s viable or not 😀 my skies are 20.88, they could be worse! Mark

I managed to go out again and try the focusing away from centre...it made a huge difference and much better! I will look into this though since I still have a little bit of elongation of stars at the very bottom, I usually crop them out. What would you recommend for a D5300 and Samyang? I’m guessing all mounted to a single dovetail?

I have the samyang and a few issues with coma that seem to vary night to night. I always stop down to f2.8 but one corner is pretty bad, and what has me at a loss is tonight the worst corner was the opposite corner of the image! Bearing in mind the rotation of the lens/camera was not changed from previous nights. I think I may need to try out your idea, I normally just focus at the centre of live view with a bahtinov mask....

I took this of Rho back in May with the Samyang from South Wales, bad tracking meant I lost a lot of data so it’s only 16 minutes worth, I’m hoping to top it up!

I use the Samyang and was thinking of a QHY183C as an upgrade to my D5300 in the near future, a good match possibly? I was looking at the QHY247C with the same sensor as the Nikon but it’s quite a step up in price!

Most definitely portable! To be honest the guiding scenario I’d really want to avoid for now, I’ve done a fair bit of research and I’m trying to keep my setup as simple and straightforward as possible. There’s no doubt I’ll eventually go for it though!

Hello all So I’m at the stage where I think I want to upgrade to a better mount. I’m using the star adventurer currently, and although it’s great, I find I might be pushing it a bit unguided. I know most people would recommend guiding, but I want to try imaging unguided for simplicity and ease of setup. Less things to go wrong essentially. I’m using the Samyang 135mm with a crop sensor (6.1arc secs per pixel scale) with the view of getting a WO Redcat in the next year or so, what would be my options for a mount around £500-£1000? Are there any mounts in this price bracket that would have low enough periodic error for unguided performance to say, 400mm focal length? I look forward to hearing your views! Mark

My latest example with this awesome lens! Gamma Cygni region, 50x60 secs, ISO 800. Imaged with the moon in the sky but I was itching to get out, so probably lost a fair bit of detail, the moon gradient was a nightmare to remove!

Thank you for the kind comments! I will be adding more data to this in future so I can clean up some of the noise and hopefully get some more of the red Ha showing! The colours are definitely what make it my favourite object! I'm using a Nikon D5300 but the field of view is about 6x10 degrees so very similar! Great picture! Your's has a lot less noise than mine, how much integration time do you have if you don't mind me asking? I'm using a stock dslr too, I find I can capture some Ha but it just takes A LOT of total integration time 😀

Thanks Olly! I have to be honest when I saw with my own eyes how low it actually was and frame after frame of egg shaped stars I was starting to think I’d wasted my time ? Apart from looking through more atmosphere, Is it harder to track objects lower in the sky? My periodic error seemed like it was through the roof Mark

Well I got lucky with the weather last night and took a trip down to Rhossili on the Gower peninsula, with a nice dark southern horizon. Unfortunately my tracking was awful, not sure if this was due to the wind or the fact that it was so low in the sky, but I managed to stack the best frames I could. Probably threw about 70 % of them! I think guiding would have helped a lot, something which I’m going to start doing. Anyway here it is 16 frames x 60 sec ISO 1600, manually dithered, very pleased!

Thanks! Nikon D5300 unmodified, ISO 400

NA nebula region widefield, the dew got the better of me unfortunately! 3 x 150s @ f2.8 Bortle 3 skies