Best advice for capturing Horse Head - Forums

Topic starter

Sep 18, 2021

My first real, target will be in orion using the following kit
William Optics Fluorostar 81 APO Triplet 540mm f/5.9
William Opics P-FLAT6AIII Flattener 0.8 Effective focal length 432mm
Nikon DSLR Z50 Unmodified

I will be auto-guiding from moon lit skies. I was originally going to go for the veil but thats a project for the new moon.

I would quite like to try and frame orions belt in the shot. Can anyone offer any advice in terms of exposure length? I know im gonna have to try and get as much data as possible with the moon almost 97%

My nikon works well at really low ISO400

Rgds

Ricky

GoldfieldAstro

Sep 18, 2021

Having used a few newer Nikon cameras I'd agree that ISO 400 is a good place to start. I'd suggest 180s exposures would work well if the other Nikons I've used correlate over.

andrea tasselli

Frequent contributor

Sep 18, 2021

It's way too early for such a shot and having an un-modified DSLR your chances are pretty slim on top of consideration of pixel scale. At any rate Nikons are by and large ISO-less but I'd use 200 ISO, giving you more dynamic range to accommodate the brighter stars in the field. 180s is a good value for these cameras, as already advised.

Ricky Graham

Topic starter

Sep 18, 2021

andrea tasselli:
It's way too early for such a shot and having an un-modified DSLR your chances are pretty slim on top of consideration of pixel scale. At any rate Nikons are by and large ISO-less but I'd use 200 ISO, giving you more dynamic range to accommodate the brighter stars in the field. 180s is a good value for these cameras, as already advised.

I’ll try a lower ISO as as you say and see how it goes, by what do you mean it’s way too early? My latitude? I’m thinking aim south since the moon is in my way

andrea tasselli

Frequent contributor

Sep 18, 2021

Southern Scotland is a couple of degrees north of where I am which isn't ideal. Tonight the moon sets at around 4.45 around there at which point the IC434 should be around 23.5 degree in altitude over where you are, with 2.3 airmass which means a significant drop in brightness. If the shot is taken earlier than that you'll also have to contend with the moon glare further limiting your actual effective image dynamic. In around half an hour from that moment dark night ends and you start to shoot in nautical twilight, ever brightening sky background every minute. And the Horsehead is faint (well the nebulosity around it is anyway) and your aperture is small (same as mine) so I'll wager that the chance of a successful session are slim. Well, that depends on how you define successful. If it is just giving it ago then by all means…

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Arun H

Sep 18, 2021

The best advice for capturing the Horsehead is to not do it so close to the full moon!

Well Written

Ricky Graham

Topic starter

Sep 19, 2021

andrea tasselli:
Southern Scotland is a couple of degrees north of where I am which isn't ideal. Tonight the moon sets at around 4.45 around there at which point the IC434 should be around 23.5 degree in altitude over where you are, with 2.3 airmass which means a significant drop in brightness. If the shot is taken earlier than that you'll also have to contend with the moon glare further limiting your actual effective image dynamic. In around half an hour from that moment dark night ends and you start to shoot in nautical twilight, ever brightening sky background every minute. And the Horsehead is faint (well the nebulosity around it is anyway) and your aperture is small (same as mine) so I'll wager that the chance of a successful session are slim. Well, that depends on how you define successful. If it is just giving it ago then by all means...

It’s kinda “just giving it a go” if I’m honest. Pretty much a framing exercise for later at new moon.

Dong Liang

Sep 19, 2021

Just wrap things up a little bit.
1. It's too early to capture horse head at this time of the year. It rises too late and too low to make good imaging. Best time window for this is from december to february.
2. It's a very dim target. You will want to do this without moon light.
3. It's a target very rich with Hα lights. So you might want to modify your camera to allow Hα through.
4. The usual ISO setting is to put it at 'unity gain', a balance point between sensitivity and full well capacity. For most DSLR its 800ish. But it depends on the specific camera. Don't worry about the noise showes on single frames. They will be dealt with stacking later on.
5. If you have guiding, do dither between each frame! DSLRs are very hard to do accurate drak frame calibration. Otherwise, you might end up with nasty band noises on final image.

Hope this helps.

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