Does stacking negate the need for wide apertures for astro?

Messages
6,425
Name
Graham
Edit My Images
No
More of a musing than maybe something I'll act on but anyway...

When I've shot wide field astro to date, I've done it the 'simple' way, wide aperture lens, high iso, single 20 something exposure, bit of PP after, Job done. I'm happy enough with the results but there are some practical downsides, the biggest being that I end up owning expensive, heavy, fast wide lenses for the sole purpose of astro shooting which makes up only a small proportion of my photography. If that requirement was removed, I could buy much more practical f/4 zooms etc that would serve a much wider purpose.

So I'm starting to question whether I could actually achieve better results by taking lots of noisier images with slower lenses and stacking them.

I would try this experiment for myself but have had very opportunities to shoot in last few weeks and the go to software for mac seems to be starry landscape stacker which costs £40 so would love to garner some opinions before I take the plunge.
 
I'm a bit puzzled why a wide aperture lens is less practical other than being a bit heavier? you can still shoot normal stuff with it.
I know stacking can reduce noise, whether it's a replacement for a fast lens... not convinced. Maybe someone has done a comparrison or could do one. I just dont get the chance to get out at night to do a test these days... sadly..
 
I'm a bit puzzled why a wide aperture lens is less practical other than being a bit heavier? you can still shoot normal stuff with it.
I know stacking can reduce noise, whether it's a replacement for a fast lens... not convinced. Maybe someone has done a comparrison or could do one. I just dont get the chance to get out at night to do a test these days... sadly..

The widest aperture lenses tend to be primes and no filter thread which makes them less useful (to me at least) for other stuff.
 
Stacking does not remove the need for a fast lens, it is mainly used to reduce noise by increasing the signal to noise ratio. If you use a slower lens, you are really starting yourself off on the wrong foot because you are going to get less light into your sensor and the only way you can negate that is to crank the ISO (which doesn't increase the light you are getting, only the sensitivity of the sensor).

I also don't understand the notion of having to own "fast, heavy lenses" just for astro. The Samyang 14mm f2.8 isn't a big lens...the 12mm f2.8 isn't a big lens...the Laowa 9mm f2.8 is one of the smallest lenses I've seen...And all sub £500 (The Samyang 12mm f2.8 can be had for £280...)
 
14-24 and bite the bullet on the SW150 system. It's a great very wide lens, gives AF (unlike some very wide and expensive primes) and is sharp edge to edge.

Although, I appreciate the 14-24 is a really nice lens, it doesn't really tick any boxes for me in the sense that filters become specialised (and expensive) for normal landscape stuff and it's especially fast for astro.
 
Stacking does not remove the need for a fast lens, it is mainly used to reduce noise by increasing the signal to noise ratio. If you use a slower lens, you are really starting yourself off on the wrong foot because you are going to get less light into your sensor and the only way you can negate that is to crank the ISO (which doesn't increase the light you are getting, only the sensitivity of the sensor).

I also don't understand the notion of having to own "fast, heavy lenses" just for astro. The Samyang 14mm f2.8 isn't a big lens...the 12mm f2.8 isn't a big lens...the Laowa 9mm f2.8 is one of the smallest lenses I've seen...And all sub £500 (The Samyang 12mm f2.8 can be had for £280...)

I've read a bit on this subject, and though it's all theory and not my experience, the explanation for stacking appears to be that by combining many shots, you're to some extent working with more gathered information (or total photons) even if each individula shot is poor, you're averaging out the noise. That's the theory at least. I've seen some good results too but I'd like to prove it for myself.

I suppose I don't really think of 2.8 lenses as being especially fast for astro. They certainly to the job but I've more recently being using 1.4 or 1.8 primes. But any of these prime lenses mentioned is a one trick pony for me as I'd still want a wide zoom for landscape that can take filters and even if the additional astro lens cost less than £500, that is still a lot of money to spend on something that gets little use.

Currently, I'd compromising with a tamron 17-35 2.8. Which actually is a very good compromise but it was really the only lens I could choose that ticks all the boxes. Nothing wrong with it, I'm just curious to know how well alternative approaches work.
 
Although, I appreciate the 14-24 is a really nice lens, it doesn't really tick any boxes for me in the sense that filters become specialised (and expensive) for normal landscape stuff and it's especially fast for astro.

You probably shouldn't have sold me your Sigma 24mm...and I am not selling it back :p

The Nikkor 20mm F1.8 is really nice and can take 100mm filters. For conventional landscapes I prefer it to the 14-24 BUT if you end up doing interiors (domestic) it isn't quite wide enough - and a few times shooting landscape it's ideal if you need wider than 20mm...

Filters die in the end - they get scratched beyond the point of no return. I chose that moment to do the 14-24 and SW150.

I had a 16-35 Nikkor which is what most people buy given your remit - and @NeilA1975 has a very nice barely used on for sale - it does everything you'd want but I didn't like the rendering compared to the 20mm F1.8 or the 14-24 but it's still a decent wide zoom. There is the old Nikkor 17-35 F2.8 but you have a Tamron 17-35. There is the Tamron 15-30 but I think it's specialist filters time.

You might be able to get an 18-35 - they're supposedly sharper than the 16-35 but less contrasty. Sure there is one on sale here.

If you go Mirrorless the Z7 takes a 14-30 - which takes standard filters.

These are your choices IMHO laid bare. All are expensive and compromises in some way or another.
 
You probably shouldn't have sold me your Sigma 24mm...and I am not selling it back :p

The Nikkor 20mm F1.8 is really nice and can take 100mm filters. For conventional landscapes I prefer it to the 14-24 BUT if you end up doing interiors (domestic) it isn't quite wide enough - and a few times shooting landscape it's ideal if you need wider than 20mm...

Filters die in the end - they get scratched beyond the point of no return. I chose that moment to do the 14-24 and SW150.

I had a 16-35 Nikkor which is what most people buy given your remit - and @NeilA1975 has a very nice barely used on for sale - it does everything you'd want but I didn't like the rendering compared to the 20mm F1.8 or the 14-24 but it's still a decent wide zoom. There is the old Nikkor 17-35 F2.8 but you have a Tamron 17-35. There is the Tamron 15-30 but I think it's specialist filters time.

You might be able to get an 18-35 - they're supposedly sharper than the 16-35 but less contrasty. Sure there is one on sale here.

If you go Mirrorless the Z7 takes a 14-30 - which takes standard filters.

These are your choices IMHO laid bare. All are expensive and compromises in some way or another.

Glad you still like it.

Many of those options are f/4 ish. which suit me down to the ground most of the time. It's really what this thread is about as traditionally I would say that is too slow for astro but I speculate that with current techniques, the playing field may have been levelled. Or not...
 
I have just started having a go at night photography using a Tokina Firin 20mm f2 lens and so far I am quite pleased with the results wide open @ 15-20secs I have the manual version which is a very manageable size & weight , this thread got me thinking about stacking and I have been watching a couple of vids on youtube about the starry landscape app so next time out I will shoot some images with a view to stacking, this will probably be around the end of September when the nights are a bit longer.
I did try a few months ago with a Samyang 14mm 2.8 but I must have had a really bad copy ended up giving up and sending it back.
 
Glad you still like it.

Many of those options are f/4 ish. which suit me down to the ground most of the time. It's really what this thread is about as traditionally I would say that is too slow for astro but I speculate that with current techniques, the playing field may have been levelled. Or not...

Bump the ISO - stack lots etc. Not my area but reckon you are better with an F4 zoom and an wide prime for astro use - even if you don't use it much. You'd be surprised by the 20mm F1.8 - if you can live with the lack of zoom it's a great wee lens for landscape and astro as it's a 1.8
 
Surely the challenge for stacking is movement. Not a problem for say a inside a cathedral with camera on a tripod. For astro-photography the ground is moving with respect to the stars so you need a fast lens to avoid very slow shutter speeds? I do not do astro -photography myself so perhaps I am wrong about this.

Dave
 
Surely the challenge for stacking is movement. Not a problem for say a inside a cathedral with camera on a tripod. For astro-photography the ground is moving with respect to the stars so you need a fast lens to avoid very slow shutter speeds? I do not do astro -photography myself so perhaps I am wrong about this.

Dave

Yes, it's a problem but stacking software is pretty clever. Essentially it will align each image so that the relative movement is compensated for. The foreground area is excluded from this adjustment so, in theory it should be seamless.
 
Last edited:
I own the rokinon 14mm 2.8, I am pretty happy with the results of the basic “recipe” iso 6400, 25 sec etc for a single shot. I have tried stacking and haven’t really decided if it works for me either. If I lift the exposure on a stack it seems to bring back noise, but I might not have figured out the processing correctly yet. I listened to an interview with Royce Bair recently and he recommended taking no more than 5 or 6 shots I think and overlaying in photoshop at progressively lower opacity for noise reduction of the foreground. I tried and that was a good improvement in foreground noise reduction.

I think you need to get the processing right and it’s not as simple as take several shots and stacking. I don’t think boosting exposure by stacking really works.
 
Back
Top