The time has come for some new gear. You want to upgrade to a mid-range focal length like a modern 35mm and 50mm prime or a 24-70mm zoom, but which option is right for you? A prime or zoom lens?

If you’ve had a fast ultra-wide lens for some time now, but maybe you’re not happy with the size of the Milky Way in your frames, or you want to try some new Milky Way Photography tricks like creating epic focal length-blended images, then it’s time for you to upgrade.

If that is the case, your options include a 35mm f/1.4 and 50mm f/1.4 prime lenses combination or a 24-70mm f/2.8.

My Lens Kit Choices

For the first year of owning my Pentax system, my primary lens kit for night photography was my Pentax D FA 15-30mm f/2.8 wide-angle lens. Now, my night photography kit often includes my Pentax D FA 24-70mm f/2.8 or my Pentax D FA* 50mm f/1.4 and Sigma 35mm f/1.4 Art.

I use my 15-30mm to shoot most of my foregrounds while my 35mm, 50mm, and 24-70mm have been used mainly for my sky exposures.

This is by no means a budget-friendly lens collection, but if you’re looking to upgrade lenses, maybe a 35mm f/1.4 and 50mm f/1.4 should be on your list. An alternative to two fast primes is a single fast zoom like a 24-70mm f/2.8.

It’s Not Just a Prime or Zoom Question

This question isn’t one of those classic “primes vs. zooms” debates. Instead, it will serve as a loose guide for serious or amateur night photographers that need help choosing their next lens, or lenses to pair with a wide-angle lens.

Which combination is right for you?

For this comparison, I will be using three lenses that are available on most systems in some form. I’ll discuss the advantages and disadvantages of two fast primes versus a single fast zoom lens.

Sigma 35mm f/1.4 DG HSM Art

Announced at the 2012 Photokina trade fair, the Sigma 35mm f/1.4 DG HSM Art is still one of the top performing lenses for astro photography. Prime or Zoom.
Announced at the 2012 Photokina trade fair, the Sigma 35mm f/1.4 DG HSM Art is still one of the top-performing lenses for astro photography.

Sigma’s 35mm f/1.4 was one of the earliest Sigma Art lenses that, when released, set a new bar for image quality for fast primes.

The lens features a fast f/1.4 aperture and top-notch build quality with all-metal construction and a mixed gloss and matte black finish.

Sigma’s Art lenses are said to be weather-resistant but may lack rubber seals around the lens mount, making them less than ideal to use in rainy or sandy conditions.

On the side of the lens is a single manual/auto focus switch.

Sigma’s 35mm is available for Canon, Nikon, Pentax, and Sony lens mounts and most of the lens mounts offered can be adapted to a number of APS-C and Micro 4/3 mirrorless cameras.

Pentax D FA* 50mm f/1.4 SDM AW

The Pentax D FA* 50mm f/1.4 SDM AW has several special lens coatings. The propietary HD Coating and Aero Bright Coating II are designed to reduce flare and ghosting in contrasty scenes. The front element has Pentax's Super Protect coating to keep dust and moisture off. Prime or Zoom?
The Pentax D FA* 50mm f/1.4 SDM AW has several special lens coatings. The proprietary HD Coating and Aero Bright Coating II are designed to reduce flare and ghosting in contrasty scenes. The front element has Pentax’s Super Protect coating to keep dust and moisture off.

Released in mid-2018, Pentax’s D FA 50mm f/1.4 represents Pentax’s official launch into modern, high-quality primes for digital and is a continuation of Pentax’s Star series lens lineup.

The Pentax 50mm f/1.4 features Pentax’s “AW” label, which means “all-weather,” so the lens is completely sealed from the elements and includes an o-ring around the lens mount.

The lens also features a fast f/1.4 aperture and superb build quality including an all-metal construction and a textured matte black finish.

On the side of the lens is a single manual/autofocus switch.

Almost every camera manufacturer has a 50mm f/1.4 in their lens lineup. Third-party manufacturers like Sigma, Samyang, and Rokinon, amongst others, offer photographers several fast 50mm prime lenses for most lens mounts.

Pentax’s 50mm can also be adapted to a number of mirrorless cameras via several K-mount lens adapters.

Tamron/Pentax D FA 24-70mm f/2.8 ED SDM WR

The Tamron/Pentax D FA 24-70mm f/2.8 ED SDM WR is known for good sharpness regardless of aperture or focal length. Prime or Zoom?
The Tamron/Pentax D FA 24-70mm f/2.8 ED SDM WR is known for good sharpness regardless of aperture or focal length.

The zoom lens used in the comparison is the Tamron-built and Pentax-branded Tamron/Pentax D FA 24-70mm f/2.8 ED SDM WR.

The Tamron version is available for most lens mounts, but every manufacturer makes a pro-grade 24-70mm f/2.8 for their native lens mounts.

The lens features a mostly-metal construction with a plastic lens barrel and a constant f/2.8 aperture.

The lens is also marked as “WR” or “weather resistant” and features a rubber o-ring to protect the lens and camera’s lens mounts from dust and moisture.


Photography is by no means a cheap hobby with most pro-grade camera bodies and lenses costing well over $1000. The question of prime or zoom is often of concern when discussing price.

These three lenses are priced like the pro glass that they are, and if you are trying to choose between the two primes versus a single zoom, there is a difference in price.

If you’re buying new, the Tamron and Pentax 24-70mm f/2.8s are on the mid-low end of 24-70mm f/2.8 lenses priced at just under $1300.

For Canon, Sony, and Nikon users wanting to use native glass, a new 24-70mm f/2.8 can be anywhere from $1500 to well over $2000.

Sigma’s 35mm f/1.4 Art is available for all major lens mounts including Canon, Nikon, Pentax, and various Sony mounts for $899 making it one of the least expensive high-quality autofocus 35mm f/1.4’s available.

For a fast 50mm prime, prices can be a bit tricky ranging from just over $100 for a cheap “nifty fifty” to well into the thousands.

An excellent mid-level 50mm lens would be Sigma’s 50mm f/1.4 Art, also available for almost every lens mount for $949 or, in this case, the Pentax D FA* 50mm f/1.4, which is a little pricier at $1196.

(Note: There are several less-expensive options for 35mm and 50mm primes, but most other budget-friendly primes made by brands like Rokinon, Samyang, or Bower often lack autofocus and sometimes only have manual aperture rings, making them tricky to use for other types of photography involving moving subjects. A “nifty fifty” is not part of this review because of the slower f/1.8 aperture and cheap construction.)

When put side by side, the Tamron/Pentax 24-70mm f/2.8 is the more budget-friendly option for top-quality glass.

Downgrading to a $400 50mm f/1.4 would put the cost of two high-quality primes at around $1300, almost even with the 24-70mm.


Are all of these lenses sharp?


Is there a difference in sharpness?


35mm at f/2.8

The difference comes early on. The below two images are a 100% crop of an image shot at 35mm at f/2.8.

Example Image #1 - 35mm at f/2.8
Example Image #1 – 35mm at f/2.8
Example Image #2 - 35mm at f/2.8
Example Image #2 – 35mm at f/2.8

Can you see a difference?

The first image is shot on the Pentax/Tamron 24-70mm at 35mm and f/2.8.

The second image is shot on the Sigma 35mmf/1.4 Art, and despite the slight trailing, the prime is noticeably sharper.

The prime also has less chromatic aberrations around the brighter stars.

35 mm at f/4.0

Now, compare the lenses stopped down to f/4.0.

Example Image #3 - 35mm at f/4.0
Example Image #3 – 35mm at f/4.0
Example Image #4 - 35mm at f/4.0
Example Image #4 – 35mm at f/4.0

There is trailing in both images as I’m likely maxing out the abilities of Pentax’s Astrotracer function during this test, but now the lenses are much closer to each other. (More on Pentax’s Astrotracer here.)

Because the chromatic aberration in the zoom is now mostly gone, the primary difference is in the slight sun star around the bright spot in the image, which is Jupiter.

Because of the large jump from f/1.4 to f/4, the prime is stopped down three stops from wide-open while the zoom is stopped down a single stop from f/2.8 to f/4.

On top of being sharper, the 35mm prime does a much better job rendering a more defined sun star around the brightest objects in the image at f/2.8 and f/4.

50mm at f/2.8

The results at 50mm are almost identical. The two images below are 100% crops of images shot at 50mm and f/2.8.

Example Image #5 - 50mm at f/2.8
Example Image #5 – 50mm at f/2.8
Example Image #6 - 50mm at f/2.8
Example Image #6 – 50mm at f/2.8

The first image is the 24-70mm f/2.8, and the second is the 50mm prime.

Once again, the prime is considerably sharper, and in this image, there is more noticeable chromatic aberration around the brighter stars in the image shot with the zoom.

The 50mm f/1.4 also creates a beautiful sun star around Jupiter thanks to stopping the lens down two stops from wide open.

The 50mm prime also has no noticeable chromatic aberration.

50mm at f/4.0

Example Image #7 - 50mm at f/4.0
Example Image #7 – 50mm at f/4.0
Example Image #8 - 50mm at f/4.0
Example Image #8 – 50mm at f/4.0

Stopped down to f/4, the zoom is actually sharp enough to produce some very usable images, if you can avoid trailing like in my test image.

At f/4, the chromatic aberration is no longer present in the image from the zoom, and there is a decent sun star around Jupiter.

However, once again, the prime lens is performing better overall likely because the lens is stopped down three stops from wide open.

The sun star around Jupiter is very crisp, but there is also more detail in the small nebula at the left-center of the image shot with the prime.

Sharpness Conclusion

In the area of sharpness, all elements being equal, the primes are the clear winners in image quality, but the zoom is not by any means unusable.

Since zooms have so many moving elements and so much glass in them, it’s not unusual for them to be softer than a good prime.

Despite the performance difference, the zoom performs well enough stopped down that medium-size prints will look fine and images for web display only will still look excellent because of the resolution of our screens and because of file compression on social media sites like Instagram and Facebook.

However, there is one more consideration if choosing between the zoom and primes for night photography.


Chances are if you’re spending almost $2000 on a few new prime lenses, you didn’t buy them because they are sharp at f/4.

Though a 24-70mm f/2.8 lens performs very well and is reasonably fast at f/2.8, it is still only an f/2.8.

As mentioned above, at f/2.8, the prime lenses are stopped down two full stops from wide-open, but their widest apertures are f/1.4, leaving plenty of room to open them up to gather more light.

With a wider aperture, you can decrease exposure times for sharper stars, or you can shoot at a lower ISO to reduce noise.

The image below is shot with the Pentax 50mm at f/1.4 in an attempt to test the limits of Pentax’s built-in Astrotracer function.

Pentax 50mm at f/1.4, 80s, ISO 200
Pentax 50mm at f/1.4, 80 seconds, ISO 200

The single-frame above was shot at 50mm, f/1.4, and tracked for 80 seconds, but most importantly, I was able to shoot at ISO 200.

With the 24-70mm at 50mm and f/2.8, I would have had to shoot at ISO 800; a two-stop difference.

The extra two stops of light mean less noise reduction in post, less need to stack exposures in post-processing, and less of a chance of star trailing because of shorter exposures.


Despite the faster aperture, lens vignette is a concern if shooting wide open.

As shown in the test images below, all three of the lenses do have a vignette, especially wide open.

Vignetting at 35mm

24-70mm @ 35mm f/2.8
24-70mm @ 35mm f/2.8
Sigma 35mm @ f/1.4
Sigma 35mm @ f/1.4

The 35mm prime wide open has a considerable vignette when compared with the zoom at f/2.8.

50mm Vignetting

24-70mm @ 50mm f/2.8
24-70mm @ 50mm f/2.8
Pentax 50mm @ f/1.4
Pentax 50mm @ f/1.4

As shown above, the 50mm prime has the worst vignetting of the three lenses wide open with most of the frame underexposed.

Thankfully, vignetting is very easy to correct in post at the cost of increasing noise in the corners and on the edges of your image.

The zoom is the clear winner wide open, however, in the case of both prime lenses, their vignette at f/2.0 is similar to the zoom at f/2.8.

Sigma 35mm @f/2.0
Sigma 35mm @f/2.0
Sigma 35mm @f/2.0
Pentax 50mm @ f/2.0

That translates into a difference of one full stop of light gathering capability while also reducing the vignette


Size is a simple consideration.

Without lens hoods, the three lenses, individually, are reasonably compact and much smaller than most large wide-angle lenses and 70-200s.

Still, a single 24-70mm f/2.8 takes up less space and weighs less than two pro-grade primes. Period.

If you’re into backpacking and long hikes, your back will appreciate every ounce of weight you can save.

In desert environments like the American Southwest, every little bit of weight you can shed is an extra ounce of water you can carry.

The Tamron/Pentax 24-70mm f/2.8 is my second lightest lens at 823 grams (1.9lbs) without a lens hood due to its partially plastic construction.

Pentax 24-70mm f/2.8 weighs 823 grams. Prime or Zoom?
Pentax 24-70mm f/2.8 weighs 823 grams.

The Sigma 35mm and Pentax 50mm without lens hoods weigh 724 grams (1.6lbs) and 974 grams (2.14lbs) respectively, adding up to 1625 grams (3.6lbs) of total weight.

The Sigma and Pentax primes weight 1,625 grams. Prime or Zoom?
The Sigma and Pentax primes weight 1,625 grams.

The difference in weight is exactly two pounds with the primes weighing more than the single zoom.

For reference, choosing the single zoom would save you enough weight to carry about one full liter of water instead of two heavier lenses, a wise decision in a place like the desert.


It is worth noting that all three of the lenses handle as pro-grade glass should.

The three lenses feel well built and have a nice weight to them, so they balance nicely on large camera bodies, like my Pentax K-1.

Because of their heavy construction materials and smaller size, the 35mm and 50mm do feel heavier in hand. (The Sigma is the lightest, and the Pentax 50mm is the heaviest of the three.)

Zooming is obviously not an option on the 35mm and 50mm (that’s what your feet are for), but the 24-70mm has a nice stiff zoom ring with no lens creep when carrying it on a strap.

The focusing rings are where the small difference in quality shows.

The 24-70mm has a thin focusing ring that moves easily, but the total throw of the ring is just over 90 degrees, and the feel is somewhat gritty.

The Sigma 35mm also has a rather short throw on the focus ring at right about 90 degrees of rotation from infinity to the closest focusing distance, but its focusing ring is large and smooth making manual focusing easy.

The Pentax 50mm features the longest focusing ring throw at just under 180 degrees of rotation.

A long throw helps with manually focusing, especially when fine-tuning focus on subjects, like the night sky, at f/1.4.


When it comes to my night photography, I primarily use my 15-30mm, 35mm f/1.4, and 50mm f/1.4.

The reason is I have the opportunity to work slowly and can take my time; changing lenses often doesn’t affect my work.

In a genre like photojournalism, amongst others, I prefer the flexibility of a zoom that can act as a 24mm, 35mm, or 50mm prime at the twist of a ring.

The versatility of these two lens combinations is purely subjective and requires you to factor in many variables, including the other types of photography you do.

Prime or Zoom Final Thoughts

I’m in no position to tell you which combination is right for you, primes or zooms. Hopefully, some of the areas of this comparison have helped you decide.

 I can offer my final thoughts and suggestions based on my experience.

On Primes

If you’re a “pixel-peeper” and image quality is your primary concern, then there aren’t many zoom lenses available that can compare to a few good primes for shooting the night sky.

When paired with my wide-angle lens, the prime lenses have had a considerable impact on the quality of my images, and I don’t see myself using a zoom to shoot the night sky much anymore.

Focal Blend by Aaron Martinez using the Pentax 15-30mm for the foreground and Pentax 50mm f/1.4 for the sky pano.
A focal-length blended image by Aaron Martinez using the Pentax 15-30mm for the foreground and the Pentax 50mm f/1.4 for the sky pano.
Single Exposure by Aaron Martinez using the Sigma 35mm f/1.4.
Single exposure by Aaron Martinez using the Sigma 35mm f/1.4.

On Zooms

If night photography is just a hobby or if the price is a big concern, or you want a lens you can use for everything, then a 24-70mm f/2.8 is an excellent investment.

What the zoom lens lacks in image quality, it makes up for in versatility.

Sometimes, the rock face behind you won’t back up any farther, so 35mm just isn’t wide enough, or that cliff in front of you won’t let you take another step forward, so 50mm isn’t long enough, so a single lens that can cover those focal lengths and then some can be convenient.

You also have the perk of not needing to change lenses as often, especially in bad weather.

I had my 24-70mm for almost eight months before I bought a prime and I produced some fantastic images with it.

Focal Blend by Aaron Martinez using the Pentax 15-30mm for the foreground and Pentax 24-70mm @ 50mm for the sky.
Focal blend by Aaron Martinez using the Pentax 15-30mm for the foreground and Pentax 24-70mm @ 50mm for the sky.

So should you get a prime or zoom lens? To put it as simply as I can, for shooting the night sky, you will benefit from a set of fast prime lenses because they’re sharper and the wide aperture is ideal for low-light situations. But if you want a true jack-of-all-trades lens, a lighter kit, and a smaller price tag, then there is nothing better than a 24-70mm f/2.8.


  1. As a pentax user this article definitely caught my eye. These days I’m using the 15-30, 31Ltd, and FA50 (the old autofocus 1.4) as my primary milky way lenses. One of my primary gripes is issues with star alignment with the 15-30 when I get wider with it and stack. Photoshop can’t handle it but Sequator can (MOST of the time).

    • @Peter K Absolutely hear you there! The 15-30mm is great for single exposures but it’s almost unusable with Astrotracer beyond 30 seconds or so. Thanks for reading!

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