[Karen the Star]

The reason that I start to think about this problem is because one day I found that as a lens without inner zoom, 55-300PLM will intruded by dust very easily, this makes me getting so angry with it, it's compact, sharp at this price, though the dust can't effect the image quality now, after 2 months I bought this lens, I already find at least 7 dust inside the lens.
However a prime focus lens will be very limited to choose subject, Though I'm feeling quite fun to take distance or be closer to a subject myself instead of turning the zoom circle.
If somebody could help me to know that how better will DA☆300 F4 does on image quality than 55-300PLM at 300mm, I want to know if this lens is worth me to buy.
Thanks

[MetalUndivided]

The 300 F4 is in a completely different league IQ-wise. If Image Quality is all you're after, then it's a no brainer. Bear in mind, however, that you lose lightning fast AF, compactness and weight, not to mention that it costs at least 2 PLMs.

[david94903]

It all depends on what you want to do with the lens, and does it meet your needs. It's not a simple Yes or No answer. I had the original version of the DA 55-300 for many years, and for me during that time it was the perfect going to the playground lens when my kids were growing up. The flexibility of the focal length and the IQ was perfect for my needs. As I moved into wildlife photography, sports, etc... it wasn't such a good choice. From the DA55-300 I moved to the F-300 f/4 lens for IQ, as that became more important for me.


As MetalUndivided states above, the IQ difference alone is reason enough alone, if that's what you're most interested in. The DA 300 is is significantly sharper that the 55-300 zoom, which is to be expected. Additionally, the DA 300 is significantly more expensive than the 55-300 too. However the DA 300 is a prime, and does not have the flexibility of a zoom.

At the end of the day, it all depends on your needs and how they are best met. If dust in the lens is going to make you unhappy, and nobody wants to be unhappy with their kit, then it might make sense to look at prime lens alternatives.

[BigMackCam]

All lenses - primes and zooms, new and old, weather- and non-weather-resistant, internal focusing or otherwise - will get dust in them over time. Indeed, many will have a certain amount at the point of manufacture. Even in controlled clean environments, it's virtually impossible to prevent this. I can almost guarantee you have more than seven bits of dust in your lens... it's just that the others are too small for you to see.

Unless you have a lot of dust - enough that you can't see clearly through the lens - or one or more pieces of debris that are several millimetres in size, don't worry. Your photos will not be affected.

[aslyfox]

I was taught that any zoom was a compromise vs.number of primes

now today's zooms are a much better compromise than many that were made in the past

I have purchased a PLM for one purpose, to have a light weight lens that is good for its purpose - a very capable zoom easy to use and carry

if there is no issue carrying a number of primes to cover the focal length of the zoom, the changing of the lenses and the weight of the primes, I prefer the primes

and if you get lucky you can get good quality " experienced " lenses to help with the cost of lenses

you must determine what you need and can obtain.

simple as that.

a number of prime lenses vs.55 - 300 zoom

______________________

as BigMackCam notes, all lenses can get dust, even primes, the question is how, if any, does that affect your photography. Can you see to use the lens. Is the dust affecting your photos ?

perhaps these articles might help the OP and others

https://photographylife.com/what-to-do-with-dust-inside-lens

" . . . 4) What to do with lens dust
Once you spot lens dust, what should you do with it? The answer is – nothing. Don’t worry about it and just keep on shooting, concentrating on creating great images. As I have explained above, lens dust is a normal fact of life, just like dust on your camera sensor. Even if you take a good care of your gear on a daily basis, you will eventually end up with dust in your lenses and cameras, guaranteed. You can certainly minimize the amount of dust getting into your gear by storing it properly and performing regular cleaning and maintenance (which I will cover in an upcoming video tutorial), but you cannot fully prevent it from happening. Dust is inevitable and it does get into camera gear one way or another, so you should not be sweating over it if you have it. Try an experiment – come close to a dirty window in your house and look outside. When your eyes focus on the outside, can you see the dust or dirt on your window with your eyes? No, unless the dirt particles are huge. The same thing happens inside the lens, if there are small dust particles, it is not a big deal. So take a deep breath, chillax and stop worrying about dust.

The only case where you might need to call your lens manufacturer, is if you spot an abnormally large spec of dust more than several millimeters in size that moves when you rotate the lens. There are cases, when particles break off inside lenses, typically after lenses are dropped/damaged. . . . "

another source:

https://www.lensrentals.com/blog/2011/08/the-apocalypse-of-lens-dust/

" . . . Does any of this have any real world implications? Nah. Unless you get a bug inside your lens there’s not much need to worry about dust. Until there’s so much dust that it interferes with contrast or light transmission. When is that? Well sounds like another article coming up, doesn’t it? But it would be a lot of dust. "

[Rondec]

I wouldn't worry so much about the dust issue. I think you just have to balance what is important to you. The DA *300 is a lot faster lens (with regard to aperture) and is going to be sharper at apertures wider than f8. On the other hand the 55-300 is one of the fastest focusing Pentax lenses out there and is more flexible since it covers 55-300. The 55-300 should be weather sealed so that should limit somewhat the dust that gets in through it, but of course some will get there over time.

[PJ1]

Some good advice there - in particular, don't worry about dust unless it is thick enough to affect your view through the lens. As has been said also, a 300mm prime will be better than a 55-300mm zoom (or any other zoom range). If I wanted to try for maximum IQ on wildlife, I would go for the prime. If I wanted a good travel lens (say for a trip to Africa), I would go for the 55-300 for its flexibility. But there are some very fine images taken with the 55-300 - just look at those in the lens reviews here. Always keep in mind that some photographers are better than others, but the best images in those reviews are very, very good.

I have an F* 300mm and I like it. But I don't use it much because it is a special purpose lens, not an every day one. I can get by without the 55-300 at the moment because I use an 18-200 as an every day lens. But the 55-300 is on my wish list and if the holiday I want comes up, I will be getting it

[swanlefitte]

As to dust, changing lenses leaves the sensor open to dust that does show up in photos. So it can be cleaned but how comfortable are you and how often do you want to clean the sensor?
The zoom means changing lenses less.

[aslyfox]

As to dust, changing lenses leaves the sensor open to dust that does show up in photos. So it can be cleaned but how comfortable are you and how often do you want to clean the sensor? . . .

I have, per my owner's manual, set my camera bodies to activate the " dust removal " function automatically

[jddwoods]

I will keep it short and simple since you have received a number of good responses already. I have both the 55-300 PLM and the DA*300. The DA* is sharper at 300 mm than the PLM and paired with the 1.4x TC it is a fairly lightweight 420mm f5.6 lens. This is what I use when photographing birds and wildlife in a place like a wildlife refuge where all of the subjects are far away.
On the other hand the PLM is so compact and lightweight that I can now bring it in my bag almost everywhere including places where I would never have brought a telephoto lens before.
Both lenses are WR and quiet focusing and I never had any issues with water or dust intrusion into the lenses. In summary as others have said, the DA* is the lens for sharpness at 300 mm and the PLM is the lens for its exceptional versatility.

[aslyfox]

one thing that hasn't been discussed, the * ( star ) lens difference:

" . . . Is it possible to combine outstanding function and beauty in a lens? Yes, one of the Pentax lenses that proves it is the DA* 300mm F4.0 ED Supersonic Drive Motor (SDM). The DA* lens line currently consists of six lenses that feature the highest quality materials and outstanding construction. Two of the unique features of the DA Star line are weather and dust resistant construction and quiet SDM focus system thanks to a built-in autofocus motor . . . "

Read more at: Pentax-DA* 300mm F4 Review - Introduction | PentaxForums.com Reviews

__________________

" To be designated as a Star-series product, a lens must demonstrate extremely high resolving power and contrast — from the center of the image field to the edges, even at open aperture — and exceptional optical performance with minimal distortion and color bleeding. In addition, it must be a very bright lens with one of the largest open apertures in its class. It must provide extreme strength, superior dustproof and weather-resistant performance, and outstanding operability. Only when all these requirements are satisfied, it is named a Star-series lens because it incorporates the very best of our state-of-the-art technologies that optimize the photographer's creative freedom. "

PENTAX STAR LENS | RICOH IMAGING

____________________________________

this thread might be of interest:

Pentax * lenses do they live up to the reputation and why - Page 5 - PentaxForums.com

[jeffdrew]

I also have & use both for different purposes...what jddwoods said. Becoming my mainstays for outdoor use!

[kh1234567890]

As to dust, changing lenses leaves the sensor open to dust that does show up in photos.

My sensor is always covered by the shutter blades when I change lenses - have I been doing it wrong ?

[normhead]

The reason that I start to think about this problem is because one day I found that as a lens without inner zoom, 55-300PLM will intruded by dust very easily, this makes me getting so angry with it, it's compact, sharp at this price, though the dust can't effect the image quality now, after 2 months I bought this lens, I already find at least 7 dust inside the lens.
However a prime focus lens will be very limited to choose subject, Though I'm feeling quite fun to take distance or be closer to a subject myself instead of turning the zoom circle.
If somebody could help me to know that how better will DA☆300 F4 does on image quality than 55-300PLM at 300mm, I want to know if this lens is worth me to buy.
Thanks

The big advantage to the 300 ƒ4 is when you put a TC on it. My guess is both out resolve any current APS-c sensor, so in many images it's the sensor that's the limitation, not the lens. But if you'e interested in 420 with a TC the 300 ƒ/4 is the way to go.
This test does with a DA*60-250 and TC against aDA 55-300 PLM and TC, I assume the DA* 300 ƒ4 results would be similar.
I've had the Sigma 70-300, and 18-250, and Pentax FA 28-200. None of them compare to the 55-300 PLM.

I seriously wonder about people who think the 300 will be better, without having done any kind of test.

What more do we need for sharpness?
K-3 and DA 55-300 PLM


I have images like this, taken with the DFA 100 macro that are so sharp they produce sharpening artifacts when you reduce the size, without applying sharpening in post. I'm not even sure that's better.

K-1 and DFA 100 macro

K
K-5 and DA*60-2250


I would suggest most of the people suggesting the DA 300 is a no brainer for IQ, have never seen comparison images of both. The big advantage of the DA*300 of course is ƒ4. IN the last image I'm at 1600 ISO on a K-5, ƒ/4 (wide open) and 1/40s. I'm not sure you can even take that image with an ƒ/6.3 lens. Your odds are certainly reduced, even if you do manage to nail it. That one was shot indoors at the Niagara Falls butterfly conservatory. That's the biggest advantage of the 300 ƒ4, the ƒ/4 part.

The 300 ƒ4 is heavy and big. Not really walk around lens.
The DA 55-300 PLMis small and light, and great walk around lens.
You need both, they are very different lenses.

With the DA 55-300 PLM

You can do this


And this


But you can also do this


And this


or This


How much flexibility will you give up for a barely detectable improvement in IQ?

[BigMackCam]

I seriously wonder about people who think the 300 will be better, without having done any kind of test.

...

I would suggest most of the people suggesting the DA 300 is a no brainer for IQ, have never seen comparison images of both.

I can't speak to the DA*300, but I own the DA*60-250 which is a highly regarded lens, and for good reason (it's one of the best lenses I own). Whilst it has a constant f/4 aperture and therefore has the advantage for lower light work and subject isolation, even the humble screw-drive HD DA55-300 is capable of remarkably comparable results when stopped down just a little, unless viewing images at 100% reproduction. That plus the compact size and light weight make it an extremely versatile lens. I understand the newer PLM is even better optically...