Irix 15mm takes 95mm front filter as well as a slot for a gel on the back.

Irix 15mm f/2.4 Wide Angle Lens

[UncleVanya]

I think it's more your scene, UV, everything so close it's converging around you.

Have a look at: DA12-24 on Full Frame - PentaxForums.com and the rest of that thread.

That’s a fair point. However when I use the Sony 24-105 at 24mm from that same vantage point the coverage is narrower and the lines show a lot less perspective distortion. Fisheye might be unfair of me, very wide angle lenses often have perspective distortion. The DA 12-24 may be wider because it lacks the in camera image correction on the Sony vs the 24-105. In either case the image is wider.

[Bob 256]

There's another reason for not using filters in front of ultra-wide lenses. The edge rays are passing through the filter at such oblique angles that they travel much further through the filter material than the axial rays. This can introduce over (non-uniform) filtering and undesired optical effects as the outer edges of the image are approached, particularly if the filter glass is thicker. For these lenses, the filtering is best done at the rear of the lens where all the rays are more colminated (and smaller filters can be used).

[mbukal]

here's the first to demonstrate my cheap in FF with ultra-width coverage and cpl-filter:
Pentax K1
ProMaster Spectrum 7 19-35 / 3.5-4.5 MC
GPE Digital Hight Definition Low Profile Filter ,Ring 77mm

jpeg original directly from the card, out of hand without a tripod or any backrest,

minimal deviation of cpl, at 19mm and f3.5 ((maximum width and aperture)


maximum cpl deviation, at 19mm and f3.5 (maximum width and aperture)


cpl "slim" filter (bought on ebay for approx. $ 30) I was left with the apsc I used DA12-24 / 4 from before, ProMaster Spectrum 7 MC 19-35 / 3.5-4.5 I bought a new one (in the original packaging) on ebay for approx. $ 100

a tripod or some kind of backrest for balancing the vertical and horizontal when taking photos and the raw format can really help in later photo editing,
maybe this cheap variant of ultra-wide coverage in combination with slim cpl (Low Profile Filter) will help someone

I use the mentioned equipment for amateur purposes, I am not a professional

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Last edited by mbukal; 05-26-2021 at 10:34 AM.

[garywakeling]

Don't forget the FA 20mm it takes 67mm filters, also here are some pics from the FAJ 18-35, I find it quite usable too

https://www.pentaxforums.com/lensreviews/SMC-Pentax-FA-20mm-F2.8-Lens.html

Single in December 2019 SMC FAJ 18-35mm | Flickr

https://flic.kr/s/aHsmGCtxMA

[Kwong]

Don't forget the FA 20mm it takes 67mm filters, also here are some pics from the FAJ 18-35, I find it quite usable too

SMC Pentax-FA 20mm F2.8 Reviews - FA Prime Lenses - Pentax Lens Reviews & Lens Database

Single in December 2019 SMC FAJ 18-35mm | Flickr

Single in Sept 2019 SMC PENTAX-FA 1:2.8 20mm | Flickr

I too have the FAJ 18-35 and also find it not bad and can deliver some decent results.

[madbrain]

I use the mentioned equipment for amateur purposes, I am not a professional

Thanks, nice pics. This is for amateur purposes too, not pro. Had not heard of that lens.

---------- Post added 05-26-21 at 03:22 PM ----------

Irix 15mm takes 95mm front filter as well as a slot for a gel on the back.

Irix 15mm f/2.4 Wide Angle Lens

I'm sure this is a great lens, but I'm looking for an autofocus lens, per thread title.

---------- Post added 05-26-21 at 03:22 PM ----------

There's another reason for not using filters in front of ultra-wide lenses. The edge rays are passing through the filter at such oblique angles that they travel much further through the filter material than the axial rays. This can introduce over (non-uniform) filtering and undesired optical effects as the outer edges of the image are approached, particularly if the filter glass is thicker. For these lenses, the filtering is best done at the rear of the lens where all the rays are more colminated (and smaller filters can be used).

I don't suppose you can use a CPL as a rear filter ? And which lenses would support that, if so ?

[Bob 256]

I don't suppose you can use a CPL as a rear filter ? And which lenses would support that, if so ?

That's a bugger and one filter that won't work well as a rear filter (you can fabricate one) unless you know the angle to set it to prior to installing the lens (and then it's not adjustable). It's usually not preferable to use a PL with an ultra-wide because you get quite a variation in the sky effect across the frame. You can have a very dark sky on one side and a lighter sky on the other side (as shown in some of the shots in this thread). The other issue with front mounted PL filters is that they usually use a double mount to allow rotation and many are thick mounts which can cause some vignetting with an UW. I've used standard CPL filters on my 28mm and got significant vignetting because of the filter mount, and a 28mm probably wouldn't be considered an UW lens. But, to answer your original question, you can use polarizers as rear filters, just with a lot of trouble, and difficulty in finding them (assuming your lens allows their use).

[clackers]

That’s a fair point. However when I use the Sony 24-105 at 24mm from that same vantage point the coverage is narrower and the lines show a lot less perspective distortion. Fisheye might be unfair of me, very wide angle lenses often have perspective distortion. The DA 12-24 may be wider because it lacks the in camera image correction on the Sony vs the 24-105. In either case the image is wider.

I think you're onto something there. A 24mm prime at that same vantage point would sort this mystery out, if curiosity was eating you.

The m43 cameras also do lots of distortion correction in RAW, the lenses have chips that contain the necessary parameters. Distortion correction as you've seen in Lightroom or whatever involves cropping.

[dtrego]

There was a similar thread here a few years ago - let me quote myself

The Sigma 12-24mm f4.5-5.6 EX DG sort of meets this criteria. The lens has a permanent petal hood with no threads, but it comes with a slip-on adapter that is threaded, and is what the pinch-style lens cap attaches to. 82mm filters fit the adapter. No idea as to what part of the zoom range could be used with a filter on a FF body without vignetting, as I only have crop-sensor bodies.

Link to older thread:
Wide Angle Lenses That Still Have Threads - PentaxForums.com

Link to an in-depth comparison that includes the Sigma:
DA 12-24mm vs Sigma and Tamron 10-24mm Comparison Review - Introduction | PentaxForums.com Reviews

Link to our lens review section:
Sigma 12-24mm F4.5-5.6 EX DG Aspherical Lens Reviews - Sigma Lenses - Pentax Lens Review Database

[Sandy Hancock]

FA 20/2.8 takes 67mm filters
FA 20-35/4.0 takes 58mm filters

Both are nice, compact lenses.

If you want all the modern bells and whistles, the DA* 11-18/2.8 covers full frame reasonably at the "long" end, and takes 82mm filters.

[madbrain]

FA 20/2.8 takes 67mm filters
FA 20-35/4.0 takes 58mm filters

Both are nice, compact lenses.

Yes, if one can find them. Not certain if 20mm is wide enough, though, still pondering.

If you want all the modern bells and whistles, the DA* 11-18/2.8 covers full frame reasonably at the "long" end, and takes 82mm filters.

I'm really more concerned about the wide end than the long end, as I think I wrote before.

This lens is quite pricey also, even pricier than the Pentax 15-30 at the moment. For $105, one can buy an adapter for 150mm filters on the 15-30, bringing them at the same price as the DA 11-18. Of course the 150mm CPL filter itself is at least another $100, and bulkier. If I was going to shell out that kind of cash, that would be my choice, though.

[clackers]

This lens is quite pricey also, even pricier than the Pentax 15-30 at the moment. For $105, one can buy an adapter for 150mm filters on the 15-30, bringing them at the same price as the DA 11-18. Of course the 150mm CPL filter itself is at least another $100, and bulkier. If I was going to shell out that kind of cash, that would be my choice, though.

Amen. Serious landscapers will tell you that a decent filter system is what you get to minimize vignetting, to get correct value out of lenses that maybe costed more than the camera itself.

[madbrain]

Amen. Serious landscapers will tell you that a decent filter system is what you get to minimize vignetting, to get correct value out of lenses that maybe costed more than the camera itself.

I'm still thinking about the never-reviewed Sigma 12-24 HSM II DG at 42nd st photo at $799 in K-mount.

BH Photo has a filter holder for $7.95 .
https://www.bhphotovideo.com/c/product/1201945-REG/vu_filters_vfhlrs1_150mm_...981&

Edit: it's just the ring at that price, other parts also needed, but which ?

No idea what kind of filters you can mount on it, though, or if any other parts are needed. Couldn't find a web site for Vu filters. I would really only need a CPL (or square PL, I guess?).
I sent an email to B&H to inquire.

[clackers]

I'm still thinking about the never-reviewed Sigma 12-24 HSM II DG at 42nd st photo at $799 in K-mount.

I've got one, it's not bad.

I would really only need a CPL (or square PL, I guess?).

Oh, a CPL? I hope you won't be shooting outdoors with the sky in the shot?