[madison_wi_gal]

Have a converted K-01 (27mm filter size). Was converted to 590nm but I *might* choose to have it re-converted to Full Spectrum (Isaac Szabo says that is doable, no big deal) so I can use 550, and the Kolari IR Chrome filter which looks very cool.

I have a variety of Pentax glass, some are in the "Good Performer" category and some are not.

I have ordered a step-up ring for the 27 --> 52 but in general I'd prefer to have one size filter for all and use step-up (or slight step-down) as needed.

My K-01 is not compatible with clip-in (flange) filters.

My 15 and 21 are definitely on the GP list, those have 49mm
The 18-55 DA is (I have the DAL) but the DAL was mentioned elsewhere as being good for IR- that is 52mm
The Tam 90 (272E) is 58mm
The 20-40 is not listed but 58 55mm
The 55-300 (58mm) might be OK but I have the DA WR ED version
The 18-135 (62mm) is not, so no point getting 62 filters.
Ignoring the Sigma, and Tam zooms.

So:

I could get a 58mm set and use step ups as needed, or stick with 52mm and use step downs for the 58mm guys, but worry about vignetting.

What would Pentaxians do?

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Last edited by madison_wi_gal; 07-16-2022 at 07:02 PM.

[jlstrawman]

Have a converted K-01 (27mm filter size). Was converted to 590nm but I *might* choose to have it re-converted to Full Spectrum (Isaac Szabo says that is doable, no big deal) so I can use 550, and the Kolari IR Chrome filter which looks very cool.

I have a variety of Pentax glass, some are in the "Good Performer" category and some are not.

I have ordered a step-up ring for the 27 --> 52 but in general I'd prefer to have one size filter for all and use step-up (or slight step-down) as needed.

My K-01 is not compatible with clip-in (flange) filters.

My 15 and 21 are definitely on the GP list, those have 49mm
The 18-55 DA is (I have the DAL) but the DAL was mentioned elsewhere as being good for IR- that is 52mm
The Tam 90 (272E) is 58mm
The 20-40 is not listed but also 58mm
The 55-300 (58mm) might be OK but I have the DA WR ED version
The 18-135 (62mm) is not, so no point getting 62 filters.
Ignoring the Sigma, and Tam zooms.

So:

I could get a 58mm set and use step ups as needed, or stick with 52mm and use step downs for the 58mm guys, but worry about vignetting.

What would Pentaxians do?

Size your filter for your largest lens, and use adapters to match the smaller lenses. I have 77mm filters and adapt them to 49, 52, 58, 62, and 67mm lenses. I think it works well,
plus the the step-up/step-down adapters are much cheaper than filters.

[acoufap]

Have a converted K-01 (27mm filter size). Was converted to 590nm but I *might* choose to have it re-converted to Full Spectrum (Isaac Szabo says that is doable, no big deal) so I can use 550, and the Kolari IR Chrome filter which looks very cool.

I have a variety of Pentax glass, some are in the "Good Performer" category and some are not.

I have ordered a step-up ring for the 27 --> 52 but in general I'd prefer to have one size filter for all and use step-up (or slight step-down) as needed.

My K-01 is not compatible with clip-in (flange) filters.

My 15 and 21 are definitely on the GP list, those have 49mm
The 18-55 DA is (I have the DAL) but the DAL was mentioned elsewhere as being good for IR- that is 52mm
The Tam 90 (272E) is 58mm
The 20-40 is not listed but also 58mm
The 55-300 (58mm) might be OK but I have the DA WR ED version
The 18-135 (62mm) is not, so no point getting 62 filters.
Ignoring the Sigma, and Tam zooms.

So:

I could get a 58mm set and use step ups as needed, or stick with 52mm and use step downs for the 58mm guys, but worry about vignetting.

What would Pentaxians do?

The 20-40 Ltd.‘s filter thread is 55mm.

[Bob 256]

I have a full-sized IR filter for my largest lens filter size and some others for my most used lenses, but I also have step down rings for that large one (as jlstrawman suggested) should the need arise. A filter for an ultra-wide might not be available for front mounting, but Wratten gel filters can usually be adapted to stick on the rear of the lens (using a "ring" of double stick tape or other means to secure the filter). This assumes there is room for the rear filter.

A side note: Full Spectrum will allow you to use your camera for any IR range with the appropriate IR filter, and it will allow you to use it for normal visible light with an external IR/UV reject filter although the latter requires a different set of filters with the same issue you bring up in this thread - multiple sizes for different lenses or one large one and step down rings. Anyone considering a conversion should consider full-spectrum as the most adaptable.

[kypfer]

Mostly I use Ilford SFX (R72 compatible) or Lee 87 sheet filters, appropriately mounted, in a Cokin filter holder … so I just need one of each type of filter and a selection of mounting rings
More expensive options are available!

[madison_wi_gal]

The 20-40 Ltd.‘s filter thread is 55mm.

Ah yes, typo. Thanks!

---------- Post added 07-16-22 at 20:29 ----------

Anyone considering a conversion should consider full-spectrum as the most adaptable.

I was going to do that but I had read on this forum that FS + filter is not as good as [whatever wavelength] native. I guess I should have asked around a bit more.

I can reconvert to FS, let's see how today's shoot went (40XS no filter, so 590, and 18-55 w and w/o Hoya 72, so 590 and 720).

So far things look very slick, but it was not always a sunny day.

---------- Post added 07-16-22 at 21:06 ----------

Size your filter for your largest lens, and use adapters to match the smaller lenses. I have 77mm filters and adapt them to 49, 52, 58, 62, and 67mm lenses. I think it works well,
plus the the step-up/step-down adapters are much cheaper than filters.

Good idea.

I bought a complete 49 -- 77 step-up set from Neewer just now.

I can't think of a reason to get 62mm filters since the 18-135 supposedly is not good, but I *could* in case that review is wrong.

My LBA is not strong right now so no plans to add *more* lenses that might be more than 62mm