[motorhead9999]

Hello all,

I shoot with a full spectrum infrared modified Sony mirrorless camera. For those who aren't aware, most modern lenses cause hot spotting on images (basically a very concentrated circle of brightness in the center of your image, making it mostly unusable) and so I have to resort to vintage lenses most of the time. I use a vintage Pentax K 28mm f3.5 with excellent results. I'm trying to see if I can assemble a good infrared kit from mostly pentax glass, but one of the keys is i need a 52mm filter thread (to try and share my filters among only one size). Obviously I have the 28mm, and I'm looking for a 20ish, a 50 or 55mm, and a 135mm.


Has anyone used any primes in those focal lengths with that filter thread diameter? Obviously I had good luck with the K series, but I don't know much about the M or A series lenses. Looking for something comparable (or better) in image quality to Olympus OM lenses

TIA!

[sergysergy]

You can find information about the filter size here (check the A, M and K lenses):
Pentax Lenses - Pentax Lens Reviews & Lens Database

I can think of the 55/1.8 and the 55/2

[Serkevan]

You can always use one of the multiple lenses with 49mm threads and use a 49-52mm step-up ring.
That opens up the M50/1.7, the M135/3.5 and (*with* vignetting, unfortunately) the M20/4. All of them are good lenses for "normal" photography - but bear in mind I haven't tested them for IR.

Hello all,

I shoot with a full spectrum infrared modified Sony mirrorless camera. For those who aren't aware, most modern lenses cause hot spotting on images (basically a very concentrated circle of brightness in the center of your image, making it mostly unusable) and so I have to resort to vintage lenses most of the time. I use a vintage Pentax K 28mm f3.5 with excellent results. I'm trying to see if I can assemble a good infrared kit from mostly pentax glass, but one of the keys is i need a 52mm filter thread (to try and share my filters among only one size). Obviously I have the 28mm, and I'm looking for a 20ish, a 50 or 55mm, and a 135mm.


Has anyone used any primes in those focal lengths with that filter thread diameter? Obviously I had good luck with the K series, but I don't know much about the M or A series lenses. Looking for something comparable (or better) in image quality to Olympus OM lenses

TIA!

The Takumar Bayonet 135mm F2.5 comes to mind. It has no SMC! Be sure to get the Japanese version. It is just a bit better than the Taiwan version. But I guess you won't see the difference on a Sony camera.

[MJKoski]

Do you have extensive collection of 52mm IR-filters? I have full-spectrum K-1 and my strategy has been to go with large filter (77mm) and use step-up rings with every lens not having that threadsize. 77mm just because Samyang 24mm T/S works fine all the way up to 850nm and is able to perform most movements even when used with STEPDOWN from 82mm -> 77mm.

Also, check this out: clip_filter_for_sony_alpha_7r_7s

I just ordered 642-variant for my K-1. It should make lots of things easier as there will be no need for attaching extra glass in front of the lens.

[pcrichmond]

Greetings, there are a few of us that shoot with FS modified so imagine you will get a wealth of knowledge here for this request.
I'm using modified K1 and K01.
I use primarily 52 and 67 mm filters and then step up or down as needed. Found this covers lenses from 20mm to 400mm.
(Seems like Pentax M,A,F,FA used a lot of 49, 52, 55 mm filters so you should be able to step without much vignette.)

Rarely shoot below 720nm except for the IRchrome filter and am not sure if different bandwidths would cause hotspots differently for a particular lens (faux color vs monochrome), but with that said I have had good luck with the following:
Pentax: M20/4, K30/2.8, A35/2.8, M50/1.7, A50/2.8 macro, M100/4 macro, FA135/2.8, M200/4, FA300/4.5, F35-70, F80-200, DA15, DA70 and DA18-55 II.
Sigma miniwide 24/2.8, Tokina 400/5.6 SD and Tokina 70-210 SD. Plus various other adapted lenses: Lensbaby optic swap, helios, enlarger lenses, etc.

Found my Sigma DG or DC versions hot spot severely as did my Tamron 90 macro (72e?) and older KIron lenses.
kolarivision.com has a great list of lens compatibility under the "learn about ir" tab.

As a side note, if you ever get into the UV side of shooting, lens choices there will be tighter. I've only found two which transmit nicely down to 320nm without much focus shift. Most cut out just above the 385-395nm side with short focus area, hard focus shift or long exposures.
Hope others will join in and add to the list for you and have fun.

[gofour3]

Obviously I have the 28mm, and I'm looking for a 20ish, a 50 or 55mm, and a 135mm.


Has anyone used any primes in those focal lengths with that filter thread diameter? Obviously I had good luck with the K series, but I don't know much about the M or A series lenses. Looking for something comparable (or better) in image quality to Olympus OM lenses

The "standard" filter thread for the K Series lenses was 52mm, the other series were 49mm. Your choice for the above focal lengths are a K/A24/2.8, K/A50/1.2, K50/1.4, K55/1.8, K55/2 & K135/3.5 (as well as A/F/FA 135/2.8) that have 52mm filter threads. (As well as a K150/4 if you want something longer)

Phil.

[Derek]

If you go to kolarivision.com/articles/lens-hotspot-list/ and scroll well down the page, you might find some useful info on Pentax lenses to avoid.

[kypfer]

I don't have many Pentax lenses, and no Pentax primes, with a 52mm filter thread, but one lens with a 52mm thread I have had recent i/r success with is my Enna 28mm f/3.5 Macro-Ennalyt in M42 fitting ... just for reference


I mostly use a Cokin 'A' filter holder with a Lee 87 in it ... these older small-size filter holders are easily sourced second-hand. With a selection of fitting rings from 49-58mm and an Ilford SFX filter as well I've got most bases covered, but I will admit to having owned the hardware for very many years and prices of the filter material seems to have risen significantly in recent times!


I would agree with the suggestion of using a 49-52mm stepping ring, both to minimise expenditure and to widen the choice of lenses

[Wheatfield]

Hello all,

I shoot with a full spectrum infrared modified Sony mirrorless camera. For those who aren't aware, most modern lenses cause hot spotting on images (basically a very concentrated circle of brightness in the center of your image, making it mostly unusable) and so I have to resort to vintage lenses most of the time. I use a vintage Pentax K 28mm f3.5 with excellent results. I'm trying to see if I can assemble a good infrared kit from mostly pentax glass, but one of the keys is i need a 52mm filter thread (to try and share my filters among only one size). Obviously I have the 28mm, and I'm looking for a 20ish, a 50 or 55mm, and a 135mm.


Has anyone used any primes in those focal lengths with that filter thread diameter? Obviously I had good luck with the K series, but I don't know much about the M or A series lenses. Looking for something comparable (or better) in image quality to Olympus OM lenses

TIA!

Many, if not most of the M series lenses are 49mm filter threads, so a stepping ring would be your friend, and most of the common lenses that aren't 49mm are 52mm. You should be able to get the focal lengths you need from the M series.
Pentax is pretty well known for making excellent 50mm lenses. The old K series 50/1.4 is very good indeed (I own three of them, all are excellent), and there is a rather overlooked gem, the M150mm f/3.5 which might answer your need for something in the 135mm range. The K50/1.4 uses a 52mm filter, the M150/3.5 uses a 49mm filter.
I can't speak to the quality of the lens, but the M20/4 is about the only thing Pentax has made in that focal length with a small front filter. My understanding is they are rare as frogs hair.
The K and A series 24/2.8 share the same optical formula. I have the A series, and have found it to be very good, and it uses a 52mm front filter.

[pcrichmond]

@kypfer, thanks for answering a question I've had for a long time.
I've had a Cokin P setup for years and have tried it with the IR too.
Didn't care for the Cokin 007 IR but then decided to try the Lee 87c.
I would still occasionally end up with a hotspot on lenses that weren't normally prone for such due to photographer error, not paying attention to the side light that would come into the filter holder and reflect between filter and lens.
Always wondered if the smaller Cokin A series would have been a bit more forgiving.
My favorite filter has always been the Tiffen 87. I was impressed with how nice the Lee 87c is.

[MJKoski]

So, A24/2.8 works fine in IR?

[kypfer]

@kypfer, thanks for answering a question I've had for a long time.
I've had a Cokin P setup for years and have tried it with the IR too.
Didn't care for the Cokin 007 IR but then decided to try the Lee 87c.
I would still occasionally end up with a hotspot on lenses that weren't normally prone for such due to photographer error, not paying attention to the side light that would come into the filter holder and reflect between filter and lens.
Always wondered if the smaller Cokin A series would have been a bit more forgiving.
My favorite filter has always been the Tiffen 87. I was impressed with how nice the Lee 87c is.

I've made up a clip-on cardboard shade that covers the Cokin holder, just the top and both sides, once the filter is fitted. I hold it in place with an elastic band


Admittedly, fitting it is one more step in the sequence of things, but I tend to work on a tripod for this sort of stuff, my *ist DL2 is unmodified, so the shutter speeds are usually quite slow, a few seconds here or there are rarely of any consequence

[kds315]

Greetings, there are a few of us that shoot with FS modified so imagine you will get a wealth of knowledge here for this request.
I'm using modified K1 and K01.
I use primarily 52 and 67 mm filters and then step up or down as needed. Found this covers lenses from 20mm to 400mm.
(Seems like Pentax M,A,F,FA used a lot of 49, 52, 55 mm filters so you should be able to step without much vignette.)

Rarely shoot below 720nm except for the IRchrome filter and am not sure if different bandwidths would cause hotspots differently for a particular lens (faux color vs monochrome), but with that said I have had good luck with the following:
Pentax: M20/4, K30/2.8, A35/2.8, M50/1.7, A50/2.8 macro, M100/4 macro, FA135/2.8, M200/4, FA300/4.5, F35-70, F80-200, DA15, DA70 and DA18-55 II.
Sigma miniwide 24/2.8, Tokina 400/5.6 SD and Tokina 70-210 SD. Plus various other adapted lenses: Lensbaby optic swap, helios, enlarger lenses, etc.

Found my Sigma DG or DC versions hot spot severely as did my Tamron 90 macro (72e?) and older KIron lenses.
kolarivision.com has a great list of lens compatibility under the "learn about ir" tab.

As a side note, if you ever get into the UV side of shooting, lens choices there will be tighter. I've only found two which transmit nicely down to 320nm without much focus shift. Most cut out just above the 385-395nm side with short focus area, hard focus shift or long exposures.
Hope others will join in and add to the list for you and have fun.

Well there are quite a few suitable lenses for UV (if someone is into that), I wrote about that on my Blog here: Photography of the Invisible World: [UV] Lenses tested good for UV

Btw. I use magnetic filter holders for using filters on my lenses as I have to change often: the Manfrotto XUME ones.