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Archive 2015 · Infrared and alt lenses (on A7)

  
 
timballic
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p.2 #1 · p.2 #1 · Infrared and alt lenses (on A7)


Actually Jim, the 21/3.5 may not be good for IR anyway?? The only example I've seen shows a lot of smearing.
See: http://www.ayton.id.au/wp02/?p=4331 (Though he doesn't specify if his is SC or MC. I did email him about it a few years back, but I've forgotten what his reply was! ) My MC version certainly isn't any good for IR, very "clouded" and unsharp.
You need to try it!

EDIT: I now know that the OM Z 21/3.5 has some of the best corner performance on my IR A7, though the mc version has hotspot/ghost.

Edited on Jul 15, 2016 at 05:17 AM · View previous versions



Aug 20, 2015 at 02:30 AM
timballic
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p.2 #2 · p.2 #2 · Infrared and alt lenses (on A7)


I wish I'd continued with my intended testing of lenses for IR! With the preparations to change over to to FF IR last year, I forgot.

Now I have an A7 converted to 830nm (B&W IR), I'd like to find some more options.

So far I'm happy with the single coated OM Z lenses, the earlier silver-nose, the better, for simpler coatings. (24/2.8, 28/3.5, 35/2.8, and 50/1.8mm)

Now, I've "remembered" that the Nikon E series lenses were also single coated, so this summer I hope to try out the range, (28/2.8, 35/2.5, 50/1.8 and 105/2.8) to see how they compare with the OM Zuikos
Diglloyd rates the E 35/2.5 very highly in IR (and also the much more expensive Nikon P AiS 45/2.8.)

So far with the A7, I've only tried the FE 24-70/4, which for convenience is very good, and only hot-spots at the wide end and then only when stopped down below F/9, which is fine.
A couple of examples with the FE 24-70 below:

Spring Woodland Path IR by Tim Ball, on Flickr

Butterbur on the Brock by Tim Ball, on Flickr



May 26, 2016 at 08:45 AM
timballic
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p.2 #3 · p.2 #3 · Infrared and alt lenses (on A7)


I can no longer recommend the Zony FE 24-70/4 for IR use.

I need to add a strong caveat to all I've said about the Zony FE 24-70/4, for IR use.

Having returned from holiday where the sun rarely showed its face, I found that with cloudy skies, the Zony zoom has a large pale diffuse hot spot, which isn't apparent with strong sun and clear skies, (visible at all apertures except F/22, where it becomes a defined central spot) This is clearly flare from the large white area of cloud.

Thankfully, being so diffuse, I can work round it with Lightroom's "Adjustment Brush", especially using "Clarity" and "Contrast" sliders, so that the problem is no longer visible, but it is extra work and a nuisance.

Thankfully I also had my set of OM Z prime lenses with me, that I could use.



Jun 21, 2016 at 05:00 AM
mcbroomf
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p.2 #4 · p.2 #4 · Infrared and alt lenses (on A7)


Tim, have you tried the radian filter tool next to the adjustment brush? It has the same adjustment sliders but you can easily adjust the size and feathering to a circular spot. you can also save settings so that you can quickly deploy it on different photos, then make minor tweaks as needed.

I'm glad you updated this thread. I still want to get a more modern IR conversion done, perhaps on an older A7R

Mike



Jun 21, 2016 at 06:38 AM
timballic
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p.2 #5 · p.2 #5 · Infrared and alt lenses (on A7)


mcbroomf wrote:
Tim, have you tried the radian filter tool next to the adjustment brush? It has the same adjustment sliders but you can easily adjust the size and feathering to a circular spot. you can also save settings so that you can quickly deploy it on different photos, then make minor tweaks as needed.

I'm glad you updated this thread. I still want to get a more modern IR conversion done, perhaps on an older A7R

Mike


Thanks Mike, I'll try that too.



Jun 21, 2016 at 09:36 AM
timballic
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p.2 #6 · p.2 #6 · Infrared and alt lenses (on A7)


After discovering the large diffuse hot spot from the Zony zoom in cloudy-bright conditions, I carried out a test to see which of my 28mms performed best in these conditions.
This was on holiday, so means were limited, but I did have a folded piece of matte black A3 plastic card with me, which I set up with its face in shadow, with a bright, but flat cloudy sky. Seems these conditions a harder trial than full sun and a clear sky!

I compared each lens at F/16 (worst case) and F/8 (user aperture) I increased contrast equally in Lr to make the results clearer.

First, as a "control" the OM Z 50/1.8(single coated), which I know to have exemplary IR performance.
This even grey is as good as could be expected and what all should look like. (Ignore vertical centre fold line and lower edge shadow)


Then the Zony FE 24-70/4 @28 (again F/16 : F/8)
Large, bright hotspot at F/16, and more diffuse, but still bright, hot spot at user aperture


The OM Z 28/3.5, I expected to be very good, but....
Concentric rings hotspot!


The Nikon H (pre Ai) 28/3.5 (Bjorn Rorslett's favourite IR lens)
Again, no where near perfect. A hot-spot when fully closed down, but it's reasonably even at F/8, although lower contrast (= brighter)


The Nikon AiS (Latest SIC coatings) 28/2.8
Concentric rings again, and a more defined central region at F/8


And finally the C/Y 28/2.8
A variation of the concentric rings! Roughly similar at F/8 to the OMZ 28/3.5



To sum up: None of the lenses performed as well as the OM Z 50/1.8 sc (All these lenses have tested well for no, or little hot-spotting, with clear sky, full sun)

FE 24-70/4 produces a large bright, low contrast hot spot
OMZ 28/3.5 and C/Y 28/2.8 both produce a variation of concentric rings.
NAiS 28/2.8 again concentric rings closed down, but a more "defined" large hot spot at f/8
Nik H 28/3.5: Hot spots fully closed down, but is probably the best of my 28mms at user aperture F/8.

Again, I reiterate, all these lenses perform well in bright sunny conditions, with a clear sky, it's the large area of white cloud that is creating these hot-spot "flare" patterns.



Jun 22, 2016 at 04:23 AM
timballic
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p.2 #7 · p.2 #7 · Infrared and alt lenses (on A7)


An extreme example of concentric-ring flare.

With the CV 20/2.8 on, I need to see if my Nikon 20/2.8 NAiS is any better. ( Maybe I should have held on to the Nikon 20/3.5 which I sold last year, which, according to Bjorn Rorslett, is "faultless" for IR. However the corners, at least on the A7, were very poor, FAR worse than the CV.)

I've lightened the area to highlight the "rainbow" of concentric rings flare It's so "bad" as to be almost "good"!


Yes,it's definitely the CV 20/3.5


I'm rather annoyed, as I used it a lot on my IR A7, on a recent holiday, having seen it was rated as "Good for IR" on "some-one's" hot-spot lens list, (can't remember where). Stupidly I didn't do any checks first. (It's not visible on the camera monitor) I think I stopped well down to 11-16, as corners are then so much better. That's probably the problem, it may well not be an issue at 8 or 8-11, where I uisually shoot. More testing!
Thankfully it isn't this obvious on every shot.

A quick test of the OMZ 21/3.5, CV 20/3.5 and NAiS 20/2.8 shows no clear winner. The OM Z has worst corners, the Nikon, lowest contrast, and the CV falls apart when stopped down beyond F/8-11. (Diffraction and concentric ring flare)

Edited on Jun 25, 2016 at 11:17 AM · View previous versions



Jun 24, 2016 at 11:28 AM
timballic
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p.2 #8 · p.2 #8 · Infrared and alt lenses (on A7)


Just had this reply from KolariVision re A7 conversion:
We can apply a thin filter 850nm conversion which helps corner performance with non-Sony lenses. We can also add an AR coating upgrade that reduces hot spots, I think this is the best way to get good performance on the camera.



Jun 26, 2016 at 01:35 AM
mcbroomf
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p.2 #9 · p.2 #9 · Infrared and alt lenses (on A7)


That's interesting. I had planned to use Kolari for the next conversion I have done. I'd stick to 720 I think as I like the colour that seeps through and I do the odd channel swap, but the AR coat is new info. I may stick to my old EM5 rather than an A7R though where it's not difficult to get good corner performance (on m43)

Thanks for the updates ...



Jun 26, 2016 at 05:08 AM
timballic
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p.2 #10 · p.2 #10 · Infrared and alt lenses (on A7)


Managed to retest my six 28mm lenses on the IR A7

Only the OM Z 28/3.5 and the Pentax K 28/3.5 really impressed The OMZ being generally sharp all over, whilst the PK was slightly sharper in the centre and slightly weaker on the edges and corners, (compared with the OMZ), but still better edges and corners than the following:

The Nikon K 28/3.5 probably had the best overall contrast, but was poor on sharpness generally, and especially poor corners.
The NAiS 28/2.8 sic was reasonably sharp, but had lower contrast (modern coatings!)
The C/Y 28/2.8 very similar result to the NAiS
The Pentax K 30/2.8 was generally poor sharpness and especially poor corners



Jun 26, 2016 at 10:42 AM
timballic
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p.2 #11 · p.2 #11 · Infrared and alt lenses (on A7)


jcolwell wrote:
Wow. The SC vs. MC difference is profound.

I was going to sell my Oly 21/3.5 SC, which is the best of four OM 21/3.5 SC & MC that I've owned (for visible light). Now, maybe not.


Pity we're not nearer, I'd like to compare my MC version with an SC to see if there is the same difference as with the 24mms. They're getting expensive to buy one "just-in-case", and there are so many poor copies around too.



Jun 26, 2016 at 10:51 AM
timballic
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p.2 #12 · p.2 #12 · Infrared and alt lenses (on A7)


Oh dear, I thought the OM Z 21/3.5mc would be fine and without hot-spots, but no.

Comparison of Top Row: CV 20/3.5; Bottom Row: OM Z 21/3.5mc. Both series F/3.5-16



My search is on for a 20mm that doesn't do this!
Looks like I'll be getting another NAi 20/3.5, despite its poor corners. Sorry I let mine go now!
Also need to try a Pentax M 20/4

Edited on Jun 30, 2016 at 12:20 AM · View previous versions



Jun 29, 2016 at 12:43 PM
timballic
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p.2 #13 · p.2 #13 · Infrared and alt lenses (on A7)


Here's the Nikon AiS 20/2.8 sequence, for completeness.
Same exposures, I noticed earlier that it is lower contrast in IR. Compare with top row CV above, with very good contrast. The OMZ does horrible half and half flare
(The colour graph for the NAiS is totally different from all my other lenses too, as it shows red, not magenta.)




Jun 29, 2016 at 01:25 PM
retrofocus
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p.2 #14 · p.2 #14 · Infrared and alt lenses (on A7)


Thanks for posting all those unfortunately negative but good to know lens properties in IR. Rule of thumb: if a lens doesn't has an IR metering mark, there is a higher likelihood that this lens does not work well in IR light. I have seen this a few times with IR-unmarked EF lenses from Canon and Sigma which didn't do well in IR. Not sure about Leica M lenses - when I hold my 35/2 and 50/2 lenses in front of my IR-converted DSLR, it doesn't look like there are hotspots, but I can't tell for sure since I don't get a sharp image. And Leica M lenses also don't have the IR metering mark.


Jun 29, 2016 at 05:47 PM
timballic
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p.2 #15 · p.2 #15 · Infrared and alt lenses (on A7)


If only it were that easy! I think that the red IR focus dot/line was on most SLR MF lenses "of a certain age", Contax C/Y, Pentax M42/K, Nikon PreAi/Ai/AiS, Olympus OM Z, Minolta MC/MD and Canon FD MF lenses mostly have them, and they're certainly NOT all good for IR.



Jun 30, 2016 at 12:25 AM
retrofocus
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p.2 #16 · p.2 #16 · Infrared and alt lenses (on A7)


timballic wrote:
If only it were that easy! I think that the red IR focus dot/line was on most SLR MF lenses "of a certain age", Contax C/Y, Pentax M42/K, Nikon PreAi/Ai/AiS, Olympus OM Z, Minolta MC/MD and Canon FD MF lenses mostly have them, and they're certainly NOT all good for IR.


This would actually be interesting to find out more. My experience is that lenses with the IR focus dot/line mark are at least usable to a middle aperture stop in infrared light. All my L lenses have such IR focus mark, and they all are at least decent in IR (no hot spots at middle f-stops f/8 or wider open). But there are still differences in how well each of them works in IR - some are better than others. Primes in general seem better than zoom lenses for IR with the exemption of the 17-40/4 L lens which is superb here.



Jun 30, 2016 at 07:02 AM
timballic
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p.2 #17 · p.2 #17 · Infrared and alt lenses (on A7)


retrofocus wrote:
This would actually be interesting to find out more. My experience is that lenses with the IR focus dot/line mark are at least usable to a middle aperture stop in infrared light. All my L lenses have such IR focus mark, and they all are at least decent in IR (no hot spots at middle f-stops f/8 or wider open). But there are still differences in how well each of them works in IR - some are better than others. Primes in general seem better than zoom lenses for IR with the exemption of the 17-40/4 L lens which is
...Show more

I can think of a few with the IR dot/line that are totally useless for IR at any aperture, the MD 24/2.8 comes immediately to mind, (whilst the C/Y 35-70/3.4 hasn't got it and yet works very well in IR) ! I really think it was just "the done thing" for most prime lenses of that era to have them, whatever their IR performance....or, maybe our digital sensors are showing up faults that were never visible on IR film?

...or maybe later, only better IR lenses were given the mark?
(I agree about the EF 17-40. Very good for IR. It's my fall back option if I can't find any wide legacy prime lenses over 24mm, that will work on the A7.)



Jun 30, 2016 at 07:59 AM
retrofocus
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p.2 #18 · p.2 #18 · Infrared and alt lenses (on A7)


timballic wrote:
I can think of a few with the IR dot/line that are totally useless for IR at any aperture, the MD 24/2.8 comes immediately to mind, (whilst the C/Y 35-70/3.4 hasn't got it and yet works very well in IR) ! I really think it was just "the done thing" for most prime lenses of that era to have them, whatever their IR performance....or, maybe our digital sensors are showing up faults that were never visible on IR film?


This is indeed quite possible. IR film was and is quite likely not as "perfect" in showing the issues we see now with modern digital sensors, especially the ones with high resolution.

...or maybe later, only better IR lenses were given the mark?
(I agree about the EF 17-40. Very good for IR. It's my fall back option if I can't find any wide legacy prime lenses over 24mm, that will work on the A7.)


+1. Quite possible, too. And as you said, there are many out there which work well in IR but don't have the IR focus mark. Likely it was determined by lens manufacturers that it only increases cost for them to have lenses marked with the IR focus dot (additional testing required etc). Before digital took off, only a small group of people did IR film shooting - and only those made actual use of this red dot or line. And now lenses don't have aperture rings anymore, and the focus scale has turned into a very minimalistic one even on many expensive lenses.




Jun 30, 2016 at 09:31 AM
timballic
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p.2 #19 · p.2 #19 · Infrared and alt lenses (on A7)


Rebought an EF 17-40/4 (like new) to try on the IR A7, and compare with some primes in the range.

First with the Tokina RMC 17/3.5, PK mount(a nice copy) On KolariVision's "Good for IR" list
Both using Kipon Adapters. On the colour A7 camera, both lenses checked out as well centred copies.
I think the adage, that if a lens has weaknesses, they will be magnified in IR, really shows true for the EF 17-40 here.

Hot-spot patterns slightly with each: I'll upload the F/8 results as that's where I'd use them. This is probably a worst case, as the sun isn't far out of the right of frame and both needed careful flagging to prevent multiple flares, the EF zoom is particularly prone to them.
First the Tokina:
Tok RMC 17/3.5 @8 by Timothy Ball, on Flickr

Now the EF zoom:
EF 17-40 @17/8 by Timothy Ball, on Flickr

Slightly more "patterns" with the Tokina, but also slightly lower contrast on the EF zoom, which surprises me.
It would be easier to hide the more diffuse EF patterns in pp, than the Tokina patterns, but neither are bad.

An "overall shot", again F/8 (Full size files in Flickr link) Less than 2mins between series, but those clouds were racing! Both focussed on the sharp corner of the concrete tub to right of centre foreground. (I tried a refocus with the zoom, because of the poor corners, but these were the best I could get them. NB. If I focussed just for the near lower corners, I can improve them slightly, but then lose the necessary depth of field.)

First the Tokina:
Tok RMC 17/3.5 @8 by Timothy Ball, on Flickr

The EF Zoom:
EF 17-40 @17/8 by Timothy Ball, on Flickr

Now the lower corners from each 1:1
L. Left, Tokina
L. Left Tok RMC 17 @8 by Timothy Ball, on Flickr

L. Left EF Zoom
L. Left EF 17-40 @17/8 by Timothy Ball, on Flickr

L. Rt Tokina
L. Rt TokRMC 17 @8 by Timothy Ball, on Flickr

L. Rt. EF Zoom
L. Rt EF 17-40 @17/8 by Timothy Ball, on Flickr

Comments: In use the Tokina is obviously smaller and lighter at 312g, than the EF 17-40 at 520g, but then the zoom replaces several lenses.

The EF 17-40 is easy to focus manually and the image snaps in and out of focus at F/4, the Tokina is soft and diffuse at F/3.5 making wide open focussing difficult, but a ½ stop down, it sharpens up nicely.

At F/8 where I'd use them, the EF Zoom is perhaps a tad clearer, but not a lot in it, both similar sharpness in centre, but the corners (and to a less extent, edges), are where the difference is revealed. I remember that on my old 5DII, the zoom at 17mm had poor corners, on the A7 and in IR, they're MUCH worse. The Tokina is better, still only "adequate", but a lot better than the zoom. (Look at the foliage under the front of the mini.)

Overall: it could be a case of, 6 of one, half a dozen of the other:

Hot spot flare patterns are slightly present on both.

Focussing the EF Zoom is easy (manual), the Tokina needs to be stopped down a little to sharpen up and never seems as positive as the zoom.

The corners are the real issue. I could "just" accept the Tokina corners, the EF 17-40 corners are very, very poor, (on the A7)

Then of course the EF 17-40mm covers 3-4 prime focal lengths, if you use 17mm, 20mm 24mm, 28mm 40mm
However, the corners really don't become "acceptable" until 28mm, and I think that will be the clincher for me.

I'm sure that on a FF Canon IR converted camera they'd be a lot better, if never exactly good. When I owned this lens I had an IR converted 40D which being apsc, never showed into the corners.

I'm hoping to compare the EF 17-40/4, with Nik Ai 20/3.5 and Pentax SMC M 20/4 next, having discounted the CV 20/3.5, NAiS 20/2.8 and OM Z 21/3.5 MC, because of their bad hot-spot characteristics. (Really not sure whether to try a single coated copy of the OM Z 21/3.5)



Jul 06, 2016 at 08:54 AM
timballic
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p.2 #20 · p.2 #20 · Infrared and alt lenses (on A7)


Quick comparison of 20mm lenses: Pentax M 20/4; Nikon Ai 20/3.5; CV 20/3.5; OM 21/3.5mc; EF 17-40 @20mm
Not a clear sky for days, or to come according to the forecast, so I can't tell about hot spots, but these are good enough for assessing clarity and sharpness.

The CV I have already discounted for its weird rainbow patterns with clear skies, but as I originally chose it as good, I wanted to use it as a yardstick to measure the others against.

Comments: Two things stand out
How good the OM Z 21/3.5mc is for its clarity. I must find an sc copy to compare.
Then the PKM 20/4 stands out for its poor corners, maybe even worse than the EF at 20mm (remember, this is on the A7, on a D750 or 6D, they may be quite acceptable)

Here are the 1:1 enlargement of the lower left corner, bad to good: (Exactly the same scene as the last test)
All at F/8, (which is generally the user aperture for IR, roughly equivalent to F/11 in colour) NB, I tried to equalise exposure on each, but the corners on the EF are noticeably brighter than the primes.

First, the worst, Pentax:
L.Left PKM 20/4 @8 by Timothy Ball, on Flickr

Nearly as bad, EF 17-40: I'd consider both these first two as unacceptable.
L.Left EF 17-40 @20/8 by Timothy Ball, on Flickr

Next the Nikon Ai 20/3.5.Closer to acceptable.
L.Left NAi 20/3.5 @8 by Timothy Ball, on Flickr

Then the CV: I'd accept this.
L.Left CV 20/3.5 @8 by Timothy Ball, on Flickr

And finally the OMZ, I see a big improvement: (Not quite as wide of course)
L.Left OM Z 21/3.5 mc @8 by Timothy Ball, on Flickr

For central clarity they are very close but I put the OMZ just a nose ahead: (note the darker roof tiles and bright foliage)
Centre OM Z 21/3.5 @8 by Timothy Ball, on Flickr

Then the CV:
Centre CV 20/3.5 by Timothy Ball, on Flickr

Then the EF 17-40:
Centre EF 17-40 @20/8 by Timothy Ball, on Flickr

Then the PKM:
Centre PKM 20/4 @8 by Timothy Ball, on Flickr

And last the N Ai, but I'm splitting hairs, all are acceptable in central areas:
Centre NAi 20/3.5 by Timothy Ball, on Flickr

Now I REALLY want clear skies to assess the hot-spotting...But it's obvious to me that I REALLY do need to try a single coated OM Z 21/3.5! Non around at "reasonable" prices on ebay UK or EU.




Jul 12, 2016 at 11:43 AM
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