[July 2021] - I have recently become aware that some of the latest Tamron lenses for Sony Mirrorless cameras are excellent in Infrared, with little or no hot spots. I contacted Tamron's UK Distributor [transcontinenta.co.uk] and they have kindly agreed to loan me a few lenses to test specifically in IR. This page will expand in the coming weeks and months as I work through their range, they will not be detailed reviews, but general impressions with real world examples.
[29/10/21] - To date I have tested five Tamron lenses for full frame and APS-c cameras, they have all been very good in IR with little or no problems with hot spots, I would be happy to use any of them at any aperture up to f/11 at any focal length. The full frame 17-28mm and APS-c format 11-20mm are my favoured ranges, in fact I have purchased my own Tamron 17-28mm for my full frame cameras, but the 11-20mm is highly recommended for crop sensor cameras.
Tamron 28-75mm f/2.8 Di III RXD [Model A036] Lens in 720nm Infrared
Tamron 28-75mm f/2.8 Di III RXD [Model A036] Lens
The false colour image on the left was taken at 17mm and f/8.0 on my Full Spectrum Sony A7R with a 590nm STC Clip In filter, with the Red and Blue Channels swapped in Photoshop. The Black and White image on the right was taken with the same set up at 17mm f/2.8, but converted to BW using Nik Silver Efex Pro 2.
Tamron 11-20mm f/2.8 Di III-A RXD [Model B060] Lens for APS-c Format
Tamron in the UK have just sent me a batch of lenses to test, first up is the recently announced APS-c format 11-20mm f/2.8, a small light, but well made lens, again with a 67mm filter the same as most other Tamron AF lenses. I have been using it in crop mode with my 720nm IR Sony A7RIV, but it would be ideal on any of the Sony Nex, a5000 or a6000 series cameras. I can quickly confirm it focuses quickly and smoothly and best of all, is free from hot spots right up to f/16. Here is one of the first images - Full APS-c frame area no extra crop at 11mm and f/6.3 in 720nm IR.
Tamron 20mm f/2.8 Di III OSD [F050] Lens
The Tamron 20mm f/2.8 lens is the 1st of the latest batch of lenses Tamron in the UK have kindly loaned me, it's very very sharp from corner to corner even in IR and only a hint of a hot spot past f/8.0 - Plus again 67mm filters.
The image on the left is taken with an STC 590nm Clip In filter on a full spectrum Sony A7R at f/11 and processed for false colour with a Red/Blue Channel swap in Photoshop. The central area definitely had a lighter red tone after the channel swap which was almost certainly a hot spot aberration, I have however darkened it a bit with Photoshop's Burn Tool. The image however does has a remarkable range of colour tones, with very deep reds, oranges and blues.
I would not say the 20mm Tamron is ideal for false colour work as the images do have a reddish centre and blueish corners at most apertures, it's not impossible to correct, but it's far better in Black and White.
Having been searching for a good standard zoom lens for a while, so I was thrilled when I first got my hands on the Tamron 28-75mm f/2.8 Di III RXD Lens. The images are almost completely free from hot spots at any aperture, certainly from f/2.8 to f/11. The above shot at f/5.6 is the full width of the frame, cropped slightly at top and bottom, but very little other work other than just levels and BW conversion. No sign of any hot spot and not too much darkening towards the corners. As of July 2021 this is my new favourite lens for IR work, I have tried Sony's GM 16-35 f/2.8 and although not bad is not a patch on the Tamron in IR, the Sony G 24-105 f/4.0 and the Sony 28-70 Kit lens are not great either, both have significant hot spot issues at all apertures. I haven't tried Sony GM 24-70mm F/2.8 lens, but there are some good shots in the Full Frame Gallery from that lens, so that's one to look at as well.
Here's a few more shots with the Tamron 28-75mm f/2.8 Lens, Click on the images for a larger view;
Tamron 17-28mm f/2.8 Di III RXD [Model A046]
The Tamron 17-28mm f/2.8 has just arrived and it throws the cat amongst the pigeons, the lens is quite a bit smaller and lighter than the Tamron 28-75mm and the focal length range is more to my liking for IR work as with the wider angle you can get more sky and clouds in the shot. First impressions are very good indeed, very little sign of any hot spots at apertures up to f/11 at any focal length, perhaps a smidge worse than the excellent Tamron 28-75mm above, but I think my favourite lens may be changing to this one as of August 2021!! Both Tamrons tested so far are condsiderably better in IR than any other zoom lens in this range I have tried.
Here are a few shots with the Tamron 17-28mm f/2.8 Lens, Click on the images for a larger view;
As you can see from the above/below shots the lens is excellent in IR, it focuses very quickly and completely silently and also the minimum focus distance is very short, only an few inches from the front element. I would probably say the Tamron 28-75 may be a tad sharper across the frame and into the corners, but the 17-28mm is still excellent and generally wide enough, 17-35mm would be better, but you can always crop the frame a bit to get a 35mm equivalent. Using the 28-75 I found I was mostly at 28mm and wanting a bit wider, but the 17-28mm feels just right for most work, but the pair combined cover most eventualities. The lens is very light [420g] and compact in comparison to the Sony GM 16-35mm [680g] which is at least double the price and weighs 50% more, it takes 67mm as against 82mm for the Sony GM although they both have a f/2.8 maximum aperture. Tamron have standardised on 67mm filter sizes on all their mirrorless lens designs, with the exception of the new 150-500mm lens. This may partly account for the slightly less generous zoom ranges, the 17-28mm and 28-75mm [550g] lenses would certainly be bigger, heavier and more expensive if they were like the more common Sony GM 16-35mm and 24-70mm f/2.8 [886g] lens ranges. The Tamron pair combined cover the same range [ish] as the Sony GM pair, but weigh about the same as just the GM 24-70mm and cost a lot less than just one of the Sony's.
I found that the image quality of both the 28-75mm and the 17-28mm were much improved by turning off all "Lens Corrections" in the camera's Menu. The Chromatic Abberation introduced by the "correction" was much worse than the lense's actual abberation. This was with my 720nm Infrared converted Sony A7R4, but I suspect it will be the case with all 720 or 850nm uses, where there is very little colour information in the actual image.
Tamron 17-70mm f/2.8 Di III-A VC RXD [Model B070] Lens for APS-c Format
Tamron's fast aperture standard zoom for Sony APS-c crop sensor cameras is a great all rounder for IR, free from hot spots upto f/8-11 at all focal lengths. It's sharp across the frame, probably the best overall of all the Tamron's I have tested so far and they have all been very good. It focuses quickly and smoothely, has image stabilisation built in and takes 67mm filters just like most other Tamron's. Here are some results on my 720nm IR Sony A7RIV in Crop mode;
Tamron 70-180mm f/2.8 Di III VXD [Model A056] Lens
The Tamron 70-180mm f/2.8 lens is the 3rd of the latest batch of lenses Tamron in the UK have kindly loaned me, it's probably the best technically of all the lenses so far, very very sharp from corner to corner even in IR and practically no sign of hot spots at any aperture or focal length - Plus again 67mm filters. For me however the focal length range is not as useful for IR work as I prefer wider angles to enable more dramatic skies etc, but there is no doubt its a great lens. Here are a couple of shots at each end of the zoom range taken in full frame mode on my 720nm IR Sony A7RIV;
The image above left is with the Tamron 20mm f/2.8 lens at f/5.0 with STC 720nm Clip In on the FS Sony A7R, the image on the right at f/7.1 on my 720nm A7RIV, both are sharp right across the frame with no sign of a hot spot. Edge and corner definition is definitely better than any of the wide angle zoom lenses, but also better than my Zeiss Loxia 21mm f/2.8 lens in IR, as that lens, although great in normal light, does suffer from some field curvature in IR as well as a significant hot spot. The Tamron 20mm is not the quickest to focus and seems to chatter away to itself occasionally, which I think may be the aperture opening up for focus acquisition, but it gets the job done very well. There is a mild hot spot appearing past f/8, which may start to show when pushing the processing in false colour.
The Tamron 11-20mm f/2.8 lens really is one of the best wide angle zooms for IR work using crop sensor Sony cameras, it's sharp at all focal lengths over most of the frame [APS-c Format] although there is some mild field curvature affecting the corners, as is common in infrared especially with wide angle lenses.
Here are a few more with the Tamron 11-20mm in 720nm IR, click on the images for larger size and details;