Full-Frame & Keeping The Compactness

For nearly three years now, Sony's A7 series have been the uncontested champion of compact, full-frame ILC's (Interchangeable Lenses Cameras). Keeping them small can be tricky however. In a push for ultimate image quality most of Sony's newer lenses are large and heavy.

Although I've since sold the Voigtlander 35mm f/1.4 (above) because it was bad for infrared, I have tried a few other small lenses during my time with the A7. Here are my thoughts on what makes a good choice when trying to keep the size and weight of your camera bag to a minimum.

Before I go any further though, let me iterate why this camera/system is so interesting for infrared... 

• EVF means you get to see in the wavelength you're shooting in
• Ability to adapt to any SLR/RF lens helps choose lenses that don't suffer from hot spot
• Cleaner Full-Frame IQ helps with heavy manipulation often needed for IR processing

Adapting to SLR lenses (especially older ones) often helps with the IR hot spot issue, but it also adds to the size & weight (due to the larger, usually metal, adaptors), thus compromising on size & weight.

Shown off the camera you can see the difference in size a little more easily. This also illustrates how a moderately sized SLR lens can become quite front heavy when added to an adaptor for the A7. Although the Nikon 35mm f/2 lens is a great IR performer I will not be featuring it here due to it's lack of compactness. Here are the lenses I will be talking about...

35mm and 40mm lenses are a great for general / travel photography in my opinion. Just the right balance between wide and tele. Plus they're usually the smallest option, as long as you don't want them too fast. Over the last two years I have used the three lenses above and I wanted to compare them all here because I like each of them for different reasons. Here are some technical details before I start to get into more opinions.

NOTES: The dimensions, below (length & weight) are including the camera. The weight is with no strap or lugs (not to reduce weight, but because I hate camera straps). The weight also doesn't include a lens cap or hood, but it does include the battery and memory card, so this is what you'll notice when actually using them (in most cases). I haven't included the price of the adaptor (where needed) here, but I will mention it in the text below.

Weight

In this regard the Zeiss is king by a mile. Even with it's meager f/2.8 max aperture it's hard to believable how light it is. The official weight of the camera is listed as 474g (including battery and media), but mine comes to 455g, for some reason. The breakdown for the full Zeiss 35mm package is as follows:

• Camera: 411g
• Lens: 119g
• Battery: 42g
• Hood: 12g
• Cap: 5g
• SD: 3g

So, the total (including the hood and lens cap this time) is 592g. It makes a rather interesting comparison to my previous camera - the Nikon D3. Now I know these cameras are very different, but what do I really miss from the transition? The main thing is AF speed, especially in low light, because the D3 was a miracle by comparison. Apart from that I really don't miss much about the pro DSLR. My camera is now with me most of the time and much of this is down to the weight.

Let me put this change into perspective - The Sony A7 body, Zeiss 35mm lens, memory card and 5 (yes five) batteries weighs less than half that of the Nikon D3 body alone (with no lens)! OK, how about this... All of this next list weighs less than the Nikon without anything (no memory cards, battery or lens):

• Sony A7
• Zeiss Batis 25mm f/2
• Zeiss 35mm f/2.8
• Zeiss 55mm f/1.8
• 2x batteries + SD card

To be fair 5 Sony batteries probably don't last as long as 1 in the Nikon D3, but that's not totally fair because of the EVF and live-view being on constantly. Before roasting me about dual memory cards and other features; I do admit that it's not exactly fair to compare the cameras on this level. This is purely about how amazing it is to have a functioning camera that weighs so little, whilst still being able to produce amazing quality images. It has made a huge difference to me and where I take it.

Size

The other two lenses are much heavier. If we concentrate on AF options the Canon + Metabones is quite a bit heavier. It weighs almost as much as the Zeiss 55mm f/1.8, which is not only a phenomenal lens for colour, but for IR as well. That said it is quite a bit longer, so apart from it being the wrong focal length I didn't include it here for that reason. The newer Sony 50mm f/1.8 lens is different story and I am tempted to add that one to the comparison because I do own that one as well.

If you're OK with spending good money on manual focus lenses there are some other choices that I will mention now, but can't talk about extensively here because I haven't tried them. If you're curious I advise looking in to rangefinder lenses from Leica and Voigtlander. It's not just because they're small, but the adaptor is much thinner too (see the top image for reference). 

There is an AF adaptor for rangefinder lenses now, in the form of the Techart Pro. This is about the same price as the Metabones (£350), which isn't too bad in of itself, but the price of the lenses and the fact that it only focuses "well" on the A7RII has stopped me from being able to try one. If you have the high-end Sony however then that's not your only other option for mini AF lenses though. Techart also make an AF adaptor for Contax G mount lenses. This would enable you to use the fabulous looking Contax 35mm f/2 lens (which is actually Zeiss made). The lens is not too expensive for what it is either, but be warned this AF adaptor is no longer listed (or supported?) on the Techart website and the lens doesn't have a 'normal' manual focus ring.

Cost

Including the Metabones adaptor in the cost of the Canon lens makes it almost as expensive as the Zeiss, but with the latest firmware (June 2016) it allows pretty decent phase detect AF, even on these first generation A7 models. This makes it a really nice option if you want to use other Canon lenses. If you're only buying it for this pancake lens however then you might want to think twice, unless you're more interested in IR performance and have to have AF.

The Konica 40mm lens is a great option if you're on a tight budget and can live with manual focusing. It's possibly the best lens here for IR image quality too. The fact that it's over a stop faster than either of the two AF options and weighs less than the Canon, despite being all metal and glass and needing a big SLR adaptor is really impressive. The wide open performance is fine on close up portraits, but for distance shots it's awful. You'd need to stop it down to f/4 to get real sharpness, but is that really different from many other lenses? and here the sharpness does impress. For something so cheap it's stunning. 

Autofocus Only Options

Since the latest update for the Metabones adaptor (June 2016) the Canon 40mm STM lens focuses so much faster on the first generation Sony A7 bodies! Getting proper access to phase detect AF. This is a huge benefit  to owners of the older Sony cameras (like me), but this update wasn't really hyped so some may have missed it. Before this it was painfully slow to focus on anything, even with good light. With low light it would generally fail to focus at all. This would really put you off using Canon lenses on the original A7/r/s. Now that it's got PDAF however it seems faster to focus than the new Sony 50mm f/1.8 lens (although I haven't done a direct comparison for that yet, or been able to try the firmware upgrade for the 50mm).

I could have included Sony's new nifty 50 here (purely based on size), although it would have been the biggest, but I decided to stick to slightly wider lenses that are better suited for travel. If you're really curious to see this comparison let me know because I could add it later...

Comparing the two AF lenses together directly doesn't come out particularly well in favour of the Canon. The 35mm Zeiss lenses extra 5mm of FoV makes it a bit better as a travel lens, but it's also smaller, significantly lighter, has better image quality overall, focuses noticeably faster and hunts less as well. 

Where the Canon pulls ahead is with infrared performance and this is why I keep it around. That and I managed to save £300 on the Metabones adaptor by getting it with the camera. That saving made it less than half the cost of the Zeiss, so if you can find a deal like that I highly recommend it. 

Filters For IR

Ultimately I couldn't resist the charm of the little blue badge. It's IR performance can be annoying, but I'm soon going to be trying it out on an AR (Anti Reflective) coated internal filter conversion, so I'm hoping it does a lot better there. Time will tell on that one, but one other thing I wanted to mention about IR is when using filters. The Zeiss lens' hood is quite clever, but when using thicker (49mm) filters the hood may not attach any more. If that happens then you also can't get the lens cap on and this is a really stupid design flaw. If only they included a 49mm lens cap in the box as well as the weird 40.5mm version then this wouldn't be a problem. If you're buying this lens for use with a full spectrum conversion then do yourself a favour, buy a spare 49mm lens cap as well. The official ones can be picked up for as little as £6, so why on earth they didn't include one in the box is beyond me.

The Canon lens' filter size is the most common 52mm, thus making it cheap and easy to find anything you want for a full spectrum or IR conversion. The Konica is more annoying, with a 55mm filter thread. It may not sound like much, but this is a pretty rare size to find second hand options, so this will push the price up if you want some specialised filters. What's most annoying about this is that stepping down to 52mm works fine, with no vignetting, If this was just because they wanted the weird text on the front that's super annoying.

Here's one more shot of the two main AF options on the original Sony A7...