All images on this site are © Toby Houlton and must not be used without permission Interested in an image? Please contact me using the contact link on the navigation bar Return to main page Sigma 300mm f2.8 with converters - viable? Around a year ago I reached the point that many wildlife photography enthusiasts had reached before me. I wanted a prime lens that was sharper than the Sigma 50-500mm I was currently using but there was no way that I could afford a 500mm prime. The next alternative appeared to be using a 300mm prime and adding to the reach using converters. Scouring the internet I found many opinions on the subject but really struggled to find decent images that convinced me this was a good idea. Sigma have 1.4 and 2.0 converters that are specifically designed for use with a few of their lenses, the Sigma 300mm f2.8 being one of them and the fact that they also retained autofocus was enough to encourage me to buy a secondhand lens that showed up locally and I also went ahead and bought the converters to match. I find this lens used on it’s own is super sharp and being an f2.8, ensures a bright image in the viewfinder and allowed use in situations where my trusty old 50-500 f5.6 just wouldn’t have coped. Apart from the obvious gain in the sharpness of the image by using a prime lens, being able to shoot on dull days in the shade of trees was something of a revelation for me.   This image is a 100% crop, is totally unprocessed and was shot at ISO 400 in a fairly dark area of the garden but allowed a shutter speed of 1/400s at f6.3. I used a 1.4 converter with this shot to get extra reach. It’s clear to see that plenty of detail has been captured. I use a Nikon D300 which handles noise very well in my opinion so I have no qualms about pushing the ISO up when required. The image to the right shows the finished article. I tend to resize my images to 1200 pixels on the longest side as I feel this allows me to display them at a pleasing size without going overboard and this way the viewer can enjoy the close detail of the subject(s). This image has had a small amount of sharpening and noise reduction applied - just quickly to demonstrate the quality and detail that the lens captures. Long Tailed Tit example crop Image#56 - Long Tailed Tit (Aegithalos caudatus) - My Garden - Nikon D300 with Sigma 300mm f2.8 + 1.4 TC - 1/400s, f6.3, ISO 400 So if using converters is an option, what are the drawbacks? You will of course lose light by adding them, 1 stop for the 1.4 and 2 stops for the 2x, effectively making a 420mm f4 and a 600mm f5.6 lens. Add the crop factor of a digital sensor and you have (with a Nikon) a 630mm and 900mm equivalent. That’s not bad at all but in my opinion the main loss is the detail at distance. Remember that the lens can still only resolve detail at 300mm and by adding the 1.4 converter you are magnifying the detail already captured. Now think about that with a 2x converter and you can start to see a drawback. For close shots the detail is fantastic but the further your subject becomes, the less detail is recorded. This is of course the same for any lens, but a 500mm prime records good detail at that range and that is the main tradeoff - you pay less but obviously have to lose out somewhere. Also bear in mind that you will lose some Auto Focus speed when adding a converter. Blackcap example crop with 2x converter Blackcap taken with 2x converter This is an example of a shot using the 2x converter. Left side is 100% crop and is un-processed. Right side is the finished article after levels and some sharpening. So is it for you? I guess that depends on your budget. If you can afford a larger prime then you probably won’t be reading this. Personally speaking I was very happy that I took this step. I don’t regret it in the slightest. Not only did it make an immediate impact on my images whilst being fairly flexible, it became a stepping stone until the point I could obtain a 500mm prime. With these samples you need to bear in mind that it is a 100% crop and is unedited. By 100% crop I mean that it has been cut right from the full size RAW image without being processed. When you reduce the size of an image it will automatically become sharper, even if you don't actually sharpen it yourself, I believe it's just the way the compression works. As an extreme example, how many times have you looked at an image in the viewfinder and it looks sharp but when you view it full screen you think..oh..not sharp. It's the same principal. The important thing to consider is the size of the finished image that you require. Wanting an image that's sharp for postcard size is a little different to wanting an A3 print. That said I do indeed sharpen my images for their 1200 pixel size.