Who needs a telescope part II: Going crop-frame with the Canon 70D + Tamron 150-600mm x Sigma 1.4x

by Guest Contributor

posted Thursday, December 3, 2015 at 6:27 AM EDT


Wake up with IR! Here's today's dose of Caffeine Priority...

We're pleased to bring you our first guest posting in this column by our reader Stephen Barlow from the UK! If you've yet to read our part I "Who needs a telescope" post and would like to start there, please do. For everyone else, please read on!

By IR reader Stephen Barlow

I did a moon shot with my Canon 70D, Tamron 150-600mm + Sigma 1.4x converter tonight after being inspired by Dave Pardue's "Who needs a telescope" caffeine priority feature. I'd not thought to try the Sigma 1.4x converter on it before. Not only does it fit, but surprisingly it will AF, although at reduced speed.

This photo was taken using MF though (as was Dave's shot with the 5DS R). The Sigma 1.4x converter on this combo is non-reporting, so it still says 600mm and the aperture is one stop smaller than it indicates on the camera (that threw me a bit, as I started of shooting at f11 (really f16)). It had been cloudy earlier but when I went out I noticed a gap in the clouds, and grabbed my gear. Unfortunately, I only had a short time to shoot the moon and so it was a rush job!

Canon 70D + Tamron 150-600mm + Sigma 1.4x teleconverter
(840mm eq. focal length)

I couldn't find my quick release plate for the geared head, which is best for this, so I used a gimbal head. It was shot using magnified live view (although I also forgot to take my reading glasses along), and a remote release, using MF, in manual mode. The EXIF says 600mm f9, but as it's a non-reporting teleconverter on this combo, it should really be 840mm, f13. I used ISO 400 because I should have opened the aperture up a touch more to allow for it being one stop smaller than reported (but I never thought of that until after).

I cropped the photo down to similar proportions as the 5DS R shot from the earlier article, although obviously being in a different part of the world and it being a waxing moon, the view is not identical. In theory, as the pixel pitch is more or less the same as the 5DR S, it's roughly the same per pixel. I've included an uncropped photo, but this is edited as well. Just some noise reduction, sharpening, and a levels adjust.

Uncropped version of the above image to show the actual size captured on the frame.

To see more of Stephen Barlow's work click here!

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Thanks so much, Stephen, for this submission! A very cool comparison, especially given the similar pixel pitch you mentioned. For any of our readers who'd like to share an interesting image with us, especially as relates to the gear used, please see this article on how to make your submission!

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Caffeine Priority is a new series of short photo-tidbits to ease you into your day, and give us a chance to share a bit more of what life’s like here at IR. We're more like a group of friends testing and talking about cameras and lenses than the buttoned-down, big-corporation world that some of our photo-friends at other companies work in; hopefully these little snippets will share some of that. So... grab another coffee and join in the conversation with us down below!