- last edited on by
Danny
I'm a novice and completely confused after researching this question
Can anyone please tell me what the combined mm and magnification this with this arrangement on my Canon R?
Hi and welcome to the forum:
Hmmm... I have the Sigma 60-600mm myself and your arrangement is not a construct I would recommend. I assume you are keen to increase the size of an image within your photos. But, to answer your question, there are several aspects to consider here. The effective focal range of the lens, the impact on the aperture range, and its ability to gain focus and get an exposure reading. Not to mention structural integrity and weather sealing.
Native focal range of Sigma is 60-600mm f/ 4.5-6.3. Its performance in this configuration is excellent and can use all focusing and exposure modes of the camera to which it is connected. It has good image stabilization.
Attaching an extender will have several impacts on the lens performance.
Adding a 1.4 extender will increase the effective focal length by a factor of 1.4 but also reduces the effective aperture performance by at least a stop. That results in a focal range of 84-840, f/6-8 at best.
Adding a further 2x extender doubles the focal length again but loses you a further two stops of aperture
so, 168-1680 f/9-f11 (at best). It is likely this will adversely effect focus and image stabilization.
But it's not as simple as that. Depending on the version of each extender (and the one closest to the body appears to be old) camera and lens to which it is attached, will cause the number of effective focal points to be reduced to basically ONE and focus will be pedestrian at best. Given this is not a native Canon lens, Canon does not support or predict how the lens will behave, and I doubt Sigma would be too keen to make any comments with the extenders and the EF-RF adapter added in the mix.
Finally, you are compromising the structural integrity and certainly any weather sealing with so many mechanical joints, each of which adds a risk factor.
So, the bottom line is this. If you really want to get up and close with a subject, I would strongly advise to use the lens in its native format. The quality of the image will be better, it will focus quickly and accurately and perform as advertised. I use this lens frequently and it is a great unit with both DSLR and R-series MILCs.
The more stuff you attach, the more the performance and image quality will suffer, and the more the lens will be hard to hold steady, and to focus. The light performance of all that stuff will likely be that close to a blind person in all but the brightest light.
With all this in mind, exactly what subjects do you want to shoot and what do you want to produce? The EOS R has a 30MP sensor, so if you are producing images for social media, digital display or even moderate size prints, you can crop the image to contract the Field of Capture.
The following examples were taken by the Sigma 60-600, sans extenders, and shot on the Canon EOS 6D, a 20MP sensor.
My advice is use the lens as designed and massively increase your chances of a decent shot.
I have stacked extenders for fun. I hope you have fun too. The biggest obstacle to photographing the moon is changes in air density between the camera and the moon.
The extender will
- increase the F number
- leave the minimum focus distance unchanged
- reduce the contrast for small features
- possibly magnify any defects in the lens
- possibly increase small aperture diffraction blur
Canon DPP software "digital lens optimizer" does well at removing small aperture diffraction blur. If your camera can save DPRAW, then the DPRAW tool in DPP can correct some of the loss of contrast for small features. With extenders, I have been able to see the moons of Jupiter. The moon picture below was hand held and with a shutter speed of 1/20 second gave the IBIS a workout even though I was sitting in a chair with my elbows braced.
Others make better moon photos, but this was fun for me.
