Sigma 150-600mm Contemporary + 1.4x extender vs Canon RF800mm F11

I’m looking for a 800mm lens for birding and astrophotography on a Canon R10.

I’m considering the Sigma EF 150-600 Contemporary + 1.4x extender or the Canon RF800mm F11

The canon is lighter and cheaper, but fixed focal length and fixed F11. Should be good for birding but not ideal for astrophotography (except the moon).

The sigma is heavier and more expensive (with extender), but more flexible and wider aperture, even with with extender (F9). Probably slightly better for astrophotography (planets) than the Sigma.

Anyone have experience with these two lenses? Any opinions?

The 150-600 and a 1.4x converter will work but it will not be the sharpest combo.

Have tried it with various DSLRs and MILCs in the Eos range,

The RF 800 will probably be sharper

I used the Sigma with and without the 1.4 TC for about a year. I owned the 600 and 800 f11 lenses for a couple of months. For me the Sigma was fine for birding but it does pulse in and out of focus in servo mode. For me it was very heavy. The weight is further forward as well due to the RF to EF adapter and the TC. I ended up selling all 3 and bought the RF 100-500. It is very sharp so I haven’t missed the added reach. I have it on an R7 now. The only issue I had with the 600 and 800 was the long minimum focus distance. One day while using the 600mm on my R6 I watched a Green Heron eat a snake a few feet in front of me. It was too close to focus on and I couldn’t back up without going into deep water. I was so disgusted that I listed both lenses on eBay that night. Both lenses were great performers outside of the long MFD. Don’t expect much with the Sigma and the TC. I found that the TC really affected sharpness and focus speed. Because of that I rarely used it. For me the flexibility of the zoom would likely win out but I got some really nice shots with the f11 lenses.

Kmccarthy wrote:

I’m looking for a 800mm lens for birding and astrophotography on a Canon R10.

I’m considering the Sigma EF 150-600 Contemporary + 1.4x extender or the Canon RF800mm F11

The canon is lighter and cheaper, but fixed focal length and fixed F11. Should be good for birding but not ideal for astrophotography (except the moon).

The sigma is heavier and more expensive (with extender), but more flexible and wider aperture, even with with extender (F9). Probably slightly better for astrophotography (planets) than the Sigma.

Anyone have experience with these two lenses? Any opinions?

I agree with the earlier comment about some kinds of astro. Some stuff might work though assuming you've got a tracker. The Sigma is faster, but with a tracker you could take longer exposures anyway. The 150-600 C not the greatest lens, but a great value. I got mine before the 600mm and 800mm RFs came out, and I keep it because I prefer and need the zoom.

But it does have the pulsing problem on an RF camera. More apparent close in, and if you use other means to focus vs continuous you can work around it. But that would argue in favor of the 800mm. I don't see Sigma making any attempt to fix it with firmware, and it's not Canon's problem.

My Sigma softens up above 300mm, and is acceptable, but softer at 500-600mm. The 1.4x III TC makes it pretty soft wide open at 600mm. The advantage of the Sigma is the versatility, not necessarily the sharpness. I've seen a lot of sharp, good shots with both the Canon 600mm and the 800mm. It's hard to knock the lenses at f/11 for what they deliver.

BobKnDP wrote:

Just curious: planetary photography?

At its closest, Jupiter is supposed to have an angular diameter of 46.9 arc seconds. With an 800mm lens, that would give an image diameter of 182 microns.

The R10 has a pixel pitch of 3.72 microns. That's less than 50 pixels across the image. It also ignores the reduced resolution associated with the Bayer mosaic color mask.

There are ways of getting a higher resolution by combining multiple images, but I'd think that a telescope would be a better way to go, even if its aperture is no larger than the nominal 73mm entrance pupil of the RF 800.

Fully agree. You can do some basic planetary photography with a 400-800mm tele lens, mostly planetary and Moon conjunctions and for trying it out. But you get relatively little detail for the reasons you outline.

If you get really serious, a telescope of around 5 inch or 125mm aperture is a good minimum. Also you get vastly better results shooting pixel res video, either in cam or using BackyardEOS to capture to a PC. Then you use free special PC software to select and stack the clearest frames and to sharpen the result.  Good youtube videos give more details.

Here are some of my results with a Canon M6ii and Meade ETX-125:

https://www.dpreview.com/forums/post/66707947

I just bought the Siggy 150-600C to use for deep sky astro of nebulae and galaxies on a star tracker.  The lens is a sweet spot for those.