How should I resolve my birding GAS?

Larry Rexley wrote:

User1303423862 wrote:

Hi all.
I have a dilemma to solve. I've been trying to get some nice shots of birds and I'm pushing the limits of what I can achieve with my M6 + EF-S 55-250 IS + Rexley 2X TC. The AF on the M6 isn't really quick enough and often hunts when pointed skyward.

I inherited an EOS R + 24-105 L from a company I was working for as part of the severance deal when they unexpectedly had to cancel the project I was involved with. The AF is great, but I get a mandatory crop to 12MP if I mount the EF-S 55-250 IS to it.

I'm between jobs at the moment so funds are limited, but I have time to be out trying to get nice shots. What to do? I've sold some cameras and lenses I'm not using and have a budget of around £600.

I could sell the M6 and upgrade to a M6ii or M50ii for better IS, and have a couple of hundred left over towards a better lens.

I could buy an RF 100-400 and save for a RF TC

I could buy a beat-up EF mount Sigma 100-500 and use it solo or with my Rexley 2xTC at high f-stops on the EOS R or M6

I could treat my wants for better bird shots as a passing phase and buy a 32 f/1.4 EF-M prime.

Please offer some advice on AF at higher f-stops and tick a box in the poll below.
Will I get much better AF and IS with a dedicated RF zoom?
WIll an older EF lens do the job and give me more flexibility?

Here are a few of the shots I've got in the last week with my current set-up to help you decide whether I could be a better birder with a better lens, or whether I should just scale back my ambition and concentrate more on other photograhy subjects.

The results you're getting are about the limit that the M5/M6 (I) AF and resolution can do, and are quite good. I had the original M6 for about 2 months, it was the camera I used when I DIY'd that teleconverter you're using. I upgraded to the M6ii in late Nov 2020.

Value for money-wise, upgrading to the M6ii may be your best option. The AF ability of the M6ii is quite superior in terms of speed, and ability to focus in low light. I found that the EF-S 55-250 IS STM plus 2X teleconverter could not autofocus with the M6 in anything but the best lighting, whereas the M6ii has no problem autofocusing with that combo even in quite poor lighting. Plus you get a little more reach with the higher res sensor --- however that 2X teleconverter can't really resolve the full res of the m6ii sensor, so it won't be that much of a gain for you. On my M6ii I use the 2x converter when shooting 4k video or if I absolutely need the most reach possible, otherwise I normally use the Kenko 1.5x SHQ on my EF-modded 55-250.

I do wish I had a longer lens at times, but the cost and weight of the EF 100-400 has kept me from buying it, it's too big to take along on my bicycle which is how I do most of my shooting. For astrophotography I use a meade ETX-125 telescope (1900mm, f15) for high magnifications which is quite a sharp instrument, with the Viltrox 0.71x speed booster I can even get the entire Moon through the scope on the frame as it becomes a 1350mm f11 scope with the booster.

Thanks for your prompt thoughts Larry! I'm guessing your astro work is the reason you're answering at this time of day in the U.S.

AF does seem to be my main limitation, although it sounds like my M6 is doing better than yours was. I've been having a lot of fun with that 2X TC you made. Resolution and reach is 'good enough' for me with the current setup. Hopefully, one of the forum members who has or has had an EOS R might give me an idea of the difference, if any, in AF capability between the M6ii + 55-250 + TC and the EOS R + 100-400 + TC.

I mostly go birding on my motorcycle, and the current setup allows me to zip up my leather jacket over it, just. A 'big gun' EF lens on the R would present an issue for sure.

The M6 uprade to M6ii is attractive for the benefits it would bring to my enjoyment of other photography genres too, so thanks again for your sage advice.