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mochikat

Sony 90mm Macro AF performance - to upgrade or not

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Hi all

I recently swapped from a Nikon D7500 cropped-sensor DSLR w 85mm DX macro lens to a FF Sony A7C w 90mm macro lens. I've been shooting the Sony for about a week now in Anilao and Puerto Galera, with the 90mm lens almost always on 0.28-0.5mm focus limiter, and sometimes with a Inon UCL 67 (+15) diopter added on top. Initially I found the lens very frustrating to use compared to my old Nikon, as the focus would keep hunting and is very slow, or sometimes can't find the subject at all, but after a week getting used to the working distance and switching the focus limiter on I've gotten some great shots, and even find super macro with the UCL-67 on not as frustrating. If the subject has color I can pretty much get it right, but where I still struggle with the lens finding the correct focus is when there is no contrast or a lot of sand - 2 examples were when we were in a sandy bottom, there was a bit of surge and current blowing lots of particles around, and I was trying to take photos of 1) a black seahorse, 2) a black leaf fish - in both cases the camera just can't find the eye w AF even with a focus light. I spent 5min trying to get it to focus before giving up in both instances.

The A7C has the same sensor and AF performance as the A7III I believe - and I have heard the A7RIV is a huge step up in AF performance - with the A1 being even better (I have read Backscatters' review which calls the A1 + 90mm macro lens the best combo even better than Nikon D850). My dilemma is I JUST bought the A7C (selected for its compact size) and can still get 80% of the shots I want even if it takes me a bit longer - so question whether it's worth upgrading to the A7RIV or A1 or if I just need more practice and get better. I have noticed a huge difference at how quickly I can find the right focus between my first few dives and right now- but I'm not sure if there is a limit to what the A7C can do and if either the A7RIV or the A1 can AF in the scenarios like the 2 above where there is no contrast on the subject.

The other thing that intrigued me about the A1 is the 1/400 sync speed - my A7C can only do 1/160 although I've been shooting up to 1/250 and the black bar on top is not too noticeable and can easily be cropped - it does cover 1/3 of the frame at 1/320 tho. I'm shooting Inon Z330s with a fiber optics cable and Nauticam mini flash trigger, but my housing distributor said he wasn't sure if my current set up can do 1/400 even with the camera body change. Does anyone know? I don't want to invest in new strobes or HSS connection for sure.

Thanks!

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There's been a few posts n here regarding the Sony 90mm macro performance and indeed performance is reported to be a lot better with the A1.  Phil Rudin will hopefully chime in and address your specific questions.

On your question regarding sync speed, the sync speed is all down to the body, the strobe just needs to be triggered as the pulse is usually significantly shorter than the time the shutter is open.  Some strobes have long pulses which limit power at higher shutter speeds, but the INON strobes have a short pulse and should be fine.

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Thanks Chris, that’s helpful to know on the strobes. The Sony lens is limited to f22 also (which I did not know nor researched properly, had assumed it would be f32 like the Nikon and Canon lenses) and there were definitely many instances where I’m already at F22 100iso and 1/250 shooting against open water and can’t get a black background. I know the other workaround is snoots but I’m so bad at it haha

I had another dive today trying to shoot a tiny black frogfish w the +15 diopter and I literally couldn’t see the eyes through the viewfinder, so of course couldn’t achieve manual focus… wondering if that’s a situation where the A7Riv or A1 can find it 

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Black frogfish are the worst - if it's anything like the frogfish around Sydney, they suck up the light like a black hole, so the camera is left with little to work with. 

On black backgrounds you can extend your ISO range to 50 which will help some, but you must be in fairly bright waters if those specs are not enough.  As for f32, it may be nice but you don't have any other options in the Sony system - you could adapt a Canon lens but you'd be complaining about the AF more so most likely.  Other than that moving the black point across in post may also help you out.

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..... and the problem with f32 is diffraction. Yep, you get more DOF but the image quality might well be degrading.

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Maybe this helps, maybe not.

I had been using the Sony 90 with my Sony A7RII and focusing was a pain on small subjects, so I often used manual focus.

I recently shifted to a Sony A7IV and the focus improvement is outstanding. I don't have the same problems with the lens that I used to have with my Sony A7RII.

Granted, the A7RII is older and slower, but my overall point is that I am content using the lens on my Sony A7IV.

I can't pry myself from this lens because of its capabilities underwater. For me, it is just superb in terms of color and contrast.

Best of luck!

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Thanks John, that's helpful to know.

I went into the Sony store today and tried the new A7IV, as well as the A9 and A9II, and A1 for fun but did not seriously consider it due to price. I could definitely see a huge improvement in AF speed especially in low light on the A9, could see some improvement from A7IV vs A7C but not too much, and between A9 and A9II also not too much. I could see an improvement in A1 vs A9, and the EVF is incredible, but A9 seems fast enough. I did also find the tracking on the A9/A9II/A1 to be much better as well, rarely loses the focus point when I hold down back button focus and recompose, whereas the A7C will if I move too fast or in low light. This is all above water so who knows how it stacks up underwater. And I didn't think I would care about the blackout free shooting but it was nice! All the EVFs were a huge upgrade over A7C, I wonder if part of my issue is I just couldn't see clearly when it's in focus cuz the EVF is so tiny. I think I could probably get used to manual focus on A7C eventually but the EVF swayed me - thought it wouldn't be an issue with the magnified viewfinder but it is.

Someone locally recently upgraded to A1 and is selling his A9+housing, I think his old A9 is the answer for me. A9II is 2x the price, A1 is 3x. A9 is smaller than A9II/A1 also and fits better in my hands (does feel heavy tho after getting used to A7C). My housing distributor also told me he doesn't recommend the Inon UCL-67 for the Sony 90mm macro, so I'm going to test a few other diopters too - let me know if any recommendations that works well w the 90mm specifically.

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On 5/7/2022 at 2:32 PM, mochikat said:

The A7C has the same sensor and AF performance as the A7III I believe - and I have heard the A7RIV is a huge step up in AF performance 

The other thing that intrigued me about the A1 is the 1/400 sync speed - my A7C can only do 1/160 although I've been shooting up to 1/250 and the black bar on top is not too noticeable and can easily be cropped - it does cover 1/3 of the frame at 1/320 tho.  
 

 

Some observations: 

1) I’ve used the A7c and A7iii. Continuous focusing/tracking is much better with the A7c. The A7c AF may compare to the older A7riv, but it’s quite a bit stickier and less prone to jumping off a subject compared to the A7iii. The higher end bodies, which I’ve not used, should be even better I expect.

2) The Sony 90 macro isn’t the fastest at autofocusing. But it is sharp and perfectly serviceable if you can get it to awaken from slumber. A contrasty subject and a staying within a set range is helpful. (I wish for a slower (f4-5.6), macro with 1.5x magnification and AF.  What say you #Sony? Canon’s RF 100 f2.8 does 1.4x.)

3) My Nauticam flash trigger allows me to cheat the 1/160th flash sync, which I typically use at 1/200th. I try to get around the sync speed by dialing down ISO. 

— Craig Fujii (Waipahu, HI)

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Posted (edited)

Update! So I don't muddle the waters for anyone reading this, turns out this is my own fault for not packing the 90mm lens well enough that something got loose inside and messed up the focus. Sony replaced my 90mm and now I have zero issues with focus, there is still a bit of hunting if you set focus limiter to full and use a diopter but it is useable and it DOES lock when it finds the focus! Before with the defective lens it would just keep hunting and hunting but the focus square never turns green. 

I went to buy the used A9 and when I put my old 90mm lens on it there was absolutely zero difference - still the same hunting issues when using a diopter. Tried all the diopters they had. Nauticam SMC-1 performed noticeably better with less hunting but the focus still doesn't lock green over half the time. The guys at the store tried all kinds of different settings for over an hour and finally concluded the lens must be defective, so back to Sony it went. This did convince me to pick up the SMC-1 since it was so much better even w the defective lens. It also showed there's negligible difference between A7C and A9 autofocus, at least from what I can perceive with the diopter. 

I'm in Lembeh now with the replaced 90mm and new SMC-1, plus my original A7C, and this thing is a joy to use. Super sharp, bokeh is so nice, and focus speed feels pretty similar to my old Nikon with the focus limiter on. I've tried a few dives with it off and found I was shooting through too much water anyway when I needed more than the 0.5m of distance, so even if I could fit the subject in the frame it wasn't super nice. But A7C autofocus is actually top notch - I also didn't use the tracking mode before! It's buried under the last option and I was always using flexible spot S or M wondering why it doesn't lock and track with current. Now that I'm using flexible S/M + tracking a bit of current is no issue. Still a bit of a challenge with the diopter, but base 90mm feels super fast and AF very accurate. 

I'm keeping this - no need to upgrade.

Edited by mochikat
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