A question re Tamron 28-200 and SS

Started 2 months ago | Discussions thread
Photo Pete Veteran Member • Posts: 5,389
Re: A question re Tamron 28-200 and SS

Foto4x4 wrote:

Photo Pete wrote:

Jeff2013 wrote:

The age-old formula of 1/FL came from the film and early digital cameras with an effective 8 to 12mp of resolution. Higher resolution sensors, such as 42mp, will require at least 1/2*FL or 1/3*FL for equivalency.

Shooting 200mm at 1/100 second will need to take advantage of IBIS to obtain a high statistical average of sharp shots, for the average shooter. In testing, I have shot 200mm on the 28-200m at 1/20 second and obtained about a 20% probability of a critically sharp shot. As a note, I developed stable shooting techniques back in the film days when wasted shots were costly.

At 200mm, on this lens, I will try to shoot 1/200 second minimum (relying on IBIS). If I shoot at slower speeds, I will often take multiple shots to increase the probability of obtaining a critically sharp shot on the 61mp A7RIV.

Ugh. That’s not what I had hoped to hear. I’m planning on switching from Olympus to a Sony A7Riv. At 200mm equivalent on my Olympus I get over 90% critically sharp at 1/3 second, but appreciate that is only a 20MP sensor.

What sort of shutter speed does the A7Riv need when using a stabilised lens (such as the new Sigma 100-400) at 200mm?

I’ve owned an EM1.2 & lenses such as 12-40 Pro, 12-100 Pro and PL100-400. Let’s not beat around it, the IS of that body was sensational and with the 12-100 in particular incredible. But like you’ve noted limited to 20Mp.

I own the A7RIII not an IV and have the 100-400GM not the Sigma but I think the IS is similar enough those units to comment. There is no way you’ll get consistent sharp images at 1/2, 1/3 or even 1/8s with even the best OSS/IBIS combinations like the Oly was capable of. But what light and subjects will you be shooting that needs such low speeds? I can get fairly consistent shots at 1/15s even at 300-400mm but your subject needs to be dead still and bear in mind you will get much cleaner images at 3200, 6400 and even 12800 ISO than M4/3 can produce. So it’s all relative really.

Also, while Jeff2013 is proposing to use 1/FL at 200mm with the 28-200 I have been able to get consistently good images at 1/50s at 200mm with IBIS on. With older OSS lenses, eg the 70-200G 1/30s is achievable and with newer lenses like my 100-400 @ 200mm I can get down to 1/15s but probably with one in two showing some motion blur. But with the cleaner high ISO the images are comparable to what I used to get with the EM1.2.

Thanks. That is sounding a little more positive.

My main concern is the quality I’m likely to get in the 80 - 300mm range. I have the Olympus 40-150 f2.8 (80-300 FF equivalent). So for a focal length of 200mm, in low light situations, I can comfortably achieve acceptable quality hand held results by shooting that at 1/6second, f2.8 and iso 3200.   The replacement on the Sony is likely to be the Sigma 100-400 which at 200mm has a max aperture of around f5.6. To match the low light performance of my Olympus kit I would need to be able to shoot hand held with the Sony at 1/6second, f5.6 and iso 12800... which sounds like it won’t be achievable. I’ll probably be at least 2 stops worse off.

If you are saying hand held shots with the Sony at 200mm are possible at around 1/15 second then this probably isn’t a major issue for me as the use case above is obviously a performance outlier with extreme low light and extreme length hand held shutter speeds. For more normal shooting at 1/15 second or faster I’ll just be able to shoot the sony at f5.6 and 2 stops higher iso than the Olympus kit, but benefit from the extra detail of the Sony.

If, as was suggested earlier in this thread, I needed to shoot the Sony at 1/focal length for sharp results, even with IS, it would be a whole different ball game.

At the end of the day, I’ve never regretted moving from M4/3 and I’m extremely impressed with this new Tamron with just the A7RIII IBIS. But that is just me, YMMV.

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Cheers, John
Quote: “If your pictures aren’t good enough, you’re not close enough.”, Robert Capa

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Have Fun
Photo Pete

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