Higher ISO or slower shutter?

Was out shooting the moon yesterday with 1400mm equivalent ISO 100, 1/30. With 1400 mm one can expect the moon to move across my view rather quickly. Should I expect a bit of blur at 1/30 shutter speed? Could I be better off raising the ISO for a faster shutter? I'd test it out but it's cloudy tonight.

I would be suprised if there was much motion in 1/30 of a second, but most cameras should be able these days to shoot at least ISO 400 without any real degrading of the image, so I would shoot there anyway just to make sure. Off the top of my head 1/30 seems pretty slow to start with, I always read the sunny 16 rule works with the moon which would mean you may be overexposed by a few stops. For me personally, focusing on the moon perfectly has always been far harder than preventing motion blurr Good Luck.

I've always tried to use 1/200 or 1/250 and set ISO accordingly and get pretty good results.

I try to stay above 1/100... this at 420/600mm. I can only imagine it would be worse at 1400mm. I find there can be slight movement blur under 100.. moreso under 1/60.

I would try for the fastest shutter speed possible at that magnification. At 1400mm, even the slightest movement will cause blur.

The maximum open shutter time you can have before the sky or the Moon will show motion smear depends on your focal length. Longer FL's will require faster shutter speeds since the long lenses magnify everything, including motion.

Here's a decent rule for an APS sensor:
longest shutter speed to avoid motion smear = 60/FL seconds

So for 1400 mm, you need to be faster than about 1/25 sec so you should be OK at 1/30.

You're better off having your exposure a little high (without saturating) because it decreases noise so a little longer is better. But keep your ISO as low as possible for the same reason, I wouldn't go above 400 unless you really have to.

Hope that helps!

Shoot at whatever ISO you need to totally stop the motion blur but take multiple shots and stack them for non destructive noise removal

Pi_314 wrote in post #14915635
Was out shooting the moon yesterday with 1400mm equivalent ISO 100, 1/30. With 1400 mm one can expect the moon to move across my view rather quickly. Should I expect a bit of blur at 1/30 shutter speed? Could I be better off raising the ISO for a faster shutter? I'd test it out but it's cloudy tonight.

Considering that you are shooting something that is in direct sunlight (the moon is, even if you aren't), then you should be basing your exposure on the sunny 16 rule...