3.5 minutes exposure with Omegon Mount Mini Track ?

Started 2 months ago | Questions thread
Lyle Aldridge Senior Member • Posts: 1,101
Re: 3.5 minutes exposure with Omegon Mount Mini Track ?

kurt130 wrote:


planning to get an A7s for star photography. Along with it am planning to also get the Omegon Mount Mini Track. However it is recommended that you have an exposure of (T[min]=100/fl[mm]) as per Mini track review . So with a lens of 28mm, I can have exposure of up to 3.5 minutes (100/28). I have checked the specs of the A7s and the Min Shutter Speed is 30s. Are there cameras out there that can go up to several minutes of exposure... ?

Seems I'm missing something...

Thanks for clarifying...

In case it's not clear from other responses, the "Minimum shutter speed" found in the DPR specifications is the maximum definite duration setting, without using the "bulb" function. What often doesn't appear in the specs is that most cameras with interchangeable lenses also have some kind of "bulb" function that allows user-controlled exposures of longer duration. Generally this requires some kind of remote control, wired, wi-fi, IR, Bluetooth, what have you.

It's pretty important, though, to download and review the manual for the particular model you're considering, because details of the function vary. I've noticed, in particular, that some cameras still have a 2- or 3-minute maximum exposure limitation, and will automatically terminate the bulb exposure when that limit is reached, regardless of how you've set your remote. As swims has already mentioned, there are also Sony cameras (and perhaps others) that apply different in-camera processing to bulb shots than they do to shots of 30 sec and less. 

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