Photographing Neowise with 600mm lens

Started 3 months ago | Questions thread
PHXAZCRAIG
PHXAZCRAIG Forum Pro • Posts: 16,748
Re: Photographing Neowise with 600mm lens

W5JCK wrote:

PHXAZCRAIG wrote:

I've been shooting 500mm and 700mm the last three nights.

Total newbie at this astro stuff. I have a new 500F5.6 prime, and an old 1.4TC, so I've been trying that from my porch.

If you are shooting with f/8 and using a 1.4x teleconverter, Then that adds another stop meaning you are actually shooting at f/11. Way to small of an aperture.

No, I'm shooting a 1.4tc on a 500F5.6 lens, giving me a starting point of F8.

You should probably be using a 200 to 400 rule, which means 0.3 sec to 0.6 sec shutter. To get a view of the tail you are having to use 4 sec, which causes long tails and high noise.

Exactly.   Through trial and error, I'm finding 1 second too fast, so max shutter speed needs to be in the range you state.   Which at F8-F9 leaves me in ISO values so high I have a soup of noise.

Bottom line is this: To get decent photos you need to use a much shorter FL lens which is much faster.

I agree with the faster part.   But if I had a 500f4 or 600f4, I'd be using that with a lot less problems.

Or you need to track. Right now you are at GIGO (Garbage In, Garbage Out).

Yes, when I posted my best shot and it's bad, it's definitely a problem of starting with near-impossible conditions.

Sorry, but there is no better way to say it politely. Your setup will never produce good results under these conditions. Switch lenses and toss the teleconverter and you will see a huge difference. Trying to compensate by increasing shutter length and ISO isn’t a good solution.

I started without the TC.   Ended up with a huge crop.

Another possibility not mentioned is that I could drive to a better location with darker skies, though I suspect it might only buy me a stop.    Currently I'm just standing on my balcony looking northwest from the edge of Phoenix.   I'm using these nights to learn what to do to shoot this comet, or at least a bunch of things not to do.   For instance, I re-learned the important of remote release, coupled with mirror-up and electronic first curtain shutter.   I also am learning that when a car drives by, I might be picking up vibration in the balcony that shows up at 700mm, so it's possible I could get  a slightly more stable platform.

I've also inquired as to a star tracker, but they seem too expensive for a one-off like this.  I have a relative who was into this stuff, but he only has mounts for his Canon on his telescopes.

___
Phoenix Arizona Craig
www.cjcphoto.net
"In theory, practice and theory are the same. In practice, they're not."

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