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Large format Astrophotography
Here is the first step in practicing before hooking up to the the telescope for prime focus imaging.
Next us making adapter to hooking up to telescope itself. If I want full frame coverage will need a lens that throws a huge image circle, but won't further reduce the f-ratio from like 8. Not sure how putting to f/8 objects would add. Not well. Image light already at f/8. So if put another f/8 or f/16 I suspect it will be like shooting at f/24 or f/32. Doable, but painful.
Re: Large format Astrophotography
Whoa!
Steven this is interesting AND Large Format!
Re: Large format Astrophotography
I say "Go For It!"
back in the early 1990s I cobbled together a bracket to mount an old press camera behind a B&L Discoverer spotting scope. Had it set up to project the eyepiece image directly onto the film plane through a shutter with no lens elements.
Guessed at the exposures. Got a few interesting images of the sun rising behind an agricultutal windmill. Got a few of the moon setting behind a different windmill. Interesting I say, but not great. Too much guessing. Never did any real astrophotography with it.
The 8x10 set up is impressive. I really hope to see images from this rig. I would worry about vibration as the telescope tracks the astro target. My 8x10 2D is shaky even when locked down. . . .and it is in good shape.
I would think that dropping back to 4x5 would help with that as all the parts are lighter and less suseptable to vibration. Even further; I might use a even more rigid camera such as a TravelWide coupled directly behind the telescope.
Best wishes in this. Tells us about it and show us what images you get.
Cheers
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I'm picking up a Celestron C8 next weekend. Plan to try some wide-field images with 4x5 strapped on the back.
Telescope won't even cover my full-frame sensor. Why not just use your LF lenses? What do you want to photograph? I plan to use my 250mm f/5.6 Zeiss, maybe Nikkor 450mm f/9.
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Re: Large format Astrophotography
I love using my 4x5 for astrophotography. Been at it for a couple decades now. I was just out last month with this getting some exposures made!
Re: Large format Astrophotography
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Re: Large format Astrophotography
Quote:
Originally Posted by
Corran
Please share your work!
These are some quickly made 8x10 prints from my darkroom. The film enlarges beautifully corner to corner sharp at 16x20.
Re: Large format Astrophotography
Nice, thanks! I like the one of Rho Ophiuchi especially. I really want to try shooting that area on color. The images I've seen online are fascinating. Perhaps you can share details on lenses - looks like a 90mm f/5.6?
Re: Large format Astrophotography
Corran, I have and use a 90mm f/5.6, 180mm f/5.6, 300mm f/5.6. Please be wary that lens samples vary a lot. It took me many years to find some examples buying, testing, trading to find some that performed well from the center to all the way out in the corners. That corner sharpness and a lack of distortion there was key and important to me. Manufacturing tolerances, lenses are dropped and/or had a hard life before being sold. The lenses can be fabulous for day to day work, landscapes, general use, but stars are an utter torture test of optical performance.
Re: Large format Astrophotography
Long story but small telescopes for amateur / visual use generally don't have a large field of coverage, or a large back focal distance. (Unless you obtain a relatively rare and $$ telescope designed for astrophotography.) Meaning one may need reimaging lenses to bring the image from the telescope focus to the detector, and to expand the image size. This is basically what eyepiece projection does for small format astrophotography, but one would need something much bigger for 4x5. Much care is needed in designing a reimager to match focal ratios, avoid vignetting, etc.
Large format astrophotography with a lens as prime imager and using the telescope to guide, seems like a potential application for those big, fast-ish lenses that have no shutter or no iris and that nobody really knows what to do with. Like the f/4.5 or f/5.6 copy lenses that are always floating around. I don't know how well they perform at infinity. Of course, aerial camera lenses might be a contender.