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Viewing 15 posts - 1 through 15 (of 22 total)
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  • #2611
    chupathingie
    Participant

    The Astrotrac was just punted to the porch by the UPS guy. First impression is it’s solidly built. Very little plastic, not made in china (“Made in the UK”). I was under the impression that it didn’t come with a power supply, which is partly true… it comes with a 12 volt auto plug and cord.

    I ordered the polar alignment scope as well. The illuminator came with batteries, and worked right out of the box. It has a variable illumination switch that ranges from too-dim-to-see to can-see-in-daylight. The “eyepiece” lens is a good 3/4″ in diameter with plenty of eye relief. This looks like it will be very comfortable to use, or as comfortable as doing the limbo while aligning a mount can be.

    Tomorrow the heads from B&H are due, and if the skies cooperate maybe I’ll get to shoot some frames this weekend assuming this blasted flu ever gives up.

    #45527
    ravnostic
    Participant

    Yay! We’ll have to start an astro fark group!

    #45528
    Plamadude30k
    Participant

    Can’t wait to see the results from this, especially since it the next thing on my “Big Ol’ List O’ Camera Stuff To Buy”

    #45529
    chupathingie
    Participant

    Things I’ve discovered thus far:

    The polar scope typically needs to be collimated before the first use; which basically means centering the illuminated reticle in the tube assembly so that the center crosshairs stay centered as the scope is rotated. Not a real big deal, but polar alignment will be inaccurate unless this is done properly. The scope does have adjustment set screws for this, you need a small allen key.

    The reticle in the scope does not match the instruction manual. This is going to be a point of frustration for most, especially for those who have never used a polar scope before. Delta Ursa Minor (the next star up the little dipper’s handle from Polaris) is marked, as well as 51 Cephei, but are not mentioned in the manual; which shows a discontinued reticle with different marks for different stars for alignment.

    The rough alignment from the polar scope is great for short focal length use, but most users’ comments indicate that a drift alignment is necessary for long exposures above 200mm. I’ve seen some impressive examples of 7 minute subs at 500mm; which is phenominal accuracy for an unguided rig (also with an APS-C sensor, so 800mm effective). I’m expecting my max FL to be at 400mm f5.6 (200mm f2.8 with a doubler) so I should be good.

    hmmmm…. I’ve got an old 300D laying around that is just itching to have it’s hi-pass filter removed. That would give me an additional ~2 1/3 stops of HA sensitivity. Gonna have to see who’s published comparisons between it and other cameras modded and unmodded. Since the noise on the 300D limits the usable ISO to 800, I may actually get better results with an unmodded 5DII at 3200-6400.

    #45530
    ravnostic
    Participant

    I’m definitely going to get my old camera body (the one that died in Colorado) resurrected for astro shot.

    Incidently, I didn’t use a reticle and I found I really didn’t need one, even with my focal length. There are 3 ‘prominent’ stars around Polaris, SAO 209, 460, and 75. If you imagine that they are ‘facing’ Polaris in a circle, take 209 (the brightest and between the other two in our ‘circle way of thinking. and head out toward Polaris, making a 125 degree turn when you get there. Then head that new direction twice as far from Polaris as is 209. This should put you within 1/4 degree of ‘true’ north, and worked fine for exposures of up to 4 minutes–even 7, if you play a little looser with the definition of ‘fine’ (I captured the Horsehead at those long exposure settings, though not ‘perfectly’ on the 7—that was a bit of a stretch.)

    #45531
    chupathingie
    Participant

    oooohh… I’d be interested in what the Horsehead shots look like, even if you wound up with trailing. It’s a pretty dim HA target that most astrophotogs will use a modded body or dedicated CCD to capture. Zeta Orionis can easily swamp exposures long enough to capture the emission from the area with a hi-pass filter in place. That was on my list of first-lights when I get the rest of my gear. I’m looking at framing the whole southern Orion complex hoping to get the Horsehead, Flame, M42/43 and the Running Man in one image. I’ve got the Rosette on my list as well, simply because it’s also on the list of HA’s that are normally done with CCD’s or modded DSLR’s. I’d love to find that they are within reach of unmodded gear, but I realize I may just be dreaming.

    #45532
    chupathingie
    Participant

    Sweet….

    Amarillo, TX, United States 02/23/2012 5:51 A.M. Out For Delivery

    And tomorrow night’s skies are supposed to be clear, however wind may be an issue. We’ll see, I may get lucky and be able to set up on the rim of Palo Duro Canyon Friday night and run off some frames.

    #45533
    ravnostic
    Participant

    Well…you can make out the Horsehead, and if I’d taken more shots for stacking it would be better–but there’s a reason I haven’t posted it–it’s not that impressive. Somehow I’ve lost the 7 minute shot (I might have deleted it; trails were more evident though it WAS brighter.) This is the 4 minute. I think I can tighten up on these. And if I go f/2, modified for the H bands–maybe a ‘whoa’ could happen–the beauty of the wider field of view would allow for longer exposures without evident trailing.

    #45534
    chupathingie
    Participant

    That actually tells me a lot… especially that it’s easily within range of an unmodded DSLR shooting at f5.6, since you caught this much in 4 mins at f10.

    #45535
    ravnostic
    Participant

    f/6.3–I’m using the reducer lens. While my camera body kicks it back up to 2800 via sensor size, I think I keep the 6.3, no?

    #45536
    chupathingie
    Participant

    Yes, you are correct (I’d forgotten about the FR you have).

    On a side note, UPS just dropped off my box from B&H. HFSMAN! A 405 geared head is HUGE! Much bigger than it looks in the catalog! LOL!

    #45537
    ravnostic
    Participant

    Yay! Astro pikchurs shall ensue soon!

    #45538
    orionid
    Participant

    I feel like the kid who always gets picked last for kickball…..

    #45539
    Farktographer
    Participant

    I feel like the kid who always gets picked last for kickball…..

    I feel like the one that’s stuck on the sidelines for fear of an asthma attack. I know I won’t be getting one of these awesome rigs in a long time 😳 🙁

    #45540
    ravnostic
    Participant

    Orionid–I was the kid who got picked last for kickball (and every other team sport throughout his entire scholastic career–which is exactly why I don’t follow any pro sports and instead enjoy sports that are about individual merit like the X-Games or (traditional) Olympics).

    I’m long overdue. YMMV.

Viewing 15 posts - 1 through 15 (of 22 total)
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