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About jacksdad

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    Salisbury, UK
  1. jacksdad

    Can anyone explain this wiring diagram?

    While it's a simple circuit, it might be a bit too simple really... I'm assuming the component U1 is a linear voltage regulator, something like an LM317, and these aren't the most stable of devices... Also, by just cutting the voltage you reduce torque along with speed on a small DC motor, which makes it much easier to stall, which also affects the stability of the drive speed. A much better bet would be a cheap PWM - about a quid off Aliexpress. Because of the way a PWM regulates the voltage it exhibits better stability and less loss of torque.
  2. jacksdad

    Yet another "which dslr camera?"

    Well, I rethinked... Decided on a 600d as a 'new' daily camera because there's lots it'll do better than either of the two in the OP. Now I've decided also to save my pocket money up again and get a cheap 1100d body later in the year as well and dedicate it to astro use, I can strip out the filter myself easily enough and not have to bother about focus issues as it'll be purely live view usage. I don't think I'll be missing out on much, starting imaging on warm, short, light nights will probably only frustrate me anyway...
  3. The only bit I can really comment on is the power supply question. A car battery charger is definitely a bad idea - the modern smart chargers might not supply anything unless they get feedback from a battery, so they're out. The old type (straight rectified transformer type with or without current control) are also no good - the ocv (open circuit voltage) can be as high as 22V+ on 'fast' chargers, which is highly likely to cause electronic arguments and very sad magic pixies almost instantly... They rely on a load to somewhat regulate the voltage. Even trickle chargers can be 14-15V which is right on the spec limit of most equipment (astro or otherwise). Any specific power tank of the appropriate voltage (6 or more likely 12) will be fine though, or a car battery - or a decent quality FULLY REGULATED mains power supply. The dedicated power tanks have the bonus of extra features (torches, red light, correct connectors) but a portable jump start unit (not the plug in type) is almost the same, but you'll need to make or source leads etc.
  4. jacksdad

    Messing about with spare parts

    The moon is out, so... 400mm telephoto lens came out too Not a huge magnification due to focal length, but with the 'rifle' grip it means it's steady enough for wandering about.
  5. jacksdad

    450D modded worth it?

    Your sensor is more likely to die of old age before your shutter fails... Spec might be 200k, but some fail sooner, some achieve well over double that figure. Even taking half that into account as a bad-case scenario (say 100k), that's approx 10 years worth from your figures. Buy a used camera with 50k clicks on - you've got "5 years left". What are the chances of wanting an upgrade sooner than that? Is shutter count really worth losing sleep over?
  6. jacksdad

    450D modded worth it?

    I'm not so sure shutter count is anything to really be concerned about... In the old days, when I used a film camera, I must have pressed that button many many thousands of times - never had a shutter fail. The mechanics of a dslr are no different to those in a fslr. I've been looking into it myself recently, and that conclusion is what I've drawn. Have a look around the photography forums - some dslrs die after 5,000 clicks, some others of the same model still work after 250,000. If it works now, the chances of failure are really pretty equal on a unit with 1,200 clicks as one with 120,000. What can actually make a difference is type of use - a dslr that's astro modded is likely to have been used for long exposures, which creates heat, and heat kills electronics. 20k 5 minute clicks is probably worse than 100k daily use clicks - but that's from a sensor/cpu perspective, not the shutter itself. But, even then it's not exactly like a 90% lifetime shortening situation... I await flames and arguments
  7. I had a play this morning with some bits I had laying about... Ingredients: 1 absolutely terrible 3x barlow (plastic) 1 old m42 macro tube Superglue Method: Attack the barlow with a hacksaw, a stanley knife and a file (childish maniacal giggling optional). Glue into macro tube. Result: Yeah, doesn't look like much... Add another macro tube (whichever length required), an eyepiece and a camera lens though... Works with any m42 lens, or anything I have that I can adapt to m42 (such as T2 mount). Well, I thought it was worth the time anyway
  8. Is your laser collimator itself correctly adjusted?
  9. jacksdad

    Hi folks....bit of a stuttered start

    Eye relief is the distance you need your eye from the glass to see the image properly. Somewhat a matter of preference as to whether long or short suits you best...
  10. jacksdad

    Yet another "which dslr camera?"

    I know they can be used as-is (which if I'm honest is what'll happen), but does one have something inherent that makes it that bit better? My 350d (or pentax k100d) can be used (although lack of live view combined with mirror flip is a pain) and if it weren't for those two things I'd carry on with that. I don't want modded because it makes general use hassle (the 350 might get it's glass ripped out, and I have a compact I defiltered for playing with). Edit to add: the 3rd party modding takes it well out of budget right now, but I'd consider replacing the filter myself in future... Either would be a big step up in function from the 350, but which has the larger step? If it were just general use I'd go for the 500 (higher res, better video)...
  11. Right, so I've been looking for a 'new' (to me) dslr, to use for general photography and astro. It'll get used for general stuff more, but astro capability is important. Canon only really - I like them... I think I've got it down to between the 1100d and the 500d which I believe are the best around budget - budget is roughly £100ish (which can be body only). I'd be happy enough with either for general purpose, but if one outshines the other in astro then that'd be the decision maker. The 500d is slightly higher resolution (still and video), but the 1100d seems to have a good astro rep. So: 500d 1100d A better choice around the same price?
  12. jacksdad

    AE Zoom EP - 7 to 21mm

    PM on the way
  13. Received diagonal from @CraigT82 - much appreciated.
  14. That'd be brilliant, thanks. PM on the way.
  15. It's as aligned as possible without removing and reattaching it, and I have nothing suitable on hand right now - so rather than take it off and risk damage I'd rather it stay there for a few days until I dig out sticky stuff. It's not a bad view as it is to be fair, I'm just being deliberately picky - there's symmetrical aberrations right on the edge of field (ep might be slightly too wide angled for it) and it's just not as pinpoint sharp as the 150 PL or skymax 102...

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