Messages

331

Lenses / Re: Filter for direct sun photography

« on: September 05, 2011, 08:04:29 AM »

Since having a further look today at few a links you'd provided and noticing a link on Wikipedia that shows the area that will be covered I realised it won't be too dramatic from here with probably only 10% covered. Anyway I'll proceed as planned, no harm seeing how it goes and from time to time I've seen some shots that would be interesting straight into the sun that I wouldn't want to take without a proper filter so I'm sure I'll find some other uses for it.

332

Lenses / Re: Filter for direct sun photography

« on: September 05, 2011, 03:36:38 AM »

Ahh yes I must have looked at the wrong column. Just had a check and the time of greatest eclipse is about 3 hours before sunset for that time of year. That's probably good though because from my location I don't get very good sunsets because of a mountain range that probably covers at least the last half hour of sunset.

333

Lenses / Re: Filter for direct sun photography

« on: September 04, 2011, 10:44:56 PM »

For continuum light solar filters I've tried and recommend those from Thousand Oaks Optical, they even have camera threaded filters. For a 400/2.8 I would recommend purchasing a mylar sheet (or black polymer) and produce a filter yourself for placement in front of the lens.

Thanks for that and all the other tips, I've just e-mailed to get a shipping quote on a 77mm threaded filter, they sound convenient and I don't imagine I'll be buying any big primes in the near future.

I checked your numbers BTW, they are OK. The Sun is only 0.5 deg in diameter. But where do the 5 min come from? The eclipse should start at least 30 min before sunset.

I got that number from http://en.wikipedia.org/wiki/List_of_solar_eclipses_in_the_21st_century although I see now it's the central duration so I'll follow you advice of checking the position the day before for framing so it enters the frame during the sequence. Thanks once again for all the advice, I'm just about to take a better look at the NASA info and I'll be sure to post the results  .

334

Lenses / Re: Filter for direct sun photography

« on: September 04, 2011, 08:13:06 AM »

If you want to photograph the sun directly, try this stuff: http://www.baader-planetarium.com/sofifolie/sofi_start_e.htm

Nice photo and that sounds like a good product, from what I could see it's just a film layer so how did you go about mounting to the front of your lens? I saw their suggestion of rolled cardboard for a telescope but can't see that working too well with the small ridge on an DSLR lens, maybe same idea near the base of the lens hood might be OK? The price versus the large size of the film certainly makes it look like an attractive option to experiment with.

Solar photography is quite a serious affair, something to take with great care and prudence.
The solar filter I have in my Mead LX-200 telescope seems a dark mirror and the manufacturer suggesta to check it very carefully for any small hole in the treatment, since the consequences for eyes and sensors can be dramatic. Follow a very well learned procedure before starting to aim and checking, since a small mistake can be irreparable.

Another impressive piece of work, thanks for the advice on pinholes I see the site lol linked to mentions the importance of that also. Don't worry I'm taking it seriously, reason for my post because I knew I'd get some great tips on things I hadn't thought of .

335

Lenses / Re: Filter for direct sun photography

« on: September 04, 2011, 05:46:10 AM »

Hi Haydn, thanks for the info. Do you know if the B&W ND1000 is still a current product? While having a look around it looked like it may be a better alternative but I got the impression they no longer made them.

I forgot when I posted I had a little app on my droid phone that calculates FOV and it comes up with 2 degrees vertically for that combination. My astronomy / trig is not so good but think at 360 degrees per day which is 1440 minutes it should move 360 / 1440 * 5 = 1.25 degrees which should be OK if I anticipate the direction and get the first shot near the edge, or could go portrait for 3 degrees and crop later. Then again that's not taking into account the size of the sun, so might be something to try in advance once I have a filter.

336

Lenses / Filter for direct sun photography

« on: September 04, 2011, 05:10:04 AM »

In a few months they'll be a partial eclipse visible here in Tasmania and I'd like to take a few snaps of it. I don't want to fork out too much for the excercise so will be using my existing 7D + 70-200 + 2x TC but don't mind buying a filter which I'm sure I'll find other uses for. While I don't want to fry my 7D sensor I'm even less inclined to fry my eyes so after some Googling so far my thoughts are:

Purchase a Hoya NDx400 77mm filter which is a 9 stop / 1/500 filter and shoot at around f/11. I've got no intention of looking through the viewfinder so thought I'd quickly compose and focus in live view so the sensor isn't exposed a long time and then switch back to normal mode, lock the focus and take the shots using an intervalometer for a time lapse sequence. I haven't worked it out properly yet but guess at 640mm effective length the sun will be small enough and won't move enough in the 5 minute period to need me to recompose the shot.

Anyway I just thought I'd post and see if anyone sees any holes in my plan or better filters and/or techniques I can use? One possible thing I could do is 10 mins before starting is focus the lens on something at infinity and lock it, but seem to remember reading that somewhere that apparently large objects in the sky may not require infinity focus, but can't really remember the theory and if it was a reputable source.

337

Software & Accessories / Re: Aperture converting RAW to .jpg?

« on: August 31, 2011, 04:19:43 AM »

Should i format my CF every shoot. As far as i know that just deletes the pics on the card.

It's probably a good idea, as well as deleting the files it gives the directory structure a known starting point and you might have something a bit odd in that area causing your problem that isn't visible. I normally use a format and can't think of any drawbacks to doing it that way, of course after I have a few backup copies of everything

338

Canon General / Re: Panasonic, I love you!!!!!

« on: August 29, 2011, 04:24:38 AM »

Dynamic range is probably a more critical improvement to be made but the sensor technology itself seems to be the limiting factor here.

I was pondering this recently and wonder if it's the sensor or limitations of ADC technology? It's pretty easy to get a 24-bit delta-sigma converter, but they normally take in the order of thousands of samples per second at best. For say 20MP at 8fps you'd need a 160MHz minimum sample rate. Looking at a few manufacturers while some have products that can do that sample rate at 16 bit resolution the ones I took a quick look at only had 20MHz odd analog bandwidth which I imagine would be "OK" but presumably would give some softness around sharp contrasty edges.

I work with embedded electronics but not imaging, so my comments are far from expert, but I thought I'd throw it out there that the current 14-bit sampling is probably pushing the limits of affordable and practical analog converter technology. To "fix" the problem the usual way would be to use an array of ADC converters, but they aren't real cheap at the high-end and draw quite a bit of current. I think it will change over time as they become cheaper and draw less power all the time. At the moment using an array of converters (or more if they already use that idea) probably wouldn't be off the cards for a 1 series camera from a cost / size point of view, but I imagine it might slash battery life by an amount a lot of people wouldn't care for.

339

Canon General / Re: What is a good site besides Canon to install software for an older Canon camera?

« on: August 20, 2011, 03:05:15 AM »

It looks as though Canon stopped updating the software for it before Vista came along, so if the XP version won't install you may be out of luck. Does it get recognised as a storage device OK so you can copy files from it? If so I imagine the XP versions of the software may work under Vista, but you wouldn't have the drivers for camera control and to launch the software automatically but it's certainly worth a try, just remember to try installing as administrator if a default user install won't work.

You could also take a look at installing XP inside a virtual machine if you have an XP CD & license. There are a number of ways to do it and you can install USB drivers in a virtual machine OK. Personally I use a paid-for version of VMWare but another easy free option is Microsoft Virtual PC 2007.

340

Canon General / Re: DIFFERENCE BETWEEN MACRO LENS

« on: August 09, 2011, 08:08:12 AM »

I'd go for the 100mm f/2.8L as well. I was in the same situation and wanted to "play" with macro without too much expense and the IS and focal length lets you get some plausible hand-held shots just being careful with lighting, and of course it works great for the preferred solution of better lighting, a tripod and manual focus. For hand-held you're looking at a few mm DOF at 2.8 which isn't too easy for me at least so the IS and ability to get good light in from a speedlite is great when you invariably need to stop it down a lot.

In reality I decided macro wasn't entirely my thing but I still get great enjoyment from it taking "somewhat macro" shots where my other lenses won't focus near enough. For smaller pets and animals for example it gives great results, and I've also used it to take photos of some cooking and products etc. It's not a bad general 100mm lens either, although focus is a bit slower compared to say a 70-200 f/2.8 so I don't use it a lot as a general lens. But it's a lens I'm sure you'll find lots of uses for either way.

341

Canon General / Re: 580EXII SpeedFlash

« on: August 05, 2011, 11:00:14 PM »

I'd guess a defective flash, being an amateur I commonly pull mine out for a few shots once a week and often don't charge the batteries for months. I guess you've probably thought of this but have you tried different batteries or swapping the batteries between flashes to make sure it's not one or more of those?

It might also be worth checking the battery compartment is clean in case some sort of slightly conductive material has managed to work its way in. I've had leakage in batttery compartments before that has caused problems with replacement batteries.