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  #81  
Old 04-07-2010, 05:54 PM
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troypiggo (Troy)
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Quote:
Originally Posted by sejanus View Post
...
Given how utterly incompetent canons repair area can be, chances are it'll be returned in about the same amount of time.
Sorry to get off-topic, but I don't understand this comment. Based on my experiences, I'd give Canon service full marks. I thought they were very professional, prompt return, and the fee was reasonable.
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  #82  
Old 05-07-2010, 08:35 AM
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sejanus (Gavin)
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lucky you. I've had the opposite. Pretty much every pro photog I know shares that sentiment as well - maybe it's related to sydney.
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  #83  
Old 05-07-2010, 08:48 AM
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Barry, D-D ship from their Sydney location, so their prices INCLUDE the GST. DWI ship from Hong Kong so their price does not include GST, but YOU will be charged the GST by Aust Customs when it arrives, so remember to add it to your estimates.

I've bought a reasonable amount of kit from D-D and so far they've been great. One time I ordered at 9am online, and picked the stuff (70-200L plus 1.4x conv) at 10:30am as they had them in stock. Another time I ordered online at 4pm on a Friday, and picked the stuff (17-55 f2.8IS, 580EXII, + accessories)up at 10am on the Saturday. The only thing not in stock was a cheap cable.
Each time I've ordered I've received a phone call in short order telling me of what is in stock and ready to pick up.

Cheers,
Jason.
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  #84  
Old 05-07-2010, 07:59 PM
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Thanks again guys. I tell you what, you have to be quick around here. The prices jumped up again within two days of when I last looked.
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  #85  
Old 16-07-2010, 07:07 PM
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I have been doing some more reading and I have come across a plausible reason for doing separate bias frames... if you take bias frames then you can scale dark frames and reuse them for different length exposures at the same temperature. As H says, this is not essential, but it can potentially reduce the time spent taking dark frames in some situations.

Cheers,
Rick.

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Originally Posted by Octane View Post
Rick,

The bias is included in the darks and therefore when subtracting darks from lights, the bias is removed automatically.

H
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  #86  
Old 16-07-2010, 07:49 PM
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Octane (Humayun)
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Rick,

My whole argument revolves around the point that making dark frame libraries for a DSLR is simply not worth it. Your dark frames will be affected by the slightest change in temperature. Here's an example for you; start shooting a bunch of 5-minute dark frames, about 1 hour prior to sunrise, and let them go through to 1 hour after sunrise. Load all the files in Windows Explorer and observe their file sizes. The file sizes will get bigger, and bigger. This also happens when shooting your objects in the middle of the night; each dark frame's size will be different to the last.

Unless you are capable of building a cooling mod for your camera which will guarantee your ambient down to sub-degree level (noise doubles for every six-degree shift in temperature), it's simply not worth it.

Cooled CCDs excel in this regard in that they can be very, very closely regulated, and, therefore is quite OK to build dark frame libraries with them.

This is just my opinion, and is what has worked for me. It all boils down to how exact you want to be. I'm a perfectionist in this regard and couldn't see myself using dark frame libraries.

H
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  #87  
Old 16-07-2010, 08:26 PM
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H,

I'm happy to agree with you that a dark frame library is of limited use with a non temperature controlled camera. However, I can see that there could be value in taking bias frames independently of darks if you have temperature control.

Cheers,
Rick.
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  #88  
Old 16-07-2010, 09:42 PM
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Dudes, not that I don't appreciate the sharing of some very good knowledge here, but if someone is looking for info on dark and bias libraries, they will not be looking for it under the topic of widest and fastest lens without curvature.

I try to start topics to help myself, with headings that are searchable and helpful for others looking for similar information. A few of my threads have branched off lately.

Again, I appreciate the info and effort guys. I'm just sayin' is all.....

Baz.
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  #89  
Old 17-07-2010, 02:21 AM
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Octane (Humayun)
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Sorry. I'll refrain from commenting further.

H
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  #90  
Old 23-07-2010, 01:30 PM
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Quote:
Originally Posted by Octane View Post
Sorry. I'll refrain from commenting further.

H
O gee, I hope I haven't upset you mate! Please, comment! Comment! You have so much good and sensible advice to share!

I just wanted to keep it on topic is all. I wasn't intending to come across as rude.

Baz.
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  #91  
Old 23-07-2010, 07:16 PM
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One cheap option to consider and I will be able to provide a review shortly to help, is Pentax 67 lenses and a Pentax 67 lens to Canon EOS adapter.

These lens are older but from what I can gather are superb astrophotography performers and nothing like the prices for these L series Canon etc.

They cover a 6 x 7cm film and have a backfocus of 85mm compared to something like 46mm for EF style lenses on APS sized sensors.

So it will not vignette your 5D and hopefully is super sharp.

Here is a site that reviews each of these lenses and rates them to help tell the good ones from the not so good.

I have ordered a 165mm F2.8, 300mm F4. I am trying to pick up a narrow focus lens for super widefield. All are quite "cheap" (less than a Nagler).

http://www.antiquecameras.net/pentax6x7lenses.html

I did a post on the equipment forum giving examples for these lenses using CCD cameras which is my intended use but it seems they can also be used on an EOS Canon or Nikon with an adapter that costs about AUD$60 or so.

There are quite a few examples on the net of these lenses being used for astrophotography.

The 300 F4 67 EDIF lens seems one of the best but I have not been able to find one for sale. I foound a 400mm but it was US$3650.
You'd get a Tak scope before you'd get a lens like that but I imagine the 300mm ED may go for US$1500 or less. They are getting older now.

Greg.
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