Archived posting to the Leica Users Group, 2006/11/04

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Subject: [Leica] Re:M8 DNG vs DMR DNG
From: firkin at ncable.net.au (Alastair Firkin)
Date: Sat Nov 4 12:58:51 2006
References: <002401c6ffa0$c79fb2a0$6501a8c0@asus930> <001301c6ffab$ab4e1730$a302a8c0@ted> <454BEB21.4030805@mcclary.net> <000f01c6ffb6$4c719240$a302a8c0@ted> <454C0180.4060200@waltjohnson.com> <668FDF07-1E8E-4160-9E83-B6E0F3B195E8@ncable.net.au> <454CA504.4080501@waltjohnson.com> <454CB890.4090807@mcclary.net> <6BCCA260-D62E-4B7B-B62D-EF465523D34F@comcast.net>

I have noticed a "convert to DNG" function in Lightroom: If I convert  
my scanned tiff files to DNG I gain 30 megs over the 130meg tiff  
file: do I "lose" anything?

On 05/11/2006, at 3:31, Leonard Taupier wrote:

> Elegantly put, Harrison.
>
> Now to address Walts scanning comments. We both use the same  
> scanner and shoot the same color film. I have always scanned to  
> tiff on both color slides and bw negatives. I have recently  
> experimented with scanning Velvia to jpg. I can't find any  
> difference at all in the printed output of either file. Also when  
> editing I always save as a level 12 jpg unless I'm mailing a file.  
> There is a huge difference in the file sizes. The tiff is 55 MB  
> versus 15 MB for the jpg. Am i missing something?
>
> Len
>
>
> On Nov 4, 2006, at 10:58 AM, Harrison McClary wrote:
>
>> Walt Johnson wrote:
>>> Alastair
>>>
>>> One of the things I've notices on the list is people talking  
>>> about jpgs. I was under the impression they were a  compression  
>>> formula only suitable for some things. Information lost when  
>>> opened, modified and then closed and then reopened. I've always  
>>> scanned and saved as tiffs which to me is a raw (?) file.  Don't  
>>> get me wrong, jpgs are fine for looking at online (computer  
>>> screens) but not whet one wants to print for quality. I've been  
>>> surprised when seeing digital cams using that format to compress  
>>> space and give the impression of vast storage. Wonder how many  
>>> gigs one could squeeze onto a frame of Fuji 50? :-)
>>
>> Walt,
>>
>> If one opens jpg file edits and saves as a jpg some information is  
>> lost, yes.  This all depends on how much compression is used in  
>> the jpg saving.  At level 12 you will see no difference in a tiff  
>> and the jpg that has been saved once.   For most of my clients who  
>> I have to ftp or e-mail files to I usually go as far as a level 8  
>> as that still retains most of the image information but makes  
>> transfer times reasonable.  Even at level 8 I often am  
>> transferring 100 megs of information to people.
>>
>> The key is to not open edit and resave as a jpg.  This is why I  
>> shoot RAW when I am sending a jpg file it is a first generation  
>> jpg so it has not lost much information.
>> I do not know if I explained this very well...I have not had my  
>> coffee yet.
>>
>>
>> -- 
>> Harrison McClary
>> Harrison McClary Photography
>> harrison@mcclary.net
>> http://www.mcclary.net
>> ImageStockSouth - Stock Photography
>> http://www.imagestocksouth.com
>> Tobacco Road: Personal Blog:
>> http://web.mac.com/whmcclary/iWeb/tobacco-road/Blog/Blog.html
>>
>> _______________________________________________
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>
>
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In reply to: Message from hoppyman at bigpond.net.au (G Hopkinson) ([Leica] Re:M8 DNG vs DMR DNG)
Message from tedgrant at shaw.ca (Ted Grant) ([Leica] Re:M8 DNG vs DMR DNG)
Message from harrison at mcclary.net (Harrison McClary) ([Leica] Re:M8 DNG vs DMR DNG)
Message from tedgrant at shaw.ca (Ted Grant) ([Leica] Re:M8 DNG vs DMR DNG)
Message from walt at waltjohnson.com (Walt Johnson) ([Leica] Re:M8 DNG vs DMR DNG)
Message from firkin at ncable.net.au (Alastair Firkin) ([Leica] Re:M8 DNG vs DMR DNG)
Message from walt at waltjohnson.com (Walt Johnson) ([Leica] Re:M8 DNG vs DMR DNG)
Message from harrison at mcclary.net (Harrison McClary) ([Leica] Re:M8 DNG vs DMR DNG)
Message from len-1 at comcast.net (Leonard Taupier) ([Leica] Re:M8 DNG vs DMR DNG)