Phocus to Lightroom, TIFF versus DNG

[Chris Schiller]

With my recent acquisition of a Hasselblad H3D, I found myself in search of a new workflow.  I've read the recent discussion about the best workflow when starting with the 3FR Hasselblad files.  I am another user who is not at all satisfied with Phocus after having used Lightroom, especially the new revision of Lightroom.  This is partially due to the fact that I'm using the PC version of Phocus, which still has many bugs, and only in the last revision (1.01) is it able to produce DNG files.

My previous workflow, before getting the H3D, was to start with film scans or Canon RAW files, go through Lightroom for some initial developing and overall adjustment, and then transition to Photoshop for extensive burning and dodging and adjustment.  Very, very few of my images fit my vision without using Photoshop to a greater or lesser extent.  My work is mainly B&W abstract landscapes.

My impression is that this separates me from many or most H3D users, whom I imagine to be studio photographers.  If everything is well controlled and directed, I imagine, then there is much less need for extensive burning and dodging.  I don't know if this impression is correct or not; it's just an impression.  So I'm assuming that studio photographers have much less of a need for the capabilities of Lighroom and Photoshop, and are therefore satisfied with the capabilities of Phocus.  Given what I do, I am definitely not.  For now, and given my experience, I am going to use Lightroom, and the only question what type of file to start with.

To review for those who aren't familiar with it, Phocus offers 4 things that are not presently integrated into Lightroom:
- Lens distortion correction
- Noise Reduction in shadows
- Chromatic abberation correction (tuned for each lens)
- Vignetting correction (tuned for each lens)

A TIFF file generated by Phocus can contain these corrections, but it is a non-RAW file.  A DNG file generated by Phocus cannot contain these corrections, but IS a RAW file.

I have read and heard that "DNG files generated by Phocus are lower quality than TIFF files generated by Phocus".  I wanted to observe this, and to investigate in what ways Phocus generated DNG files might be worse than TIFF files.

I don't pretend that my testing was exhaustive or is universally conclusive.  I'm reporting here to share what I've found, to see what others may have experienced, and to get comments.  I don't claim to have an understanding of what is going on behind the curtains of Phocus or Lightroom.

Conditions:
Using Phocus 1.0.1b2 on a PC running Windows XP Pro, I generated four files for comparison:
1) DNG file
2) TIFF file generated with only lens corrections turned on (no other modifications)
3) TIFF file generated with all of the above corrections turned on, but no other modifications.
3) TIFF file generated with all Phocus corrections and modifications turned off

I imported the files into Lightroom 2.2 for comparison.  I moved all of the Lightroom controls to neutral so that a direct comparison could be made without modifications applied to either TIFF or DNG.  The image I used was a high contrast picture taken in bright sunlight.  The scene included deep shadows and blown-out highlights.

Here are my conclusions separated into catagories.

Sharpness/Resolution
The TIFF files looked clearly sharper than the DNG when first imported.  The question was whether the TIFF files were higher resolution, or just sharper.  I modified the DNG file using the Lightroom sharpening tools, and found that I could sharpen the DNG to look indistinguishable from the TIFF file in terms of acuity.  Looking at different parts of the image, shadow, highlight background, foreground, I could discern no difference between the TIFF and the slightly sharpened DNG.  Conclusion: the basic "quality" of the images was equal - there was no difference in resolution.

Contrast
The TIFF files were clearly higher contrast than the DNG file, even with all contrast controls in Phocus set to neutral.  Conclusion: I see this as a negative for TIFF files, since automatic changes give less flexibility.

Color
None of the files seemed to have exactly "correct" colors, although the TIFF files were much closer to the "real" colors than the DNG.  With some modification in Lightroom, the DNG file could of course be corrected and brought closer to the "real" colors.  Conclusion: The TIFF files are better as a starting point, but this is just a calibration issue.

Highlights
Highlight recovery in the blown-out highlights using the Lightroom "Recovery" slider was much more effective with the DNG file.  The TIFF files also had a bad color cast in the highlights when the highlight recovery was used strongly.  Conclusion:  The DNG file is much superior for highlight correction.

Shadows
The TIFF files showed lower color noise in the deep shadows than the DNG file.  However, the DNG file shadow color noise seemed easily corrected using Lightroom color noise controls.  

Chromatic Aberration
The TIFF files were clearly superior for correction of chromatic aberration.  Lightroom has chromatic aberration correction capabilities, but correcting the aberration in the DNG file in one part of the image means worsening aberration in another part (I am assuming this is due to lens distortion?).  This is typical of working with raw images from Canon digital cameras.

Lens Distortion
Of course the TIFF files are superior for distortion, and there is no lens distortion correction available (yet) in Lightroom.

File Size
The DNG file was 1/2 the size of the TIFF file before modifications.

Conclusions

The TIFF files were superior in these catagories:
-Lens Distortion
-Chromatic Aberration
-Shadow Color Noise (but correctable in DNG)
-Color (but calibratable in DNG)

The DNG files were superior in these catagories:
-Highlight recovery
-Contrast
-File Size

Using DNG files as a default starting point is the best choice for me.  There is no discernable difference in basic image quality, and the lower contrast and recoverable highlights have huge advantages for me.  The smaller file size is not an overwhelming factor, but it is a factor.

The lens distortion correction would be nice, but it's something every photographer has accepted until now, and the differences shown in the files, at least for the one lens, are not all that significant.  The chromatic aberration is more significant, but most of the work I do is in B&W, where the abberation doesn't result in a significant problem.   Similarly, the shadow noise and initial color are less important because of my immediate conversion to B&W.  For specific images or color images where these corrections might be more important, there is always the choice of starting with a TIFF file.

I look forward to the day when the Hasselblad corrections get incorporated into Lightroom, and then there will be no need for making this choice.

Chris

[digitaldog]

To review for those who aren't familiar with it, Phocus offers 4 things that are not presently integrated into Lightroom:
- Lens distortion correction
- Noise Reduction in shadows
- Chromatic abberation correction (tuned for each lens)
- Vignetting correction (tuned for each lens)

So its doing this to the rendered images (TIFFs) whereby the DNG's really are just the DNG Raw data?

[Chris Schiller]

So its doing this to the rendered images (TIFFs) whereby the DNG's really are just the DNG Raw data?

My understanding is that the answer is yes, although I'm not sure if "just the DNG RAW data" is technically correct.  The files are "converted" from FFF files to DNG files through some process, but I do know that they do not contain the distortion, abberation, and vignetting corrections or the shadow noise reduction.

Chris

[digitaldog]

My understanding is that the answer is yes, although I'm not sure if "just the DNG RAW data" is technically correct.  The files are "converted" from FFF files to DNG files through some process, but I do know that they do not contain the distortion, abberation, and vignetting corrections or the shadow noise reduction.

Chris

But the DNG is a Raw, un-rendered, un-demosic linear data file?

You can save a rendered TIFF as a DNG (the point of doing so is beyond me). Its useful to know if you're comparing apples to apples.

[Chris Schiller]

>But the DNG is a Raw, un-rendered, un-demosic linear data file?

I don't know the answer to these details.  Does anyone know?

>You can save a rendered TIFF as a DNG (the point of doing so is beyond me). Its useful to
>know if you're comparing apples to apples.

Wouldn't the TIFF saved as a DNG still have the same initial deficiencies (uncorrectable highlights, higher contrast) or does Lightroom act on TIFFs differently than DNGs?

And even if the conversion from TIFF to DNG reduced the file size (does it?) it's still yet another step to perform.

Chris

[digitaldog]

Wouldn't the TIFF saved as a DNG still have the same initial deficiencies (uncorrectable highlights, higher contrast) or does Lightroom act on TIFFs differently than DNGs?

It would be no different than the TIFF. You're simply containing the TIFF in the DNG. So is the DNG really a Raw or is the DNG rendered data? It sounds like the DNG is indeed Raw data (that's what I'd expect). So then you're comparing an unbaked Raw file with a processed TIFF from the non LR Product which makes comparisons quite difficult.

[ErikKaffehr]

Hi,

It is my understanding that DNG is quite flexible in that it can contain "raw" or "demosaiced raw" and even embed the actual "raw file". One thing I have seen that DxO a raw converter I would have liked to test would not process my DNGs created by Lightroom, most other raw converters do.

Best regards
Erik

It would be no different than the TIFF. You're simply containing the TIFF in the DNG. So is the DNG really a Raw or is the DNG rendered data? It sounds like the DNG is indeed Raw data (that's what I'd expect). So then you're comparing an unbaked Raw file with a processed TIFF from the non LR Product which makes comparisons quite difficult.

[Carsten W]

Hi,

It is my understanding that DNG is quite flexible in that it can contain "raw" or "demosaiced raw" and even embed the actual "raw file". One thing I have seen that DxO a raw converter I would have liked to test would not process my DNGs created by Lightroom, most other raw converters do.

Best regards
Erik

Yes, the DNG format can contain Bayer data, or other raw formats, or the complete data, or multiple images.

[mazma]

do you guys know if there is anyway to have phocus create DNG automatically. that way i could use LR autoimport and work a solution for a tethered H3DII to LR...
i am struggling with phocus soft previews, and i am converting everything to DNG anyhow.

[jjj]

The lens distortion correction would be nice, but it's something every photographer has accepted until now, and the differences shown in the files, at least for the one lens, are not all that significant.  The chromatic aberration is more significant, but most of the work I do is in B&W, where the abberation doesn't result in a significant problem.   Similarly, the shadow noise and initial color are less important because of my immediate conversion to B&W.  For specific images or color images where these corrections might be more important, there is always the choice of starting with a TIFF file.

If you use the wider angle lenses, then the distortion correction is very important as the software correcting the lens is part of the lenses quality. These lenses were designed with the distortion correction being done by the software and it is very noticable how much better shots are with it.
Now if that wasn' the case then I'd use LR to process the Hasselbad RAW DNG files as I prefer the LR workflow, but the wide lenses need correction, so it's a clumsy place to be.
Though be thankful Phocus now exists as flexcolour is simply appaling to use. It's like using something designed [badly] from the early 90s.

[Dustbak]

I have no problem using eiter Phocus or Flexcolor. If you know what you are doing I find Flexcolor faster and more stable. If shooting multishot in any quantities larger than several Phocus is downright unusable.

I used to convert everything to DNG first as well however have now upped my processing power and altered my workflow to converting to Tiff/JPG first. Pretty rarely I need highlight recovery and in that case I can always revert to making 2 conversions of the same file.

For me the lens corrections in wide-angle is one of the reasons to use Flex/Phocus. The other larger reason is the totally awesome CA removal. This is lightyears ahead of the CA correction tool of ACR.

I find the colors, the details, the CA removal, the correction of geometry in Phocus or Flexcolor far better than ACR.

Conversion to DNG from FFF is fast ,much faster than you can convert from FFF to Tiff. So yes I would say real raw file DNG.

I find FFF/3FR support in Lightroom much more important and I wish I could have it yesterday. I don't particularly mind having to process  it in either Flex or Phocus. Naturally there are several things I would like to see in Phocus, highlight recovery being one of them as well as 'fill light'.

BTW, the only lens that has been designed with distortion correction in software is the HCD28 (and probably the new HCD35-90). The others were not, however they are corrected in software which is a (slightly) different approach.

[jjj]

I have no problem using eiter Phocus or Flexcolor. If you know what you are doing I find Flexcolor faster and more stable. If shooting multishot in any quantities larger than several Phocus is downright unusable.

So are you saying a 3 legged dog is better than a two legged dog?  

[Dustbak]

So are you saying a 3 legged dog is better than a two legged dog?  

Something like that  Comparing these converters to dogs I think I have never seen a non-limping dog.

[Nick-T]

Hi Chris
Thanks for your observations, very interesting. One area you might want to test in more detail is the colour rendering. I have been shooting with Imacon/Hasselblad backs for 9 years now and I can say with confidence that the colour rendering from flexcolour/Phocus is vastly superior to that from a DNG processed in Lightroom or wherever.
Nick-T

[jjj]

Something like that  Comparing these converters to dogs I think I have never seen a non-limping dog.

On a similar note I am currently looking for a new [smart] phone and think I'll be choosing the one that's the least annoying as opposed to the one that is the best. The difficulty is that I'll be stuck with the wretched thing for probably 18months during which time something decent may come out.
The HTC Touch HD is currently top of list, screen is very nice for displaying images - a major use of phone and no obvious annoyances.

[kaimaui]

I have also been looking at work flow for the Hasselblad files.
My problem is that I like to archive my files first then when I have time pick out the files I like.

For me that means bringing the files into Lightroom first.
I do find that Phocus does a better job then Lightroom on the files.

For me that means Having to first import the files to Phocus. Then exporting to DNG for archiving in Lightroom.
Then over time finding the files I like and if necessary going back to Phocus.

I have Started using Raw Photo Processor which seems to do a great job of Hasselblad files to my liking so far better then either Phocus Or ACR / Lightroom.
I am in the process of testing out if it makes a difference if you go from *.fff *.3fr or DNG (converted in Phocus) to tiff using Raw Photo Processor.

The nice thing about Raw Photo Processor is that it integrates with Lightroom quite well.

Having a batch converter from *.3fr to DNG would be great. Going trough Phocus is a pain.

I am going to reinstall flexcolor to see if dng conversion process is any  easier there

Any suggestions would be welcomed.
Thanks
KAI

[jonathan.lipkin]

But the DNG is a Raw, un-rendered, un-demosic linear data file?

You can save a rendered TIFF as a DNG (the point of doing so is beyond me). Its useful to know if you're comparing apples to apples.

Just came across this thread while searching for something else. If it hasn't been covered elsewhere, I'd like to add what I've recently heard from a Hasselblad tech. From what he told me, the DNG rendered out of Phocus is not a 'real' raw file. That is, it is not an 'un-rendered, un-demosic [demosaiced??] linear data file', simply a DNG wrapped around a TIFF.

[David Schneider]

If you use the wider angle lenses, then the distortion correction is very important as the software correcting the lens is part of the lenses quality. These lenses were designed with the distortion correction being done by the software and it is very noticable how much better shots are with it.
Now if that wasn' the case then I'd use LR to process the Hasselbad RAW DNG files as I prefer the LR workflow, but the wide lenses need correction, so it's a clumsy place to be.
Though be thankful Phocus now exists as flexcolour is simply appaling to use. It's like using something designed [badly] from the early 90s.

But LR can correct lens distortion on all Hasselblad lenses, right?  And, if I'm right, the DNG produced by LR will keep that lens distortion correction, whereas the DNG produced by Phocus does not keep it.

[jjj]

But LR can correct lens distortion on all Hasselblad lenses, right?  And, if I'm right, the DNG produced by LR will keep that lens distortion correction, whereas the DNG produced by Phocus does not keep it.

Actually LR could not correct Hassy lenses at time of my earlier post - in 2009! Not sure it could do any lenses at that point, as LR3 may not have been released then.