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Fun with MF images - ARCHIVED - FOR VIEWING ONLY

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EH21

Member
David,
The reason why I asked you about the aperture is I have noticed some pentagonal aperture shaped flare or specular flare in your 180/2.8 images. You can see them in both the plant image (coming from the water drops) and the woman shot (light coming through the leaves in the trees). I've noticed on a few occasions these shapes in the flare but its been pretty rare so I've been studying what creates them and how to avoid them. I just did a test on the zeiss 110/2 an found them really only noticeable at f/4 and f/5.6 - they are round and not apparent at wider apertures and too tiny and soft to be noticed at the smaller apertures.

Actually it appears that the flare is better controlled with the schneider lenses in the rollei 6000 system but I think they all have the 5 bladed apertures. From the images posted here in the MF forum quite a few lenses have this including the mamiya and hasselblad images - so not just the rollei but all of the major MF systems. I don't like these and want to avoid them - and it appears by choosing apertures carefully you can. I have never seen these from my 180 but mostly shoot either wide open or at f/11.
 

David K

Workshop Member
This is an area that Son is very familiar with. He's been busy with his graduation and family matters this past week but I'm sure as soon as he's settled he'll be willing to provide some lens suggestions which will avoid the pentagonal shaped flares. I noticed them myself but they don't bother me... in fact, I kind of like them.
 

EH21

Member
David,
No worries, while it wouldn't hurt to have an extra data point, I make an effort to test things out myself so I can both trust and understand the results. I've seen too many 'tests' on the forums where such and such is the best lens ever only to find out that lens happens to be one the tester has for sale.

Yeah in the shot of the Gehry building posted by Atanabe (http://forum.getdpi.com/forum/showpost.php?p=24289&postcount=69)
the big pentagonal shaped flare is kind of cool - so sometimes I like it but most of the time I don't.
 

Stuart Richardson

Active member
I find that if you use the stop-down preview, you can see how the pentagonal aperture will look. I don't have it in front of me, but if I remember correctly, the 180/2.8 does not really get particularly pentagonal until f/5.6. Pretty much all medium format lenses have this issue -- the ones that don't are the 200 series FE lenses. This can lead to problems though. My 110/2 for the 200 series has a recurrent problem where the aperture blades jam. I have heard that many other people have had this problem as well. The problem is that there is very little room in the barrel to hold all the blades, and the complexity of the multi-blade iris along with the rather large lens diameter means that they are prone to jamming. They have a long way to travel too, compared to most other lenses... The 5 bladed irises are more compact and simpler when folded up, so I have a feeling this makes them more reliable.
 

EH21

Member
Stuart,
Thanks for the info on the different lens systems.

I've around a thousand frames with my 180/2.8 and never saw those pentagonal shapes. But I did have one or two frames with those in shots with my 110mm f/2 and I recently did some more controlled testing. Only at f/4 and f/5.6 were these pronounced and obvious. Certainly you still have the flare but at f/2.0 and f/2.8 you get circles which look more natural. I believe the rollei aperture blades are curved too which help with making the shapes more natural. From f/6.8 on down the shape gets smaller and lighter to the point where its difficult to see the outlines. And actually its difficult to get the flare in the first place - you have to shoot with the backlight off the lens axis by 20 or 30 degrees. Not sure you can do much about little shards of light coming from water drops except be aware that they can cause this and use either wide or small apertures if you want to avoid them.


Eric
 

David K

Workshop Member
Graham,
I like that pano as well as the 40mm that you used to take it. That house clearly has a story to tell.
 

mtomalty

New member
Jim

Really like what you are doing with your triple stitch pans using the Aptus and
Horseman.
When you are shifting with the 35mm and Aptus are you running into issues with
varying colorcast across the frames?
I've heard,and seen, that the Dalsa sensors used in the Leaf and Sinar products are
a little less prone to color shift than the Kodak chips used in Phase and Blad and was
wondering if you've had issues matching your three stitched frames in your pans.

I've had a little experience using Leafs Custom Gain feature to remove cast when
using an Aptus22 on a Hasselblad ArcBody and Grandagon 45mm with decent result
but haven't tried to generate multiple image pans.

Thx,
Mark
 

JimCollum

Member
Jim

Really like what you are doing with your triple stitch pans using the Aptus and
Horseman.
When you are shifting with the 35mm and Aptus are you running into issues with
varying colorcast across the frames?
I've heard,and seen, that the Dalsa sensors used in the Leaf and Sinar products are
a little less prone to color shift than the Kodak chips used in Phase and Blad and was
wondering if you've had issues matching your three stitched frames in your pans.

I've had a little experience using Leafs Custom Gain feature to remove cast when
using an Aptus22 on a Hasselblad ArcBody and Grandagon 45mm with decent result
but haven't tried to generate multiple image pans.

Thx,
Mark
i have run into the color shift issue. Leaf Capture has the gain control software built in now. most of my stitches are horizontal, usually centered on the vertical plane.. so i have a single set of gain files that i use left, center,right shifts.
 
T

thsinar

Guest
hi Jim,

one question concerning the gain control built-in: can you apply it to as many files you want, or do you have to apply it file by file?

Also, can you create gain file un-tethered on location and then apply them?

If I understand, you are using some saved gain files which you have shot and saved: do you never have to create a specific gain file for the shot itself, because your pre-shot files don't work well?

Thanks and best regards,
Thierry

i have run into the color shift issue. Leaf Capture has the gain control software built in now. most of my stitches are horizontal, usually centered on the vertical plane.. so i have a single set of gain files that i use left, center,right shifts.
 

JimCollum

Member
hi Jim,

one question concerning the gain control built-in: can you apply it to as many files you want, or do you have to apply it file by file?

Also, can you create gain file un-tethered on location and then apply them?

If I understand, you are using some saved gain files which you have shot and saved: do you never have to create a specific gain file for the shot itself, because your pre-shot files don't work well?

Thanks and best regards,
Thierry
It has a batch capability.. so i load all of the images from each shift into one
then apply the calibration file..it's pretty easy that way

the saved gain files need somewhat specific. .. either tethered or non-tethered. the camera type is different for some reason for each, and the gain calibrator requires them to be from the same camera type.

i have a set i took in general daylight in each of the orientations (top - 3 horiz. shifts, middle 3 horiz shifts, bottom - horiz shifts).

i'd imagine if the light temp were drastically diferent (day,tungsten,flor.) then you might have an issue

Their calibration wizard walks you thru it in a tethered mode (asking you to shoot each gain file as it walks you thru)

jim
 

mtomalty

New member
Thierry

In my relatively limited experience using Leafs Gain Adjustment feature (standalone)
on an Aptus22 I had no issues applying one gain adjustment file to a number of different
shooting sessions providing the same lens and general shooting conditions were
present.
The one funky result was concerning physical dust on the sensor.
If applying a generic correction to multiple files where dust spots were in a different place the resulting file would have some odd 'ghost' dust spots where the calibration
file tried to remove dust that was not actually present resulting in a sort of
'negative' dust spot

Mark

P.S.-Thanks for the info,Jim
 
T

thsinar

Guest
Thanks Mark!

Thierry

Thierry

In my relatively limited experience using Leafs Gain Adjustment feature (standalone)
on an Aptus22 I had no issues applying one gain adjustment file to a number of different
shooting sessions providing the same lens and general shooting conditions were
present.
The one funky result was concerning physical dust on the sensor.
If applying a generic correction to multiple files where dust spots were in a different place the resulting file would have some odd 'ghost' dust spots where the calibration
file tried to remove dust that was not actually present resulting in a sort of
'negative' dust spot

Mark

P.S.-Thanks for the info,Jim
 

Graham Mitchell

New member
Today the centre of Tallinn was invaded by a Finish 'old timer' truck club. Some lovely examples of trucks, but too crowded to take any decent pics. Some of the drivers were characters too:



40mm @f5.6, ISO 50
 
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