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Schneider 35XL on IQ180 with Cambo & CF

tashley

Subscriber Member
Well, I reprieved my 35XL having been told that using a CF would make it useable for my needs and, now it has arrived, I took the opportunity of time and weather today to test it.

As is always the case with these things, I got inconsistent results and will have to go back and check my methodology. In particular, in one 9 stitcher, there must have been some camera movement though I can't see how, because stuff just didn't line up well. Then in two three frame horizontal stitches (12 left, centre, 12 right) I seemed to get better correction on the right in one attempt and on the left in the other.

I also got some really weird white balance effects, despite setting everything to daylight and double checking in post. in the nine-stitcher, the centre frame LCC had a green bias, the four corners had a blue bias, and the centre rise and fall frames had a more neutral look. There was no procedural mistake here either, so this was really odd.

Speed is of course vital and I am now going to go to a process of shooting the 'real frames first, in quick succession so that the light doesn't change, followed by doing the LCC frames.

But the good news AFAIAC is that the thing I most want, reasonably well corrected rise, seems possible. The following two shots are:

first, no movements, CF, LCC applied but light falloff correction reduced to 50%. Then, exactly the same but with 10mm rise.

I would be interested if those with very good colour vision have an opinion!



 

vieri

Well-known member
Tim,

how are you? Good to see you are giving another chance to your 35, definitely with all these optics in general the CF helps IMHO. About your question: in my opinion, and without assuming that my eyes are particularly special in any way :D I can say this, in both images there is a distinct green cast on the castle (reflection of the grass field, perhaps?) and it seems to me that vignetting has been overcompensated of about 1/2 (above) to 3/4 of a stop (below).

Being really picky, there might be a very slight magenta cast in the sky frame left, both images, and less so on frame right (like a very minor shift has been applied, if you see what I mean).

Does this help any? :D
 

Paul2660

Well-known member
Tim,

Love the perspective on the shot. I see just a bit of Magenta on the left side. Nothing that would not clean up with just a tad of Viveza by (Nik) or a simlar photoshop plugin.

Glad to see the CF made a difference.

Paul Caldwell
 

Guy Mancuso

Administrator, Instructor
Tim when I was with Doug testing the 35XL with the 180mm it was before the new C1 Analyze Tech wide was made and frankly it was pretty unusable. Now having said that after testing the new SK 28XL on my IQ 160 I have to give a ton of credit to Phase of the new tech wide tool as it is cleaning up the magenta cast I am picking up. Now I say this but we are still dealing with a IQ 180 which is like mixing water and oil with the 35XL. Honestly you maybe on to something here with the CF and the new tech tool but I think your stretching it a bit. My gut feeling is about a 7mm worth a rise/fall and once you figure that out what number works than that same number will apply to a vertical stitch since you are going in the same direction within the image circle . No need to test both and no need to do a 3 shot stitch. 2 will be fine as plenty of overlap. Start just by going out at 3mm, 6mm, 9mm rise on the camera with the CF and a good LCC shot. Figure where it falls apart stick some building in a upper corner to see where the smearing starts and the magenta cast cannot be corrected. I got the 28mm XL all the way to 15mm rise but I think the safe zone is 12mm BUT I would never have gotten their without the CF in place and also the new tech cam analyze tool in C1 otherwise I would have went with the Rodie. So take this test one step at a time figure out where the crap hits the fan on rise than you will know what you can do with the stitch end.

Now BTW on the 28mm the light fall at 100 percent was too much correction so I backed it off to 75 percent. This is also something you may try but you obviously have to keep the color correction on.
 

dchew

Well-known member
LCC applied but light falloff correction reduced to 50%.
Wow. I wonder what it looks like with light falloff at 0%! I agree with everyone else; still looks over-compensated. Almost like the LCC is applying it even though the CF already eliminated most or all of it.

Could it be the CF over-compensates on its own when combined with the 180? But I would think the LCC would see and correct for a "negative" falloff, no?

Certainly much improved though. Looks like it would be usable in less challenging situations.

Dave
 

LonnaTucker

Member
Now BTW on the 28mm the light fall at 100 percent was too much correction so I backed it off to 75 percent. This is also something you may try but you obviously have to keep the color correction on.
The C1 fall-off correction is aggressive, I'm usually dialing it back to 50% or below, but I prefer some fall-off, especially in skies. The Schneider 28mm Super Digitar has a very nice effect if not corrected all the way. (Good choice Guy!)

Tim, your test results are surprisingly good - and for general landscape work, I find it acceptable enough knowing you might need to brush in some color correction at times. A better test might be to photograph a neutral gray building or wall to see the actual color cast. Still, your results with the 35XL Digitar are promising from what was earlier stated as a lens that wouldn't work with the IQ180. A friend of mine in England is using the Switar 36mm with the IQ180, but his lovely style is dark, moody and he desaturates his landscapes a bit.
 

Guy Mancuso

Administrator, Instructor
Yes Lonna 75 percent just to get it to a balance across the frame but like you I also like to darken the corners so than I will usually do that with the vignette tool to taste. Yes really like the 28mm so far.
 

tashley

Subscriber Member
Thanks for all the input and suggestions guys... but I have to admit to being mildly mystified.

I also think I see a very slight magenta tinge. I have two 30" monitors side by side. One is an Eizo, the other an Apple Cinema display. Even when the two are freshly calibrated, the Eizo always looks a little magenta and the Apple a little blue. I use the Eizo for proofing, because when I bought it it was supposed to be very accurate and so I put it in the prime position and that's where it has stayed even though I suspect it is some way from perfect.

So, on the Eizo monitor I think I see a very faint magenta tinge in the sky, more on the left but also a tiny bit on the right. On the Apple monitor, not at all.

So if I take the fully processed TIFF into LR4 and select a dropper in HSL then choose various parts of sky and drag downwards with either saturation or luminance selected, the only changes are to Blue and Aqua. If I then paste the JPEG version from the GetDPI site into LR and do the same thing, I get the same result. I have run an INFO eyedropper over it in Photoshop, I have converted it to CMYK (having first looked at the Gamut warning) and all to no avail: there seems not to be any magenta - and yet we are all seeing it. Adjusting red has no effect either.

So... what is going on? I am stumped!

@Vieri - hello buddy, nice to see you! That tower is partly reflecting the grass and partly it has yellow lichens on it... but it is mainly a 'shade of yellow that we all call green' that you are seeing: like grass!
 

yaya

Active member
Hi Tim, try to open the same image on both screens and then switch between them

If there's a cast on the image it will show on both. If the Eizo shows cast on One side, flip the image 180º and see if the cast moves to the other side

CMYK is irrelevant unless you know exactly which engine is used, what rendering intent and into what profile your are converting the image

Yair
 

tashley

Subscriber Member
I've done all that... I see no magenta on the Apple monitor at all... but most of the posters in this thread do see some magenta: do you? If it IS there, how come I can't find any software that shows it's there? I am, as ever, confused!
 
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cunim

Well-known member
Tim, you were looking for software. A useful tool for analyzing correction issues is NIH Image. Do a search and download the version that is appropriate for your computer. Easy to use and great for the money (free) though its color analysis is very limited. For example, it won't show you discrete profiles for components in an HLS model.

Anyway, a profile taken across the sky shows an intensity change from left to right, present in both corrected an uncorrected images. Blue rises more than red relative to the left value. In other words, the proportional mix of primaries is different from side to side.

Download Image and have fun.
 

tashley

Subscriber Member
Tim, you were looking for software. A useful tool for analyzing correction issues is NIH Image. Do a search and download the version that is appropriate for your computer. Easy to use and great for the money (free) though its color analysis is very limited. For example, it won't show you discrete profiles for components in an HLS model.

Anyway, a profile taken across the sky shows an intensity change from left to right, present in both corrected an uncorrected images. Blue rises more than red relative to the left value. In other words, the proportional mix of primaries is different from side to side.

Download Image and have fun.
Thanks, I will give that a go when I get back to where the file is... Could it be because that side of the sky is closer to the setting sun, I wonder?
 

tashley

Subscriber Member
Posting a few more here for opinions and comments. All IQ180 with SK35 @F11 at ISO 35 and 1/30th shutter on Arca Cube/Gitzo CF. All shot with Centre Filter and individual LCCs. Developed in C1 with Analyse Tech WIde and then 100% light falloff correction, followed by import to LR and -20 Highlight Priority Post Crop Vignetting applied. All WB'd off a card at the start of the sequence.

In the following order:
Unshifted
5 rise
10 rise
5 right
5 left










 

Woody Campbell

Workshop Member
My experience with this lens on an IQ 180 was as follows: the center filter improved the "blue zone of death" problem dramatically but didn't eliminate it. The LCC process eats up DR in the blue/magenta and green portions of the colors space.

This means that the images are not tolerant of further processing. For example I have presets that darken and slightly desaturate blues and brighten yellows and oranges. Under this kind of treatment he edges of the image where LCC has already worked tend to fail, and fail quite visibly. Another similar issue - the long DR of the IQ 180 permits recovering shadow detail making shadows more transparent - in a 35XL images that's been LCCD the edges get grainy before the rest of the image and show what is in effect color channel clipping.

I'm a big fan of the Schneider lenses - they look more "analog" to me than their HR counterparts - but at the wide end I've switched to an HR.
 

tashley

Subscriber Member
Thanks Woody, this is more or less matching my findings though I do think that a really well exposed shot in good conditions that requires little PP can yield acceptable results, even with 10 rise. However, there is as you say no tolerance in the file.

I am curious to see what other people think of the colour renditions in the sky in the above frames and would love to hear any thoughts if anyone has a moment...
 

tashley

Subscriber Member
A few more for any opinions (and so that others interested in how the 35XL performs on the IQ180 have more points of reference). All done with individual LCCs.

Anyone with an opinion about colour shifts please post! Thanks!

First, unshifted at about f11.


Now with 5 rise:


Now at dusk with no shift:
 
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