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Strange Results from RH-10 back

 
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dstoenner



Joined: 03 Jun 2016
Posts: 29
Location: North Carolina

PostPosted: Tue Aug 30, 2016 11:01 pm    Post subject: Strange Results from RH-10 back Reply with quote

I had written in the other thread about my lens test to both test the RH-10 back for number and position of exposures as well as compare my 101 Raptar to a newly acquired 101 Ektar. Using XP2 at ISO 100 I took a series of speed/aperature combinations to test shutter and lens clarity. I started at 400/F8 and went to 25/F32. I set up my camera, confirmed focus. Since the sun was to my back I left off my lens hood, mounted my RH-10 pulled the darkslide and took 5 pictures in sequence as fast as I could. When I got back the film I was surprised to find that the first 3 pictures with the 101 Raptar had a strange halo, then on the 50/F22 shoot it completely went away. The edge of the negative doesn't show any darkness. This has always been a great lens and never done this before. I have just recently started using this again but have 3 rolls before this roll without this effect. I have taken another roll after this roll with no bad effects.

Any advice of what caused this.

Here is frame 1




Frame 2



Frame 3



Now here is frame 4 taken in sequence without any of this



I could have thought that this was reflected sun but it seemed to just stop too quickly for how the sun might be moving.

David
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Dan Fromm



Joined: 14 May 2001
Posts: 2008
Location: New Jersey

PostPosted: Wed Aug 31, 2016 2:45 pm    Post subject: Reply with quote

I can't comment on the funny flare or light struck effect, but I can indeed tell you that using 6x7 to look for differences in performance between a 101 Ektar and a 101 Rapter isn't the best idea. This because, according to Richard Knoppow, whoever designed Wollensak's tessar type Raptars erred and produced a design with worse coma than the equivalent tessar type Ektar.

Coma is an off-axis aberration and gets worse farther off-axis. Both lenses were made to cover 2x3 and its in the corners of 2x3 that the Ektar should be better at the same stop. For this reason "testing" with 6x7 is doing the Raptar a favor.
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Henry



Joined: 09 May 2001
Posts: 1555
Location: Allentown, Pennsylvania

PostPosted: Wed Aug 31, 2016 7:46 pm    Post subject: Reply with quote

The first three images are overexposed; probably your shutter speed(s) were too slow, so something may have been hanging up the shutter. By the fourth shot, whatever mechanical impediment caused the overexposures had worked free and you got a beautiful b/w image.

If it were my shutter, I'd give it the Ronsonol soak with lens elements removed. This has always worked well with my Graphex shutters (I have about six), but this method is not without controversy, so YRMV!

With all respect to Dan Fromm, who is undoubtedly one of the, if not the, most knowledgeable lens person on the board, what you see is what you get, and I see a quite respectable image no. 4. I'll accept the "favor" from Raptar (=Optar). But I only shoot 6x7, and I don't own an Ektar! (BTW, the blow-out of the whites in no. 4 might have been reduced a tad by stopping down a half-stop, which is possible as this lens/shutter goes down to f32.)
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dstoenner



Joined: 03 Jun 2016
Posts: 29
Location: North Carolina

PostPosted: Wed Aug 31, 2016 10:31 pm    Post subject: Reply with quote

Dan,

Thanks for the wisdom on the Raptar vs Ektar lens formulations. I only have a 6x7 back for my baby crown. I have a 6x9 for my 45 crown but it is in storage as we are downsizing our house. This comparison may have to wait till I get my 45 out of storage.

Henry,

Some of what is going on in these first 3 pictures is that the lab that is doing the scanning is trying to level the images. Actually, the first 3 are underexposed. Yet the same lens a day later using the same speed/aperture combinations had matching exposures for all 5 sequences. And since the first 3 negatives are about equal density and the F stop was going from 8 to 11 to 16, the shutter speed had to be doing something right.

I am just really baffled by it.

David
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45PSS



Joined: 28 Sep 2001
Posts: 3626
Location: Mid Peninsula, Ca.

PostPosted: Wed Aug 31, 2016 11:32 pm    Post subject: Reply with quote

Quote:
If it were my shutter, I'd give it the Ronsonol soak with lens elements removed.

Worst thing you can do. That's great great grandpa's field tacit to get it going.
Its your equipment, destroy it if you want.
Graphex/Rapax shutter service manual:
http://www.southbristolviews.com/pics/Graphic/manual-pdf/GraphexShutterService.pdf

The 101 is in a #1 shutter. The Graphex #1 shutter assembly instructions are out of sequence in the linked manual, use the assembly sequence for the #2 shutter skipping the steps for parts not used in a # 1 that are used in a #2. Sound complicated and confusing but isn't.

Is it possible there is lens flare from the sun reflecting off a window or other shinny surface?
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Henry



Joined: 09 May 2001
Posts: 1555
Location: Allentown, Pennsylvania

PostPosted: Thu Sep 01, 2016 12:52 am    Post subject: Reply with quote

Haven't destroyed them yet; 30+ years and going strong! The whole idea is to avoid a tear-down of the shutter if you can, as described in the manual. As I cautioned, YRMV; mine have been fine.
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Henry



Joined: 09 May 2001
Posts: 1555
Location: Allentown, Pennsylvania

PostPosted: Thu Sep 01, 2016 12:56 am    Post subject: Reply with quote

dstoenner wrote:

Some of what is going on in these first 3 pictures is that the lab that is doing the scanning is trying to level the images. Actually, the first 3 are underexposed.

David


To me, a thin positive means a dense negative, which means overexposed.
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45PSS



Joined: 28 Sep 2001
Posts: 3626
Location: Mid Peninsula, Ca.

PostPosted: Thu Sep 01, 2016 3:48 am    Post subject: Reply with quote

I'll go with the underexposed based on the shadow area in the walkway.

While many degreasers contain Naphtha, the main ingredient in Lighter fluid, soaking in it only loosens the gunk. The dried lube contains lots of microfine
metal particles and soaking without a tear down only redistributes the metal particles throughout the shutter perpetuating total non repairable failure at some point in the future.

You can treat your equipment as you choose but new to the cameras need to know what the risks are rather than being left to the school of hard knocks.

P.S. Ilex shutters use hard rubber shutter blades. Naphtha destroys them.
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Henry



Joined: 09 May 2001
Posts: 1555
Location: Allentown, Pennsylvania

PostPosted: Thu Sep 01, 2016 11:45 am    Post subject: Reply with quote

I used the word "soak" and that's wrong on my part. To clarify: I squirt the Ronsonol (naphtha) into the works, then exercise the moving parts. The Ronsonol is very fugitive and evaporates within one-two minutes. My shutters are only Wollies. I have no experience with any other brands. With these qualifiers, and the success record I've had, I stand by what I said. But there's no resolution of this debate, so to each his own.
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45PSS



Joined: 28 Sep 2001
Posts: 3626
Location: Mid Peninsula, Ca.

PostPosted: Fri Sep 02, 2016 12:50 am    Post subject: Reply with quote

Quote:
But there's no resolution of this debate, so to each his own.

Poor/Bad Advice is Poor/Bad advice.
It does not matter who post it or the subject being discussed.
Your technique falls into this category.
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