October 16th, 2004, 08:15 PM | #1096 |
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Steve.
I'm not the resident expert on this subject however my understanding is that if your intended groundglass has already been finished high quality as an optical filter, all you need to do is use the 1500. Weldeing goggles glass replacements may need more thorough finishing. If low (semi-clear) spots become evident in the 1500 work you may need to go back a grade then re-dress with the 1500, otherwise perservere with the 1500 until they are gone. Recommended practice is to move your intended groundglass over a fixed dressing surface. Some people use a sheet of glass. On glass, some problems with pickup or clinging have been reported. This leads to excessive contact pressure which causes scratches and gouges. A machined piece of bronze or brass as a dressing surface yields a good result. Cast iron is used by the industry but I understand it may be a special grade which does not have hard particle inclusions in it. I found ordinary cast iron scratched my glass. Aluminium was also no good. It caused scratches and wore away too quickly which killed the grit slurry. Before you commit your intended groundglass to the process, go along to your nearest pathologist and obtain some microscope slides to practice on. These give you a good feel for it. The feel as you work the glass has a lot to do with the results you get. Keep working on the microscope slides until you can achieve a result without gouges or scratches. It is frustratingly pointless trying to do it any other way. Finally, cleanliness is next to godliness in this process. If you leave the project unattended and you have pets, you can guarantee contamination with dust or house grit in your absence. Your intended groundglass needs to have a chamfered edge on the intended groundglass side otherwise the edge corner will sharpen, flake off then roll under into the slurry and gouge your glass. You will need to do this to your microscope slides. The intended groundglass will already have a chamfer if it was an optical grade product but check it anyway. One of those new little diamond laps for sharpening knives is good for this task. Do it under running water. |
October 18th, 2004, 08:17 AM | #1097 | |
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Quote:
Move your grinding glass over your GG -- in this was you maintain a more even pressure across the GG's surface. It's uneven pressure and dry slurry that cause scratches, and scratches take hours to properly grind out. Properly mixed slurry and care taken will yield a great GG within a half-hour. Be sure to: Pre-mix grit and water to ensure a thorough soaking of the grit. Mix this "paste" with even more water at grinding time (grit to water ratio should be about 1:5, respectively.) Keep your glass on an even surface. Check your GG and grinding glass surfaces for dirt prior to grind. Err on the side of caution when replenishing your slurry -- do it early and often. - jim
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October 19th, 2004, 12:55 PM | #1098 |
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Found an interesting GG. I'm not sure if this has been posted before.
http://www.satinsnowglass.com/index.html Has anyone used one of these before? If so how was it and how much light does it lose? Seems promising at least (and probably well known to medium format shooters) |
October 19th, 2004, 03:54 PM | #1099 |
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Satin Snow glass
Aaron-
Nice find!. They can cut to any size, dont have any gridelines on it, nearly no grain, and did you check out that price?! Just ordered ordered one. I'll post my results. -Brett Erskine |
October 19th, 2004, 03:56 PM | #1100 |
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I think my brain skipped. ;-)
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October 19th, 2004, 04:04 PM | #1101 |
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Yeah same here :D
I was absolutely shocked by the price. Especially after going through lots of other GG pieces on-line and seeing their prices! Looking forward to seeing your results! Actually I was just looking at their website again and it seems they are located in Montana - same state as me. I'm going to contact them and see about going down to have a chat. |
October 20th, 2004, 12:44 AM | #1102 |
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Re: Satin Snow glass
<<<-- Originally posted by Brett Erskine :
Just ordered ordered one. I'll post my results. -Brett Erskine -->>> Please do -- I'm hesitant because they compare it to 125grit GG -- it's little wonder it compares favorably. Apparently micro wax is the way to go for most medium format photgraphers -- the Bosscreen is highly sought -- so I'm going down that path next... - jim
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October 20th, 2004, 02:58 AM | #1103 |
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They quoted me a 3-4 week shipping period. They are going to try and get it to me in 2. Either way it will be a little bit before I can get back to you guys with info. I'll let you know.
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October 20th, 2004, 06:52 AM | #1104 |
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"Sorry to disagree, but this isn't the case, Bob -- you're increasing the likelihood of scratches and the amount of time required to get a uniform surface this way." ----
Which is why I took care to announce I was not the resident expert. Thanks for the correction Jim. One more poor innocent is saved a few hours of useless puersuit down a dead-end. |
October 20th, 2004, 08:42 AM | #1105 |
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None of us are resident experts :D Your contributions have always been helpful.
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November 7th, 2004, 09:06 PM | #1106 |
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Quartz
I am very very new to this but I've been reading for hours for the past few days (I don't really know an F-stop from a stop sign).
This may be out of place in the "static" adaptor post...but its a quite different idea from the spinning CD style. This may seem like a stupid question...but is there anyway that the GG could be made of quartz? I would imagine if you made it out of quartz you could take advantage of the piezoeletric effect and put a small high frequency ac voltage across the GG and then it would oscilate without a whole lot of noise. I realize this raises a whole lot of issues, but the main question is could quartz make an acceptable GG? Matt |
November 9th, 2004, 11:57 PM | #1107 |
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Brett,
Any luck with the SatinSnow GG? |
November 10th, 2004, 05:44 AM | #1108 |
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Satin Snow GG
Its finer grained then anything I've made before...but its not grainless. You will still see grain with this glass. Its better then anything I used but not the perfect solution Im sure everyone is looking for. However it should work great for oscillating adapters.
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November 10th, 2004, 10:08 AM | #1109 |
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Does anyone on this board have a Kit I can buy? I LOVE my 35 adaptor but the build quality is low..I would like to buy a high-quality kit...anyone?
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November 11th, 2004, 03:04 AM | #1110 |
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Brett.
How's the hotspot without condenser (when the satinsnow groundglass is used)? The erecting version has a real issue with polished-back AO5 glass through a 7+ achromatic diopter. |
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