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Old January 21st, 2008, 10:02 PM   #31
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Rich,

I made 3 adapters for mid format and 35mm lenses and for SD and HD cameras, they come in different lens threads,
during the process I have used different diameter diopters ranging from 55m, 67mm and up to 72mm.

I believe 72mm achromat is better suited for cams with bigger lens thread.

The sweet spot of these optical devices are in the central part and diminishes in the rims so if the diameter is increased the sweetspot gets bigger thus a giving you a lot of "usable" area. With the smaller SD cams this is just ok but for HD its not optimum. It works but not well.
This increase in diameter allows for a bigger gg image to be captured by your camcorder relay lens. Also, a 10+ is also better than lesser power for it lessens the overall length of your set up.

I even observed an improved image when i used the bigger diameter diopter on the SD cameras with smaller lens threads.

I have a cinevate diopter BUT i'm using it on a spinning adapter similar to the SG and Redrock. This allows me for a hybrid adapter setup that provides a bigger GG image allowing me to use dual lens format.

As someone working in the advertising industry for a while, I DO AGREE with you that "HD" has been sort of abused, just like "PRO" or "broadcast quality" and so forth.

But i think its in good faith that some companies use this on their achromats for the HD format is less forgiving in showing defects in the frame. What is deemed as an acceptable "slightly soft" in SD becomes unacceptable "blurry" or "out of focus" in an HD shot. Thus the market label for HD became necessary for them.
Personally i would prefer just labeling them according to lens threads. But then again the dominant target market for their product are those from the consumer, prosumer, rich enthusiasts and hobbyist, a smaller segment in the industrial consumer bracket, and a small high end work with small budget. Another segment are those in the indie-student and start ups, wedding category.

With this in mind there was probably a need for them to label it in a semi-consumer product fashion.

The terminology in marketing and packaging that is dominant in this product category are commonly found in the 35mm camera/ handycam users bracket. Quite different when you look at the way, Sinars, Arris, Cinealta, panavision and high end products are sold. High end tend to be less glossy and highly technical and usually they come shipped in plain boxes.



Ted

Last edited by Ted Ramasola; January 21st, 2008 at 11:39 PM. Reason: modified text
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Old January 22nd, 2008, 10:31 AM   #32
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Dennis

A caveat on scratch removal. If there is a penetrating scratch through the optical coating into the glass itself, you will create an astigmatism in the lens if you polish the scratch out.
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Old January 22nd, 2008, 03:23 PM   #33
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Quote:
Originally Posted by Martin Catt View Post
Just a quick note: any good quality metal polish (like Simichrome) can remove the antireflective coating from lenses. Just use a dab on a soft cloth and a lot of elbow grease. We use it to remove damaged AR coatings from instrument lenses without damaging the glass underneath.

Martin.
Beautiful idea Martin. Thank you for sharing. It opens a wide range of possibilities now. :D
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Old January 22nd, 2008, 11:03 PM   #34
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Bob, according to a recent surface tomography scan of my eyes, introducing astigmatism might actually improve personal image quality :-) Good point though.

Ted, you've hit the major issue with regard to the 72mm size. The HD designation has more to do with the fact that when we got into the game, a few folks were selling "SD" achromats as you've described. It's not that the glass could resolve less, but more that the smaller size was an issue on prosumer HD cameras with their larger lenses. No one asks anymore if the unit is OK for HD, or conversely if we have an SD version of the adapter...so really the issue is slightly historic at this point.

We do use various designations (REV2, MC, CINEFUSE) etc. but their value has less to do with marketing, and more to do with identifying what exactly a user purchased. For example, because nearly everything we do has an upgrade path, we can pull up an order history and intelligently answer questions on what (or not) is required to bring a unit to current specs.
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