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Old January 16th, 2008, 06:47 PM   #16
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thanks to all =) i guess ill just have to save up and get the redrock HD one so i dont have any problems. Thanks though! all very informative and helpful, this is why i love this forum!
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Old January 16th, 2008, 09:01 PM   #17
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Loren,

I think the Cinevate achromat for their brevis adapter is the same power and specs with the Red rock, Check out their site because its cheaper than the redrock.
I got my achromat from them. I used it in my DIY adapter.

Ted
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Old January 16th, 2008, 09:49 PM   #18
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That cine city achromat is 7+ diopter.
If you look at the first video here:

http://www.jetsetmodels.info/sample_footage.htm

It was shot using the cine city Achromat. I haven't personally
used this achromat, but, it seems to do a good job.

-Rh

Last edited by Rich Hibner; January 17th, 2008 at 01:29 AM.
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Old January 16th, 2008, 11:22 PM   #19
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Rich,

Are you sure that its a 7+? I personally corresponded with Dennis about his achromat and he said its 10+. Not to mention that i compared it with my 10+ close-ups and its of comparable power.

The distance i measured in my set up from GG to achromat rim in order to achieve a near 35mm image is consistent with a diopter of 10+ power.

Ted
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Old January 17th, 2008, 01:29 AM   #20
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Apologies. I meant Cinecity. I'll edit my post.
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Old January 17th, 2008, 11:35 AM   #21
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Quote:
Originally Posted by Ted Ramasola View Post
Loren,

I think the Cinevate achromat for their brevis adapter is the same power and specs with the Red rock, Check out their site because its cheaper than the redrock.
I got my achromat from them. I used it in my DIY adapter.

Ted
Would that achromat fit on the m2?
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Old January 18th, 2008, 12:31 AM   #22
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It's actually a touch more powerful than the RRM version and would work just fine on an M2. Our optics folks have done an outstanding job with quality control, so the design, surface finish and coatings could be compared with confidence to the Century Optics glass.
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Old January 18th, 2008, 12:45 PM   #23
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Century optics is a 7+ diopter as well.
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Old January 18th, 2008, 11:12 PM   #24
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Rich.

I may be misinformed but I think the Century is only available in 58mm thread diameter as 7+. It was last time I tried to get one.

58mm did work fine for me with a home-build flip adaptor in a 58mm to 72mm step-up ring on Sony Z1 or FX1 and also on the Standard Fujinon for JVC GY-HD100 if it is lcoated as close to the front element of the lens as possible.
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Old January 19th, 2008, 11:47 AM   #25
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Bob, you're right. The 72mm is only 3.5+. But, look at it this way. Wayne Kinney's achromat is 10+ diopter and the size of a 52mm, threaded 72mm and his works fine with HD. I think it's more hype than actual performance when it comes to the 72mm achromats being the best.
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Old January 19th, 2008, 12:11 PM   #26
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Wow, Rich, that's quite a statement. Ask yourself if, as a manufacturer, we would have developed a 72mm achromat at the diopter level we did if it did not absolutely make a difference. On an HV20 with 43mm threads, a 58mm would likely work just fine...but consider this.

1. Most lens manufacturers do not maintain spec. in the outer 10 to 15 % of the glass. Our flip achromat has been specifically engineered to deal with both chromatic and spherical aberation..and 72mm was determined to be the "safe" diameter (not me, but one of our optical engineers!) given the wide variety of cameras in use.

2. The ring is 72mm but the glass cannot be...otherwise you'd have no ring to contain it. Same thing applies to 58mm achromats.

3. Many cameras that our customers use have 72mm or larger filter threads, with offset imagers. I can send you an HD100 grab of a 58mm ring causing physical vignetting (in other words, the ring edge was visible in one side of the image) with that combination.

4. Most users are not comfortable with 18" rigs...meaning a weak/smaller achromat used at those ranges would not work in terms of form factor.

5. Our achromats can be removed (both flip and non-flip) and used as very high quality macro "filters" on the bare camera...either SLR, digital SLR, or video. We've sold a few to folks who were only interested in macro photography. That did not factor into our decision..but is nice to have this option with a faster still lense.

So it's not hype at all. Our achromats are purpose engineered and manufactured for adapter use. They are not surplus or off the shelf optics...and believe me if less expensive 58mm achromats would work as well as our 72mm versions, we'd be using them.
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Old January 19th, 2008, 12:47 PM   #27
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Rich.


Dennis has a point. When I mounted up the 58mm to the JVC HD100 it was sitting inside the antireflection cone right in front of the front element of the Fujinon standard lens and could not have been gotten much closer without the risk of clashing glass or anodised metal on glass.

When I conducted this test it was in haste during a visit to the camera owner. I did not set this camera viewfinder to underscan so I cannot assert that it does not vignette except to suggest it did not for the TV safe area.

The diameter of the front element of camcorder lenses is not necessarily linked to the filter thread mount diameter and for a universal appliance, as Dennis suggests, you had better cater for the worst scenario. The JVC HD100 Standard Fujinon actually has a fixed 82mm diameter thread mount. The front element diameter is smaller. Better safe than sorry with the wider diameter achromat. When you want that last few percent to nearer perfection as you can get it helps to shoot through the centre of wider glass.

Last edited by Bob Hart; January 19th, 2008 at 12:54 PM. Reason: error
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Old January 20th, 2008, 11:05 PM   #28
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This is another relative debate. How about this. Take cinevate's achromat and put it on a SG Pro, vice versa. See if the performance is the same. It probably depends on the adapter. Sg pro has and still holds some of the best sharpness in HD footage to date in the grand ole 35mm adapter shoot out. So, when I make the statement the the whole 72mm is more hype than performance, I say that because Sg pro's footage is performance using 52(possibly 58mm). I can't make claims if Wayne will start using an actual 72mm achromat, but for a product who doesn't use a achromat like cinevate's there's no reason for someone to have to buy one, when the performance and quality is fine with an achromat at 52(possibly 58). I don't know your optical engineer's. To me when I see "72mm", it reminds me of someone trying to market something that isn't necessary. Like the acronym HD. Everything is assigned an HD name tag so people will think you're getting something extraordinary. Common, try our HD Capn' Crunch, or our HD microwave oven, or how about our new and improved HD running shoes.
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Old January 21st, 2008, 07:01 PM   #29
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Quote:
Originally Posted by Mike Oveson View Post
Just a thought on cheaper achromats. I've been off the adapter scene for a long time, but when I made a few I often used the achromats out of binoculars. You can get a good pair of binocs with a 10x or 12x magnification for $50. Only problem is that most of the lenses are coated with either a red or green tint and it messes with the colors. If you can find non-coated optics it's not a bad way to go. Is it the best way? No, obviously you can find even better quality glass. But it's a good place to start, especially if you don't have a lot to spend.
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.
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Old January 21st, 2008, 08:15 PM   #30
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Martin, this is a good tip for those lenses that get coatings damaged by light abrasion etc. It never occured to me to just finish the job with the polish technique ... and achieve a usable lens out of the deal :-)
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