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Old November 22nd, 2007, 12:38 AM   #1
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Lens recommendations for Brevis?

I'm looking into getting a HV20 and Brevis35 adapter. Since I don't own any lenses yet, is there a prefered mount people like for this combo? Also, if I get primes, are there a group of focal lengths that are a must have?
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Old November 23rd, 2007, 11:44 PM   #2
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- Nikons are popular, particular for their sharpness.
- Canon FD mounts are popular, as well, for their ubiquity as much as anything, which leads to some awesome eBay deals.
- In either case, the three lenses I would start with are: 28mm, 50mm and 85mm. All of them as fast as possible (lower f-stop numbers.)
- From there, I would add a really wide (like and 18mm) and either stronger tele (100mm or greater) or a zoom. Again, always go for as fast as possible because the adapter will eat some of the light, and you're probably trying to open-up as wide as possible for shallow DOF, or else you wouldn't be bothering with the adapter.

With the Brevis, the actual mounts are fairly inexpensive, and fairly easy to change, so you can mix and match if you want. I personally went with the Canon FD mount. I got some perfect mint lenses on eBay, and didn't spend more than $50 on each. An F1.2 50mm is used for 80%+ of all my shots.
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Old November 23rd, 2007, 11:46 PM   #3
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PS. The HV20 and the Brevis are a great match. The HV20's manual controls suck, but basically you set them and then don't touch them, adjusting focus and aperture on your 35mm lenses.
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Old November 25th, 2007, 11:04 AM   #4
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Thanks for the info. I haven't used the HV20 or an adapter before. I'm assuming there isn't any kind of lens conversion factor like using 35mm lenses on a DSLR because the camera is focusing on the image on the GG? So a 50mm stays a 50mm?
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Old November 25th, 2007, 11:12 AM   #5
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It's all a little fuzzy, but you're basically correct. The DOF "look" and the exact crop factor can vary from adapter to adapter, and even from different "diffusers" in the same adapter. But you are correct in that the lens is projecting its image onto a full-size imager.
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Old November 25th, 2007, 11:43 AM   #6
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I have been shooting HV20 with Letus35a for about 8 months now. Learning a bit about the technology. I actually also have a Brevis achromat that I use with a self built spinner.

1. I'm betting that with the Brevis, you will be right at the edge of zoom/focus vignetting capabilities--- meaning that when you try to zoom past the prime lenses vignette, you will have trouble with some of them, focusing. The result is you will have to back off a bit on the zoom, and you may end up with some corner darkness. Can anyone using the Brevis comment on that ?

2. Lens selection: You are correct that a 50 mm lens will project a similar angle of view on the ground glass as it does with the 35mm film. I have mounts for both the Canon and Nikon for my 35a, and have found the Nikons preferable for ease of use.
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Old November 25th, 2007, 12:26 PM   #7
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Quote:
1. I'm betting that with the Brevis, you will be right at the edge of zoom/focus vignetting capabilities--- meaning that when you try to zoom past the prime lenses vignette, you will have trouble with some of them, focusing. The result is you will have to back off a bit on the zoom, and you may end up with some corner darkness. Can anyone using the Brevis comment on that ?
Not for me with the Brevis, the HV20 and a fairly wide compliment of lenses. (18, 28, 50, 85, 100, 35-200 zoom).

Even though the HV20's imager is not centered, I was able to easily frame the diffuser (minus vignette) and focus on it with edge to edge sharpness. The HV20 actually has good close focus ability. Haven't needed a spacer with any lens yet.
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Old November 25th, 2007, 12:55 PM   #8
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Thats great news....

With the 35a, when I add the second Cinevate Achromat, I have plenty of zoom room..... But with the standard 35a achromat, it is very tight.
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Old November 25th, 2007, 01:44 PM   #9
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Chris,
With the HV20? Is the Letus a good bit shallower than the Brevis, thus putting the diffuser closer to the HV20's lens?
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Old November 25th, 2007, 01:56 PM   #10
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Well, of course, I don't have the Brevis, I just bought the achromat from them a year ago to use with my self built spinner. But you do raise an issue.

The diffuser lens in 35a is mounted in a the white plastic insert. Orginally, it was was in place with bits of black tape holding it in a position. At one point while I was cleaning, it slippled back, and I was never sure after that where exactly it should be. I do find that the further away I get that lens from the ground glass, the less chance there is of dust particles on it affecting the image. But I have not tested the moving it back and forward in relation to the tube ends to any extent to see how that affects vignetting.

The tube on the 35a is almost exactly 3 inches. What is length of Brevis ?
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Old November 25th, 2007, 02:07 PM   #11
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I don't have it handy (mine was stolen) but I don't think the distance between the camera lens and the diffuser could be much more than 3 inches.

I don't have to zoom very far at all, though, in order to get a proper image. I assume that with the Letus you're having to zoom in quite a bit to get past the fall-off? (Since the more you have to zoom, the less likely you'll be able to focus at a given distance.)
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Old November 25th, 2007, 02:51 PM   #12
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With a single achromat, its actually at the wide end of the zoom, maybe within the first 25%, and there just isn't a lot of play before losing focus capability.
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