http://www.thecinecity.com/product.php?productid=16243&cat=258&page=1
could this possibly be the answer to my prayers for finally being able to afford the redrock? or is it just a cruel joke ment to tease me! lol please tell. thanks =D

The old saying comes into play here.... You get what you pay for!

This lens is not necessarily bad. It is even better if it is glass and not polycarbonate.

I have seen some polycarbonate optical products that have changed shape over time so I am not a huge fan of them.

My main concern is not knowing or being able to read from the website what power dioptre it is. Without this knowing you are really on a guesswork ride to maybe success, maybe a good way of using the sun to light the barbecue if it is not a success.

Rule of thumb :-

Non-flip adaptor 7+ to 10+ with 10+ beginning to introduce edges softness issues in some designs, to keep length of adaptor manageable.

Flip adaptor 3+ to 7+ to allow distance in the optical path for the foldback prism or mirror path to fit between GG and front of lens and still be able to focus sharply on GG.

I've been using a plain old +10 close-up on my redrock.
It cost me $20 dollars off B&H used.
The only problem I have is a bit of vignetting from the apature and just shoot accordingly and crop.

Samuel, so instead of buying the like 400 achromat from redrock, you can just buy something from bh? can i have a link or something please =D

If this lens is the Hoya 10+ or an unbranded equivalent, you may find it unsatisfactory depending on what camcorder type you use. The exit pupil diameter is too small to use on some camcorders without vignetting or soft edges or corners.

You can as suggested, crop out the vignette in post but then, you have a smaller view of the groundglass itself and consequent magnification of the texture, the proportional resolution loss associated with rescaling this image and the resolution losses arising from the digital effects process itself.

For $20 it is an easy tryout but most who have been playing with adaptors for a while, have tucked their heads into the doorway of this dead-end, backed out and moved on. (This population includes Redrock who started off as enthusiasts refining Agus Casse's original).

Redrock, SGPro, Brevis and Letus, which have their origins in the dvinfo community, sought alternative sources or placed custom orders for achromatic dioptres.

The suitable on-shelf lenses were fairly costly and not available in the higher powers needed for non-flip adaptors at the wider diameters required for initially the Panasonic HVX100 and subequent HDV cameras.

i mean i dont know if this is the same thing, but on my photographs i love using vignetta, i mean its kinda my style, but i dont know if its the same thing for video. does anyone have a screen shot of somethign with one of these adaptors?

Phil Bloom who posts on the Letus forums has previously for some clips, deliberately chosen the vignette effect of groundglass adaptors as a creative tool by not zooming in quite far enough to eliminate it.

You may find his clips or links to them here

www.philipbloom.co.uk

It is more desirable to have the choice rather than have to live within it by cropping in post.


(Whilst not normally given to adding oneliners on end of messages I could not let this one roll by without giving it a helping kick down the hill - I put myself in the frame for this comment - "The twins of genius and insanity were with him but genius did not like what it saw and went back."

Bob is totally right about what he is saying.

I do most of my work for the web and so the loss in resolution and all is acceptable to me. Ground glass texturing hasn't been a big problem with the M2 since it spins fast (more of an f-stop issue there). The local noise produced by the camera image sensor is however there in less than perfect lighting and if scaled will cause issues.

I will say, as I'm gearing up to go to HD, that I will probably be sucking it up and just spending the $400 dollars.

What I'm doing is down right unacceptable for the larger hvx or a1 type cameras unless you want dv resolution out of an hd camera or need a purposed filter to create the vignetting and soft edges. I'd just do it in post though.

This is a good example of why you might want to stay clear of this direction

I bought my achromat from Cinevate for about $250.00, and use it doubled with the Letus 35a achromat to get better zoom incapability to eliminate vignetting on my FX1 and HV20 with that adapter. I also use with my self builth Redrock based spinner and a 5inch tube to give me a good image on it.

I saw a similar achromat on Ebay for $120.00. Never know what you are going to get there, though.

Samuel.

What you have there is not so much of a vignette as not being zoomed in close enough on the groundglass because you have picked up the outer edge of the disk, edge of lens rim or macro tube in bottom of frame.

I'm guessing the achromat is a 3+ if you are zoomed in all the way but as you suggest it is a 10+ something else is obviously going on. There seems to be no vignette from insufficient exit pupil diameter.

How long is the distance between front of achromat and groundglass?

Is the achromat mounted directly to the camcorder filter mount or very close to the front element of the camcorder's own lens? If that edge is the frame of the achromat and not the disk edge, then there seems to be a vertical offset because the centre of groundglass projected image is not centred to the optical centre axis of the achromat, which is itself not centred on the camcorder optical centre axis. This is a circumstance which is really really hostile to image sharpness.

Can you zoom in closer or position the achromat closer to the groundglass to be able to frame inside the bright part of the groundglass image.

If you can zoom in closer, do you lose ability for close focus at the "close" end of the camcorder lens focus or at the infinity end or is it pretty much centre in the camcorder's focal range?

Seems like you are not realising the best potential of the M2 at present which is a pity because properly set up it is a great adaptor. There's two feature movies, one in significant theatrical release in the US, originated on the M2 so you definitely have room to move here even by fine tuning what you already have.

Conservatively, I think I could get you another 50 TV lines of resolution just by fine tuning those two adjustments, achromat-camcorder lens optical axis centricity and position of achromat relative to the front lens element of the camcorder, closer = better so long as they do NOT touch glass and get scratched.

Loren. You'll find Phil Bloom's vignette effects on the JVC HD 250 Brevis page on the 35mm Shootout article he has there.

@bob

I'm using an older Panasonic dvc20. The issue I have is that I can focus on an image (with the camera alone) to about 2 cm from the lens. The camera probably wouldn't need any glass between the adapter except that the M2 is a big box and the camera has a bit of protrusion past the lens itself with the zoom controls and hand grip, so they can't get close enough to each other.
This causes me to have to zoom in, but then I lose focus. That's why I got the macro and I just took B&H's word that it was a +10, maybe it's not.

The M2 has that IMHO dumb reverse threading coming out of the camera side of the adapter and haven't bothered to to get a male-male ring to get them screwed into each other yet. I was going to get another generic macro and a reversing ring or whatever those male to male filter rings are called and see if it worked or not. I never lost a job from not having the M2 before so it's been mostly a toy for now.

What you see is from the aperture and will get better or worse at different stops. So maybe it isn't getting close enough to the GG. I just assumed it was that exit pupil phenomenon you mentioned.

The image was from some of my first shots when I had it all rigged up on wood and has since been fixed to be properly aligned, although not connected.

I really just wanted to play with one when I bought it, because to do it right, it seems you have to spend $2000-$3000 after lenses and mounts and matte boxes and monitors and on and on.

Samuel.


Wood is good even if sometimes ugly. Doesn't do much for the pose value on location but if results alone count -- .

The accessories are the icing on the cake for practical utility in an intense production environment where you need things to work predictably and fast.

You can get equally good images with much less, even just using a sharp f1.8 50mm on front of the M2 and no other lenses.

When you get the achromat centred and mounted to the threads, the distance from camcorder to achromat closed up, the correct distance achromat to groundglass for focus through the achromat established to be as close to infinity as you can get it but still leaving trim room for final focus - sharp on about 15 metres should be fine, you may find yourself a lot happier.

Sit on an aperture of f2.8 on a f1.8 50mm SLR lens, as close to f5.6 on the Panasonic as you can get with ND filters or none depending on available light, 1/50th or 1/60th sec shutter.

Bob

I found that you can use just about anything for building camera gear as long as you paint it black: wood, metal, plastic, anything. Your right, results are the supreme decision maker.

Now I use a 50mm f1.4 on f2-2.8 and just close the aperture as much as possible on the camera, so ends up about the same as you saying.

This camera is gonna retire soon. His twin brother had an imager go bad and I'm not up to sending it out for repair when I'm already going to buy a few new cameras in the next month or two.

To stay on topic though, I'm gonna see if $50 might make it work just for kicks

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.

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!

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

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

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

Apologies. I meant Cinecity. I'll edit my 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?

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.

Century optics is a 7+ diopter as well.

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.

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.

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.

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.

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.

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.

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 :-)

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

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.

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

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.