richg101

​Most medium format cameras, digital backs and lenses are designed by and sold to people while they are drunk.  If sober, they'd just go for aps-c and not spend £20k on digital backs.  :).

​

I suppose the reason for the difference is that generally from what I see an 85mm at f2.8 is almost always sharper than a 50mm at f2.  Since the 85mm will be used on full frame, the full frame setup has the advantage in sharpness of the in focus subject.  as a result the actual ratio between in focus and out of focus is greater.

Also, from my experiences using usually full frame lenses on both full frame and aps-c/s35 on a full frame sensor the whole image circle is being utilised to deliver the sensor resolution.  Assuming a full frame lens wide open will resolve 30lp/mm on a full frame sensor the horizontal resolution 36mm x 30x30 = 2160px.  crop into that for s35 and you only have 1440px of horizontal resolution.  So assuming the actual lenses are full frame lenses - an 85mm on the full frame sensor, and a 50mm on a s35 sensor, the 50mm will project the same fov as the 85mm but the actual overall line pairs is divided by 1.5 on s35.

The difference is less obvious when true s35mm lenses are used on the frame they're designed for.  The sigma 18-35 f1.8 for example will outresolve most full frame lenses.

Then we have speed boosters - which compress the resolution down onto a smaller area, so if there was a 'optically perfect' speed booster available you could take the 30lp/mm full frame lens and compress it by the 0.7x and have around 45lp/mm of resolving power onto your s35 sensor.  Unfortunately no commercially available speed boosters allow optical perfection so some of the lens resolution is lost.      Still the delivered resolving power onto the s35 sensor is normally more from a 50mm + speed booster than the resolution from a 35mm lens without a focal reducer.

The only real way to properly illustrate the difference would be to take a m4/3 camera and a 25mm lens and put it against a 645 camera and an 80mm lens.  The 80mmbeing set at f2.8 and the 25mm lens having to be set at something like f0.7 to get the same amount of defocus.  Quite obviously the 80mm will blow the 25mm lens out of the water in terms of sharpness. 

I prefer a full frame sensor because I can use a longer fl for the same fov.  I prefer the way a longer lens separates the in and out of focus areas of a frame.  Added to this is the affordability of wide lenses.  A 25mm f2.8 is as wide as you ever need on full frame and usually looks better to my eye than an 18mm f2 on s35 due to being sharper and with less distortion.

Cheers for the info Nick.  It's irritating there isn;t something slap bang between these Alzo's and the Westcott in terms of pricing and CRI. Also the Alzo's seem less accessible in the UK:(  

I'm hoping to invest in some lighting and think now might be a good time to look at LEDs.  I'm particularly interested in a 350w fresnel from Ianiro

http://www.ianirouk.com/product.php?ProductID=763

as well as a pair of matching 100w fresnels 

http://www.ianirouk.com/product.php?ProductID=772 

Has anyone here used such lighting or have any feedback on how they would compare to Arri tungstens or hmis  

I don;t want to have to deal with the issue of generators or taking special feeds from a ring main.  I just want to run lights off either an dc-ac inverter and some leisure batteries or from normal 13a sockets as found in the home.

I'm seeing a 95% CRI rating, and quoted tungsten/hmi equivalents, but in real life are they a worthwhile investment over say a set of 3 redheads which work out at about 1/4 the price for good condition used 800w jobs.  

​Before doing so - and potentially killing a priceless relic, be aware that it's likely the glass they used in the design is no longer produced and thus the radii of the glass will need to be changed anyway.  If manufacturing a new anamorphic all together you'd be better off designing around current glass types with similar indexes for the specific goal of a larger sensor rather than a 8mm frame.  Get a list of the in stock glass your plant have otherwise I might find your moller is killed for no reason.  The FF38 and TRUMP38 optics needed some of the most expensive and hard to source glass and since so much time was put into an uncompromising design I had to go with it in the end, resulting in crippling material costs.  Since it's now done, I'm ok, but I recon the process aged me 10years in 6 months.  Design around available glass rather than the other way round.  It'll save you so much.

​

I see neither emails.  What was it regarding?

​https://farm4.staticflickr.com/3847/14851187693_0a0e74c4e9_o.jpg

https://farm4.staticflickr.com/3914/15374165342_4824df6f9d_o.jpg 

https://farm8.staticflickr.com/7383/15762523763_c2f750fc18_o.jpg 

​As it happens the majority of the 25mm distagons are non hft I have found!  Of all the lenses in the system, the 25mm is the crown IMO.  

http://www.ebay.co.uk/itm/Carl-Zeiss-Distagon-25mm-F2-8-f-Rolleiflex-QBM-/161491656495?pt=DE_Foto_Camcorder_Objektive&hash=item2599a71f2f

When I get dso lens users asking about wide alternatives I tend to point them towards this lens.  It's the best vintage and non multi coated wide angle lens (for sharpness).  

This is full frame on the A7R.  It's the only vintage lens I own that really delivers resolution suitable for the A7R  

​Were the vents a part of the theme of the film?  Or could you simply defocus them or better still, leave them out of frame?

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QBM's will be pretty easy to add gearing to.  One problem is that the f1.4 fast lenses (35, 50 and 85) are almost always hft coated which is rollei's own flavour of *t coating.  co developed by rollei and zeiss I believe.   also, the majority of the rollei 35mm and 85mm f1.4's are 3 blade apertures which will deliver a different defocus rendering than the rest of the set.  That said, the 85mm f1.4  '3 blade' is one I really want to add to my collection if I ever have the cash.

for now I use:-

25mm distagon f2.8 (non HFT)

35mm distagon 2.8 (non HFT)

50mm planar 1.8 (non HFT)

50mm planar 1.4 (HFT)

85mm Sonnar f2.8 (non HFT)

135mm f2.8 (non HFT)

The 50mm f1.8 non hft is imo slightly nicer than the faster sharper f1.4 version due to the lack of modern HFT coatings.  You wont find the f1.4 version without the hft coatings unfortunately.

​the pins on the metabones adaptors are too long and end up shorting.  I've had no end of problems with lenses that are fine on canon cameras yet cause bugs with the a7s and a7r.

the only solution is to tape over the connectors.  

very cool setup

​

I have the rollei zeisses - from 25mm to 135mm.  the non hft versions are indeed some of the best 'character' lenses available.  zeiss sharp, yet with less efficient coatings.  

the 25mm is a wonderful lens

Hi John.

Please now limit the bumping of this thread until you have some photos of physical finished items as well as test material showing the finished units in action.  3d renders don't need to be recycled any more now.  We all know what they look like.  we now need to see the sustenance from the actual units for sale here.  

not an easy question to answer.

if anything 'hard vignette' - a clear masking of the image due to the mechanical limitations of the optical path will be more obvious when closing down a faster lens since natural roll off of the taking lens will be less since its projected image circle gets wider when closed down.  field of view also changes very slightly when closing the aperture down and this might contribute to a small change.

35mm on a 'isco 36 on aps-c shouldnt cause any vignette when shooting 16:9 in aps-c.  

The main issue with a 35mm f1.4 is that the actual front pupil will be a lot bigger than the rear of the isco.  this wont cause vignette, but might limit overall transmittence.  closing the f1.4 lens down to f2.8 will yield in most cases much better results than a f2.8 lens used wide open.

in my experience the zeiss/contax/sl35 distoagon 35mm f2.8 is a superb taking lens on aps-c with the '36.  

The problem is in the speed booster.  Almost certain of it.  

The adjustment screw on the back  (which allows adjustment if infinity is not able to be achieved), actually knocks the focal reduction optic off-centre when tightened.  - untighten the screw and sure enough the optical cell will wobble - meaning there is play.  as you retighten you'll see the lens cell move to one side.

the way to fix this is to use the speed booster without the screw tightened. (so the optical cell can rotate freely).  in order to keep the optic from rotating you can do a number of things, such as use 3 small blobs of blu-tack.  - im unsure what it's called in different countries, but it's made by bostik.  a bit like chewing gum, but blue and for attaching posters to the wall.  using 3 small blobs evenly spaced will prevent the optic rotating freely.  and will come off easily if you ever want to adjust it.

do you have the ND's avail?  What price were you looking for?  please pm

kinda wish it was a short with dialogue rather than a music video.  Wonderful images here, and a lovely theme too.  though I think it deserves around 20 mins and some dialogue:)

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since the red dragon sensor is rather a lot bigger than s-35 at 30mm wide in 6k mode, if I had the PL mount version of the dragon I'd be looking at these in PL as a viable option.  Using s35mm lenses on the dragon in 6k will be pushing the lenses too far beyond their working limit and thus the need for 'full frame friendly' APO lenses becomes very important if the acquisition of 6k data rates is to be worthwhile.

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The price point, their 5mpx rating and their 1" capability would suggest they might do exactly what you require.  The 35mm will almost certainly cover aps-c.  the 25mm will probably be safe on m4/3.  after that I imagine those wide lenses are assumed to really be used on smaller sensors like 2/3 and 1/3.  6mm and 8mm on m4/3 is crazy wide and not a regular requirement in machine vision scenarios.   whether infinity is achieved or not is gonna be dependent on the rear diameter and whether or not the lens can seat deep enough into the m4/3 mount.  if the gh4 had a e-mount all would probably be swell.

As Julian has shown, the kowa prominar lens set offers 8.5mm f2.8, which might suggest that closing the aperture down on the 8mm f1.4, and closing it to f2.8 the circle might get big enough to deliver.   Personally I'd be looking at a fast 16mm fisheye for full frame (like the distagon 16mm f2.8) and using it with a 0.64x speed booster.  price point is about he same.  and you'll likely get better coverage of your sensor and less barrel distortion this way.  resolution might not quite match the machine lenses but it'll be close.

Generally the high end 'megapixel' lenses are designed for 1" sensors - which are only slightly smaller than the gh4 in 4k mode.  However it's normally the 35mm (and above) focal lengths that deliver onto a 1" sensor.   extreme wides like a 8mm lens will be aimed at much smaller sensors I'd imagine.  probably for 1/3rd of an inch sensors.

In order for the lenses to deliver the published specs such as resolving power of 150-200lp/mm, correction for ca, vignette and edge softness over a 1" sensor it means the actual image circle is often a lot lot bigger.  I've tested high end machine vision lenses from Schneider, Moritex and Qioptiq.  all of which, if publihsed as 1" sensor (<3.6micron px size) will deliver up to aps-c coverage at surprising levels of quality right to the edges.  Therefore these lenses are very good for m4/3.  However, the c-mount adaptors to m4/3 are often too thick and don;t allow infinity focus.  often resulting in no further focus distance than around 1meter.

add a link to the lens in question if you can

Remember to grab an Otus and shoot 3 stops closed down to deliver 50mpx onto that sensor.  And I hope they have the ability to read all 50mpx at once, without rolling shutter.  I think not and as such the new 5d will be worse than the 5dmk3 due to line skipping of 3/4 of the pixels.  

Sony on the other hand will respond with a 50+mpx camera with a sensor size that actually allows such resolutions to be a design benefit.  The D800E pushes even the Otus to its limits of resolving power, and that's the best (technically) 35mm format lens ever made.  For more mpx you need physically more image area for it to be worthwhile IMO.  

​

even worse than a mechanical focus mech then!  - for cinematic purposes at least

can you leave it as it is?  if the Dp didn;t notice, it might be that the viewer won't either.