Manual Lenses and Exposure

[Chris Harding]

Hi Guys

Then you have a manual lens on the camera via an adapter, the display (obviously) shows the aperture just with a line indicator no communication with the lens iris. Does the camera see this as a completely closed iris if you switch to auto?? I figured it would be great if you could manually set the iris and then let the camera figure out the shutter speed and gain/iso needed. Would the auto circuitry still do this based on the fact that is doesn't display an f-stop number? Can the circuitry figure out the correct shutter and gain based on the amount of light hitting the sensor from a manually controlled iris or does it need the lens to communicate with the electronics??

Bottom line here is that I'm still figuring out a way to use my Tokina 11-16mm F2.8 lens (Nikon mount) on the camera on stedicam but don't want to have to have to keep adjusting iris.

Chris

[Justin Turner]

Hi Chris,

I have only had a quick play trying a few lenses to test fit etc and yes the camera seems to adjust iso and or shutter to compensate the aperture that has been manually created. The camera must sense the amount of light hitting the sensor. No need to adjust exposure yourself

[Chris Harding]

Thanks Justin

I'm trying to get my Nikon's 11-16mm Tokina F2.8 running on the camera so I can use it on my stedicam ...at 11mm I can almost forget about focus as the DOF is massive so as long as the cam will change shutter for me (both hands are tied up on the rig!) then it's workable...my only other option is to buy Sony's e-mount 10 - 18mm lens which does everything for you BUT it's over $1000 and it's only an F4 lens so indoor shoots will have me struggling for enough light but with the Tokina F2.8 I will be fine (plus I own it already).

The FOTGA adapter just will not fit onto the camera ..it's way too tight so I'll have to go another route, probably I should stop messing around and buy what you have??

Thanks again for the input

Chris

[Justin Turner]

I would say save the money and dont buy a lens in which you already have a good alternative. Just get a better adaptor. When i get some time i will put all our lenses on it and see what they look like.

As a professional its easy to justify the cost if it makes your life easier. As a hobby then i can understand watching what you buy.

I will be testing these lenses over the next little while.

All nikkor

85mm1.4G
50mm1.4
10.5mm 2.8
45mm2.8 pc (tilt shift)
24-70mm2.8
28-70mm 2.8
14-24mm 2.8
70-200mm 2.8

I want to test them all but I thnk the 14-24 will be used for glidecam shots. Maybe the 50 or 85mm for reception where light is low and the kit lens for everything else. I tried a few and shooting even at 2.8 makes such a diiference. I will let you know if i run into any issues but with the limited time I spent the novoflex just worked and so far cant fault it.

It sounds like you shoot alot of real estate work and while its not the same as a weddng you dont need any hassles with gear. I would say spending a little more up front can save you money in the end. Last year I wanted to play with selective focus lens so I bought a cheapo lens baby I think it cost around $400 I used it once and liked it so I bought the 45mm PC lens. The 45mm let you do so much more and have never shot with the lensbaby since. Had i bought the real deal first I would have saved $400! I have done similar things over the years so I try to reseach and stay away from cheap if I can. In saying this I was looking at the same $15 adaptor too for a few days because its such a basic block of metal I thought it is worth a try. But glad I didnt now.

[Peter Rush]

Chris have you thought about the Sony E 16mm F2.8 Pancake Lens for Sony Nex - I use one with my VG20 on a Steadicam and it's great - maybe not wide enough for you but only £99

http://www.ukdigital.co.uk/sony-e-16...FbMQtAodXWcAlg

Pete

[Chris Harding]

Hi Pete

Thanks but no..great for weddings but not wide enough for Real estate!! These guys expect the room to room enormous...I do all my still shots at 11mm normally and that is what is expected ... the Sony 10-18 is great but only F4 so the Tokina from my Nikon set would be perfect!!

Justin ..Your input is much appreciated ..I would really be interested to know how the Nikon lenses on an adapter work with the camera left in full auto and the aperture of the lens kept full open (like on your 10.5mm F2.8) if you just open it up full, switch the camera to auto and shoot, will the shutter /ISO combination handle the exposure correctly as you walk around a room of a house, and even outside???

Manual exposure just isn't an option as I'm in a full vest/arm rig and zipping around a house, room by room with light conditions changing constantly!! I know Paul Wags does these up in Cairns but he uses the Sony E-Mount 10mm -18mm I think which would be perfect (but a little slow indoors) but a bit pricey for the amount of stedicam promos I would get to do in a year

Chris

[Peter Rush]

Sorry - posted twice by accident - ignore it!

Chris have you thought about the Sony E 16mm F2.8 Pancake Lens for Sony Nex - I use one with my VG20 on a Steadicam and it's great - maybe not wide enough for you but only £99

http://www.ukdigital.co.uk/sony-e-16...FbMQtAodXWcAlg

Pete

[Christopher Young]

That Sony 16mm f2.8 pancake with the Sony VCLECU1 .75 Ultra Wide Adapter will bring that lens down to 12mm and still give you f2.8. It's not fish-eye. Might do the job. Around $99 on ebay.

Sony Ultra Wide Converter Converts Sony E Mount Pancake VCLECU1 0027242801219 | eBay

Chris Young
CYV Productions
Sydney

[Chris Harding]

Thanks Chris

That is an option if I cannot get the Tokina to work with an adapter!!

I'll first see how Justin fares with his tests using a dumb lens and whether the camera in auto will be able to control exposure using just shutter and gain

Chris

[Justin Turner]

Hi Chris,

Yes the camera in auto will adjust shutter and gain to correct the exposure in auto mode.

I walked in and out of dark to light rooms and inside to outside etc and gain is adjusted first then shutter is adjusted if needed. Its just the same as with the kit lens. The only thing is you never know your aperture unless you are wide open.

I tested the 10.5 and the 14-24 same results. Im sure you are safe to let is roll in auto with these adaptors.

[Chris Harding]

Hi Justin

Awesome! Thanks for doing that test..much appreciated ..now to find an adapter that actually fits the camera that's reasonably close ..can't find any in Germany at the moment only the USA but as mentioned before there is a Aussie supplier so I'm email them first ..they might of course just be an "agent" and still have to order from over the pond.

I really don't think it matters what aperture you have on the super wides as your DOF is so massive it doesn't make a difference. However I do see the issue with tele lenses ..I'm assuming that peaking still works with a manual lens..or does it ..on the stock lens it definately works in manual so maybe that would help when DOF becomes shallow

Chris

[Chris Harding]

OK, I found a new genuine Novoflex NIK-NEX adapter from Germany now for 172 Euro including shipping from Frankfurt so hopefully this one with work a lot better than the crappy FOTGA one which I'm now done with trying to modify!

Results will follow when it arrives in Australia

Chris

[Christopher Young]

Chris ~

I trust the Novoflex will be accurate on back focus.

Using a micrometer I have found that nearly ALL of the adapters are shorter than the specified flange back distance, The adapter makers seem to do this to ensure that the lenses attached to the adapters will all reach 'infinity' focus. In fact most of them allow the majority of lenses to focus past infinity.

The problem with that is that when you zoom back on a lens that you know is a parfocal zoom, of which there are only a few, the lens will go slightly out of focus. This means you need to 'shim' up the adapter front mount to get the exact flange back distance to get true focus tracking as you zoom.

I don't know what Nikon lenses you are using but if they are the original Nikon F mount lenses they have a stated flange back distance of 46.5mm. With the e-mount flange back being 18mm your adapter should be 28.5mm front flange surface to rear flange surface. Measure in about four spots around the adapter as some of the cheaper ones vary at different points which means your lens isn't even perpendicular to the sensor. That's very poor quality control for you.

Even if that 28.5mm spec is 100% correct it does not take into account the vagaries of mass production. Only accurate measurement will ascertain if distances are correct for maximum lens performance.

On the old but still beautiful Minolta Rokkor lenses I use on the FS700 the flange back distance was stated to be 43.5mm. Though in reality that often measures up at 43.72 according to the true Rokkor aficionados. That .22mm can have a big effect on the performance of a lens.

You can buy various thickness brass shimming sheets that you can cut with scissors to shim a mount or just raid the kitchen and find the roll of Alfoil [aluminium cooking foil] and start shimming with that until you get the best focus accuracy across from close to infinity. Used to have to do this years back with film camera lenses.

Now you know why broadcast 2/3" lenses have a 'back-focus' adjustment ring.

Chris Young
CYV Productions
Sydney

[Chris Harding]

Hi Chris

Thanks for the warning..my main use will be on Realty shoots (not weddings) and on the very wide Tokina 11-16 zoom and I can basically set the focus to anything over 5' and the DOF will be sufficient to cover the stedicam shoot. However I can see the problem and the only semi-pro camera that has a backfocus adjustment is the JVCHM700 series simply cos they use Fuji or Canon broadcast lenses.

I'm actually using the DX series lenses from Nikon D90 kit but based soley on price the Novoflex is supposed to be a lot better machined (from Germany) than the cheap $20 Cinese ones ..as already stated the FOTGA adapter didn't even fit the E-Mount side!! That's how bad they are.

Once it arrives here I will certainly do some measurements and see if it's in spec ..at 10 times the price of the eBay ones I'm hoping it will be!!

The heads up is very much appreciated

Chris

[Christopher Young]

Chris ~

Yes, post your experience with the Novoflex. I think there will be a few of us keen to hear about your results. I am one for sure!

Cheers

Chris Young
CYV Productions
Sydney