Danny Bong (in charge of workshop) confirmed that the whole workshop is free (workshop and accomodation) forgot to ask about the food thou .

as a reminder, bring your Camera(batt and charger), Lenses, Flash(flash workshop), and Tripod (for night shooting).

This post has been edited by edpaul: Aug 17 2014, 06:09 PM

Antique lenses
DSC03295-2hd by Cruxiaer, on Flickr

Anyone has experience stacking ND filters? I'm talking about stacking circular filters that attached directly on the lens, not the square filters that put on a filter box (I'm not sure if there is any difference for these two methods though). I read people saying some issues when stacking ND filters (flare, glare, color shift etc). And some people said if using high quality ND filters with IR blocking can get good results. I'm not consider variable ND filters because they are not enough stops (3-8 stops). I need 10-15 stops. I was thinking to stack maybe 2 to 3 with 10/3/3 stops filters, so I can have a choice of 10/13/16 stops. Some recommend B+W ND MRC filters, already quite expensive (for 77mm 10 stops ND costs US$149 in bhphoto), but still I don't see it features IR cut.

Please advice and share your comments. Thank you masters!

Simple advice, don't.

Not forgetting that stacking that many circular filters will definitely give some heavy vignetting.

And stacking polarisers well definitely give you odd color shifts.

You're better off with variable nd which gives about workable 9 stops. With an added square nd filter in front of it for further reduced stops. Then if you want IR cut, add another filter in front with caution as it could be too thick and cause vignette, which I generally don't recommend. By the way, most sensors already have IR filtering built into them inside the camera, so it's useless to add another one.

Stacking 2 polarisers (not to mention 3) will give you funky cross patterns similar to moiré. Same goes with stacking 2 VNDs.

This post has been edited by lwliam: Aug 18 2014, 12:56 AM

for circular filters iinm you can get up to 10 stops (Hoya nd400 = 8 2/3 stops / B+@ nd110 = 10 stops / cheap nd1000 filter < rm100 oso have but more pp needed for color cast correction & IQ degradation may also be issue).
stacking may be an option but you may get vignetting , might not be an option for those who shoots ultra wide angles.

another is the IR filter, there are few variants but i donno much about them. sorry

best option is stacking filters on filter holders.
lots of sizes for different purpose and lenses. (cokin A/P series , Z series or 100mm filter, 150mm for Nikon 1424 UWA)
for these stacking is best, more options too (nd , gradual nd, reverse gradual nd, blah2)

my suggestion is go for the last one,
get the 100mm filter series, there are generic brands for filter holders and filters that may cost less than u think
easier to get filter holder and buy step up rings than to buy circular filters for every filter size.

cheers

Thanks guys for the replies, appreciate that.

For vignetting issue, I was wondering what if I buy a larger filter and then use a step up ring, that way the filter is much larger, so the vignetting may not be seen? Say buying a 77mm filter and put it on a 67mm filter lens.

I also read many saying when they expose longer time, it is easier to get color shift. Is it true that if I do not expose long time, I won't see color shift on good ND filters even if it's a 10 stops filter? I need it because I want to shoot video on the A7S using sLog2 on 25fps, which has a minimum ISO of 3200. When I need to shoot shallow DOF under the sun, I need above 10 stops ND filter in order to shoot at large aperture. Meaning, long shutter exposure is not my concern.

Thanks!

This post has been edited by yok70: Aug 18 2014, 02:00 AM

Iron Man
DSC03147-3hd by Cruxiaer, on Flickr

enjoy the photography workshop

My 3rd KLCC dreamscape shot, a composite image of 3 different photos I shot over few months.

KLCC by bdrc, on Flickr

FB gallery: https://www.facebook.com/ASDgraphy

This post has been edited by bdrc: Aug 18 2014, 12:47 PM

before that, mind i ask your purpose? sound very fishy and un-practical your method of photography/videography.

also, the information you gotten/read from online is imcomplete and a little misleaded.

from your information, not sure if u are trying to do IR videography or something weird.

lens filter (the circular filter directly on the lens)
square filter (those Cokin, tianya, Lee, Singh-ray, rosco)
filter holder (use to hold the square filter)
filter(holder) adapter, used to screw on the lens, then used to hold the square holder.

i. before going deeper into ND stuff. lets talk bout the CPL, since ray cant give a proper english explanation that everyone can understand.

the variable ND, is by stacking two cpl, facing each other (meaning the other piece is Flipped) to work, by canceling each other other. by stacking the 3rd piece (flipped opposite of the 2nd flipped piece, noone tested it or no report of this test yet) i assume it will completely block up everything up to crazy amount of stop like 20-30 due to the multiplying effect or it may has no special effect because the 3rd pieve and 1st piece will work the same as following;

as for putting 3 cpl facing the same side, nothing special will happen, the CPL will work at the highest polarizing effect, meaning it will polarize as much as any One of the highest polarizing angle CPL piece. say the 2nd piece is set at 90degree highest polarization, while the other 2piece is at 20degree and 45 degree, the image will polarized at highest of that 90degree. (i tested it)
but, you still can get stop reduction (light cut off) but its kinda pointless as it cause heavy color lost and u get weird color all over the places.

ii. like william said, stacking too much lens filter, will prologue out the front causing vignetting. even by using step up filter, the stepup filter itself already prologue 2mm outwards from the lens, wide angle lens definitely will catch that filter and cause vignetting. but base on your case, wide open aperture will be even worst vignetting.

iii. lets say you are using some magically technique and solved the vignetting issue. stacking many ND filter will work only if you do more research on the ND filter brand itself. u said ND are expensive, for a reason, they have minor color cast for the branded and expensive... B+W 77mm 10 stops ND costs US$149 in bhphoto, thats still under 500myr!, Lee big stopper rm7xx. if u get those cheapo china tianya, or the cheaper alternative cokins or 3rd party lens filter(circular) you going to have bad time trying to fix the color cast on post processing!

i used to have the b+w 10 stop before(sold it and upgrade to Lee). the biggest issue with the filter is, your camera cant even FOCUS (meaning losing ability to focus), nor your (assuming A7s?) will show bright image over the LCD, it will struggle to light gain it of 10 whopping stop! our sensor feed only manage best at 7-8 stops of light lose... but you can try~ because i myself had not testing it with A7s, but general experience lead me to the idea it will struggle to work...

then u have to unscrew to focus, then screw back to shoot, a very tedious and troublesome method, that why a lot ppl end up buying square filters system as it can take out and put back with ease.

my answer is base on experience where spec sheet will never able to show what outcome you will get. experience will let u know before buying the wrong shit and realized it dont work practically.

v. might i ask why 10/13/16 stops of ND? thats a lotttttt! from what i know, a) i used 50F1.4 with only 3 stop and i dont get any issue shooting under daylight assuming you not getting a 30sec exposure, and im not even sure b) i would avoid directly sunlight as the harsh shadow is ugly, i will have some assistance holding a 120x80mm white/translucent reflector to cover the sun, giving a diffused light over subject.

vi. this bugged me a while. IR is a deep subject. you can skip the explanation. the short answer, UV and IR has no effect on digital camera. another long explanation how those 720nm IR filter works.

hence the filter you buy, when it doesnt mention IR filter or UV filter, it doesnt matter, its a old marketing way. that why branded filter company like b+W brand their coating as MRC (multi-resistant coating), not MC-UV like -other china company does.

so, IR is not relevant to filters.



But, indirectly, it is relevant for filter trying to cut off more then 4 stops. because color cast is caused by the IR light. cheap filter doesnt filter out IR properly hence it got the red/magenta color cast(IR spectrum)... and sadly, no filter company in the world reveal their chemical for the ND effect that tells you the amount of IR cutoff.

so by getting cheap or wrong ND filter, u end up cutting out normal visible light and becomes more and more like IR image due to the escaped IR light through the filter.

i only could say, only Lee Big Stopper has near complete neutral cutoff.


answer more later, back to work first.

This post has been edited by edpaul: Aug 19 2014, 02:44 AM

http://mobile.theverge.com/2014/8/18/60287...ce-release-date

Source: https://www.facebook.com/Sony.ImagingSEA/ph...?type=1&theater

ish.. no view finder... touch screen dont really important to me actually.. find its quite useless

My daughter had a dress up party. And when she was done with her Snow White costume, she made me take pictures for her.

Here is one taken using A7 coupled with Sigma 35mm F1.4 Art. No processing, cropping etc. JPG straight out from camera. Just thought I'd share.

then get A6000

though, i'd prefer a touch screen over EVF on a (relatively) compact camera.

because of no dedicated focus point joystick like dSLRs, the touch screen functions as one. very convenient...

This post has been edited by lwliam: Aug 18 2014, 06:46 PM

May I know what kind of adapter you use to connect this lens with A7?
Mind sharing how much u bought the Sigma Art?

hmm.. true.. a6000 only have mode dial right? hopefully this year end have something new, like A6100 with A7R dial on the body.

yes, A6000 have mode dial

I use the Sony LA-EA4 adaptor. It allows you to use A-mount lenses together with full auto focus functions.

I got the lens for around 27++.00 if I remember correctly. I bought it together with the adaptor.

Thank you so much for your reply, really appreciate that.

I am looking to shoot video on the A7S with sLog2 profile, which has a limitation of using minimum ISO 3200. Since shooting video with good motion blur, we utilize some sort of "double" rule; that is, when shooting 25fps video, we must shoot with shutter speed of 1/50. And this 25fps is the best quality on video for the camera. Now I imagine I may need to get shallow DOF under bright sunlight some day. That case, on ISO 3200 and shutter speed 1/50 (these two no choice, minimum i could use), how many stops of ND I need? I tested on shooting at ISO 200, shutter 1/50, the aperture goes as small as F22 in order to get a correct exposure. Now imagine I need to get a DOF that required to shoot on F1.4. In order to shoot sLog2, ISO must be minimum at 3200, which is 4 stops. Then, I need to enlarge aperture from F22 to F1.4, which is 8 stops. So you see, I need 8+4 = 12 stops ND in order to get that video shot. It's a headache, yes! And I have little to no experience on using ND filters since before this, I only shot videos with video camcorders with built in ND filters and there is no crazy min ISO 3200 requirement.

So you see, my main intention is to shoot video, so I'll be seeing bright image on LCD (and the camera sensor), not needed to shoot "in the darkness of LCD screen" as I'm not use it for silky water still photo shoot.

btw, I'm not so much into wide angle. I guess getting to 24mm should be the max need for me, not any wider.

I asked the BHPhoto, they recommend me to get one 10 stop ND, follow by maybe a 0.9ND(3 stops) or a 1.8ND (6 stops) B+W MRC ND filters, they said they had experience stacking them before.
From the below link, it showed that B+W and Heliopan have similar quality, Tiffen is lack of contrast and very heavy color cast, while Singh-Ray is the best performer but it's very expensive.
http://www.the-digital-picture.com/Reviews...ity-Filter.aspx

My questions are:
1. Regarding vignetting. If I stack just two filters, will it be ok? I am thinking, if I buy a bigger size filter, say my lens is 67mm but I bought a 77mm filter instead (by using step down ring), will that solve the vignetting issue?

2. When stacking NDs, is there a difference between square and circular filters? Is this the very same issue of vignetting, therefore using square filters can get better results simply because they are usually much larger than lens filter thread and also the distance between filters are closer?

3. I think it's best to get variable ND filter, it's cheap and flexible. However, from many reviews, the very end of the filter are totally unusable as heavy X factor and vignetting will come in. I guess those popular 2-8 stops can only give me less than 7 stops. However, I really wish to have the flexibility of having different level of ND. So I really wish to achieve it by stacking filters, say to get a 0.9ND (3 stops), a 1.8ND (6 stops) and a 3.0ND (10 stops), then I have the flexibility of 3, 6, 9, 10, 13, 16 stops ND by just stacking two filters. Do you think this is a good idea? As if the above theory (by using a larger size filter to overcome vignetting issue of stacking filters).

4. Regarding color cast issue. Since I'm not using it to shoot long exposure still image that LCD can't see a thing and sensor can't detect much, but shooting video that actually LCD and sensor can see a normal image, the camera's auto WB should work just fine right? Or worst case I just custom WB it after putting on the filter. So if this is correct, then I don't have to worry about color cast issue on filter selection right? I just need to look for filter that is sharp and high contrast. If this is the case, I think B+W and Heliopan (according to the review I posted above) should be best mid price range choice. And among these two, B+W is cheaper, so that become the best choice.

Please advice. Thank you very much!

This post has been edited by yok70: Aug 19 2014, 01:07 AM

im not familiar with Slog2 system, so, i wouldnt know how to get around it. sorry. at first i had a assumption that you doing IR video, because it has very similar case.

to be honest, you're going to do a lot testing on a lot filter before you get to the right ND filter. i lack of the experience to advise how the filter will react and cause what kind of color shift on high iso video when stacked more then 2 ND filters. iso itself will struggle and might read the wrong color. this doesnt worry me, what really worries me is when the stop are so high, the AF refuse to work (even contrast detect)... and the feed to LCD may turn pitch black too. not sure with A7s, but the last best sensor was the sony 24mp turn black display at 10stop(lee big stopper) facing the sun (sunset shot)



if its on 24mm, i dont know which 24mm its going to be, i assumed its not sony since sony doesnt has any F1.4 24mm. the step up filter doesnt do any good. because each lens is design differently and the requirement of filter clearance are diff. but please do consider square/holder system. There are holder system are design to avoid vignetting for UWA(with few condition too).

other case is, vignetting is a big subject, you might avoided filter vignetting entirely(not sure the correct word to use it), but u cant avoid a very natural soft vignetting that cause by F1.4, even without filter. so, you will required to do some post processing towards it, or, leave it alone since natural vignetting is kinda nice too, it helps to pop the subject in center.

lets Assume you are using 35mm, i will say you are safe from filter vignetting, but the natural F1.4 vignetting will still occur.

*correction, when we/i mention filter vignetting, i'm assuming a hard black mark on 4 side of the image even at F8. meaning the filter used prologue into the filter clearance. not the natural vignetting cause by the barrel itself.



before getting out of hand, lets use the word "screw on filter" circular may lead to diff misunderstanding type of 'effect' filter.
The answer would be simple, some branded holder filter system are designed to work with UWA. hence, its pretty much 'safe' to use. for example, the LEE holder, the adapter ring has 2 type, UWA adapter and standard adapter. the UWA adapter will bring/pull/push/???? the holder backwards, giving more clearance at the front. (try google it)



The crisscross effect happen in UWA and at certain degree of the VND filter (turn-able), usually happens when you overturn till the max at 9 stops. i wouldnt recommend it for your usage, because it will introduce a lot of new possible issue/problems along the way. but if you insist, Do Not Buy ANY Brands of VND.... except, LightCraft Workshop. LCW. dato lee chong wei filter. hehehehe joke aside. it is known as the BEST and mother of VND. very pricey thou. its like buying two B+W KSM CPL MRC Nano filter. close to 1k for the 77mm pro version. thinking to upgrade my version I to version II for a long long time, but pocket empty... and btw, LCW has came out with a 100mm square VND (design for Lee square CPL holder), and i have totally no idea how it works... i suspect its a linear PL.

sadly to tell you,... the limitation of square holder to work on UWA is maximun of stackable filter are TWO...



color case happen when u stack certain resin filter aka Square type and certain brands... no matter its long or short exposure, the color cast will be there, its the issue of that chemical used, the ability to reduce visible light may be incomplete leaving certain type of light escape through. this you really have to try it out yourself. so you gotta make many photographer friends to see who has the b+w ND1000 and borrow to test it.


btw, there are many terms to ND, some put 10stop or ND1000, or 3.0. you will need to read up a little how they catagories them. the 3.0 actually means 10 stop, they calculate by 0.3 as 1 stop, hence 3.0 is 10 stop. the 1000x also mean 10 stop, but im not sure how they calculate it.

.... now.... come to settle your problem, F1.4@3200 with 1/50 at bright day light. honestly... stacking 2 ND filter isnt such great idea as it will create a lot limitation especially when using more then 10stops. my best advise, may sound very absurd so i apologies first, but, you can use a single 10stop, and not sure if its possible, coz i dont know its a controlled video environment or chasing around actual day wedding shoot with is not within your power to control, you can try choosing the right time/moment of the day when the sun isnt that harsh, eg early morning. but if its uncontrollable then sorry i dont know how to advise you. but i hope my explanation will clear up some doubt and question you had.

btw, it is okay for you to explain what/how slog2 works? maybe we can refine a solution from there.

This post has been edited by edpaul: Aug 19 2014, 03:10 AM