ND Grads - hard or soft?

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BrianI

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Brian
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Looking to invest in a couple of ND grad filters for my Pentax 18-55mm kit lens, and also for my Sigma 10-20mm.

I'm unsure whether to go for hard or soft edged grads. I'm sure I read somewhere that due to the crop factor of DSLRs (1.5x in my case), that a hard edge looks more like a soft edge grad?

I've thought about the following:

85mm 0.6 Hard with cokin wide holder, 52mm and 77mm adaptor rings.

Also does anyone have experience with the cokin P sized infrared filter? I could imagine that a non screw in infrared filter could lead to light leakage? But it might be easier to use than frame the shot, then screw in the IR filter. In anycase 77mm diameter IR filters do seem quite expensive! :shrug:

All suggestions welcome!
 
Well generally speaking you can only use hard grads effectively when you have a completely straight horizon. This is often put to use with the seascape at sunset sort of photos. I purchased a soft grad set which gives you a 0.3 (1 stop), 0.6 (2 stop) and 0.9 (3 stop) grads. Generally speaking people say the 0.6 grad is the most useful however I personally have found myself using my 0.9 a lot more. I also use the Cokin wideangle adapter which wprks pretty well although sometimes I wish it had just one more slot in it. I don't unfortunately know anything about IR filters, hopefully someone else will.
 
I'd suggest that unless your hard ND grad is a 3 stop, you can get away with using it on less than perfectly flat horizons - if used with care.

You can hold it at an angle if that helps, and sometimes a hint of darkening on a mountain top (for example) can look effective.

I often use a 1 stop hard ND grad in conjunction with a polarising filter and get some great skies.

I probably use my 1stop and 2stop hard grads equally as much. You CAN combine them as well, giving a 3 stop.

I've never used a soft grad, but if I did get one, I think I'd get a 1.5 stop version; I think Lee do one.
 
thanks for the replies.

I'll probably go for a 0.6 (2 stop) soft grad, and I think I'll also treat myself to a 10 stop ND seeing as they are only £20, as well as a cokin wide holder + adaptor for my sigma 10-20mm lens.
 
I still can't quite get my head round this crop sensor/full frame stuff so someone correct me if I am wrong, but I read that crops only use part of the filter anyways and even a hard edged is fairly soft edged on a cropped sensor.

Does that make sense?
 
BrianI said:
Looking to invest in a couple of ND grad filters for my Pentax 18-55mm kit lens, and also for my Sigma 10-20mm.

I've thought about the following:

85mm 0.6 Hard with cokin wide holder, 52mm and 77mm adaptor rings.
Click to expand...

A standard Cokin P holder intrudes into the edge of the frame at anything wider than 14mm in landscape format. It's ok in portrate format with the filter upright :(

You could always stagger a couple of hard filters to give a softer transition if you have more than one filter slot
 
jerry12953 said:
68lbs said:
I crops only use part of the filter anyways
Yes, that would make sense - the central bit.

Not quite sure about the second part though. Wouldn't it be like using a longer focal length? In which case it wouldn't go soft.

but don't quote me.....;)
Click to expand...
Click to expand...

The crux of it must be the effective focal length. If the graduation is over 5% of the height of the filter ( hypotheticaly). At a short focal length, the image will use the central 5% , plus a large part of the clear and tinted areas.

As the focal length increases, the portion of the filter being used will decrease... The graduated area is still 5%, but this now occupies a much larger proportion of the frame, with a smaller area of clear and tinted areas above and below.

Therefore a crop being 1.5 - 1.6 times the FF equivalent, the graduation will be a softer transition as it's a longer effective focal length.

:thinking:
Click to expand...
 
singlespeed said:
A standard Cokin P holder intrudes into the edge of the frame at anything wider than 14mm in landscape format. It's ok in portrate format with the filter upright :(

You could always stagger a couple of hard filters to give a softer transition if you have more than one filter slot
Click to expand...

I'd read that the cokin P wide holder with it's single slot is OK for a sigma 10-20mm lens, even at 10mm?
 
singlespeed said:
jerry12953 said:
The crux of it must be the effective focal length. If the graduation is over 5% of the height of the filter ( hypotheticaly). At a short focal length, the image will use the central 5% , plus a large part of the clear and tinted areas.

As the focal length increases, the portion of the filter being used will decrease... The graduated area is still 5%, but this now occupies a much larger proportion of the frame, with a smaller area of clear and tinted areas above and below.

Therefore a crop being 1.5 - 1.6 times the FF equivalent, the graduation will be a softer transition as it's a longer effective focal length.

:thinking:
Click to expand...

yes, that would be correct, but I doubt if it would make MUCH difference in practical terms.
Click to expand...
 
BrianI said:
I'd read that the cokin P wide holder with it's single slot is OK for a sigma 10-20mm lens, even at 10mm?
Click to expand...

Brian. Sorry if I confused things a bit. Yes, I beleive the wide holder which only has 1 slot is ok on the sigma, but compronises stacking filters. Though the standard holder has 3 filter slots, it sacrifices 4mm of the widest part of the 10-20mm sigma

Another option to have your cake and eat it would be to get wider filters and holder from a different manufacturer. There was a thread about 2 months back about the different manufacturesr, without getting rubbish or paying the large price for Lee filters.

Neil.
 
singlespeed, I'll probably opt for the hitech 85mm filters. I can't see me needing to use more than one on the sigma 10-20mm, and a 100mm filter setup would be a lot more expensive, the extra money could be used to go towards a couple of days B&B photography trip!
 
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