GND filter vs image blend

[montreal]

I regularly blend images in photoshop to avoid blownout skies. I make two tiff files from the same raw file (one with the exposure digitally compensated for the sky, the other exposed for the landscape) and I blend them in Photoshop. (Of course this method implies that nothing in my image is "off the histogram")Anyway, with this method I don't need to take several exposures (like with the HDR method) and I get the same result as I would with a GND filter.

...or do I? Are there any drawbacks to my technique (aside from the time I spend blending the images) or is digital blending (when properly done) equivalent to using a GND filter?

Do I lose anything in terms of colours, for example?

Basically I'm trying to determine if it's worth it for me to invest in a filter system. I'll be happy I can achieve the same result without extra equipement... and keep more money for lenses :)

Any thoughts?

[E-K]

I regularly blend images in photoshop to avoid blownout skies. I make two tiff files from the same raw file (one with the exposure digitally compensated for the sky, the other exposed for the landscape) and I blend them in Photoshop. (Of course this method implies that nothing in my image is "off the histogram")Anyway, with this method I don't need to take several exposures (like with the HDR method) and I get the same result as I would with a GND filter.

...or do I? Are there any drawbacks to my technique (aside from the time I spend blending the images) or is digital blending (when properly done) equivalent to using a GND filter?

I don't think there is anything wrong with what you are doing assuming the dynamic range of the scene still fits within the range of your image sensor. A GND is somewhat limited in that you have two areas that are split by a line. This is great if you have a straight horizon but otherwise it has its issues. For example, if you have something which crosses both areas (building, person, etc...) then the GND is going to distort things.

Do I lose anything in terms of colours, for example?

Only if one or more of the channels get clipped.

Basically I'm trying to determine if it's worth it for me to invest in a filter system. I'll be happy I can achieve the same result without extra equipement... and keep more money for lenses :)

Any thoughts?

Well only you can decide for you...but if you're asking my opinion :)

The only filters I see as necessary/desirable for a digital camera are:

- polarising filter
- neutral density filter(s)
- filters for IR photography

A GND filter may be handy in scenarios where the dynamic range of the scene is just to great.

I don't see visible light filters being of much use if you are willing to do some minimal editing. The only reason you would need them is if you didn't have the option of editing the image after.

Just my 2 cents.

e-k

[Mike R]

I would think that you may have situations that you would not be able to recover from a blown out sky (even with RAW). I used a GND filter in the mountains,with mid-day sun and it saved the image. setting up a GND filter can take time, just as blending the images does. They also take up room in the camera bag along with the holder and ring for each lens you own. However you can precisely set the filter where yo need it, including on an angle. No doubt that the good filters are not cheap. I have Shing-Ray filters and paid about $100.usd for each one I have. A lot of people here use HI-tech brand filters and are very happy with them, they also cost less than the Shing-Ray brand.

[montreal]

Only if one or more of the channels get clipped.

Yeah, that's what I was awkwardly trying to express when I said it only works if nothing in my image is "off the histogram".

I would think that you may have situations that you would not be able to recover from a blown out sky (even with RAW).

Yes, you are right. Some RAW images just can't be saved (if a channel gets clipped as E-K says). I guess those are the situations in which a filter would be necessary.

So what you're both saying is that as long as all the light falls in the boundaries of the histogram, there's no drawback (in terms of image quality) to blend the image digitally instead of using a GND filter?

Thank you for your comments... keep them coming.

:)

[Mike R]

[quote=montreal;2148048


So what you're both saying is that as long as all the light falls in the boundaries of the histogram, there's no drawback (in terms of image quality) to blend the image digitally instead of using a GND filter?

Thank you for your comments... keep them coming.

:)[/quote]

I guess it would work but I would not risk losing the image because of something I did not notice on the LCD
I may feel this way from my days of shooting film, remember what film was?:lol:

[E-K]

So what you're both saying is that as long as all the light falls in the boundaries of the histogram, there's no drawback (in terms of image quality) to blend the image digitally instead of using a GND filter?

I should clarify my response a little bit. There is no impact to the image quality assuming:

1. You have properly exposed the landscape in the original image (i.e. it's not pushed to far to the left in the histogram).

2. You're not worried about getting ETTR to maximise your use of the dynamic range in the landscape part.

If the image is static, then you can get pretty good results with a tripod and exposure bracketing.

e-k

[lmitch6]

My personal opinion is that a lot of the blended or HDR images I see look almost too synthetic, but I may be in the minority here. It also depends on ones' shooting style. For me, it's much more enjoyable to be out in the field doing everything I can to make the images I want than doing so after the fact. So I'd be in the "get a set of ND's" camp.

A good set of ND's (Full, Hard Edge Graduated, Soft Edge Graduated) can be put to great use in the field. The other side to it is the time of day in which one is shooting. If the light levels at a scene aren't working at the moment, I have no issues with coming back earlier/later in the day to make the shot. If it's a place that's a challenge to get to, I'll always try to get there when the light is likely to be the best.

As with most everything in photography "your mileage may vary", but hopefully this might help you a bit.

[montreal]

1. You have properly exposed the landscape in the original image (i.e. it's not pushed to far to the left in the histogram).

Yes, this part I got :p

2. You're not worried about getting ETTR to maximise your use of the dynamic range in the landscape part.

Uh... what is ETTR? :oops:

edit: Oh I get it... Expose To The Right.... yeah...

My personal opinion is that a lot of the blended or HDR images I see look almost too synthetic

I agree with you. But a try to achieve a better result that a lot of the ones we see here :) Of course with some images blending just doesn't work...

Seems like I'll have to buy filters eventually... :confused: Another thing on my list...

[E-K]

My personal opinion is that a lot of the blended or HDR images I see look almost too synthetic, but I may be in the minority here. It also depends on ones' shooting style. For me, it's much more enjoyable to be out in the field doing everything I can to make the images I want than doing so after the fact. So I'd be in the "get a set of ND's" camp.

I think that is more of an artefact of the individual doing it then the technique. That is they are trying to compress to much dynamic range into the print/final image and it looks unatural since that it goes beyond what are eye sees. Sometimes this makes for a better image, even if unrealistic, other times not.

This is different from trying to bring out some of the shadows and recover highlights.

A good set of ND's (Full, Hard Edge Graduated, Soft Edge Graduated) can be put to great use in the field.

I view full NDs as a necessity as the effect cannot be replicated by the camera (i.e. if I need a wide aperture and a slow shutter and I'm at my lowest ISO :)).

Graduated NDs are beneficial in scenes where there is movement or you have to get the shot in-camera.

GNDs are generally limited to having two areas of different density with varying degrees of gradation between them. Sometimes this just isn't going to cut it. For example, the shot of the Gear on you page. You have a complicated image were the object of attention rises into the sky/water and has portions coming through parts of the gear. A GND just would be sufficient in this case as you would end up underexposing part of the Gear (yes you could potentially edit the image to bring the underexposed part of the gear back up but then this is going to look a little odd as well).

The other side of the coin is that for certain scenes GNDs work great and if you have them then why not use them :)

The other side to it is the time of day in which one is shooting. If the light levels at a scene aren't working at the moment, I have no issues with coming back earlier/later in the day to make the shot. If it's a place that's a challenge to get to, I'll always try to get there when the light is likely to be the best.

Completely agree here, although that is not always possible for some people.

As with most everything in photography "your mileage may vary", but hopefully this might help you a bit.

It's all about compromises and it's good to discuss the pros and cons of each. My personal con for the GNDs is I don't have the money for them right now so I have no option but to handle it in other ways ;)

e-k

[E-K]

I guess it would work but I would not risk losing the image because of something I did not notice on the LCD
I may feel this way from my days of shooting film, remember what film was?:lol:

I vaguely recall this word "film", but I'm drawing a blank ;)

Check the histogram - if things look close then bracket the shot. Remember if you're spending time to set up the alignment of the GND filter, then time is probably not an issue.

In the end each will do what they are comfortable with and what works best for them. For me with my low end rotating front lenses, filters that need to be aligned are a bit of a pain to deal with :(

e-k