Ground glass upgrade on Shen Hao

[LotusEsp]

Hi
I have a 2011 Shen Hao HZX45-IIA and I am finding the ground glass a little dark in less than very bright environments, with my 90mm f6.8 lens

Could anyone advise on what would be a suitable alternative please? I've read about a Fresnel, would that be an addition to my existing GG? (wouldn't that alter the focal plane?)

thank you

Simon

[jose angel]

You can use a cheap plastic fresnel sheet for viewing (behind the GG), and remove it to focus (on your existing GG). This is the way many Sinar cameras work.

[nlambrecht]

I also have the Shen Hao HZX45-IIA. For me I have to have a fresnel under the ground glass with wide angle lenses. The Shen Hao ground glass holder has a recessed channel that the Shen Hao fresnel fits under, which does not change the distance from lens to ground glass so the focal plane is not changed. If you remove the two black clips holding the ground glass in place you will see that the fresnel is actually slightly smaller than the ground glass. The Shen Hao fresnel does a good job of redirecting the light towards you when you are under the dark cloth, lighting all the way to the corners of the ground glass. When you focus with a loupe you will see the grain of the fresnel, but that has never bothered me. My f8 lenses are nice and bright on the glass even indoors or in dark conditions.
For full disclosure I did change my ground glass, I was unhappy with the standard Shen Hao glass. I purchased a Steve Hopf (http://hopfglass.com/index.htm) borosilicate ground glass, which I love. It did brighten up the glass a bit, but I purchased it more for the fine focusing grain and a simple 1/2 inch grid without all of the roll format lines. Hope this helps.
-Nathan

[adelorenzo]

This video shows the difference between stock screen and a (very expensive) maxwell screen.

https://m.youtube.com/watch?v=j_2kvBDg63s

[LotusEsp]

I was unhappy with the standard Shen Hao glass. I purchased a Steve Hopf (http://hopfglass.com/index.htm) borosilicate ground glass, which I love. It did brighten up the glass a bit, but I purchased it more for the fine focusing grain and a simple 1/2 inch grid without all of the roll format lines. Hope this helps.
-Nathan

thanks
How much brighter is it over the standard glass?

I'll get on the hunt for a Fresnel sheet. Some stuff in photography seems pretty tricky to get hold of in Canada.

adelorenzo: wow that does look amazing. $500 is a lot for that glass though - too much for me whilst I am just starting out in LF I think

[nlambrecht]

How much brighter is it over the standard glass?


There is a slight difference in brightness between the two, maybe about a half stop brighter. For me this was not the main selling point, but I want to be upfront about what I use. In terms of brightness I was happy with the Shen Hao ground glass/fresnel combo.

As for the Steve Hopf glass without a fresnel there still was the a clear "hot spot" with fading to the edges, which was very clear on wide angle lenses. This is not due to the quality of the glass, just how light works when it strikes flat glass. If you are trying to get rid of that effect the only real way is a fresnel, or as mentioned above, a Maxwell type screen. However, my Shen Hao fresnel with either ground glass is bright at multiple angles and I hear Maxwell screens get dark if you look at it from the wrong angle (I have never used a Maxwell screen, but have seen the effect on other posts).
-Nathan

[Jim Jones]

I also have the Shen Hao HZX45-IIA. For me I have to have a fresnel under the ground glass with wide angle lenses. The Shen Hao ground glass holder has a recessed channel that the Shen Hao fresnel fits under, which does not change the distance from lens to ground glass so the focal plane is not changed. If you remove the two black clips holding the ground glass in place you will see that the fresnel is actually slightly smaller than the ground glass. The Shen Hao fresnel does a good job of redirecting the light towards you when you are under the dark cloth, lighting all the way to the corners of the ground glass. When you focus with a loupe you will see the grain of the fresnel, but that has never bothered me. My f8 lenses are nice and bright on the glass even indoors or in dark conditions.
For full disclosure I did change my ground glass, I was unhappy with the standard Shen Hao glass. I purchased a Steve Hopf (http://hopfglass.com/index.htm) borosilicate ground glass, which I love. It did brighten up the glass a bit, but I purchased it more for the fine focusing grain and a simple 1/2 inch grid without all of the roll format lines. Hope this helps.
-Nathan

This is not exactly true. Any transparent material with an index of refraction different than air placed between the ground glass and the lens will change the focus by some fraction of its thickness. If the material is thin enough, the focus change may be acceptable.