Ground glass dillema!!!!!!!!!

ruilourosa · Jul 10, 2012

having using several LF cameras i bought a shen hao TZ45-IIB as it seemed very portable, versatile and reasonably build, although it seems that it´s ground glass is a tad dark. I haven´t received the camera yet...

1º - is it so dark as people say?
2º - should i buy a expensive replacement? (maxwell boss or ebony?)
3º - Should i buy a cheaper alternative, if so which one (hopf or yanke??)
4º - To frenel or not to fresnel (related to the previous question)?
5º - should i try to make my own with abrasives?

Thanks

Rui Lourosa

ruilourosa · Jul 10, 2012

One more:
is the idea of the frenel loupe viable?

LJH · Jul 10, 2012

I put a cheap fresnel in my XPO. It's a good option. Mind you, the screen is not that bad without it, but it is much better with it.

Mind you, in a perfect world, I'd have a Maxwell et al screen in it, as well as on all of my cameras!

I use a loupe with it.

Bill Burk · Jul 10, 2012

Does anyone use the parallax method to focus? This is where you have a clear spot in center of groundglass that you mark an x with grease pencil. Then with a loupe you focus on something and move your head sideways. The image is in focus when the image doesn't move in relationship to the grease pencil x as you move your head.

Just tried this trick on a 35mm RF camera that I suspected of being out of whack, and sure enough it was wacked

Discoman · Jul 11, 2012

Don't Fresnel the camera unless they actually sell a Fresnel lens for that camera. I don't know about your specific camera, but putting a Fresnel lens on some cameras ends up shifting the plane of focus out of the plane the film resides in. If a Fresnel is offered by the company for your camera, it is probably okay.
I have a screen that isn't exactly the brightest in my graflex, but I've usually just focused it at wide open then stopped down for the exposure. If the ground glass is fairly unevenly illuminated or too dark, I would suggest a boss screen. I heard some people had issues with the beat tie screens, and the bosscreen is usually pretty recommended, even though it dislikes temp extremes.
Just my $.02

Steve Smith · Jul 11, 2012

Discoman said:
but putting a Fresnel lens on some cameras ends up shifting the plane of focus out of the plane the film resides in.

This is only true if the Fresnel goes between the lens and the ground glass. If it goes on the back of the ground glass, i.e. towards the user, it doesn't make any difference.

Steve.

Ian Grant · Jul 11, 2012

Personally I prefer a fresnel, the best combinations are the one piece fresn/screen (& cover glass0 sold with Wistas, or the Beattie screens in my experience. A Maxwell screen would be similar. I use a fresnel on the rear of my Crown Graphic and that's not too far behind in terms of brightness and usability.

As Steve says if the camera comes with a plain screen then a fresnel has to go behind not lens side of the screen. I've made screens for Shen Hoa's and they are brighter than the originals.

Ian

LJH · Jul 11, 2012

Steve Smith said:
This is only true if the Fresnel goes between the lens and the ground glass.

Isn't this only if you have to move the GG back to accommodate the Fresnel (i.e. so that the Fresnel is held in place by the GG) as you are changing the relationship between the ground image and the film holder?

I have several cameras with a fresnel in between the lens and the GG and there is absolutely no issue with their focus.

Ian Grant · Jul 11, 2012

LJH said:
Isn't this only if you have to move the GG back to accommodate the Fresnel (i.e. so that the Fresnel is held in place by the GG) as you are changing the relationship between the ground image and the film holder?

I have several cameras with a fresnel in between the lens and the GG and there is absolutely no issue with their focus.

That's because the backs were designed that way to accomadate the fresnel. Take it out and the screen would be out of register in many cases.

Ian

Laurent · Jul 11, 2012

LJH said:
I put a cheap fresnel in my XPO. It's a good option. Mind you, the screen is not that bad without it, but it is much better with it.

Mind you, in a perfect world, I'd have a Maxwell et al screen in it, as well as on all of my cameras!

I use a loupe with it.

My Tachihara has a great screen, but a cheap fresnel (got it from a junked video proj from the previous century) still makes using the 90/8 SuperAngulon WAAAAYYY easier. Considering the cost of plastic fresnel, I'd try this option before any other thing.

ruilourosa · Jul 11, 2012

Hello

Thanks for all the answers!

I am aware that adding space between the GG and the lens will add a focusing error to the camera, being a fresnel or other thing!
I had a toyo with a fresnel and i removed it since the image did not seemed a lot brighter and a hot spot was added, specially with the 90mm. Although the ground glass and fresnel were from a horseman camera... but that doesn´t seem important to me

the mais question (and the cheapest option...) yanke or hopf....

Thanks

Rui Lourosa

Steve Smith · Jul 11, 2012

Ian Grant said:
That's because the backs were designed that way to accomadate the fresnel.

Also, but to a lesser extent, because the light path through the Fresnel is not the straight path it would have been through the empty space..

Steve.

Light Guru · Jul 11, 2012

ruilourosa said:
i bought a shen hao TZ45-IIB as it seemed very portable, versatile and reasonably build, although it seems that it´s ground glass is a tad dark. I haven´t received the camera yet...
Rui Lourosa

Umm you havent even seen it so YOU cannont actualy tell.

My ShenHao ground glass is plenty bright.

TareqPhoto · Jul 12, 2012

My Shen Hao GG and fresnel are a tad dark, having very difficult time to focus, i need either a dark cloth or a hood to see something, with my Speed/Crown Graphics which they come with that folding hood i can focus easily as they are bright, would like to buy something for me Shen Hao, i bought their folding hood but it didn't attach to my Shen Hao, it helped a bit better than nothing almost same or closer to that dark cloth, but i hate holding it all the time to focus/refocus, i want to fix it on my camera, otherwise, i should buy another GG/fresnel brighter than the original one.

Ian Grant · Jul 12, 2012

I've gained over 1½ stops in brightness just by changing the glass screens in at lewast half a dozen cameras, closer to 3 stops when I've added a fresnel as well.

Over the past few years I've rarely needed to use a dark-cloth with my Wista although I always carry one and the same goes for my Grown and Super Graphic both of which have new screens alongside their fresnels and the added advantage of their focus hoods.

So you may want to get a brighter screen made.

Ian

markbarendt · Jul 12, 2012

Bill Burk said:
Does anyone use the parallax method to focus? This is where you have a clear spot in center of groundglass that you mark an x with grease pencil. Then with a loupe you focus on something and move your head sideways. The image is in focus when the image doesn't move in relationship to the grease pencil x as you move your head.

Just tried this trick on a 35mm RF camera that I suspected of being out of whack, and sure enough it was wacked

Cool. I need to try that.

ruilourosa · Jul 12, 2012

hello Ian Grant

Which ground glasses are you using?
Thanks

Rui Lourosa

@oporto

Ian Grant · Jul 12, 2012

ruilourosa said:
hello Ian Grant

Which ground glasses are you using?
Thanks

Rui Lourosa

@oporto

PM sent.

Ian

Ground glass dillema!!!!!!!!!

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