Why some lenses have a "haze" on GG and some look clear?

Namaste. I know you guys know a lot of about these technical things. Now that I seem to have collected some lenses, I'm wondering why some of them look kinda hazy in the ground glass and some look nice and clear. I'm not talking about some are like f/9 or f/12 and some are faster, it just looks like you know, someone smeared vaseline in front of the lens and now it has that soft Hallmark Movie glow look on the ground glass.

Specifically I have a 14" red dot I got a while ago. I admit, I haven't shot with it yet, I had the opportunity but I stuck my 12" Ektar on instead at the time. It looks hard to focus cause it just has that weird blur/haze/vaseline/ weirdness on GG. I mean, I can focus okay I think. I'll have to blow a few sheets this week to try it out now that I moved the car out of the garage and on the street.

Compared that to my 19" barrel Wollensak lens and that lens looks clear in GG. It's longer and slower. My 12" Ektar looks bright.

My Wollensak 159mm is same, has a weird glow on GG. But shots come out okay, albiet, the lens is old and probably been through a lot, I need to shoot it at at least 1-2 stops more to get better contrast out of it.

Your truly, my eyes aren't failing, and I've changed GG to to double check, eric.

Also, you aren't hallucinating, tomorrow is Oct 1...just like that to all of you who have been working from home and seeing only people at the grocery store most of the week and I now know all the delivery driver's names.

Just to clarify, the lens elements are fine, no scratches, no vaseline, no fungus or anything like that.

Let me take a guess...

I had heard long ago that GG was made different ways... One was ground or blasted that made a granular surface, or acid etched that was smoother, but with a "watery" grain that was brighter but less even illumination... And some makers used a secret formula of varying proportions of both...

I'm thinking you might have an old etched GG where there might be a slight refraction at certain lens angles that might be refracting a little with some blur, or maybe the GG is just dirty/hazed and needs a good wash in the sink with some dish detergent... (Note lines might wash off during cleaning, but I just use a hard lead drawing pencil to draw new lines with drafting instruments after cleaning...)

But what counts is what is on the film, and the focus is the same as on the GG...

Good luck!!!

Steve K

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Originally Posted by LabRat

I had heard long ago that GG was made different ways... One was ground or blasted that made a granular surface, or acid etched that was smoother, but with a "watery" grain that was brighter but less even illumination... And some makers used a secret formula of varying proportions of both...

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Very interesting! I had no idea!

Using a fresnel lens on the GG? Just wondering if it is playing a part in this.

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Originally Posted by Vaughn

Using a fresnel lens on the GG? Just wondering if it is playing a part in this.

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No, I don't have one. I thought maybe it would be better if I did get one. I'm hoping the "Hallmark movie" look is a good description of it.
It's a lovely SoCal day so i'll huff the big thing outside of garage and point it the street and take a shot with my new, old 14" puntu rojo and do a quick process. I'm sure the lens is fine, such a big difference in clarity with other lenses even with that old dang 19" Wollensak process lens that is I think 2 stops slower.

I have a theory: that white haze on your ground glass is probably flare caused by uncoated lenses. I tested two lenses the other day, same lens but one is uncoated and the other coated, and found the whitish haze on the ground glass was gone with the coated lens.

Is this what you want? IS THIS WHAT YOU WANT!?! Hahaha, I'm just kidding, it's Friday, and too much dang coffee. My bidet is happy to be useful.

First pic, 14" RedDot, it is in focus, I can assure you, I used 2 loupy loupes to check. Notice that Hallmark glow. Second photo is a 19" f/10 Wollensak Velostigmat process lens. The 14" and my 159mm Wollensak has this weird glow on the GG to it.

Red Dot 14"
https://i.imgur.com/cadBk6a.jpg

19" process lens
https://i.imgur.com/eoiwHDP.jpg

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Originally Posted by ericantonio

No, I don't have one. I thought maybe it would be better if I did get one. I'm hoping the "Hallmark movie" look is a good description of it.
It's a lovely SoCal day so i'll huff the big thing outside of garage and point it the street and take a shot with my new, old 14" puntu rojo and do a quick process. I'm sure the lens is fine, such a big difference in clarity with other lenses even with that old dang 19" Wollensak process lens that is I think 2 stops slower.

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Just to be sure, you don’t have a filter on either the front or the back of your lens in question?

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Originally Posted by Hugo Zhang

I have a theory: that white haze on your ground glass is probably flare caused by uncoated lenses. I tested two lenses the other day, same lens but one is uncoated and the other coated, and found the whitish haze on the ground glass was gone with the coated lens.

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Ohhhh, that's is interesting. But my 19" Wollensak is pretty old, I *THINK*, i can't tell if it is coated or not. Well, maybe I'm wrong again. I put the lenses on my desk here. And shined it with my First World Iphone with daylight balanced LED light emanating from it. Lighting the side of my 14" f/9 RedDot Artar #804910, the lens is clear. Doing same to the 19" f/10 Velostigmat #244663, there is a greenish sort of yellowish, like radiation color (not like old Pentax radiation lenses, I think it's just a color). So the 19" *MAY* actually be coated!

My 159mm Wollensak is pretty old too. I'm 99% sure, just like I'm 99% sure my 2 kids are mine, is uncoated.

I think this is going somewhere.