Source Four Gobo Size?

[rochem]

Okay, I feel kinda stupid asking this question, but is the best choice of Gobo size for use in a S4 (standard, not Jr)? I'm specing gobos for an upcoming show, and the venue has more than enough template holders of both sizes. I know that either A or B will work, but is one generally preferred over the other? Considering that the aperture of a S4 is 3" wide, I would guess that an A size pattern would have the best coverage, but I'm not sure.

[Sean]

Originally Posted by rochem

Okay, I feel kinda stupid asking this question, but is the best choice of Gobo size for use in a S4 (standard, not Jr)? I'm specing gobos for an upcoming show, and the venue has more than enough template holders of both sizes. I know that either A or B will work, but is one generally preferred over the other? Considering that the aperture of a S4 is 3" wide, I would guess that an A size pattern would have the best coverage, but I'm not sure.

A

Your guess is correct: you'll get more light/image area out of an A-size template.

--Sean

[rochem]

Originally Posted by Sean

A

Your guess is correct: you'll get more light/image area out of an A-size template.

--Sean

Thanks, that's what I thought. Two follow-up questions: I know I've had to cut gobos to get them to fit before, but I'm honestly not sure what size they were. Rosco Gobos - Gobo Holders tells me that A-size temps must be trimmed to fit into the gobo slot. Is that true? It sounds like that would be kind of annoying to do for every gobo.

And also: if A-size temps provide more light and coverage, then why are B-size temps often used in S4s? What does a B-size temp give you that an A-size cant?

[zuixro]

Originally Posted by rochem

Thanks, that's what I thought. Two follow-up questions: I know I've had to cut gobos to get them to fit before, but I'm honestly not sure what size they were. Rosco Gobos - Gobo Holders tells me that A-size temps must be trimmed to fit into the gobo slot. Is that true? It sounds like that would be kind of annoying to do for every gobo.

It may be annoying, but DO NOT just fold it over. I had a S4 that someone had folded the gobo over the edge of the holder and crammed it in there. We didn't notice until it was already hung 18 feet up on the grid. I had to yank it out while standing at the top of an A-Frame extension ladder. I sliced my thumb open (Gaff tape is sterile right?).

[derekleffew]

Originally Posted by rochem

... And also: if A-size temps provide more light and coverage, then why are B-size temps often used in S4s? What does a B-size temp give you that an A-size cant?

The smaller image area of the B-size allows for a more evenness of field, and the ability for sharp focus across the entire image, thus B-size is preferred for logos and text.

For breakups, shapes, non-realistic images, and where the image is not desired to be in sharp focus anyway, use A-size.

[Sean]

Originally Posted by rochem

Thanks, that's what I thought. Two follow-up questions: I know I've had to cut gobos to get them to fit before, but I'm honestly not sure what size they were. Rosco Gobos - Gobo Holders tells me that A-size temps must be trimmed to fit into the gobo slot. Is that true? It sounds like that would be kind of annoying to do for every gobo.

And also: if A-size temps provide more light and coverage, then why are B-size temps often used in S4s? What does a B-size temp give you that an A-size cant?

Yep, it's a pain: Rosco and GAM, are you listening??

Derek already partially answered your question: The main reason I've found that so many B-size templates are used is that before the S4 pretty much all the ellipsoidals in use used B size templates. When the S4 came out people wanted to continue to use the stock of templates they already owned.

Some places insisted on using ONLY B size for quite a while. Seems like it's only been maybe the past 5-7 years that "A" really has become the default.

My $.02

--Sean

[xander]

I think the two main reasons have been covered. But, I would like to elaborate on the second one a bit more. B-size were often used in S4s because they were already in stock, but it is also quite common practice today to still buy B-size if your inventory still contains older equipment that can't use A-size so that your gobo inventory can be utilized by all of your ERSs.

[SteveB]

B size is also used in the Altman Shakespeare, which means as well, the Altman 360Q, as well as Altman 1K ellipsoidal series and Altman 4.5" zoom series. Thus if you run into a house that uses these fixtures (like mine), B size will fit every fixture.

As a result, I only order and stock B sized gobo's and holders. If you come to our house and want A size, bring them, plus the holders.

Steve B.

[rochem]

Originally Posted by SteveB

B size is also used in the Altman Shakespeare, which means as well, the Altman 360Q, as well as Altman 1K ellipsoidal series and Altman 4.5" zoom series. Thus if you run into a house that uses these fixtures (like mine), B size will fit every fixture.

So this begs the opposite question: why are A-size gobos around? Since all the Altman fixtures accept B size anyways, the only reason I can see for continuing A size gobos is for use in Source Fours - but if you have to cut the A size to get them to fit anyways, why not just change the measurements of A size gobos to better fit in a S4? Or why did ETC not originally design the S4 to accept an A size gobo without any cutting needed?

[xander]

Anyone feel free to correct me if I am wrong...
The fact that the gobo needs to be cut is not the fault of ETC, it is the gobo manufacturers. It is the inside diameter or image size that matters, the outside edge can be any size you want and then trimmed to fit an instrument. I assume that A-size exists because ETC designed the Source4 to take an 75mm image size. But because the B-size is just a little bit smaller, they were like, "hey we can make a template holder to hold B-size so that the user doesn't have to buy all new templates." Why the Source4 was designed to take 75mm size? I have no idea. Probably has something to do with optics.