selecon Acclaim Axial 18-34 Zoomspot

[Acdisco]

Hi guys,

 

New to theatre lighting, normally just do sound and LED and club lighting, but decided to invest a bit of our spare balance into a seperate market (although obviously related to what we do!)

 

My issue is I decided to go with the Axials as they have superior optics for gobo and logo use compared to the standard ones.

 

My only issue is that if I get the center in focus the rest of the projection has a glow around it,

 

Ive used the lamp adjust on the back, and I can minimize the glow by turning it fully clockwise, although this dims the visible output by 2/3??!!

 

Am I doing something wrong?

 

Can I get rid of the glow?

 

Has anyone got any images of their profiles in use so I can see how your optics compare?

 

I just don't think it will be good enough for anything other than slightly blurred outside breakout work!!

 

Any advise massively appreciated!

 

as I said im new to theatre and gobo projection work... be gentle! :P

 

Cheers

 

J.

[Don Allen]

You have made a good choice with the axial. You have three seperate issues here that interact.

 

Lamp adjustment

Focus

Image enhancement

 

Adjustment of the lamp is critical to correct and efficient use of the Acclaim axial. Be careful when adjusting so you do not jar the filament as it will blow, so before making any adjustment, when the lamp is cool, make sure all adjustment move smoothly. Make sure the lamp is correctly seated in the socket. I use a light meter as a relative measurement across the beam projected onto a flat surface at a perpondicular angle. I usually get a four fold increase in light output with the axials, but it is hard to do the first time around. When properly adjusted they are a very good light. When not properly adjusted, they suck, so take the time to learn how to do it. Lamp life is good so you don't get too much practice.

 

Page 4 on the Acclaim Axial manual shows how to adjust the lamp for a peaked focus for stage lighting, or flat focus for gobo projection. There is a picture showing the difference.

 

With the lamp properly adjusted and the lens properly focused, if you have a halo or poor focus on the outer edges of the gobo, try using a donut. I use a low saturation gel such as steel blue or flesh pink to sharpen the image without needing a donut. Works well on stars.

 

Properly adjusted, the Selecon Axial Acclaim zoom is one of the best lights made, but a lot of techs replace the lamp or put the unit into service without doing a proper lamp focus.

[GaryM]

What you are seeing is light reflecting internally inside the lantern illuminating the back surface (the side away from the lamp) of the gobo. This is compounded by the fact that most gobos are made from shiny steel. When you have the gobo in sharp focus you are also focused on the gobo surface, hence the glow. In terms of lamp adjustment, you will probably find that if you set the lamp for maximum intensity then operate the lantern at about 60-70%, the glow will reduce to the same degree as when you wound the lamp out. In other words, it's just an intensity effect, not a lamp setting effect.

 

Goboland make black anodised gobos, which helps relieve this effect to some degree, or you could try experimenting with the shutters to frame the gobo and try and minimise internal reflections.

[jimbo6871]

Hi Ac,

 

I go with both commments from Don & Gary, setting the peak of the lamp is seriously important to get right in order to get an even light level on the lamp side of the gobo.

 

Secondly Garys comment about the back light is also right on the money (did you ever notice that good quality chrome or aluminium instruments are finished matt black on the inside) thats to reduce the amount of backlight within the instrument and give better focusing qualities.

 

The lens itself is a patial reflector (but that is unavoidable) so light bounces back of the lens towards the lamp (and in your case gobo) normaly in a instrument with no gobo this presents little or no real issue as the reflected light hits the matt black finish or the reflector behind the lamp where it is reflected back towards the lens at the same beam angle as the rest of the light output from the lamp. However if you are using a gobo that has a reflective surface the light is reflected of it with no beam pattern and hits the back of the lens again but this time as a glare randomly scattered across the lens. A simple solution is to head of to your nearest motorfactors and get a spray can of matt black V.H.T. enammel (used for spraying car engine blocks and exhausts) and spray the gobo, personaly I'd spray both sides but the lens side is the most important one, this should help reduce some of the halo your getting, but as Don said the Peak of the lamp also needs to be correct.

 

Trial and more trial to find what works best, welcome to the wonderful (and time consuming world) of the lampie.

[Acdisco]

Thanks for that guys,

 

I think I have some engine paint somewhere so I might have a bash at putting that on there.

 

Im using Rosco gobo's....

 

Wouldn't it make sense just for the manufacturer to paint them black before we get them?