Front vs Rear Projection

We have heard a lot of different input as to the benefits of front and rear projection. We are building a new building and before finishing the design we have to make a decision regarding front vs rear. We have heard that rear projection is brighter and clearer. But as I found out today, I talked to two different individuals at an AV place in town and got two different answers. One said rear was better, the other said virtually no difference in brightness and clarity. Does anyone have experience with both and which do you recommend?

Thanks
Posted by Chris Argo on Feb 14, 2001.


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In my opinion, rear projection is always better with all other things being equal and assuming building parameters do not factor into the equation. Why? Contrast. The contrast of a rear projection system is much better than a front projection system. Consider the darkest image you can obtain when shooting a black image from your projector onto a white front screen. Compared to the darkest image you can obtain when shooting a black image from your projector onto a gray or semi-translucent rear screen. Another advantage to rear projection over front is that with a front projection system any light that hits the screen will reflect back off the screen, which washes the image in some degree. With rear the light passes through the screen so it does not wash the image. In laymen’s terms this means brighter colors and a brighter image with more sharpness and clarity.

Kevin
Resurrection Computer Systems

Posted by Kevin Adkisson on Feb 15, 2001.

Rear or front. Well, what does your room look like? Is there alot of windopws to contend with? Rear projection screens will soak up all the light that hits it. So, that's from the projector and everywhere else.

Front projection will always have the cleanest and sharpest image. Unless you spend the money and use a glass screen for rear projection. I am a fan of using the brightest projector you can buy no matter what.

We have two rear projection screens in our auditorium. Our room was designed before the church started using media in the services. Our auditorium is filled with glass. Up high, in the back, on the sides. So, we had to get automated blinds so we could control the light. Now, the stage and screens are nice and bright because there is very little light in the room.

[hardyw]

I have been requested by my pastor to present a projection system solution to the board of elders for review. I think I am getting conflicting data on rear projection Vs front which is my first major decision.

It is a fact we must use dual screens due to limited viewing from all angles of a single center stage screen. This makes COST even more important since we must buy 2...very common I know.
Above is seems clear everyone is in agreement rear projection is ideal for brightness and such.

I recently spoke with a local representative who convinced me front is better for the reasons below. I welcome your inputs.

1. Rear projection screens have limited viewing angles compared to front projection screens.

2. Rear projection screens cost much more (Aprox. 4'X8'- $1,200front/$4,500 w/frame quoted). I don't think I have 12-14 feet in rear and mirror sysems are expensive.

3. Rear projection screens, since they rely on a coating for reflectivity are not as bright as a solid, reflective front projection screen.

I WAS in agreement since this "seemed" logical AND he was actually trying to save me money... but above comments seem to conflict.

My first concern is "viewability" in a fairly bright sanctuary (4-6000 Lumens??)
Second is BEST cost

Your feedback is greatly appreciated.
Thanks
Warren

[hardyw]

Tone,

Thanks for the reply. I already was struggling to find a "credible" company/consultant...now I really feel I need to do my OWN homework to help find someone I can trust! To bad you're not in the area!

I'm sure I will have more questions and am grateful I came across this site. Great resource

Warren

There are many factors that will influence your choice of front or rear, many of which have been introduced here. However, there are some issues that may force the issue one way or another.

The great thing about front projection is that you don't need to build a room to house your projector. Depending on the type of projector and its BTU output, a rear projection solution may require HVAC concerns as well as the space to house the projector. Generally, front projectors are not always as accessible as rear projectors, especially if they are hung from the ceiling, but if you plan for this with lifts; etc. this could become a non-issue.

The issue that gets overlooked the most is the screen surface. As with anything else, rear or front, you get what you pay for. A cheap rear screen will hotspot and discolor the image, especially over time. A cheap front screen will sag or discolor and may even crack over time. As with cables and their quality, buy the best quality you can. Stewart makes excellent screens, both front and rear, and screens are available for particular types of projectors and their brightnesses. Some other manufacturers to consider are Da-Lite, Draper, Vutec, Screenworks and others. If I had deep pockets and unlimited choices, I would choose Stewart, personally.

Being on this forum is a good step toward being as informed as possible before making any decisions. Don't trust the marketing ads, see for yourself. You might wish to attend Infocomm in June in Atlanta, it's the AV industry trade show which also features church AV planning. Go to www.infocomm.com and see. There are also some good links to reviews and manufacturer's web sites there.

Cheers,
Steve Farmer
CMI Communications
Rochester, NY

[dish-man-2000]

steve, I believe that is www.infocomm.org It looks like a good conference, although rather expensive.

[hardyw]

We have come to possibly the first decision on our projection system in our church. Dual REAR systems instead of a single or dual front system. Many factors went into it and now I am continuing to do my homework on equipment.
Your feedback would be greatly appreciated.
1. Max screen width can be 72" wide (4:3 means I think 50"+ high based on that width allowance)
2. Max rear throw distance is 6'-7' (depending if we cut out a portion of wall to get extra foot)
3. No light meter readings yet but thinking 4500-5000 lumens will be sufficient for PPT and Video.

Is that enough info. to get some ideas on which type of equipment and costs for I should expect to find for these 3 things?

Projector
Lense
Screen

Thank you
Warren

[Travis]

5000 lumens for a rear projection system??
Sure sounds like overkill to me.

[hardyw]

Change of plan. We measured 75' to middle of balcony seats. So a 6' wide rear projectoin screen is just too small. Looking at a front projection solution with a 9' wide screen. 4500 lumen Sanyo.

[kerwin kanago]

You might want to cruise through the Projection Formulas thread if you haven't already. It has good stuff on screen size and lumens needed.

In particular, I think it would recommend a 12" wide screen for that distance. Your milage may vary given other conditions and tradeoff's you are making, but its a great thread if you haven't been through it.

We are hoping to put in a projection system in our sanctuary this summer and we have done a lot of homework but have received mixed advice on front and rear projection. I will try to briefly describe our situation and if any of you have encountered a similar situation, or have expert advice to throw in, please do so.

Let me start by describing our sanctuary. It is long and narrow (approximately 40'w x 120'L x 45' tall. It has big 6 pairs of big glass windows (25'x4') which let an obnoxious amount of ambient light into the sanctuary. We have already succombed to the reality that we need to control this light so we will be installing black-out shades on the first 2 windows window bays on each side. Suffice it to say, we will have some control over the ambient light but there will still be enough to make projection challenging (but hopefully workable).

Because of the nature of the architecture (i.e, narrowness and recent remodeling) we have chosen a cable climbing screen that will recess into the ceiling when not in use (13' w screen). The cross is located in the only viable screen location and this allows us to have our cake and eat it too. Unfortunately, it makes it impossible to use a traditional rear projection format (black room behind screen).

Here are the pros and cons of our two possible solutions. If we choose to front project the only decent agreeable place to install our projector is the back wall of the sanctuary. This forces us to by a very expensive long throw lens to concentrate the lumens over about 120'. A local installer has cautioned us that we will lose 20% of our lumens because of the lens (not the distance). The projector will also be one of those Sanyo/Eiki 10,000 lumen beasts that sound something like a jet. On the back wall we have little hope of insulating that noise. We are concerned about losing any light because as I mentioned before our sanctuary is very bright and the more we can preserve the better. (For reference, we tested the 10,000 lumen projector on a bright day on a matte white screen with roughly the same dimensions (14'W) and we had an unsatisfactory image. We attempted some temporary blinds and this improved the image enough to give us some comfort but each lumen is precious!)

Rear projection would seem like a great option except for two challenges. There is a great empty space in the wall behind the cross for the projector to be placed. There is plenty of ventilation and it would be able to be concealed and muffled. Unfortunately the lower leg of the cross is exactly where the lens needs to shoot from. We have been advised that keystoning is not a good idea since our screen would be a 10.5' away and a wide-angle lens would have to utilized. We are interested in possible motorizing part of the bottom of the cross out of the way but have hit deadends on companies that specialize it custom stuff like that (any recommendations?) The other challenge of rear projection has to do with the fact that the screen will just be hanging there without a cute little black room behind it. There will be less ambient light behind it thatn in front but it will exist. Some of the experts we have talked to say that we will lose lumens because of this, is this true? If so, any way of estimating how much?

Finally, in both cases, we are leaning toward Stewart to provide the screen material. We have been receiving samples and have been most impressed with gained screens in the 1.3 region. The rear projection screen we liked had a gray tint that really seemed to improve contrast in our demo without sacrificing whites. The gray screens for front projection seemed to dull our brights too much. Any experience or cautions? Our goal is a vibrant image with good contrast.

Thanks much for any help you can give!
Patrick Scriven
Vancouver First UMC

[kac4him]

Rear projection would seem like a great option except for two challenges. There is a great empty space in the wall behind the cross for the projector to be placed. There is plenty of ventilation and it would be able to be concealed and muffled. Unfortunately the lower leg of the cross is exactly where the lens needs to shoot from. We have been advised that keystoning is not a good idea since our screen would be a 10.5' away and a wide-angle lens would have to utilized.

i wondering why they advised against keystoning does the projector not have keystone correction or would it be to great a angle to correct or there is a reason i haven't thought of yet and if there any negative points to using a short throw (wide-angle) lens

another question i have about rear projection with the formula for projection would you take your light meter reading behind the screen instead of in front right?