For those thinking of upgrading from a 285

[NickH]

Here's a FOV comparison with the 383L+

And it DOES work with 1.25" filters ...just...but you'll need to do flats to negate the vignetting

TMB105 F6.2 with both cameras...just a quick set of 10 x 3 minute M3 shots

383L+ needs darks though...that's for sure

And DON'T plug your whatever 285 camera PSU in to this one...it needs 2.5A...

[Ibbo!]

MMmmm

lots of real estate

mmmmm

tempting

11/4 filters

I must resist

I realy must

Steve

[Euan]

I shall be joining the 383 crew shorty Nick

One thing that would help me out, can you put a 1.25" filter in before any 2" or t-thread attachment on the nosepiece?

I can do this with my QHY5, the reason I ask is I want to sneak a IDAS LP filter in there when using LRGB on the colour wheel.

[NickH]

Not sure...I have the atik FW butted up to the camera directly...and it works.. (EDIT, but you do get vignetting...though it's manageable on the TMB)

[ollypenrice]

This is a post that will interest a lot of people!

Olly

[NickH]

Yes...still checking onw two things...one is blooming...another user mentioned it today and it's something I may have seen...going to run some long exposures on a brightish star. What does worry me though is the exposed electronics...they just look very vulnerable...but so far, holding out..

[Euan]

one is blooming...another user mentioned it today and it's something I may have seen

Strange, I've never heard this ever mentioned about the QHY9. Let's hope that is not an issue with the Atik design.

How are you getting on with calibration frames? I've read that flats become trickier with the mechanical shutter, it really needs 2 secs and upwards to avoid the shutter smearing the light.

Also I'm hoping that darks are less of an issue because of the set point cooling, and it's just a case of building a library.

[MartinB]

I imagine the microlensing will give the appearance of early blooming. It sounds as if heavy use has been made of lensing to up the QE. These do generate artefacts, typically in a vertical direction only. They could easily be confused with blooms the difference being that they aren't saturated. I have them on my QSI 532 and they can't easily be processed out. Best just to accept them although they aren't as pretty as star spikes!

I don't have a problem with needing 2 second exposures for flats with my QSI 532 but maybe the 383 is different. Not a huge problem, just add a couple of extra sheets of paper!

One thing that might be an issue for anyone not used to full frame chips is the long read times when focusing with a sub frame. With an interline chip selecting a small sub frame around a bright star gives close to real time focusing. This isn't the case with a full frame chip, a sub frame speeds up download but the whole frame still has to be read. This makes focusing using FWHM a real pain. Not a huge issue using a Bahtinov mask or focusmax though. I see that SBIG can use 1/4 frames to reduce this problem, not sure if this is a the case with other manufacturers.

Are you able to post a big bright flat Steve to see if there is any significant impact from the filters?

[NickH]

Darks are fine...set point is working well on that front (used the 4000 a lot, so that's a no brainer). Flats, Atik state 200ms is the minimum usable, but again, will see.. blooming, I have not really see it at all , but someone i spoke to at SGL5 has... I will be doing some checks on that myself.. as the ABG should not really sow any.

So far, I am very impressed with the FOV though...shame it's galaxy season and no massive nebulous targets like the Rosette or M42 can be used to check this baby out.

[NickH]

Will try som t-shirt flats next clear night.. have the camera for a good while.

The 4000's only showed a bit of tail off at the edges... and I like the idea of flats at 2s with more sheets of paper :-)

[RichieJarvis]

Very interesting comparison Nick - I look forward to seeing more soon!

I still want one though... Finances permitting! Hoping to hear re redundancy today, so fingers crossed (its not a bad thing, I already have a new job lined up, just need the payout to take the salary drop!)

Can you move the 1.25" filter to a filter wheel and see how bad the vignetting is in a more 'normal' position? Thats the thing I really want to see - some flats without the filter straight up against the chip.

Cheers,

Richie

[NickH]

It's on the Atik wheel , so will test for vignetting tonight, but having stretched the M3 shot to hell, I am not noticing any significant drop off ...but to make sure I will do the flats tonight all being well

[Euan]

Thanks Nick, it would be good to see the stretched flats using 1.25" filters in the wheel.

I've heard so many different options about this now I don't know what to believe.

Here is Atik:

For focal ratios of F5 and above standard 1.25 inch filters can be used without vignetting. Faster focal ratios will need flat field correction or larger filters (36mm or 2inch).

Here is FLO:

Please note: Due to the large size of Kodak KAF 8300 CCD, regular 1.25" filters might cause some vignetting in the corners. Whilst this might be considered acceptable at f/6 or longer, for shorter focal lengths we recommend the use of 2" filters.

[NickH]

At F6.2 on the TMB, probably a bit higher in fact...so that figures

[RichieJarvis]

Hmmm - I wonder how the Genesis will fair.... Still many questions unanswered on these cameras, but many thanks for answering the ones you have Nick!

Just to be 100% sure - this image of M3 was taken with the LRGB filters in your atik wheel, and the wheel was bang in front of the sensor (as close as it could be, right?)

Thats encouraging, as I thought you meant that you had somehow mounted the filter almost against the chip glass! Now, I wonder if I can persuade SWMBO ???

Cheers,

Richie

[Beyond_Vision]

With the F4 Newt I was getting noticeable vignetting at F5. On the TMB105 at F4.9 it was there but was manageable with flats. I did a run of flats last night and had real problems trying to take them. I had the Earlsman EL panel running from 3V instead of 12V to dim it down. I also had to put two layers of T shirt infront and set the exposure to 5 secs. There was still some amount of gradient across the picture even with the EL panel rotated. Not sure if this is still effects of the shutter or light leakage.

Regards

Kevin

[NickH]

Correct...Standard Atik USB FW...threaded directly to the camera, at F6.2 ish on the TMB

[NickH]

hmm funny you should mention light leakage...

[NickH]

Flats show that you cannot really use a 1.25" filter set even at F6.2... there is vignetting, about as much as with the 4000 series... It's manageable at Kevin says, with flats, but not the perfect solution I initially hoped..

Dark noise is also higher than the 285, but not bad...

[Euan]

Hmmm.. it's not looking too good for my F5 EQ80 or a possible F4 astrograph purchase then.

Thanks Nick, I'm going to look at the un-mounted 36mm filters as the EFW 2 can take 7 of these

[NickH]

Did not detect any blooming though... more testing to do for sure...but impressive!!

[FLO]

Here is FLO:

Please note: Due to the large size of Kodak KAF 8300 CCD, regular 1.25" filters might cause some vignetting in the corners. Whilst this might be considered acceptable at f/6 or longer, for shorter focal lengths we recommend the use of 2" filters.

We originally suggested f7 but lowered it to f6 after reading Nick's earlier comments. This is an ongoing and useful thread that addresses a question on the minds of many 314L owners so we have today replaced our recommendation with a link to this thread

Steve

[RichieJarvis]

Cool Steve Makes sense!

[NickH]

Thanks Steve....

I am trying to be methodical in my approach to each element on this camera. Last night was testing darks and H-A response...

[MartinB]

Nick, what are the download times like and how fast is it when using a sub frame with a focus star? Also, how fast does it a) get down to -20 and stabilise. How far below ambient can you go? Are you going to try measuring the read noise?